Design methods for mobility

This study demonstrates the possibility of implementing a Computational Fluid Dynamic (CFD) approach to study the behavior of a tracked vehicle when it moves on a soft terrain, such as mud, snow, or other. The advantage of tracked vehicles is their ability to move efficiently on unpaved terrains. It is well known that the power requirement increases approximately with the cube of sinkage; therefore, having a suitable track to move within a specific type of terrain is of great relevance. This paper aims to propose a simulation and calculation method for studying various track geometries based on the terrain in which the vehicle will operate. By examining the track of an existing tank, the Abrams M1, with various parameters and essential data available for this verification, the necessary simulations are carried out. By investigating the case of a soft terrain, which has a much lower density than the paved one, the track can be assumed as a rigid body and the mud will be the fluid that surrounds it at a uniform velocity. In this way, a CFD simulation can be carried out.

Keywords: CFD , Design , ground pressure , Mechanical Engineering Design , Mechanics of Solids , mobility , power , Technology , Tracked vehicles , Transport & Vehicle Engineering

Gait training is essential in rehabilitation as it promotes mobility, prevents falls, and increases independence in daily activities. However, accurate gait assessment in the context of telemedicine remains a challenge. Wearable inertial devices offer value by providing a minimally invasive means to accurately capture movement. This study aims to improve telemedicine-based gait analysis by introducing a method utilizing a class II-B medical device equipped with a chest-worn inertial sensor. To enhance the quality of acceleration signals, we designed and 3D printed an 18-face polyhedron for stationary calibration. We validated this method by comparing its performance to a marker-based motion capture system in a cohort of young healthy adults. The results showed an 82% reduction in the root mean square error (RMSE) of acceleration signals. Furthermore, the study showed statistical and practical significant improvements in spatial gait characteristics. Specifically, there was a 14% reduction in root mean square error for gait velocity, a 59% reduction in RMSE for step length, and a 53% reduction in RMSE for stride length.

Keywords: 3D Printing , Gait Analysis , Motion Capture , Telerehabilitation , Wearable Devices

Measurements for the functional evaluation of knee joint mobility are essential, e.g., to determine the need for invasive surgery and quantify patient outcomes. While vision-based motion capture systems offer high precision, they require specialized laboratories and trained staff. This paper introduces KARMA (Knee Angle Resistive Measurement Apparatus), an instrumented knee sleeve with six resistive flex sensors to measure knee joint angles. The proposed device features wearability, low cost, and flexibility, enabling pre- and post-operative evaluations for patients eligible for knee surgery. A case study was performed using a marker-based motion capture system as a reference. This demonstrated KARMA's ability to measure flexion-extension angles but highlighted its inability to measure abduction-adduction and internal-external rotation angles.

Keywords: Flex sensors , Joint angles , Knee arthroplasty , Motion analysis , Wearable sensors

The methodology for crash tests in vehicle development and homologation is based on dummies sitting in a standardized posture, defined by the H-point of the car body and design specifications. As a result, injury criteria are directly influenced by these precisely defined initial conditions. Out-of-Position scenarios are not included in passive safety tests but are usually analysed conventionally through specialized experiments. The combination of crash dynamics and improper airbag deployment can increase the forces exerted on the body. While airbags have saved numerous lives, statistics also report injuries and fatalities caused by improper contact with deploying airbags. This study examines strategies to make the Airbag Control Unit effectively adaptive to an occupant position. Pre-crash scenarios are identified using sensors in the vehicle seat and the corresponding outcomes are simulated.

