[Elenco soci]


Covarrubias Rodriguez Mario

Professore Associato


Politecnico di Milano
mario.covarrubias@polimi.it

Sito istituzionale
SCOPUS ID: 35118628900
Orcid: 0000-0003-4195-9333



Pubblicazioni scientifiche

[1] Aruanno B., Covarrubias M., Handy: Novel hand exoskeleton for personalized rehabilitation, Computer-Aided Design and Applications, 19(3), 405-425, (2022). Abstract
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Abstract: Worldwide, stroke is the third cause of disability. The majority of people affected by this disease cannot perform activities of daily living. Bringing the therapy to the patients' home is complex, and in literature, there are still open challenges to face. Starting from therapists' and patients' needs, this paper describes a possible solution: HANDY, a rehabilitative active hand exoskeleton for post-stroke patients. With a desktop application, they perform three different types of exercises: passive, active and based on activities of daily living. They can also control the exoskeleton themselves in a serious-game approach with a leap motion controller. We evaluated our method with patients at the Villa Beretta rehabilitative center. Preliminary results from the session about comfort, usability and willingness to utilize the system are promising.

Keywords: Additive manufacturing | CAD modeling | Hand exoskeleton | Interactive applications | Stroke

[2] Bastida-Escamilla E., Elias-Espinosa M.C., Franco-Herrera F., Covarrubias-Rodríguez M., Bridging Theory and Practice Using Facebook: A Case Study, Education Sciences, 12(5), (2022). Abstract
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Abstract: In the past few years, Facebook has been increasingly studied for academic purposes due to its potential benefits to undergraduate education. Problems commonly found in university education include the lack of course engagement and the gap between theory and practice. This research contributes to the literature by investigating the impact of incorporating a non-mandatory Facebook group on learning outcomes. The analysis was done using a Taguchi method design, conducted with three two-level controlled factors (term, Facebook, and teacher). Results indicated that the students who participated in Facebook groups were more engaged with the course and applied theoretical knowledge to real-life problems better than students who learned under traditional instructional designs. Moreover, the use of Facebook groups led to better evaluation of teachers by the students. Furthermore, the student academic impact (knowledge and competence) was higher even though this complementary activity was not included in the course grade. We concluded that Facebook groups are excellent support tools that boost student engagement and their understanding of theoretical concepts and applying them in practice.

Keywords: educational innovation | Facebook | higher education | real-life problems | social network | student engagement | Taguchi method

[3] Miesenberger K., Kouroupetroglou G., Mavrou K., Manduchi R., Rodriguez M.C., Penáz P., Preface, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 13342 LNCS, v-vi, (2022).
[4] Covarrubias Rodriguez M., Amui I., Beik Y., Gambirasio G., Gandolla M., Bardi E., Ambrosini E., Mechanical Arm for Soft Exoskeleton Testing, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 13342 LNCS, 387-394, (2022). Abstract
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Abstract: Soft robotic exoskeletons offer multiple advantages in the field of motor rehabilitation and assistance with activities of daily living This paper reports the design process of a mechanical arm for upper-limb soft exoskeleton testing. The main requirement of the test bench was to simulate five degrees of freedom (DOF) of the human arm, and in particular i) shoulder flexion/extension, ii) shoulder adduction/abduction, iii) shoulder medial rotation/lateral rotation, iv) elbow flexion/extension and v) forearm supination/pronation. An additional requirement included the possibility to alternatively lock each DOF. The final concept was designed using Autodesk Inventor and it is composed of 32 parts, 18 of which were particularly designed for this application. Topological optimisation and Finite Element Method (FEM) analysis were performed to some custom components to obtain the final design. The final concept was manufactured by means of additive manufacturing of PLA (polylactic acid) and laser cutting of PMMA (poly methyl methacrylate) sheets. After testing and validation, the prototype was able to meet the desired requirements and it can be used for soft-exoskeleton testing.

Keywords: Exoskeleton | Industrial sector | Motor rehabilitation | Upper limb | User feedback

[5] Pesenti M., Gandolla M., Folcio C., Ouyang S., Rovelli L., Pedrocchi A., Rodriguez M.C., Roveda L., Sensor-Based Task Ergonomics Feedback for a Passive Low-Back Exoskeleton, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 13342 LNCS, 403-410, (2022). Abstract
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Abstract: Low-back exoskeletons are a wide-spreading technology tackling low-back pain, the leading work-related musculoskeletal disorder in many work sectors. Currently, spring-based (i.e., passive) exoskeletons are the mostly adopted in the industry, being cheaper and generally less complex and more intuitive to use. We introduce a system of interconnected wireless sensing units to provide online ergonomics feedback to the wearer. We integrate the system into our passive low-back exoskeleton and evaluate its usability with healthy volunteers and potential end users. In this way, we provide the exoskeleton with a tool aimed both at monitoring the interaction of the system with the user, providing them with an ergonomics feedback during task execution. The sensor system can also be integrated with a custom-developed Unity3D application which can be used to interface with Augmented- or Virtual-Reality applications with higher potential for improved user feedback, ergonomics training, and offline ergonomics evaluation of the workplace. We believe that providing ergonomics feedback to exoskeleton users in the industrial sector could help further reduce the drastic impact of low-back pain and prevent its onset.

Keywords: Ergonomics | Exoskeleton | Industrial sector | Low-back pain | Usability | User feedback

[6] Rodriguez M.C., Mehta S., Elias-Espinosa M.C., Augmented Reality Game for Children with Autism Spectrum Disorder, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 13341 LNCS, 462-467, (2022). Abstract
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Abstract: Games play an important role in the development of children. Especially when it comes to children with special needs like autism, it is important to have a different approach when it comes to learning. Shapes and colours are the most important fundamental skills that help in the recognition of objects around and help with letters and words. Balloon Pop is an application that is designed keeping in mind the requirements of children diagnosed with autism. The paper gives an idea of the user’s needs and requirements and shows how the project solves the problem with augmented reality game design. The goal of the project is to design a game for autistic children that will help them learn the abstract concept of shapes and colours. The Digital game-based learning methodology (DGBL) is used in developing the game. The paper consists of the design rules that have been followed in designing for better interaction along with hardware and software architecture describing the flow of the project. Also, at last, the test and evaluation and 8 users have been done by using the System Usability Scale (SUS) tool. The application has been proven to be helpful for children along with parents/therapists to achieve the goal to make children interact and communicate freely, increase focus, and learn the abstract concepts of shapes and colour easily.

Keywords: Augmented reality | Autism | Balloon pop | Children | Game

[7] Miesenberger K., Kouroupetroglou G., Mavrou K., Manduchi R., Rodriguez M.C., Penáz P., Preface, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 13341 LNCS, v-vi, (2022).
[8] Roveda L., Pesenti M., Rossi M., Rodriguez M.C., Pedrocchi A., Braghin F., Gandolla M., User-Centered Back-Support Exoskeleton: Design and Prototyping, Procedia CIRP, 107, 522-527, (2022). Abstract
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Abstract: Exhausting manual labor is still predominant in the industrial context. It typically consists in manipulating heavy parts or working in non-ergonomic conditions. The resulting work-related musculoskeletal disorders are a major problem to tackle. The most-affected body section is the the lumbar spine. Recently, exoskeletons have been identified as a possible non-invasive solution to reduce the impact of low-back pain. State-of-the-art prototypes have been optimized to: follow unconstrained human kinematics, (partially) relieve the load on assisted joints, and allow anthropometric adaptation. Yet, this technology still has limited adoption. Manufacturing optimization may address the following limitations: bulky/heavy resulting designs, complex assembly and maintenance, high manufacturing costs, long procedures for adaptation and wearing, and psychological effects (e.g., cognitive load and usability). In this contribution, the aforementioned issues are tackled improving a previous low-back exoskeleton prototype. In particular, kinematic analysis, Finite-Element-Method, and topological optimization have been combined to obtain a lightweight prototype, testing different materials (Nylon, carbon-fiber reinforced PC/ABS, etc.). We applied both Design for Assembly and Design for Manufacturability. The resulting exoskeleton prototype is described in the paper, ready for end-user field tests.

Keywords: back-support; exoskeleton | backbone-based kinematics | industry4.0 | industry5.0 | materials selection | mechanical design | topological optimization

[9] Grandi A., Karthikeyan A.P., Vaz Junior E.V., Rodriguez M.C., Low-Cost 3D Printed Exoskeleton for Post-Stroke Hand Rehabilitation, Computer-Aided Design and Applications, 19(6), 1207-1215, (2022). Abstract
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Abstract: Strokes can lead to the paralysis of one or more parts of the human body and so stroke survivors more than often require rehabilitation to regain muscle coordination, for instance when trying to perform finger movements. For such an objective, an external device like an exoskeleton can be used. This paper presents a low-cost 3D printed hand exoskeleton with high flexibility degree to fit different hand, wrist, and finger sizes.

Keywords: 3D Printing | Hand Exoskeleton | Post-Stoke Rehabilitation | Stroke

[10] Rodriguez N., Sangalli M., Smukowska M. D., Covarrubias M., Haptic Feedback Glove for Arm Rehabilitation, Computer-Aided Design and Applications, 19(6), 1143-1153, (2022). Abstract
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Abstract: The following document outlines the design process of a haptic feedback glove. The aim of this project is to give the user a haptic feedback once they are in contact with an object in a virtual interactive 3D space. In order to induce a haptic feedback, Unity3D is used to simulate the 3D virtual space, Leap motion is used in order to track the hands of the user and map them on the 3D virtual space. Finally, the signal from Unity is sent to Arduino which is able to produce the signal to initiate the vibration motors and led lights. The purpose of this technology is to help people with reduced motor ability, to perform physiotherapy exercises while playing an interactive game that involves haptic feedback.

