Design methods for mobility

This paper describes the Multi Disciplinary Optimization of an airship with unconventional configuration. The shape of the airship is based upon two semi-ellipsoids, whose axis ratios can be altered for optimization purpose. The parameters to optimize are: volume, ratio between longitudinal and lateral semi-axis, ratio between vertical and lateral semi-axis, percentage of the top surface covered by photovoltaic films, dimension of the tail. The goals of the optimization are: equilibrium between buoyancy and weight, reaching of the design speed, static longitudinal stability of the vehicle. The mathematical model developed to evaluate airship features includes the computation of the ballonet volume, a weight breakdown, the energy storage for night operations, the power system evaluation and stability considerations. Six heuristic optimization strategies have been applied in order to achieve the best solution; some case studies have been developed and the final optimal configurations found by algorithms have been analyzed in order to validate the optimization framework. The approach demonstrate that the heuristic optimization strategies used are good tool for the conceptual design of unconventional airship since this problem requires a multi-disciplinary approach and several parameters including aerodynamics, propulsion, mass breakdown, aerostatics and stability, which are strongly dependent each other, must be jointly considered and addressed at the same time to obtain an optimum and balanced design. © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Unmanned Aerial Vehicles (UAVs) provide the ability to perform a variety of experimental tests of systems and unproven research technologies, including new autopilot systems and obstacle avoidance capabilities, without risking the lives of human pilots. This paper describes the activities of design, optimization, and flight operations of a UAV conceived at Clarkson University (USA) and equipped to perform wind speed measurements to support wind farmsite planning. The UAV design has been assisted and validated by the use of an automatic virtual environment for the assisted design of civil UAVs. This tool can be used as a "computing machine" for civil UAVs. The operator inputs the mission profile and other generic parameters and data about performance, aerodynamics, and weight breakdown are extracted. A mathematical model of the UAV for flight simulation and its dynamic computations, along with automatic drawing is also produced. Also an optimizer based on genetic algorithms has been added to the tools, so that the UAV design can be iteratively improved in order to most effectively perform the mission selected. A detailed design of the UAV was carried out using traditional methodologies, and results compared with new tools like X-PLANE simulator. The static stability computations described are deemed to be effective since the evaluation of the UAV pilot on flying qualities correlates with predictions. Copyright © 2013 SAE International.

In several manufacturing processes, the cutting of 2D parts from sheets is an important task. The arrangement of the parts in the sheets, supported by computers, is called nesting and is addressed to minimize the wasted material. In literature some approaches are proposed, based on genetic or heuristic algorithms which emphasize different characteristics, e. g. the time complexity or the wasted material. In shipbuilding the parts to be arranged have significantly different sizes, which are often difficult to pack in a fast way using the standard methods in literature. In this work an approach is proposed, able to arrange parts with very different dimensions, which is based on the identification of a suitable starting rotation that ensures a solution in a reasonable time. The main steps are: A) importation of the model files of the parts to be packed, b) identification of a preliminary orientation and sorting of the parts (starting position), c) optimization of the position of the parts, ensuring a minimum distance between them. For the starting rotation, three different orientations are considered: i) the original orientation, ii) the x axis coincident with the minimum inertia axis, iii) the x axis aligned with the maximum edge. The orientation is selected in order to obtain the minimum area of the bounding box. The implementaiton of the method has been investigated and the results show the advantages of the approach: reduction of waste material and time for performing the nesting. © Springer-Verlag London 2013.

Keywords: CAD/CAM , CAPP , Cutting-stock , Nesting , Packing , Shipbuilding

We developed a wearable device to improve lower limb sport training. The presented system consists of a pair of spandex shorts which embed a processor unit, 2 accelerometers and 2 vibro motors. The accelerometers are located in proximity to the knees and measure tri-axial accelerations. We present a novel method to compute and correct asymmetry of lower limbs during training. The user performs an initial calibration phase which sets the accelerometer reference frames. While running, the system continuously refines the calibration using principal component analysis to take in account occasional shorts assessments. The system activates a corrective vibro feedback on the specific leg according to an asymmetry metric based on: (i) foot ground impact, (ii) phase error between legs, (iii) transversal knee movements. User tests demonstrated that the device is ergonomic to wear, easy to use and the corrective vibro feedback is appreciated during the training.