Keywords: CAR SEAT , CRASH TEST , DRIVER MONITORING , DRIVING EXPERIMENT , INTELLIGENT VEHICLE , OUT-OF-POSITION , SAFETY SYSTEM

In recent years, significant advancements have been made in robotics, especially with the introduction of continuum and hyper-redundant robots. These robots can be highly flexible and manoeuvrable, which makes them suitable for intricate underwater maintenance, exploration, and inspection tasks. Inspired by the motions of aquatic life, underwater snake-like robots offer a good way to accomplish subsea maintenance, exploration, and inspection activities. While many studies have been conducted on hyper-redundant, snake-like robotic arms for maintenance and inspection in land-based applications, not as much about robotics intended for marine or underwater applications has been studied. This review critically examines recent advancements in the design, actuation, and modelling of these robotic systems, categorising them into two primary families: untethered mobile robots and tethered robotic manipulators. Key insights include the identification of strengths and limitations associated with various designs and actuation strategies, such as the high manoeuvrability but limited speed of bioinspired swimming robots compared to thruster-driven designs, and the complexity versus precision trade-offs inherent in tendon-driven manipulator arms. Furthermore, the modelling techniques employed across categories are systematically analysed, as well as challenges such as the modelling of fluid–structure interactions and the need for improved real-time models for compliant and soft robots.

Keywords: Hyper-redundant , Literature review , Robotics , Snake-like , Underwater

The effect on wear and rolling contact fatigue of dispersed bainitic islands, as a remnant of the production process of railway wheels, is still an open issue. To address this topic, an experimental campaign was carried out on an ER8 steel by means of a small-scale bi-disc machine. The specimens were extracted at different depths under the tread of a railway wheel, characterized by decreasing hardness and a bainite content. The tests were done in dry rolling-sliding condition, in some cases followed by a wet contact session. Various measurement techniques, including an innovative vision system, were employed to evaluate wear, rolling contact fatigue and surface degradation. The results showed that, in dry condition, the prevailing damage was delamination wear, whereas, in the wet phase, shelling prevailed. None of the obtained data highlighted a detrimental effect of the bainitic content, in the concentrations considered in this study.

Keywords: Bainite , Railway wheel steel , Rolling contact fatigue , Wear

Silicon carbide (SiC) power MOSFETs use in different fields of application leads to increase the attention on reliability issues and long-term stability. Among these, threshold voltage (Vth) stability is one of the main topics. In this work, we have carried out dynamic gate stress (DGS) reliability tests on an automotive grade, planar-gate, SiC MOSFET. The goal is to evaluate the effect of different external gate resistance Rg magnitudes. We have captured the gate-source voltage (VGS) waveforms during DGS tests at two different Rg values, namely 0 Ω and 6.8 Ω. Results have shown 2% and 1% Vth drifts in the two cases. In either case, we noticed a negligible impact on the on-state resistance (RDS,ON). No significant variations in the VGS switching gradients were observed either.

The increasing depletion of fossil fuels and their environmental impact have led to the development of fuel cell hybrid electric vehicles. By combining fuel cells with batteries, these vehicles offer greater efficiency and zero emissions. However, their energy management remains a challenge requiring advanced strategies. This paper presents a comparative study of two developed energy management strategies: a deterministic rule-based approach and a fuzzy logic approach. The proposed system consists of a proton exchange membrane fuel cell (PEMFC) as the primary energy source and a lithium-ion battery as the secondary source. A comprehensive model of the hybrid powertrain is developed to evaluate energy distribution and system behaviour. The control system includes a model predictive control (MPC) method for fuel cell current regulation and a PI controller to maintain DC bus voltage stability. The proposed strategies are evaluated under standard driving cycles (UDDS and NEDC) using a simulation in MATLAB/Simulink. Key performance indicators such as fuel efficiency, hydrogen consumption, battery state-of-charge, and voltage stability are examined to assess the effectiveness of each approach. Simulation results demonstrate that the deterministic strategy offers a structured and computationally efficient solution, while the fuzzy logic approach provides greater adaptability to dynamic driving conditions, leading to improved overall energy efficiency. These findings highlight the critical role of advanced control strategies in improving FCHEV performance and offer valuable insights for future developments in hybrid-vehicle energy management.