Keywords: Arduino | Haptic feedback | Leap motion and rehabilitation | Sharebot | Unity3D

[11] Duval-Dachary S., Chevalier-Lancioni J.P., Rossini M., Perego P., Covarrubias M., Motiv’handed, a new gamified approach for home-based hand rehabilitation for post-stroke hemiparetic patients, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 12376 LNCS, 176-183, (2020). Abstract
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Abstract: This document summarizes a master thesis project trying to bring a new solution to hemiplegia rehabilitation, one of the numerous consequences of strokes. A hemiplegic patients observe paralysis on one side of their body, and as so, loses autonomy and their quality of life decreases. In this study, we decided to only focus on the hand rehabilitation aspect. However, there is a clear tendency in stroke patients to stop training regularly when returning home from the hospital and the first part of their rehabilitation is over. They often experience demotivation, having the feeling that they will never get back to a fully autonomous person ever again and tend to put their training aside, especially when they do not see clear and visible results anymore. This is also due to the supervised training becoming sparser. All of this results in patients stagnating or even worse, regressing. Thus, we decided to offer a motivating solution for hand rehabilitation at home through gamification.

Keywords: Gamification | Hand | Stroke | VR rehabilitation

[12] Aruanno B., Caruso G., Rossini M., Molteni F., Espinoza M.C.E., Covarrubias M., Virtual and augmented reality platform for cognitive tele-rehabilitation based system, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 12376 LNCS, 130-137, (2020). Abstract
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Abstract: Virtual and Augmented Reality systems have been increasingly studied, becoming an important complement to traditional therapy as they can provide high-intensity, repetitive and interactive treatments. Several systems have been developed in research projects and some of these have become products mainly for being used at hospitals and care centers. After the initial cognitive rehabilitation performed at rehabilitation centers, patients are obliged to go to the centers, with many consequences, as costs, loss of time, discomfort and demotivation. However, it has been demonstrated that patients recovering at home heal faster because surrounded by the love of their relatives and with the community support.

Keywords: Cognitive rehabilitation | Gaming | LeapMotion | Oculus rift | VR/AR

[13] O Connor J., Abou-Zahra S., Covarrubias Rodriguez M., Aruanno B., Xr accessibility – learning from the past and addressing real user needs for inclusive immersive environments: Introduction to the special thematic session, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 12376 LNCS, 117-122, (2020). Abstract
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Abstract: XR is an acronym used to refer to the spectrum of hardware, software applications, and techniques used for virtual reality or immersive environments, augmented or mixed reality and other related technologies. The special thematic session on ‘XR Accessibility’ explores current research and development as well as presenting diverse approaches to meeting real user needs in immersive environments. The contributed research papers range from using spatial sound for object location and interaction for blind users, to alternative symbolic representation of information, Augmented Reality (AR) used in rehabilitation for stroke patients and vocational skills training for students with intellectual disabilities. The session also explores what we can learn from previous research into immersive environments – looks at opportunities for future research and collectively explores how we can together iterate accessibility standards.

Keywords: Accessibility | Augmented Reality | Immersive web | Inclusive design | Rehabilitation | Serious games | Usability | Virtual reality

[14] Rodriguez-Valencia S.A., Nava-Tellez I.A., Covarrubias-Rodriguez M., Elias-Espinosa M.C., Communication device for people with cerebral palsy assisted with head movements, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 12377 LNCS, 30-37, (2020). Abstract
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Abstract: In this project we will address the design of a manipulated electronic Augmentative and Alternative Communication (AAC) device with simple head movements for Cerebral Palsy (CP) patients with level III or IV Viking Speech Scale (VSS) and a Gross Motor Function Classification System (GMFCS) level IV or V which means they are limited in their ability to control leg and arm movements and are therefore not candidates for the use of other conventional AACs. This was accomplished using a simple hierarchical word choice system as well as a inertia sensor mounted over the user’s ear with the support of 3D printing technology as its primary manufacturing process.

Keywords: AAC | Cerebral palsy | Communication | Inertia sensor | Non- verbal

[15] Venumbaka S.A., Covarubias M., Cesaro G., Ronca A., De Capitani C., Ambrosio L., Sorrentino A., Application of multi materials additive manufacturing technique in the design and manufacturing of hand orthoses, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 12377 LNCS, 461-468, (2020). Abstract
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Abstract: The objective of this study is to demonstrate the possibility of obtaining a completely customized orthosis through the use of multi-material 3-D printing technique. Additive manufacturing with multi-material enables to print objects with two different materials at the same time. Two immiscible materials Polylactic Acid (PLA), Thermoplastic Polyurethane (TPU) are chosen to give the orthosis a good trade-off between flexibility and rigidity. Results show that with this innovative technology it is possible not only create complex functional geometries but also to overcome some of the issues associated with traditional immobilization techniques (plaster of Paris splints). Tensile and impact tests are performed on 3D printed specimens to analyze their toughness, rigidity and flexibility. Three different prototypes are developed varying the composition and the organization of the materials used. Results show that the proposed approach is capable of addressing all the issues associated with conventional plaster casts.

Keywords: 3D printing | Impact test | Multi-material printing | Orthosis | Polylactic Acid (PLA) | Tensile test | Thermoplastic Polyurethane (TPU)

[16] Miesenberger K., Manduchi R., Rodriguez M.C., Peňáz P., Preface, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 12377 LNCS, v-vi, (2020).
[17] Miesenberger K., Manduchi R., Rodriguez M.C., Peňáz P., Preface, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 12376 LNCS, v-vi, (2020).
[18] Covarrubias M., Aruanno B., Cianferoni T., Rossini M., Komarova S., Molteni F., Neuro Rehabilitation System Through Virtual Reality, Music and Fragrance Therapy, Biosystems and Biorobotics, 21, 848-852, (2019). Abstract
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Abstract: The development of systems for supporting neuro-rehabilitation is of primary importance, due to the high number of people in need of rehabilitation and the limited effectiveness of most of the current developed systems. Our research work aims at developing more engaging interaction modalities for neuro rehabilitation systems, through virtual reality, music based on harp therapy and fragrance feedback modalities and which are also fun and motivational for the patients. The proposed interaction modalities consist of a set of virtual immersive environments which includes an olfactory feedback, where odours are used to increase the sense of presence and the attention of the patients during the execution of the exercises. While the patient performs the rehabilitation exercise, the harp therapist plays the harp accordingly to the patient emotional condition. The system shows a virtual scenario, including virtual objects and/or 360 videos used to increase his sense of presence in the scenario. Odours are associated with virtual scenarios.

[19] Candeo R., Rossini M., Aruanno B., Covarrubias M., Design of a low-cost exoskeleton for hand tele-rehabilitation after stroke, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 10896 LNCS, 395-398, (2018). Abstract
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Abstract: The impairment of finger movements after a stroke results in a significant deficit in hands everyday performances. To face this kind of problems different rehabilitation techniques have been developed, nevertheless, they require the presence of a therapist to be executed. To overcome this issue have been designed several apparatuses that allow the patient to perform the training by itself. Thus, an easy to use and effective device is needed to provide the right training and complete the rehabilitation techniques in the best way. In this paper, a review of state of the art in this field is provided, along with an introduction to the problems caused by a stroke and the consequences for the mobility of the hand. Then follows a complete review of the low cost home based exoskeleton project design. The objective is to design a device that can be used at home, with a lightweight and affordable structure and a fast mounting system. For implementing all these features, many aspects have been analysed, starting from the rehabilitation requirements and the ergonomic issues. This device should be able to reproduce the training movements on an injured hand without the need for assistance by an external tutor.

Keywords: Hand rehabilitation | Post stroke | Tele-Rehabilitation

[20] Köktürk E., Molteni F., Bordegoni M., Covarrubias M., Utilization of limb orientations for a home-based immersive virtual reality rehabilitation system to treat phantom limb pain, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 10897 LNCS, 484-488, (2018). Abstract
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Abstract: The growing potential of virtual reality (VR) systems presents an immense opportunity for amputee patients who are suffering from the medical condition which causes sensation of pain at the location of the missing limb called Phantom Limb Pain (PLP). The occurrence rate of PLP is reported 60–80% [1] among amputee patients and treatment methods vary between physical therapy, surgery and medication. One of the proven treatment methods is “Mirror Therapy” [3] and it is applied by visually projecting a healthy limb on the amputated part with the help of a mirror to create the perception of presence. Similar approach can also be represented in a virtual environment and immersion of VR can enhance the rehabilitation experience. Therefore, we aimed to improve the mirror therapy treatment by a VR application and to overcome the physical limitations by presenting potentially engaging activities with a way to treat double-limb amputees.

Keywords: Mirror therapy | Phantom Limb Pain | Tele-rehabilitation

[21] Aruanno B., Garzotto F., Rodriguez M.C., HoloLens-based mixed reality experiences for subjects with Alzheimer's disease, ACM International Conference Proceeding Series, Part F131371, (2017). Abstract
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Abstract: HoloLens technology enables mixed reality experiences that integrate holographic objects into the real world in which the mixed reality head-mounted device is used. Since HoloLens' launch in March 2016, some mixed-reality applications of this technology have been announced or showcased, addressing different fields, including education, data visualization, tourism, entertainment, and professional training e.g., in medicine, architecture, manufacturing, and engineering. Still, a limited number of reported research provide examples of user experience designs and evaluations for applications using HoloLens. We are interested in the use of HoloLens as therapeutic tool for people with the Alzheimer's Disease. The paper describes a set of therapeutic activities that have been designed in cooperation with neurologists and aim at stimulating short term memory and spatial memory in this target group. We also report a preliminary study of the usability of these activities among the elderly subjects.