Keywords: Asymmetry correction , Lower limb rehabilitation , Sport training , Vibro feedback , Wearable training device

The quality of CFRP composites is highly dependent on the manufacturing process. Laminate performance is greatly affected by the void and resin fractions. Thicker structures result in lower quality. Thin composite laminates manufactured at high pressures offer best quality. However, impact and damage tolerance, buckling and concentrated stresses for rivets and bolts require redundancy which increases the thickness. Thick laminate structures lower CFRP mechanical properties. Composite laminates have advantage of good surface smoothness and low tolerances. A thin laminate tailored for the specific application with good monitoring system and support for buckling prevention with impact protection offers good solution. The bearing laminate is encapsulated between two sup porting layers with excellent outside tolerances and smoothness rep resenting the C-triplex concept. Inserts are included in the constructions for bolts or rivets. On the bearing laminate a monitoring tissue is installed for load history and structural integrity. The three layers are arranged in a way to house foam that provides support for buckling and thermal insulation. The C-triplex macro panels are bolted to a titanium or aluminum alloy skeleton of the aircraft body. C-triplex panels contain all ducts for the wires, pipes, and plug? necessary for the body interior.

Keywords: Aircraft structures , C-triplex , CFRP , Composite material , Modular construction

Maximum takeoff or maximum continuous power is surprisingly often insufficient to guarantee absolute flight safety. Modern aircraft also need a conspicuous amount of electric power. The automotive industry in many respects is technology leader while aerospace industry is more conservative due to safety concerns. Ferrari developed an electronic KERS and implemented it in their Formula-One racing cars. KERS is capable of producing peak electrical power of 60 kW for 7s at a mass of 20 kg including rechargeable batteries. The main goal of this article is to explore utilization of turbo-charged aerodiesel engines and conduct feasibility study of the F1-derived KERS to assist power generation in normal and critical flight phases. The KERS' reversible brushless electric motor works as a generator for all aircraft power needs and also provides starting power. It is demonstrated here that such design philosophy improves performance and flight safety of light-to-medium airplanes and helicopters.

Keywords: Diesel engine , Hybrid aircraft , Kinetic energy recovery system , Li-ion battery systems , Turbine engines

Composite structures such as CFRP offer significant weight reduction over the conventional aluminum alloys for aircraft. Weight reduction improves fuel efficiency of the aircraft by approximately 20% which results in cost savings and simultaneously reduces the operational environmental footprint. However, the new aluminum-lithium alloys offer significant improvements and are viable alternatives to CFRP. Aluminum lithium alloy 2195 with Friction Stir Welding is introduced as a successful alternative to CFRP primary structures. A "thick skin" monocoque design with integral stringers as crack stoppers is discussed. An old Macchi 205 WWII fighter plane has been redesigned both in CFRP and 2195-FSW for comparison. The final designs are comparable in weight, but 2195-FSW is more competitive based on mass production costs, reparability, and environmental impact. Macchi 205 airplane is used due to in-depth experience with the original aircraft geometry and loads. Knowledge gained here can be directly transferred to larger structures, from corporate jets to large transport category airplanes.

Keywords: 2195-FSW , Aircraft structures , Aluminium alloys , CFRP , Composite material

The psycho-physical state of a driver has been widely recognized as the crucial point in any issue concerning the development of models headed to improve the vehicle safety, either inherent and active, so much so that almost all the new in-vehicle technology, currently developing at a rapid rate, introduces devices to continuously monitor the driver. This paper describes the architecture of a real time, performance-based, driver monitoring system able to detect the decrease in driver performances due to driver distraction, fatigue, sleepiness and alcohol or drugs ingestion. The system processes the instantaneous lateral position of the vehicle on the road. This allows to work out an index of the lane keeping precision by means of the lateral position standard deviation (SDLP). This latter and the road environment complexity has been processed by a fuzzy inference system that has, as an output, a score reflecting the driver's ability to maintain adequate lane-tracking movements for a given road scenario. Fuzzy membership functions and inference rules has been based and optimized on data obtained on 12 subjects performing driving simulation under both baseline condition and two different cognitive overload situations induced by different secondary tasks, one with visual distraction, the other characterized by a pure cognitive load, respectively. Aim of the work is to attain to a black-box type devices that could both provide warnings or reminding in case of risky driving and encourage the driver to improve his behavior. Advantages would also come for parents of novice drivers promptly alerted for improper driving and even for the car insurance companies that could reward safe drivers.

Keywords: Cognitive load , Drive simulator , Fuzzy logic , Safe driving

In the automotive industry a significant part of research is dedicated to design and produce better products. The unavoidable presence of uncertainties in manufacturing processes and structural parameters leads to the necessity to develop stochastic models able to correctly represent physical behaviours. This paper presents numerical and experimental investigations on the effects of the fitting process on the stress/strain map of assembled automotive rim-disk systems. Different strategies of geometrical decomposition are used to condense large volumes of data by retaining essential information for the whole design process including not only manufacturing pre-stresses and operational loads but also dimensional tolerances of mating parts by means of a probabilistic model. Efficient approaches are used to identify the relative importance of input factors on the output uncertainties. A real test case of a wheel assembly is presented and discussed. Copyright © 2013, AIDIC Servizi S.r.l.