Keywords: battery , deterministic rules , energy management strategy , fuel cell , fuzzy logic , model predictive control

Guardrails are designed to improve road safety by reducing the severity of accidents, preventing vehicles from leaving the roadway. 3D model studies could perform simulations that reproduce crash tests, considering the mechanical properties best suited to meet current regulations. This research illustrates a detailed behavior analysis of the individual constituent elements of the barriers and advances some improvements to be applied to their future development, evaluating a new guardrail with a greater elasticity given by a release device and a rhomboid spacer by analysing its dynamics and energy absorption during a road impact. Through experimental tests and FEM models, it was possible to determine the most significant parameters for the dynamic behavior of the new system, such as deformability, torsional and flexural stiffness. The progressive axial and flexural plastic collapse of the structure was studied by analysing the stress and strain states of the components reproducing, through a metal cylinder, the impact of a heavy vehicle with the guardrail at a speed of 3.5 m/s with impact angles of 20°, 45° and 90°. The proposed modifications to the guardrail increased the Acceleration Severity Index (ASI) by 10% and improved impact energy absorption by 39%, significantly reducing structural deformation. In light of the results, the proposed methodology allows the dynamic behavior of the rhomboidal spacer to be characterized through a limited number of experimental tests. In fact, the authors found in the scientific literature the lack of numerical-experimental methodologies to characterize and compare the elastoplastic behavior of different types of spacers.

Keywords: Crash test , Dynamic simulation , Guardrail , Impact performance , Rhomboid spacer , Road safety

This study investigates the impact of Voronoi tessellation parameters on the dynamic behaviour of a leaf spring employed in a tensioner for internal combustion engine timing systems. The research utilizes a custom-developed algorithm to apply Voronoi tessellation while maintaining a constant mass by varying the number of seeds and scaling factors. Modal simulations were carried out to determine the natural frequencies, participation factors, and mode shapes of the component. These simulations were validated through experimental tests performed using a hammer impact test, which provided reliable and detailed measurements of the system's dynamic response under different loading conditions. The experimental results revealed a strong correlation with the simulated data, demonstrating the accuracy of the proposed methodology. By modifying Voronoi tessellation parameters, it was possible to control and predict changes in natural frequencies and participation factors. These findings underscore the potential of Voronoi tessellation in dynamic system optimisation, enabling the design of components with tailored properties for improved performance. This research opens new avenues for integrating Voronoi-based design approaches with topology optimisation, particularly in the frequency domain, paving the way for innovative applications in mechanical and structural engineering.

Keywords: CAE approach , Modal frequencies , Optimal mass distribution , Participation factors , Tensioner leaf spring , Topology optimisation , Word

Featured Application: The present work provides a characterization of the key drivers and related enablers of New Space engineering design. The findings can serve as a conceptual and informative baseline to support design engineers in the early development of competitive and innovative systems, helping to align technical decisions with evolving market trends and design drivers. The recent evolution of the space industry, commonly referred to as New Space, has changed the way space missions are conceived, developed, and executed. In contrast to traditional approaches, the current paradigm emphasizes accessibility, commercial competitiveness, and rapid and sustainable innovation. This study proposes a research methodology for selecting relevant literature to identify the key design drivers and associated enablers that characterize the New Space context from an engineering design perspective. These elements are then organized into three categories: the evolution of traditional drivers, emerging manufacturing and integration practices, and sustainability and technology independence. This categorization highlights their role and relevance, providing a baseline for the development of systems for New Space missions. The results are further contextualized within three major application domains, namely Low Earth Orbit (LEO) small satellite constellations, operations and servicing in space, and space exploration, to illustrate their practical role in engineering space systems. By linking high-level industry trends to concrete design choices, this work aims to support the early design phases of New Space innovative systems and promote a more integrated approach between strategic objectives and technical development.

Keywords: design drivers , design enablers , engineering design , new space economy , space systems

The space industry represents a thriving yet challenging environment for developing innovative solutions. Small companies may struggle to succeed due to time limitations, budget, resources, and the sector's inherent complexities. Design methods are essential for managing the design complexity while considering constraints, requirements, and standards. However, the applied methodologies must support the designer in finding innovative solutions. The present work proposes a streamlined design framework tailored to meet the needs of small and micro enterprises engaged in engineering and developing innovative high-tech products for the New Space economy. The proposed methodology is applied to support the design of an innovative water-electrolysis space propulsion system for satellites.