Keywords: Alzheimer's | Augmented reality | Cognitive training | Hologram | HoloLens | Memory | Mixed reality | Rehabilitation

[22] Rodriguez M.C., Aruanno B., Bordegoni M., Rossini M., Molteni F., Immersive virtual reality system for treatment of phantom limb pain (plp), Proceedings of the ASME Design Engineering Technical Conference, 1, (2017). Abstract
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Abstract: This paper presents an immersive virtual reality system (IVRS) that has been designed for unilateral amputees in order to reduce the phantom limb pain (PLP). The patient's healthy limb is tracked by using a motion sensor. Data of the limb in motion are used as input parameters to move the phantom limb in the immersive virtual reality system. In this way, the patient has the illusion of moving the phantom limb while moving the real and contra-lateral limb. The system has been implemented by using low cost and open technologies, and combines the Oculus Rift SDK2 device, the LeapMotion device, a motion sensor, and an engine for interactive 3D content and gaming generation (Unity 3D). The Oculus Rift head mounted display is used to provide the immersive experience.

[23] Mansutti A., Covarrubias Rodriguez M., Bordegoni M., Cugini U., Module with direct actuation system, SpringerBriefs in Applied Sciences and Technology, 61-88, (2017). Abstract
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Abstract: In order to cope with the issues arisen by analysing the first version of the system presented in Chap. 5, a new version of the module has been designed and it will be described in this chapter. It will be based on direct actuation of the joints. Furthermore, we will describe the introduction of an important feature as the possibility to regulate in real time the nominal distance between the modules. This feature allows the control sectors to slide on the strip, thus increasing the performances of the whole system. In this chapter we will also describe the kinematic analysis that have been performed, the design of the components and the developed prototype so as to to evaluate the pros and the limits of this implemented solution. Eventually, we will describe the developed control process, which allows to perform the rendering of virtual surfaces.

[24] Mansutti A., Covarrubias Rodriguez M., Bordegoni M., Cugini U., Introduction, SpringerBriefs in Applied Sciences and Technology, 1-3, (2017). Abstract
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Abstract: This chapter will introduce the research work described in this book. The final output of the research work is a new concept of a desktop Tactile Shape Display. This device allows the designer to perform the tactile evaluation of the virtual model of the products they are creating in real time. In particular, we will describe the hypothesis and the starting point of the research.

[25] Mansutti A., Covarrubias Rodriguez M., Bordegoni M., Cugini U., Augmented reality visualisation system, SpringerBriefs in Applied Sciences and Technology, 101-108, (2017). Abstract
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Abstract: As explained in Chap. 3, the aim of the development of the tactile interface is to allow users to perform the tactile evaluation together with the visual one. Thanks to the desktop and portability features of the developed tactile display, the user can use as a visualisation device the monitor of the PC/Laptop, which he/she is using in order to create the digital model. However, Augmented Reality (AR) technology can be used and exploited to create a more immersive experience. AR technology allows us to superimpose a 3D visual representation of the digital model directly onto the tactile interface. In this way, the user can interact at the same time with the tactile interface, in order to perform the tactile evaluation, and with the digital representation of the model shape, thus performing the visual evaluation.

[26] Mansutti A., Covarrubias Rodriguez M., Bordegoni M., Cugini U., Conclusions and future works, SpringerBriefs in Applied Sciences and Technology, 109-112, (2017). Abstract
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Abstract: In this last chapter we will summarize the results of the described research work which consist in the development of an innovative Tactile Shape Display. Moreover, we will describe the future works that we are planning in order to proceed with the research activites related to the tactile devices.

[27] Mansutti A., Covarrubias Rodriguez M., Bordegoni M., Cugini U., Related works, SpringerBriefs in Applied Sciences and Technology, 5-14, (2017). Abstract
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Abstract: Tactile interaction consists in providing the user of a Virtual Reality (VR) system with sensations related to touch, mainly during the evaluation and the manipulation of virtual objects. In some cases the term tactile is used to refer to mechanical stimulation of the skin, which -together with the kinaesthetic sense- creates the haptic feedback. For these reasons, the tactile devices are strictly related to the haptic interfaces. Therefore, in order to give a complete and exhaustive overview of the interfaces related to touch, we have analysed the different categories of devices, such as vibrotactile interfaces, force feedback devices, local and full shape displays. Nowadays, a larger number of applications have been developed for tactile and haptic interaction in Virtual Reality. These applications belong to various fields: Medicine (chirurgical simulators, rehabilitation), Education (display of physical or mathematical phenomena), Industry (virtual prototyping, training, maintenance simulations), Entertainment (video games, theme parks), Arts and Creation (virtual sculpture, virtual instruments), etc. Hereafter the State of the Art related to the tactile and haptic technologies is presented.

[28] Mansutti A., Covarrubias Rodriguez M., Bordegoni M., Cugini U., Discussion and users test, SpringerBriefs in Applied Sciences and Technology, 89-99, (2017). Abstract
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Abstract: In this chapter we will describe the characteristics of the developed system in terms of: performances, modularity, portability and implementation costs. In order to perform an accurate analysis of the rendered trajectory and of the usability of the system we will describe the user tests performed and we will analyse their results.

[29] Mansutti A., Covarrubias Rodriguez M., Bordegoni M., Cugini U., Conceptual development of the tactile interface, SpringerBriefs in Applied Sciences and Technology, 27-39, (2017). Abstract
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Abstract: In order to develop the tactile interface that allows users to touch a 3D shape by means of a continuous and free hand interaction, it is needed to conduct a preliminary study for evaluating the concept. In this chapter we will analyse how it is possible to render a 3D shape by means of a trajectory according to the designers needs. After that, we will study the ways to make possible the physical rendering of this trajectory by controlling the elastic behaviour of a continuous plastic strip. This analysis allows defining the degrees of freedom that have to be controlled in order to actuate the system and the different kinematics solutions. Various conceptual solutions for the actuations systems will be investigated, and the best solution according to the project goals will be chosen.

[30] Mansutti A., Covarrubias Rodriguez M., Bordegoni M., Cugini U., Research context and concept of the system, SpringerBriefs in Applied Sciences and Technology, 15-25, (2017). Abstract
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Abstract: Product design process is typically based on loops between the design and the evaluation phases, which require the creation of digital models and physical prototypes. In the last years, real prototypes have been partially substituted with Virtual Prototypes (VPs). These consist in computer simulations of physical products that can be presented, analysed, and tested from concerned product life-cycle aspects, such as design/engineering, manufacturing, maintenance, aesthetic and ergonomic evaluation, as if these activities are conducted on a real physical model. VPs allow designers to evaluate the characteristics of the future product in order to reduce the number of physical prototypes needed, thus leading also to a reduction of developing time and costs. The currently available tools enable the designers to access only the visual information of the virtual prototypes, while in order to get tactile information, physical prototypes are still needed. In this Chapter it is described the product development methodology where the designer can perform the tactile evaluation of a model of a product at the same time of the visual one. Furthermore, the concept of the system that will allow obtaining this goal will be presented.

[31] Mansutti A., Covarrubias Rodriguez M., Bordegoni M., Cugini U., Module with indirect actuation system, SpringerBriefs in Applied Sciences and Technology, 41-59, (2017). Abstract
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Abstract: This chapter presents the concept of the solution based on indirect actuation approach. This configuration aims at positioning the control points of the rendered trajectory in the space. The degree of freedom of the device are controlled by using indirect actuation systems, which are described in the following paragraphs. Moreover in this chapter we will describe the performed kinematic analysis, the design of the components and the developed prototype. In this manner, it has been possible to evaluate the pros and the limits of the presented solution.

[32] Bordegoni M., Covarrubias M., Caruso G., Cugini U., Freehand Gesture and Tactile Interaction for Shape Design, Journal of Computing and Information Science in Engineering, 16(4), (2016). Abstract
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Abstract: This paper presents a novel system that allows product designers to design, experience, and modify new shapes of objects, starting from existing ones. The system allows designers to acquire and reconstruct the 3D model of a real object and to visualize and physically interact with this model. In addition, the system allows designer to modify the shape through physical manipulation of the 3D model and to eventually print it using a 3D printing technology. The system is developed by integrating state-of-the-art technologies in the sectors of reverse engineering, virtual reality, and haptic technology. The 3D model of an object is reconstructed by scanning its shape by means of a 3D scanning device. Then, the 3D model is imported into the virtual reality environment, which is used to render the 3D model of the object through an immersive head mounted display (HMD). The user can physically interact with the 3D model by using the desktop haptic strip for shape design (DHSSD), a 6 degrees of freedom servo-actuated developable metallic strip, which reproduces cross-sectional curves of 3D virtual objects. The DHSSD device is controlled by means of hand gestures recognized by a leap motion sensor.

[33] Mansutti A., Covarrubias Rodriguez M., Caruso G., Bordegoni M., Cugini U., Visuo-tactile system for 3D digital models rendering, Computer-Aided Design and Applications, 13(2), 236-245, (2016). Abstract
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Abstract: Abstract: The product design process is based on a sequence of phases where the concept of the shape of a product is typically represented through a digital 3D model of the shape, and often also by means of a corresponding physical prototype. The digital model allows designers to perform the visual evaluation of the shape, while the physical model is used to better evaluate the aesthetic characteristics of the product, i.e. its dimension and proportions, by touching and interacting with it. Design and evaluation activities are typical cyclical, repeated as many times as needed in order to reach the optimal and desired shape. This reiteration leads to an increase of the development time and, consequently, of the overall product development cost. The aim of this research work is to develop a novel system for the simultaneous visual and tactile rendering of product shapes, thus allowing designers to both touch and see new product shapes already during the product conceptual development phase. The proposed system for visual and tactile shape rendering consists in a Tactile Display able to represent in the real environment the shape of a product, which can be explored naturally through free hand interaction. The device is designed in order to be portable, low cost, modular and high performing in terms of types of shapes that can be represented. The developed Tactile Display can be effectively used if integrated with an Augmented Reality system, which allows the rendering of the visual shape on top of the tactile haptic strip. This allows a simultaneous representation of visual and tactile properties of a shape. By using the Tactile Display in the initial conceptual phases of product design, the designers will be able to change the shape of a product according to the tactile evaluation, before the development of the physical prototype. This feature will lead to a decrease of the number of physical prototypes needed, thereby reducing, both cost and overall time of the product development process.