In considering the design activities of a stratospheric gondola for a multiuser experiment, the exchange of information between the structural designer and the various teams involved may be a critical issue. In fact, only part of the information is available at the beginning of the project, thus necessitating the use of a trial-and-error approach that leads to results which involve considerable expenditure. For small-and medium-size experiments, the problem of the exchange of information from the mechanical designer's point of view can easily be solved by using a pre-built gondola supplied by a hypothetical launch consortium. This is what we proposed as the "Strato-Bus" approach at the ESA Symposium 2009. Furthermore, in 2011 we also introduced a possible solution of a multi-user gondola design: a shared design for many combinations of experiments, the total weight of which is just below the maximum lift capacity of the balloon produced by several dedicated manufactories. But when the characteristics of the instrumentation make the use of a pre-built platform impossible, the problem of exchanging information arises once again, and this is what we have experienced in the case of the Large-Scale Polarization Explorer (LSPE) experiment. The design activities of the LSPE gondola are used here in order to introduce a "systematic approach" that is capable of saving both time and money for each team involved in the overall project.

In offshore applications and moreover in transports from ship-to-ship, the needs of highly sophisticated motion compensation solution are increasing. They consist of sensors, actuators and control units. To design the best mechatronic solution, it is necessary modeling the mechanical system in order to identify the transfer function and the dynamic behavior of the system. Currently Active Heave Compensation Systems are widely used in order to compensate for heave vessel motion, between a vessel moving under sea state and a fixed base or vice versa. Several research projects are ongoing in order to develop solutions able to compensate undesired movements also in ship to ship offloading operations especially in defense and military area in ship to ship operations. In this work we present an application of multibody modeling in Matlab/Simulink platform to simulate the dynamic behavior of Mother-Feeder ships during thansfer made by a marine crane, installed on Mother ship. In particular it will be payed attention on the dynamic quantities like position, velocity and acceleration needed to compensate for heave load movement.

Currently, directional and stability control systems (rudders and flaps) of high speed craft (HSC) are made by heavy steel box-shaped elements. This is mainly caused by the high hydrodynamic stresses applied on these elements due to the high cruising speed of HSC. In order to reduce the weight of these elements and to increase the resistance to external corrosive action, innovative manufacturing technologies and new materials are studied. In this paper, innovative hybrid steel-composite rudder are presented to use in high speed craft.

Nowadays, economical, technical and ergonomic factors have a great importance on the design of the agricultural tractors. The paper illustrates the use and the management of heterogeneous product information (manual measurements and drafts, 2D drawings, technical documentation, photos), advanced CAD modeling tools and digital human models, for the redesign and the ergonomic optimization of an agricultural tractor's driver cab. The project development has been organized using a top-down approach in a collaborative environment. At first, a manual measurement with gauges allowed to realize a technical draft of the whole agricultural tractor and of each component part of the driver cab. Then a main skeleton has been created in Catia V5 environment in order to specify all the datum elements necessary to model each sub-assembly of the tractor. Cabin, platform, engine, tires, seat, dashboard and controls have been organized separately and modeled considering the details related to the manual measurements and to the technical standards. Once obtained the 3D CAD model of the tractor, an opportune questionnaire was prepared and a test campaign was carried out with real operators in order to define the more critical control devices within the driver cab, as regards to usability and ergonomic issues. An "Ergonomics' Evaluation Index" (EEI) was defined taking into account the posture angles of the operator and the Rapid Upper Limb Assessment analysis tool available in the "Ergonomics Design & Analysis" module of Catia V5 based on the use of a digital human model. The index was validated comparing the results of tests carried out using virtual manikins of different percentiles performing a specific driving task, with the results of tests carried out by real operators, of the same percentiles, performing the same driving task. Critical values of the EEI obtained during some driving tasks in virtual environment, suggested to modify the shape and the position of some control devices in order to optimize the ergonomics of the driver cab. The adoption of the top-down modeling based approach allowed each change on a singular component part to be automatically propagated on the whole assembly, making easy the changes on the virtual prototype. Copyright © 2012 by ASME.