Keywords: Design Structure Matrix , New Space economy , Space Satellites , Systems Engineering

The Reynolds-averaged Navier-Stokes (RANS) equations are the industry-standard computational fluid dynamics method for estimating forces, viscous effects, and boundary layer behaviour in various flow conditions, including adverse pressure gradients and flow-separation regimes. However, despite the ever-increasing availability of computational power, there are several scenarios in which more rapid methods, based on suitable simplified assumptions, offer advantages with respect to the RANS approach. Foil devices often operate at low angles of attack, high Reynolds numbers, and without fluid separation. These conditions make the Vortex Lattice Method (VLM) a viable and faster alternative for exploring the wide design space of yacht foils. In this study, the hydrodynamic forces generated by various foil geometries are computed using an original VLM formulation for generally curved lifting surfaces. The case study is focused on the foils of an ecofriendly dinghy designed and manufactured by students in the international framework of 1001VELAcup.

Keywords: CAD modelling , Computation fluid dynamics , Foil design , Vortex lattice method

This study examines the hydrodynamic behaviour of a 15-meter stepped planing hull through full-scale sea trials and numerical simulations. The sea trials, conducted in calm water conditions, provided key performance data, including pressure resistance, shear resistance and heave. A simplified procedure for conducting the sea trials was developed and implemented and these experimental results served as a baseline for a comparison with the results of a multiphase Computational Fluid Dynamics (CFD) model. This procedure enabled efficient testing while maintaining the accuracy of the results. The CFD simulation focused on understanding the natural ventilation process beneath the hull, a crucial factor in improving performance. Detailed studies were carried out on the wave profiles and resistance distribution under various flow conditions. The analysis explored the behaviour of natural ventilation in relation to resistance reduction, offering critical insights into optimizing hull performance through natural air flow mechanisms. This study underscores the potential of combining full-scale trials with advanced numerical modelling to enhance the design and performance evaluation of planing vessels. The findings contribute to the development of more efficient ships, with implications for improved energy efficiency and sustainability in recreational marine applications.

Keywords: Air Cavity Ships , CFD , Hydrodynamics , Sea Trials

Directed Energy Deposition is mainly adopted for the construction of large parts and structures or the reparation of worn and damaged components, but also in Hybrid Manufacturing systems, to combine features of different technologies. An additional emerging application is the Remanufacturing of existing components by integrating further features and materials to enhance products' functionality. Nevertheless, residual stress and strain are among the most relevant drawbacks since thermal gradients and cooling rates are more intensive compared to other Metal Additive Manufacturing processes. With the aim to define the build strategies (e.g.: tool paths and scanning patterns) for multiple depositions on actual existing components and mitigate the substrate deformation, this work is focused on the laser-based Direct Metal Deposition process design and optimization. To find the best trade-off between process efficiency and product quality, the goal is achieved identifying the build strategies (i) to guarantee the expected product requirements and (ii) to provide functional and assembly requirements. The case study is the Additive Remanufacturing of an automotive component, requiring a functional tolerance control, which implies to contain process-induced distortion. The build process is assessed through Finite Element thermo-mechanical simulations of 316L deposition, cooling, and unclamping steps. The effects of factors as the deposition strategy, orientation, direction, and sequence, are studied through a Design of Experiments approach. The model maximum displacement is the primary response, and the build time is the secondary one.

Keywords: AISI 316L , Finite element method , Laser metal deposition , Process optimization , Process simulation

Value is a polysemic word when used in engineering design, suitable to create fully-optimized entities. However, its multifaceted nature can hinder the development of effective design approaches. To address that, this research aimed at systematically reviewing the value definitions found across literature to establish a common theoretical basis for future value-based design methodologies. Considering the importance of value in the aeronautical sector, this research was performed both from a general viewpoint and focusing only on aeronautical papers. The main result achieved is the lack of a general-valid value definition, requiring deeper investigations of every element concurring to generate value.