Keywords: augmented reality | shape rendering | Tactile display | virtual prototyping

[34] Rodriguez M.C., Rossini M., Caruso G., Samali G., Giovanzana C., Molteni F., Bordegoni M., Sound feedback assessment for upper limb rehabilitation using a multimodal guidance system, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 9759, 529-536, (2016). Abstract
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Abstract: This paper describes the implementation of a Multimodal Guidance System (MGS) for upper limb rehabilitation through vision, haptic and sound. The system consists of a haptic device that physically renders virtual path of 2D shapes through the point-based approach, while sound technology provides audio feedback inputs about patient’s actions while performing a manual task as for example: starting and/or finishing an sketch; different sounds related to the hand’s velocity while sketching. The goal of this sonification approach is to strengthen the patient’s understanding of the virtual shape which is used in the rehabilitation process, and to inform the patient about some attributes that could otherwise remain unseen. Our results provide conclusive evidence that the effect of using the sound as additional feedback increases the accuracy in the tasks operations.

Keywords: Haptic guidance | Sound interaction | Upper-limb rehabilitation

[35] Alducin D., Borja R., Ortega E., Velazquez-Salazar J.J., Covarrubias M., Santoyo F.M., Bazán-Díaz L., Sanchez J.E., Torres N., Ponce A., José-Yacamán M., In situ transmission electron microscopy mechanical deformation and fracture of a silver nanowire, Scripta Materialia, 113, 63-67, (2016). Abstract
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Abstract: In this paper a fivefold twinning silver nanowire is mechanically tested in real time within a transmission electron microscope using an atomic force microscopy sensor. Our experimental setup allows us to measure, by bending the silver nanowire, the elastic modulus (E), the fracture toughness (KIC) and the stress intensity factor (σI) for elastic and plastic deformation regions and finally the fracture of the nanowire. Data of the force applied and the bending of the nanowire was recorded during the deformation and after the point of fracture. The mechanical properties of the nanowire were extracted and compared with nanoindentation using atomic force microscopy.

Keywords: In situ TEM measurements | Mechanical deformation | Silver nanowires | Transmission electron microscopy

[36] Covarrubias M., Bordegoni M., Rosini M., Guanziroli E., Cugini U., Molteni F., VR system for rehabilitation based on hand gestural and olfactory interaction, Proceedings of the ACM Symposium on Virtual Reality Software and Technology, VRST, 13-15-November-2015, 117-120, (2015). Abstract
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Abstract: The study of new systems for supporting upper limb rehabilitation is of primary importance, due to the high number of people in need of rehabilitation and the limited effectiveness of most of the current systems. The research work described in this paper proposes a VR system for upper-limb rehabilitation that is immersive, is based on hand gestures to interact with virtual objects, and which can deliver odours when a goal is reached.

[37] Covarrubias M., Bordegoni M., Immersive VR for natural interaction with a haptic interface for Shape Rendering, 2015 IEEE 1st International Forum on Research and Technologies for Society and Industry, RTSI 2015 - Proceedings, 82-89, (2015). Abstract
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Abstract: This paper presents an immersive virtual reality system that includes a natural interaction approach based on free hand gestures that is used to drive a Desktop Haptic Strip for Shape Rendering (DHSSR). The DHSSR is a mechatronic display of virtual curves intersecting 3D virtual objects, and aims at allowing designers to evaluate the quality of shapes during the conceptual design phase of new products. The DHSSR consists of a 6DOF servo-Actuated developable metallic strip, which reproduces cross-sectional curves of 3D virtual objects. Virtual curves can be interactively generated on the 3D surface of the virtual object, and coherently the DHSSR haptic interface renders them. An intuitive and natural modality for interacting with the 3D virtual objects and 3D curves is offered to users, who are mainly industrial designers. This consists of an immersive virtual reality system for the visualization of the 3D virtual models and a hand gestural interaction approach used by the user for handling the models. The system has been implemented by using low cost and open technologies, and combines a software engine for interactive 3D content generation (Unity 3D), the Oculus Rift Head Mounted Display for 3D stereo visualization, a motion capture sensor (LeapMotion) for tracking the user's hands, and the Arduino Leonardo board for controlling the components. Results reported in the paper are positive for what concerns the quality of the rendering of the surface, and of the interaction modality proposed.

[38] Covarrubias M., Bordegoni M., Cugini U., A hand gestural interaction system for handling a desktop haptic strip for shape rendering, Sensors and Actuators, A: Physical, 233, 500-511, (2015). Abstract
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Abstract: This paper presents a hand gestural interaction system that is used to handle a Desktop Haptic Strip for Shape Rendering (DHSSR). The strip is a physical display of virtual curves intersecting 3D virtual objects, and aims at allowing designers to evaluate the quality of shapes during the conceptual design phase of new products. The DHSSR consists of a servo-actuated developable metallic strip, which reproduces cross-sectional curves of 3D virtual objects. In order to generate the virtual curve intersecting the virtual object it has been implemented a hand gestural interaction system, which allows moving the curve or the 3D object. Specifically, through an interaction approach based on a magnetic pinch the user can move the virtual strip until reaching the desired position. Instead, an interaction modality based on index finger recognition allows moving the 3D object while the virtual curve is floating in space. The virtual curve generated by the interaction is used for deforming the physical strip. The hand gestural interaction system has been implemented by using low cost and open technologies, and combines an engine for interactive 3D content generation (Unity 3D), a motion capture sensor (LeapMotion) and the Arduino Leonardo board. In particular, the user's hands are tracked by means of the Leap Motion sensor. The Unity 3D environment is used to virtually render the virtual objects (curve and shape) and the virtual avatar of the users' hands. The virtual environment is connected with the Arduino Leonardo board in order to control the six servo-actuators of the DHSSR. The paper also presents some studies performed to evaluate the performances of the DHSSR system and the usability of the hand gestural interaction modalities.

Keywords: Hand gestural interaction | Haptic strip | Motion capture sensor | Shape rendering

[39] Covarrubias M., Mansutti A., Bordegoni M., Cugini U., Flexible touch sensor for evaluating geometric properties of virtual shapes through sound: This paper reports a sonification approach to visualise geometric features that are missing in haptic display, Virtual and Physical Prototyping, 10(2), 77-89, (2015). Abstract
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Abstract: This paper describes the design and implementation of a system for rendering virtual shape through vision, haptic and sound. The system consists of a haptic strip that physically renders virtual curves. A flexible capacitive touch sensor (FCTS) is integrated with the haptic strip, and allows the system to track the position of the user's fingers on the strip. According to the position, the system renders curve properties such as curve shape, inflexion points and curvature through sound metaphors. The goal of this sonification approach is to strengthen the user's understanding of the shape of a virtual prototype, and to inform the user about geometrical attributes that could otherwise remain unseen. Such unseen attributes may either be a result of limitations in the visual and haptic display hardware or a result of limitations in human perception.

Keywords: conceptual design | haptic rendering | human-computer interaction | immersive virtual reality | product design

[40] Mansutti A., Rodriguez M.C., Bordegoni M., Cugini U., Tactile display for virtual shape rendering based on servo actuated modules, Proceedings of the ASME Design Engineering Technical Conference, 1B-2015, (2015). Abstract
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Abstract: This paper presents a new concept of a desktop tangible shape display for virtual surface rendering. The proposed system is able to represent in the real environment the shape of a digital model of a product, which can be explored naturally through a free-hand interaction. Aim of the shape display is to allow product designers to explore the rendered surface through a continuous touch of curves lying on the product shape. Ideally, the designer selects curves, which can be considered as style features of the shape, on the shape surface, and evaluates the aesthetic quality of these curves by manual exploration. In order to physically represent these selected curves, a flexible surface is modelled by means of servo-actuated modules controlling a physical deforming strip. The behaviour of the strip is controlled by acting on the position and rotations of a discrete number of control sectors. Each control sector is controlled by a module, which is based on an absolute positioning approach and equipped with five degrees of freedom. The developed system is able to manage the elastic behaviour of the strip in terms of bending, twisting and local tangency. The tangency control allows us to manage the local tangency of the strip to the rendered trajectory, thus increasing the accuracy of the representation. Moreover, a preliminary second version of the module is presented, which has been designed so as to allow the control sectors to slide on the strip. Thanks to this feature, it will be possible to place the control sector in a given point of the trajectory, such as point of maximum, point of minimum or inflection points. The device is designed to be portable, low cost, modular and high performing in terms of types of shapes that can be represented. A prototype equipped with three modules has been developed in order to evaluate the usability and the performances of the display.

[41] Gonizzi Barsanti S., Caruso G., Micoli L.L., Covarrubias Rodriguez M., Guidi G., 3D visualization of cultural heritage artefacts with virtual reality devices, International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives, 40(5W7), 165-172, (2015). Abstract
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Abstract: Although 3D models are useful to preserve the information about historical artefacts, the potential of these digital contents are not fully accomplished until they are not used to interactively communicate their significance to non-specialists. Starting from this consideration, a new way to provide museum visitors with more information was investigated. The research is aimed at valorising and making more accessible the Egyptian funeral objects exhibited in the Sforza Castle in Milan. The results of the research will be used for the renewal of the current exhibition, at the Archaeological Museum in Milan, by making it more attractive. A 3D virtual interactive scenario regarding the "path of the dead", an important ritual in ancient Egypt, was realized to augment the experience and the comprehension of the public through interactivity. Four important artefacts were considered for this scope: Two ushabty, a wooden sarcophagus and a heart scarab. The scenario was realized by integrating low-cost Virtual Reality technologies, as the Oculus Rift DK2 and the Leap Motion controller, and implementing a specific software by using Unity. The 3D models were implemented by adding responsive points of interest in relation to important symbols or features of the artefact. This allows highlighting single parts of the artefact in order to better identify the hieroglyphs and provide their translation. The paper describes the process for optimizing the 3D models, the implementation of the interactive scenario and the results of some test that have been carried out in the lab.

Keywords: 3D modelling | Cultural Heritage | Leap Motion | Oculus Rift | Unity | Virtual Reality | Visualisation

[42] Covarrubias M., Bordegoni M., Cugini U., Haptic Trajectories for Assisting Patients during Rehabilitation of Upper Extremities, Computer-Aided Design and Applications, 12(2), 218-225, (2015). Abstract
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Abstract: In this paper, we present a pilot study of a haptic system that leads the patients' limb to follow trajectories performed on a plane or in space (2D or 3D haptic trajectories). This function is implemented by the Multimodal Guidance System (MGS) whose aim is to provide robotic assistance during the rehabilitation of upper extremities when patients perform 2D and 3D tasks during manual activities such as drawing, coloring and gaming. The MGS consists of a virtual environment including several technologies as haptic, sound and video gaming. The patients are able to feel virtual objects and haptic trajectories, which act as virtual guides taking advantages of its force feedback capabilities. A virtual environment is used forming a haptic interface between the patient and the game. The haptic device is driven under the user's movements and assisted through the Magnetic Geometry Effect (MGE). Several 2D and 3D haptic trajectories have been tested in order to analyze the use interaction with the MGS. Preliminary evaluation has been performed in order to obtain more information related to the accuracy of the haptic trajectories. The haptic device has been used as an input means for tracking the hand trajectory made by the patient according to the feedback received from 2D and 3D tasks. The performance has been evaluated by comparing the analysis of the tracking results.

Keywords: desktop haptic system | haptic guidance | multimodal guidance | rehabilitation system

[43] Covarrubias M., Bordegoni M., Cugini U., Mansutti A., Co-simulation based method for driving a Desktop Mechatronic Interface for shape rendering, MESA 2014 - 10th IEEE/ASME International Conference on Mechatronic and Embedded Systems and Applications, Conference Proceedings, (2014). Abstract
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Abstract: This paper describes an efficient methodology based on the co-simulation between several software tools that has been developed to drive and increase the dynamic behavior of a Desktop Mechatronic Interface (DMI) for shape rendering. The co-simulation is performed by using a multi-body software, which is linked to MATLAB/Simulink. With the multi-body software the virtual simulation of the DMI is performed in order to sense the rotation angles of the virtual servo-actuators. By using this interaction it is possible to control the real servo-actuators presented in the DMI. In addition, through this methodology it is possible to perform experimental simulation in kinematics, dynamics and control of the DMI. A collision approach is presented taking into account both, friction and restitution coefficients which are required in the virtual simulation of the DMI. Simulation results show that the co-simulation platform is established successfully.

[44] Covarrubias M., Mansutti A., Bordegoni M., Cugini U., 2D shape and force tracking in rehabilitation therapy of upper extremities through a Multimodal Guidance System, Proceedings of the ASME Design Engineering Technical Conference, 1B, (2014). Abstract
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Abstract: This paper describes a shape and force tracking approach aimed for the assessment and training of patients' upper extremities functionalities, while performing 2D tasks in a post-stroke rehabilitation program. The 2D tasks are assisted by a Multi-modal Guidance System (MGS), which consists in a combination of visual, haptic and sound interaction. The device enables users to haptically interact with a virtual template, which acts as a virtual tool path taking advantage of its force feedback capabilities while the patient performs a 2D task, as sketching and hatching operations. Furthermore, the patient receives sound information, which provides audio feedback related to the hand velocity. By tracking the shape and the forces required to complete the tasks according to the visual feedback provided on the computer screen, the system can inform about quantitative measurement of a patients progress. The paper concludes by presenting a preliminary test using the device for sketching and hatching operations.

[45] Covarrubias M., Mansutti A., Bordegoni M., Cugini U., Interacting game and haptic system based on point-based approach for assisting patients after stroke, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 8547 LNCS(PART 1), 289-296, (2014). Abstract
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Abstract: This paper describes a system that combines haptic, virtual reality and game technologies in order to assist repetitive performances of manual tasks to patients, which are recovering from neurological motor deficits. These users are able to feel virtual objects by using a haptic device, which acts as a virtual guide taking advantages of its force feedback capabilities. A virtual environment is used forming a haptic interface between the patient and the game. The haptic device is driven under the users movements and assisted through the Magnetic Geometry Effect (MGE). Preliminary evaluation has been performed in order to validate the system in which two different tasks have been performed (throw down bricks in an hexagonal tower without and with haptic assistance) with the aim to obtain more information related to the accuracy of the device. © 2014 Springer International Publishing.

Keywords: Gaming | Haptic interface | Post-stroke Rehabilitation | Virtual Reality

[46] Covarrubias M., Gatti E., Bordegoni M., Cugini U., Mansutti A., Improving manual skills in persons with disabilities (PWD) through a multimodal assistance system, Disability and Rehabilitation: Assistive Technology, 9(4), 335-343, (2014). Abstract
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Abstract: In this research work, we present a Multimodal Guidance System (MGS) whose aim is to provide dynamic assistance to persons with disabilities (PWD) while performing manual activities such as drawing, coloring in and foam-cutting tasks. The MGS provides robotic assistance in the execution of 2D tasks through haptic and sound interactions. Haptic technology provides the virtual path of 2D shapes through the point-based approach, while sound technology provides audio feedback inputs related to the hand's velocity while sketching and filling or cutting operations. By combining this Multimodal System with the haptic assistance, we have created a new approach with possible applications to such diverse fields as physical rehabilitation, scientific investigation of sensorimotor learning and assessment of hand movements in PWD. The MGS has been tested by people with specific disorders affecting coordination, such as Down syndrome and developmental disabilities, under the supervision of their teachers and care assistants inside their learning environment. A Graphic User Interface has been designed for teachers and care assistants in order to provide training during the test sessions. Our results provide conclusive evidence that the effect of using the MGS increases the accuracy in the tasks operations. Implications for RehabilitationThe Multimodal Guidance System (MGS) is an interface that offers haptic and sound feedback while performing manual tasks.Several studies demonstrated that the haptic guidance systems can help people in recovering cognitive function at different levels of complexity and impairment.The applications supported by our device could also have an important role in supporting physical therapist and cognitive psychologist in helping patients to recover motor and visuo-spatial abilities. © 2014 Informa UK Ltd. All rights reserved: reproduction in whole or part not permitted.

Keywords: Disabilities | Down syndrome | Haptic feedback | Manual tasks | Multimodal guidance device | People without skills

[47] Mansutti A., Covarrubias M., Bordegoni M., Cugini U., Haptic strip based on modular independent actuators for virtual shapes rendering, IEEE Haptics Symposium, HAPTICS, 7-12, (2014). Abstract
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Abstract: This paper presents a new concept of a desktop haptic shape display that allows rendering and exploring virtual surfaces. Such device allows continuous and free hand contact on a developable plastic strip that is actuated by a modular handling system. Each module is based on an absolute positioning approach, which allows controlling the represented trajectory, thus overcoming the limits of relative handling systems. The developed system is able to manage the elastic behaviour of the strip in terms of bending, twisting and local curvature control. The latter allows us to handle the local tangency of the strip to the rendered trajectory. The absolute approach allows configuring the system with a variable number of modules, so as to customize it according to the application needs. © 2014 IEEE.

Keywords: Curve rendering | Desktop haptic system | Haptic strip | Virtual Prototyping

[48] Covarrubias M., Bordegoni M., Design of a Desktop Haptic System driven by CAD and Multi-body Systems Associativity, Computer-Aided Design and Applications, 11(4), 450-458, (2014). Abstract
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Abstract: This paper describes a Desktop Haptic System, which supports designers in the evaluation and modification of aesthetic virtual shapes. This System includes the advantages of using the associative data to both CAD and multi-body tools and thus maintaining the parametric dependencies between them. In this way, as the parametric data model gets modified according with the designer's needs in the CAD system, the changes are consistently reflected in the multi-body system. Modifications on the virtual shape can be done by using a global approach or by using a CAD drawing, then the data model in the multi-body system is used to render a real 2D cross-section of the aesthetic virtual shape through a Desktop Haptic Interface (DHI), which allows a free-hand interaction with the aesthetic virtual object. The DHI is linked to the multi-body system by means of using MATLAB and Simulink in order to control their servo-actuators. We also present the results of the validation process specifically carried out to evaluate the accuracy and the effectiveness of the DHI while rendering 2D cross-sections of a virtual shape. © 2014 CAD Solutions, LLC.

Keywords: CAD associativity | desktop haptic system | multi-body interaction

[49] Covarrubias M., Bordegoni M., Interaction with virtual aesthetic shapes through a desktop mechatronic system: A desktop system that supports designers in the creation, evaluation and modification of aesthetic virtual shapes, Virtual and Physical Prototyping, 9(1), 27-43, (2014). Abstract
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Abstract: In common industrial practice the definition of shapes of styling products is performed by product designers. They usually produce aesthetic shapes by handcrafting scale models made of malleable material like clay, and often expensive physical prototypes are also manufactured. The paper describes a Desktop Mechatronic System (DMS) that has been conceived to support designers in the creation, evaluation and modification of aesthetic virtual shapes. The objective in designing this system is to develop a system allowing a continuous and smooth free hand physical interaction with a virtual shape, which is rendered through a dynamic cross-sectional contour or curve in three-dimensional (3D) space. The DMS is a useful tool for designers, who are not certain about the quality of the shape of the product, and can use it for testing out ideas. The DMS consists of a servo-actuated developable metallic strip, which reproduces 3D cross-sectional contours, which has been devised and implemented by using the Minimal Energy Curve (MEC) spline approach in which the equidistant interpolation points scheme has been adopted to imitate the virtual object created via a Computer Aided Design (CAD) tool on a physical bendable strip-like surface. © 2013 © 2013 Taylor & Francis.