Keywords: Aerospace , Design , Product Development , Value engineering

The Enhanced Basic Seat Assembly Concept Assessment is a design methodology applying Conceptual Design for Assembly theory to assess seats installation complexity in civil aircraft cabins. Initially assessing the installation process with only conceptual data, the method incorporates information across various levels of granularity, encompassing both conceptual and embodiment parameters. This research aims to include additional features to the original BSACA model as well as its software tool. The effectiveness of this approach was validated through different use cases (seats configurations based on airlines requirements), demonstrating the ability of the methodology in assisting seat concept assessment and redesign, yielding significant savings in time and costs throughout the Product Development Process.

Keywords: cabin equipment , design for assembly , design for manufacturing , installation , system engineering

In modern industries, standard and well-known product development strategies require customization and dedicated methods to effectively conceive and manufacture complex products. The present research work aims at solving new challenges in product development targeting the aeronautical sector, specifically for the purpose of designing seat systems to be assembled and installed into commercial aircraft cabins. Basic Seat Assembly Concept Assessment (BSACA) design approach has been developed to assess seats assembly complexity in aircraft assembly line and to provide design guidelines in the early stages of product design. BSACA comprises four steps, starting from gathering the company's knowledge to identify all the attributes characterizing the Seat Installation process. A series of scoring matrices is built, serving as a tool to translate the qualitative data gathered from design experts into quantitative values. Those matrices are used to create a software tool to help designers judge the goodness of new seat conceptual variants from an assembly viewpoint. Finally, the effectiveness of both the methodology and its stemming tool has been proven through a validation process carried out on four case studies. In essence, this research contributes a structured and rigorous framework to assess the ease and complexity of installing aircraft components, with a specific emphasis on seats, resulting in an improved assembly process of the whole aircraft.

Keywords: Design for assembly , Design for manufacturing , Seat installation

This paper proposes an AI-driven framework for designing multimodal, symbiotic human-machine interfaces (HMIs) in modern vehicles. As automotive systems evolve toward higher levels of automation and user-centric design, the integration of data fusion techniques with deep neural networks becomes essential for enhancing driver safety and comfort. The proposed framework continuously monitors a range of inputs—including driver gaze, facial expressions, posture, and vehicle telemetry—and processes these signals through a hierarchical data fusion methodology. This approach involves raw signal preprocessing, feature extraction and selection, and decision-level integration using advanced deep learning models. Experimental validation using a high-fidelity driving simulator across varied scenarios (high-stress, relaxed, and frustration-inducing) demonstrates the framework's capability to accurately detect driver distraction and drowsiness.

Keywords: Adaptive HMI , Data fusion , Deep Learning , DMS , Symbiotic HMI

In recent years, maritime industries have focused their attention on hydrofoils as one of the main technologies for the development of eco-sustainable solutions in the field of boating. The aim of the current research was to analyze the front wing of a Kohlkida class hydrofoil and to describe the methodology employed for the reconstruction of the 2-D airfoils by means of photogrammetry. Considering the limitations of the photogrammetry methods, some sections were extracted from the model. The airfoils were properly scaled and first compared with the model obtained by means of a laser scanner. Under the operating condition of the hydrofoil and with the use of Reynolds-averaged Navier–Stokes simulations, the behavior of the airfoils was simulated, allowing us to verify how the geometric differences due to the photogrammetry approach affect the fluid dynamics, in comparison to the model obtained from laser scanning. The proposed methodology led to a geometry reconstruction with adequate accuracy for the identification of both the characteristic curves for the lift and drag coefficients with a maximum error of 6% in the angle-of-attack range investigated in the study, also highlighting fluid dynamics problems that characterize this type of airfoils with a flat bottom and a knife-sharp leading edge.

Keywords: Computational fluid dynamics (CFD) , hydrofoil design and modeling , laser scanning , measurements , photogrammetry , reverse engineering