Keywords: 2D cross-section rendering | CAD associativity | desktop mechatronic system | industrial design | virtual prototyping

[50] Covarrubias M., Bordegoni M., Cugini U., Force sensitive handles and capacitive touch sensor for driving a flexible haptic-based immersive system, Sensors (Switzerland), 13(10), 13487-13508, (2013). Abstract
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Abstract: In this article, we present an approach that uses both two force sensitive handles (FSH) and a flexible capacitive touch sensor (FCTS) to drive a haptic-based immersive system. The immersive system has been developed as part of a multimodal interface for product design. The haptic interface consists of a strip that can be used by product designers to evaluate the quality of a 3D virtual shape by using touch, vision and hearing and, also, to interactively change the shape of the virtual object. Specifically, the user interacts with the FSH to move the virtual object and to appropriately position the haptic interface for retrieving the six degrees of freedom required for both manipulation and modification modalities. The FCTS allows the system to track the movement and position of the user's fingers on the strip, which is used for rendering visual and sound feedback. Two evaluation experiments are described, which involve both the evaluation and the modification of a 3D shape. Results show that the use of the haptic strip for the evaluation of aesthetic shapes is effective and supports product designers in the appreciation of the aesthetic qualities of the shape. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Keywords: Conformable sensor | Flexible sensor | Haptic interface | Haptic strip | Tactile data processing

[51] Covarrubias M., Bordegoni M., Cugini U., Gatti E., Supporting unskilled people in manual tasks through haptic-based guidance, Assistive Technologies: Concepts, Methodologies, Tools, and Applications, 947-969, (2013). Abstract
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Abstract: This chapter presents a methodology that the authors developed for the evaluation of a novel device based on haptic guidance to support people with disabilities in sketching, hatching, and cutting shapes. The user's hand movement is assisted by a sort of magnet or spring effect attracting the hand towards an ideal shape. The haptic guidance device has been used as an input system for tracking the sketching movements made by the user according to the visual feedback received from a physical template without haptic assistance. Then the device has been used as an output system that provides force feedback capabilities. The drawn shape can also be physically produced as a piece of polystyrene foam. The evaluation methodology is based on a sequence of tests, aimed at assessing the usability of the device and at meeting the real needs of the unskilled people. In fact, the system has been evaluated by a group of healthy and unskilled people, by comparing the analysis of the tracking results. The authors have used the results of the tests to define guidelines about the device and its applications, switching from the concept of "test the device on unskilled people" to the concept of "testing the device with unskilled people."

[52] Covarrubias M., Bordegoni M., Cugini U., Continuous surface rendering, passing from cad to physical representation, International Journal of Advanced Robotic Systems, 10, (2013). Abstract
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Abstract: This paper describes a desktop-mechatronic interface that has been conceived to support designers in the evaluation of aesthetic virtual shapes. This device allows a continuous and smooth free hand contact interaction on a real and developable plastic tape actuated by a servo-controlled mechanism. The objective in designing this device is to reproduce a virtual surface with a consistent physical rendering well adapted to designers' needs. The desktop-mechatronic interface consists in a servo-actuated plastic strip that has been devised and implemented using seven interpolation points. In fact, by using the MEC (Minimal Energy Curve) Spline approach, a developable real surface is rendered taking into account the CAD geometry of the virtual shapes. In this paper, we describe the working principles of the interface by using both absolute and relative approaches to control the position on each single control point on the MEC spline. Then, we describe the methodology that has been implemented, passing from the CAD geometry, linked to VisualNastran in order to maintain the parametric properties of the virtual shape. Then, we present the cosimulation between VisualNastran and MATLAB/Simulink used for achieving this goal and controlling the system and finally, we present the results of the subsequent testing session specifically carried out to evaluate the accuracy and the effectiveness of the mechatronic device. © 2013 Covarrubias et al.

Keywords: Desktop haptic strip | Mec (minimal energy curve) spline approach | Surface rendering

[53] Covarrubias M., Bordegoni M., Cugini U., Positioning system for the interaction with virtual shapes through a desktop haptic device, Proceedings of the ASME Design Engineering Technical Conference, 4, (2013). Abstract
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Abstract: The paper describes the results of a research activity on the design of a positioning system which includes both a physical 3-DOF and virtual platforms which carries out a Desktop Haptic Interface (DHI). The positioning system allows the user to interact with a virtual shape through a combination of linear and rotation motions, some of them driven by the user and some driven by the virtual shape. On the other hand, by rendering a physical 2D cross-section through the DHI permits the assessment of virtual prototypes of industrial products with aesthetic value. Typically, virtual objects are modified several times before reaching the desired design, increasing the development time and, consequently, the final product cost. The desktop haptic system (which includes the positioning system and the DHI) that we propose here, will reduce the number of physical mockups during the design process allowing designers to perform several phases of the product design process continuously and without any interruption. In particular the system is developed with the aim of supporting designers during the evaluation of the aesthetic quality of a virtual product. Copyright © 2013 by ASME.

[54] Covarrubias M., Bordegoni M., Cugini U., Rendering physical 2D cross-sections of aesthetic shapes driven by equidistant interpolation points, Proceedings of the ASME Design Engineering Technical Conference, 2 B, (2013). Abstract
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Abstract: The paper describes a desktop-haptic interface (DHI) that has been conceived to support designers in the evaluation and modification of aesthetic virtual shapes. The objective in designing this device is to reproduce a 2D cross-section of virtual objects with a consistent physical rendering well adapted to designers needs allowing a continuous and smoothly free hand contact interaction on a real and developable metallic strip. The desktop-haptic interface consists in a servo-actuated metallic strip that has been devised and implemented by using the Minimal Energy Curve (MEC) spline approach in which the equidistant interpolation points scheme has been adopted for modeling the structure chain consisting of several rigid struts and pivots. Then, we present the co-simulation between the multi-body environment and MATLAB/Simulink used for achieving this goal and control the system and finally, we present the results of the experimental validation session specifically carried out to evaluate the accuracy and the effectiveness of the interface. Copyright © 2013 by ASME.

[55] Covarrubias M., Bordegoni M., Cugini U., Servo-actuated stylus for post stroke arm and fore arm rehabilitation, Communications in Computer and Information Science, 373(PART I), 523-527, (2013). Abstract
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Abstract: This paper describes the design and implementation of a 1- DOF servo-actuated stylus, which is used as an end effector in a desktop haptic device. The desktop haptic device is part of a multimodal system aimed for the assessment, training and rehabilitation of the arm, forearm and hand while the user perform several tasks. Patients will use the haptic device which carries out the servo-actuated stylus in order to draw simple and complex sketches, in this way, the patient is able to feel the virtual sketch by using the haptic device, which acts as a virtual guide taking advantages of its force feedback capabilities. The therapist is able to control the 1-DOF-stylus rotation according to the requirements of the patient. © Springer-Verlag Berlin Heidelberg 2013.

Keywords: Haptic guidance | Multimodal system | Sketching task | Stroke patient

[56] Covarrubias M., Bordegoni M., Cugini U., Gatti E., Supporting unskilled people in manual tasks through haptic-based guidance, Information Systems Research and Exploring Social Artifacts: Approaches and Methodologies, 355-378, (2012). Abstract
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Abstract: This chapter presents a methodology that the authors developed for the evaluation of a novel device based on haptic guidance to support people with disabilities in sketching, hatching, and cutting shapes. The user's hand movement is assisted by a sort of magnet or spring effect attracting the hand towards an ideal shape. The haptic guidance device has been used as an input system for tracking the sketching movements made by the user according to the visual feedback received from a physical template without haptic assistance. Then the device has been used as an output system that provides force feedback capabilities. The drawn shape can also be physically produced as a piece of polystyrene foam. The evaluation methodology is based on a sequence of tests, aimed at assessing the usability of the device and at meeting the real needs of the unskilled people. In fact, the system has been evaluated by a group of healthy and unskilled people, by comparing the analysis of the tracking results. The authors have used the results of the tests to define guidelines about the device and its applications, switching from the concept of "test the device on unskilled people" to the concept of "testing the device with unskilled people." © 2013, IGI Global.

[57] Covarrubias M., Bordegoni M., Cugini U., Gatti E., Mansutti A., Pantograph mechanism for increasing the working area in a haptic guidance device for sketching, hatching and cutting tasks, Proceedings of the ASME Design Engineering Technical Conference, 2(PARTS A AND B), 1377-1384, (2012). Abstract
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Abstract: The paper presents the design, construction, validation and testing of a Haptic Guidance Device whose aim is to provide dynamic assistance while performing manual activities such as drawing, hatching and cutting. A commercial phantom haptic device was modified by adding a pantograph mechanism in order to increase the haptic working area. The force feedback workspace provided by the phantom device is quite limited, 160 W x 120 H mm. This workspace sometimes is not enough to reproduce manual tasks in a large-scale area as is often required in several educational activities (e.g. sketching, hatching and cutting tasks). In this paper is evaluated a low cost solution for increasing the haptic working area provided by the phantom device. The pantograph mechanism has been linked with the haptic device in order to increase the working area in a 2:1 scale. The users hand moves a pen linked to the device through 2D predefined shapes in which the pens position have been tracked in 2D coordinates at 25 kHz in order to record all the data for the posterior analysis. The haptic guidance device is also equipped with a cutting system using hot wire for physically producing the drawn shape as a piece of polystyrene foam. The haptic guidance device has been tested by people with specific disorders affecting coordination such as Down syndrome and mental retardation under the supervision of their teachers and care assistants. The results of the study prove that higher performance levels can be achieved while performing manual tasks as sketching, hatching and cutting operation using the haptic guidance device. Copyright © 2012 by ASME.

[58] Covarrubias M., Gatti E., Mansutti A., Bordegoni M., Cugini U., Multimodal guidance system for improving manual skills in disabled people, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 7382 LNCS(PART 1), 227-234, (2012). Abstract
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Abstract: The paper describes a multimodal guidance system whose aim is to improve manual skills of people with specific disorders, such as Down syndrome, mental retardation, blind, autistic, etc. The multimodal guidance system provides assistance in the execution of 2D tasks as for example: sketching, hatching and cutting operations through haptic and sound interactions. The haptic technology provides the virtual path of 2D shapes through the point-based approach, while sound technology provides some audio feedback inputs about his or her actions while performing a manual task as for example: start and/or finish an sketch; some alarms related to the hand's velocity while sketching and filling or cutting operations. Unskilled people use these interfaces in their educational environment. © 2012 Springer-Verlag.

Keywords: Haptic Guidance | Sound Interaction | Unskilled People

[59] Covarrubias M., Bordegoni M., Cugini U., Supporting Down people in cutting operations trough haptic technology, Proceedings of the IADIS International Conference Interfaces and Human Computer Interaction 2011, Part of the IADIS Multi Conference on Computer Science and Information Systems 2011, MCCSIS 2011, 201-208, (2011). Abstract
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Abstract: The paper deals with the application of haptic technology when improving manual skills of people with specific disorders, such Down syndrome, mental retardation, etc. The development of a cutting haptic system is the base of this paper to show specificity of the development and verification of hardware for the given group of handicapped users. The paper shows suitability of using haptic technology for a concrete application, which is designed for user with specific disorders. The cutting operation is performed using a hot wire tool, which is linked through an R-R mechanism to a PHANTOM device. The haptic cutting device is able to cut soft materials as expanded and extruded polystyrene foam from 5 to 20 mm thickness. The device is driven under the user's hand movement and assisted through the Magnetic Geometry Effect (MGE). The haptic cutting device has been used as an input system for tracking the sketching movements made by the user according to the visual feedback received from a physical template without haptic assistance. Then the cutting device has been used as an output system that provides force feedback capabilities. Finally, the system performance has been evaluated by comparing the analysis of the tracking results with the final polystyrene components. © 2011 IADIS.

Keywords: Assisted cutting system | Haptic technology | Unskilled people

[60] Covarrubias M., Bordegoni M., Cugini U., Antolini M., Transmission system improvements in actuating a desktop haptic strip for exploration of virtual objects, Proceedings of the ASME Design Engineering Technical Conference, 3(PARTS A AND B), 545-553, (2011). Abstract
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Abstract: This paper describes the servo actuated transmission system required to drive a desktop haptic strip interface. The haptic strip is a mechatronic device which is used for exploration of virtual surfaces with aesthetic value. The simulation of tasks, such as the exploration of aesthetic real surfaces made by industrial designers in order to check the quality of prototypes, require full hand contact with the shape on a one-to-one scaled representation of the object. Our mechatronic device allows a continuous, free hand contact on a developable real plastic tape actuated by a servo-controlled mechanism in which is used the tessellation approach. In fact, the triangular mesh simplifies the conformation of the developable real surface as the virtual one. This paper discusses the design concept, novel kinematics and mechanics, improvements of the transmission system and control for the Desktop Strip. © 2011 by ASME.

[61] Covarrubias M., Bordegoni M., Cugini U., Multifunctional device for assisting unskilled people in hand movements through the haptic point-based approach, Proceedings of the ASME Design Engineering Technical Conference, 2(PARTS A AND B), 1499-1506, (2011). Abstract
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Abstract: This paper describes a multifunctional haptic machine, a device that is used for assisting unskilled people in the assessment and training of hand movements. Sketching, hatching and cutting operations are assisted through the multifunctional device by using the haptic point-based approach. The device has enabled users to haptically interact with a 2D virtual template, which acts as a virtual tool path taking advantages of its force feedback capabilities. For sketching, hatching and cutting operations the haptic device is driven under the user movement and assisted through the Magnetic Geometry Effect (MGE). Two configurations of the multifunctional device have been analyzed; the cartesian and the RR mechanism attached to the PHANTOM device. For sketching and hatching several pencils and pens colors are available. Regarding the cutting operation, a hot wire cutting tool can be replaced for cutting soft materials as expanded and extruded polystyrene foam. This paper discusses the design concept, kinematics and mechanics of the multifunctional haptic device. A brief test using the device in sketching, hatching and cutting operations is also given. © 2011 by ASME.

[62] Covarrubias M., Bordegoni M., Cugini U., Sketching haptic system based on point-based approach for assisting people with down syndrome, Communications in Computer and Information Science, 173 CCIS(PART 1), 378-382, (2011). Abstract
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Abstract: This paper describes the 2D sketching haptic system (2DSHS) designed for the assessment and training of sketching control movements. The system has been developed for people with Down syndrome, who can use the system for drawing simple and complex sketches. These users are able to feel virtual objects by using a haptic device, which acts as a virtual guide taking advantages of its force feedback capabilities; in fact, the haptic device is driven under the user's movements and assisted through the Magnetic Geometry Effect (MGE). The 2DSHS has been used as an input device for tracking the sketching movements made by a user according to the visual feedback received from a physical template without haptic assistance. Then, the 2DSHS has been used as an output device that provides force feedback capabilities through a point-based approach. Preliminary evaluation has been performed in order to validate the system. Two different tasks have been performed -sketching a template and hatching a surface- with the aim to obtain more information related to the accuracy of the device. The performance has been evaluated by comparing the analysis of the tracking results. © 2011 Springer-Verlag.

Keywords: assisted sketching | Haptic technology | unskilled people

[63] Bordegoni M., Ferrise F., Covarrubias M., Antolini M., Geodesic spline interface for haptic curve rendering, IEEE Transactions on Haptics, 4(2), 111-121, (2011). Abstract
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Abstract: Several haptic devices have been developed in recent years in order to reproduce the sensation of physical contact with virtual objects. Many of these devices are point-based, and some haptic interfaces behave like small surfaces that conform to a virtual shape. None of these allow a full-hand contact with the shape, and they are, in general, too small to render big surfaces. The simulation of tasks, such as the exploration of aesthetic surfaces made by industrial designers in order to check the quality of prototypes, require full-hand contact with the shape on a one-to-one scaled representation of the object. These explorations follow trajectories that can be approximated with planar or geodesic curves. In this paper, we describe the design and implementation of a linear haptic device that is able to render these trajectories. The device is part of a multimodal system including stereoscopic visualization that allows visual representation of the entire surface. Industrial designers use the system for checking the quality of shapes while exploiting their manual and visual skills. The system has been tested by industrial designers and the results are reported in this paper. © 2011 IEEE.

Keywords: curve rendering | Haptic strip | industrial design | mixed reality | multimodal interfaces | virtual prototyping

[64] Covarrubias M., Bordegoni M., Cugini U., Antolini M., Desktop haptic Strip for exploration of virtual objects, 3DUI 2011 - IEEE Symposium on 3D User Interfaces 2011, Proceedings, 101-102, (2011). Abstract
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Abstract: This research work describes the Desktop Strip haptic interface, a device which is used for exploration of virtual surfaces with aesthetic value. Such a device allows a continuous, free hand contact on a developable plastic tape actuated by a modular servo-controlled mechanism using the tessellation approach. The device has enabled users to interact with and feel a wide variety of virtual objects by using the palm of the hand. This research work discusses the design concept, novel kinematics and mechanics of the Desktop Strip. © 2011 IEEE.

Keywords: H.1.2 [Models and Principles]: User/Machine SystemEvaluation/Methodology | H.5.2 [Information Interfaces and Presentation]: User InterfacesHaptic I/O

[65] Covarrubias M., Bordegoni M., Cugini U., Mansutti A., Kinematic and workspace analysis of a 2-DOF haptic end-effector that carries out a developable haptic strip, ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 7(PARTS A AND B), 223-232, (2011). Abstract
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Abstract: This paper presents the analysis of a 2 DOF end-effector that carries out a haptic tool consisting in a developable servo-actuated plastic strip. To overcome some drawbacks of conventional systems related to the use of point based force-feedback, tactile and glove devices we have developed the triangular mesh approach in the developable haptic interface. The developable haptic strip, has evolved as a result of this research. The haptic interface of our system consists of a haptic strip that is inspired by the deformable tape that designers use for creating and modifying aesthetic shapes. The first step for designing the end effector and the haptic strip mechanism has been the assignment of both the total length of the haptic strip and the number of tessellation triangles required to control the strip as a developable surface. The strip is aimed at haptically rendering medium sized design objects (vases, lamps, household appliances, etc.). Thus, the total length of the strip has been set to be 160 mm. This length value also ensures the possibility to easily manipulate the strip. Seven triangles have been assigned in order to maintain the haptic strip symmetric; this consideration is particularly important because guarantees an adequate balancing of weight in the mechanism. The device is based on a modular architecture of elements that deform a plastic tape. Copyright © 2011 by ASME.

[66] Antolini M., Covarrubias M., Bordegoni M., Cugini U., A framework for managing multiprocess applications based on distributed finite-state machine approach, Proceedings - IEEE International Workshop on Robot and Human Interactive Communication, 680-685, (2010). Abstract
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Abstract: This paper describes a framework based on a publish/subscribe paradigm for interprocess communication based on XML messages sent over a TCP/IP connection. The framework manages the exchange of data within the clients of a system and permits the definition of a specific behavior for each client using a finite-state machine approach. Whilst the server-side of the framework is able to receive and dispatch events and data, the client-side of the framework is modeled as a finite-state machine able to perform state transitions after receiving the correct message. This architecture permits the loose-coupling between producers and consumers of data and the bidirectional mapping between the design of the behavior of a system and its implementation. © 2010 IEEE.

[67] Bordegoni M., Cugini U., Covarrubias M., Antolini M., A force and touch sensitive self-deformable haptic strip for exploration and deformation of digital surfaces, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 6192 LNCS(PART 2), 65-72, (2010). Abstract
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Abstract: The paper describes a haptic device whose aim is to permit the assessment of digital prototypes of industrial products with aesthetic value. The device haptically renders curves belonging to digital surfaces. The device is a haptic strip consisting of a modular servo-controlled mechanism able to deform itself, allowing the user to feel the resulting shape with his free hands. The haptic strip is also equipped with two force sensitive handles placed at the extremities, and a capacitive touch sensor along its length, which are used for applying deformations to the digital shape. © 2010 Springer-Verlag Berlin Heidelberg.

Keywords: Haptic linear strip | Multimodal application | Virtual Prototyping

[68] Bordegoni M., Ferrise F., Covarrubias M., Antolini M., Haptic and sound interface for shape rendering, Presence: Teleoperators and Virtual Environments, 19(4), 341-363, (2010). Abstract
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Abstract: This paper presents a system for the evaluation of the shape of aesthetic products. The evaluation of shapes is based on characteristic curves, which is a typical practice in the industrial design domain. The system, inspired by characteristic curves, is based on a haptic strip that conforms to a curve that the designer wishes to feel, explore, and analyze by physically touching it. The haptic strip is an innovative solution in the haptics domain, although it has some limitations concerning the domain of curves that can be actually represented. In order to extend this domain and make users feel the various curve features, for example curvature discontinuities, sound has been exploited as an additional information modality. © 2010 by the Massachusetts Institute of Technology.

[69] Bordegoni M., Ferrise F., Covarrubias M., Antolini M., A linear haptic interface for the evaluation of shapes, Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference 2009, DETC2009, 2(PART B), 1571-1579, (2010). Abstract
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Abstract: The paper presents a haptic device that allows a user to explore a virtual object along a continuous line. In particular the device is developed with the aim of supporting designers during the evaluation of the aesthetic quality of a virtual product. This is generally done by means of the global and local analysis of the shape in terms of curvature characteristics, presence of inflections points and discontinuities. In order to evaluate such features, designers are used to work on physical prototypes, relying on their skilled sense of touch. It is known that physical prototypes are expensive in terms of cost and time for their re-alization, and a modification on a physical prototype implies a reverse engineering process for appling such modifications on the virtual model. A linear haptic interface, that adapts its shape reproducing a generic curve on a surface, has been developed to replicate the behavior of a physical strip. This is the way to replace real prototypes with virtual ones without changing the evaluation paradigms that designers are used to. The physical limitations encountered in representing discontinuities in po.sition, tangency and curvature, not renderable by bending and de-forming a physical strip, have been overcome thanks to the application of some principles of the theory of haptic illusions by means of sonification of some curve characteristics, The paper describes the linear haptic interface developed and the solution based on haptic illusion that has been implemented to overcome the strip limitations. Copyright © 2009 by ASME.

[70] de Araújo B.R., Guerreiro T., Fonseca M.J., Jorge J.A., Pereira J.M., Bordegoni M., Ferrise F., Covarrubias M., Antolini M., An haptic-based immersive environment for shape analysis and modelling, Journal of Real-Time Image Processing, 5(2), 73-90, (2010). Abstract
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Abstract: Currently, the design of aesthetic products is a process that requires a set of activities where digital models and physical mockups play a key role. Typically, these are modified (and built) several times before reaching the desired design, increasing the development time and, consequently, the final product cost. In this paper, we present an innovative design environment for computer-aided design (CAD) surface analysis. Our system relies on a direct visuo-haptic display system, which enables users to visualize models using a stereoscopic view, and allows the evaluation of sectional curves using touch. Profile curves are rendered using an haptic device that deforms a plastic strip, thanks to a set of actuators, to reproduce the curvature of the shape co-located with the virtual model. By touching the strip, users are able to evaluate shape characteristics, such as curvature or discontinuities (rendered using sound), and to assess the surface quality. We believe that future computer-aided systems (CAS)/CAD systems based on our approach will contribute in improving the design process at industrial level. Moreover, these will allow companies to reduce the product development time by reducing the number of physical mockups necessary for the product design evaluation and by increasing the quality of the final product, allowing a wider exploration and comparative evaluation of alternatives in the given time. © 2009 Springer-Verlag.

Keywords: Haptic | Immersive | Stereo | Tracking

[71] Covarrubias M., Antolini M., Bordegoni M., Cugini U., A spline-like haptic tool for exploration and modification of digital models with aesthetic value, ASME 2010 World Conference on Innovative Virtual Reality, WINVR 2010, 285-294, (2010). Abstract
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Abstract: This paper describes a multimodal system whose aim is to replicate in a virtual reality environment some typical operations performed by professional designers with real splines laid over the surface of a physical prototype of an aesthetic product, in order to better evaluate the characteristics of the shape they are creating. The system described is able not only to haptically render a continuous contact along a curve, by means of a servo controlled haptic strip, but also to allow the user to modify the shape applying force directly on the haptic device. The haptic strip is able to bend and twist in order to better approximate the portion of the surface of the virtual object over which the strip is laying. This device is 600mm long and is controlled by 11 digital servos for the control of the shape (6 for bending and 5 for twisting) and by two MOOG-FCS HapticMaster devices and two additional digital servos for 6-DOF positioning. We have developed additional input devices, which have been integrated with the haptic strip, which consist of two force sensitive handles positioned at the extremities of the strip, and a capacitive linear touch sensor placed along the surface of the strip, and four buttons. These devices are used to interact with the system, to select menu options, and to apply deformations to the virtual object. The paper describes the interaction modalities and the developed user interface, the applied methodologies, the achieved results and the conclusions elicited from the user tests. © 2010 by ASME.

[72] Bordegoni M., Cugini U., Covarrubias M., Design and assessment of a 3D visualisation system integrated with haptic interfaces, Journal of Design Research, 8(3), 235-251, (2010). Abstract
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Abstract: The paper presents a system we have studied and developed to aid the stereoscopic visualisation of virtual models of products whose shape can be explored and modified using a haptic interface. The haptic system has a wide working space that allows users to stand in front of the system and to operate as they are used to do in real life for making physical prototypes. The paper also shows several visualisation solutions that have been studied before obtaining the best performing one in which the stereoscopic glasses worn by the user as well as his point of view are tracked in order to enhance the realistic perception of the 3D mixed image. Some initial tests have been performed with end-users, both CAS designers and model makers, with the support of human factors experts in order to correctly assess the usability of the system and to understand how potentially effective it is in aiding product designers in their work. © 2010 Inderscience Enterprises Ltd.

Keywords: haptic interfaces | projection based visualisation systems | stereoscopic visualisation | virtual prototyping | visuo-haptic display

[73] Bordegoni M., Ferrise F., Covarrubias M., Antolini M., A linear haptic interface for the evaluation of shapes, Proceedings of the ASME Design Engineering Technical Conference, 2(PARTS A AND B), 1571-1579, (2009). Abstract
X

Abstract: The paper presents a haptic device that allows a user to explore a virtual object along a continuous line. In particular the device is developed with the aim of supporting designers during the evaluation of the aesthetic quality of a virtual product. This is generally done by means of the global and local analysis of the shape in terms of curvature characteristics, presence of inflections points and discontinuities. In order to evaluate such features, designers are used to work on physical prototypes, relying on their skilled sense of touch. It is known that physical prototypes are expensive in terms of cost and time for their realization, and a modification on a physical prototype implies a reverse engineering process for appling such modifications on the virtual model. A linear haptic interface, that adapts its shape reproducing a generic curve on a surface, has been developed to replicate the behavior of a physical strip. This is the way to replace real prototypes with virtual ones without changing the evaluation paradigms that designers are used to. The physical limitations encountered in representing discontinuities in position, tangency and curvature, not renderable by bending and de-forming a physical strip, have been overcome thanks to the application of some principles of the theory of haptic illusions by means of sonification of some curve characteristics. The paper describes the linear haptic interface developed and the solution based on haptic illusion that has been implemented to overcome the strip limitations. © 2009 by ASME.

[74] Cugini U., Bordegoni M., Covarrubias M., Antolini M., Geodesic Haptic Device for surface rendering, Proceedings of the Joint Virtual Reality Conference of EGVE - The 15th Eurographics Symposium on Virtual Environments, ICAT, EuroVR 2009, 21-28, (2009). Abstract
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Abstract: This paper describes a haptic device whose aim is to render the contact with a continuous and developable surface by means of the representation of a geodesic trajectory. Some preliminary tests conducted with industrial designers have showed that the trajectories performed while exploring the surface of a style product, for a qualitative evaluation, follows some particular trajectories that may be mathematically described as geodesic curves. In order to represent these particular curves a haptic strip based on a modular servo-controlled mechanism has been developed. Each module of mechanism allows us to control both the curvature and the torsion. This device, in respect to the commercial existing haptic devices, allows a hand-surface contact with the virtual model in real scale without artifacts, by self-deforming its shape in order to conform to the mathematical curve to render. The strip is 900 mm long and has 9 control points for bending and 8 control points for torsion. Due to these characteristics, it allows us to render exploration trajectories of several kinds of product shapes and dimensions. In order to allow users to fully explore an object surface, we have mounted the strip on a platform consisting of two MOOG-FCS HapticMaster devices, which permits 6DOF orientation of the strip and force feedback control. The paper describes the mechanism of the strip and the 6DOF platform starting from the empirical observations of the exploration of surfaces and highlights the problems encountered and the solutions adopted.

[75] Bordegoni M., Covarrubias M., Direct Visuo-Haptic Display System Using a Novel Concept, Eurographics Symposium on Virtual Environments, EGVE 2007 - Short Papers and Posters, 33-34, (2007). Abstract
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Abstract: In this short paper we describe a Direct Visuo-Haptic Display System (DVHDS) setup based on a DLP projector, an overhead projection plane and a half silvered mirror. The system is specifically designed for being integrated with a haptic system. It offers a large viewing area with a proper haptic work space ideal for full arm movements in an immersive environment. The system allows superimposing the virtual scene onto the user's perspective of the real world. The system supports controlling the sense of depth and the correction of the distortion of the projected image.