The paper deals with a functional approach to optimal dimensioning of automotive transmission shafts. In particular, the paper summarizes the results of a research activity developed on automotive transmission shafts to reduce the unpleasant movement of the transmission lever known as "shift lever movement". The design problem was faced by focusing the axial clearances of the wheels assembled on the transmission shaft. First, the functional approach to optimal dimensioning proceeds from the study of different working conditions of the automotive manual transmission and focuses on corresponding geometrical constraints and design parameters. Then, it uses simplified schemes, each of them related to a different working condition, to set a series of functional dimensioning loops for the transmission shaft. Subsequently, the approach introduces an appropriate index to evaluate the Information Content for each dimensioning scheme and it addresses the optimal dimensioning scheme, related to the minimization of the Information Content. After this, the approach foresees worstcase to check the axial clearances of the wheels assembled on the shaft. In a such way the effect of the dimensioning are directly evaluated in terms of performances of the transmission. In fact, the reduction of axial clearances for the wheels assembled on the shaft causes a direct reduction of the "shift lever movement". The functional approach to optimal dimensioning is applied to an automotive transmission set and the proposed dimensioning schema of the shaft is compared with different dimensioning schemes including one currently used in an international automotive company. A final discussion of the results, in terms of reduction of axial clearances of the parts assembled on the shaft, is provided. Copyright © 2012 by ASME.

Keywords: Functional dimensioning , Information content , Transmission set

Background: A fundamental pre-requisite for the clinical success in dental implant surgery is the fast and stable implant osseointegration. The press-fit phenomenon occurring at implant insertion induces biomechanical effects in the bone tissues, which ensure implant primary stability. In the field of dental surgery, the understanding of the key factors governing the osseointegration process still remains of utmost importance. A thorough analysis of the biomechanics of dental implantology requires a detailed knowledge of bone mechanical properties as well as an accurate definition of the jaw bone geometry.Methods: In this work, a CT image-based approach, combined with the Finite Element Method (FEM), has been used to investigate the effect of the drill size on the biomechanics of the dental implant technique. A very accurate model of the human mandible bone segment has been created by processing high resolution micro-CT image data. The press-fit phenomenon has been simulated by FE analyses for different common drill diameters (D A = 2.8 mm, D B = 3.3 mm, and D C = 3.8 mm) with depth L = 12 mm. A virtual implant model has been assumed with a cylindrical geometry having height L = 11 mm and diameter D = 4 mm.Results: The maximum stresses calculated for drill diameters D A, D B and D C have been 12.31 GPa, 7.74 GPa and 4.52 GPa, respectively. High strain values have been measured in the cortical area for the models of diameters D A and D B, while a uniform distribution has been observed for the model of diameter D C . The maximum logarithmic strains, calculated in nonlinear analyses, have been ε{lunate} = 2.46, 0.51 and 0.49 for the three models, respectively.Conclusions: This study introduces a very powerful, accurate and non-destructive methodology for investigating the effect of the drill size on the biomechanics of the dental implant technique.Further studies could aim at understanding how different drill shapes can determine the optimal press-fit condition with an equally distributed preload on both the cortical and trabecular structure around the implant. © 2012 Frisardi et al.; licensee BioMed Central Ltd.

Full field optical techniques can be reliably used for 3D measurements of complex shapes by multi-view processes, which require the computation of transformation parameters relating different views into a common reference system. Although, several multi-view approaches have been proposed, the alignment process is still the crucial step of a shape reconstruction. In this paper, a methodology to automatically align 3D views has been developed by integrating a stereo vision system and a full field optical scanner. In particular, the stereo vision system is used to remotely track the optical scanner within a working volume. The tracking system uses stereo images to detect the 3D coordinates of retro-reflective infrared markers rigidly connected to the scanner. Stereo correspondences are established by a robust methodology based on combining the epipolar geometry with an image spatial transformation constraint. The proposed methodology has been validated by experimental tests regarding both the evaluation of the measurement accuracy and the 3D reconstruction of an industrial shape. © 2011 Elsevier Ltd. All rights reserved.

Keywords: Multi-view measurements , Optical tracking , Stereo vision , Structured light

The paper describes the development of a multimodal environment that can be used as a tool to train operators to perform maintenance tasks of industrial products during their lifecycle. The environment provides a visual and haptic representation of a product through the use of commercially-available hardware and software technologies. The new environment mixes interactive simulations of products, based on Virtual Reality technologies, and the information included in the traditional instruction manuals. The paper discusses about what can be effectively simulated with the available technology, and how the current technological limitations can be overcome by using the potentialities offered by a multimodal approach. Technology limitations can also be overcome by mixing two different strategies for coupling parts: the physics-based and the constraint-based approach. A case study provided by a company working in the field of household appliances has been used to prove the concept, to develop, test and finally refine the multimodal environment. The paper describes the development of the multimodal environment and presents the results of the user tests. Copyright © 2012 by ASME.

Developing green propulsion concepts for aviation requires some changes in standard procedures for the preliminary aircraft design. Standard design procedures are not readily applicable to aircraft/rotorcraft that use multiple energy sources; innovative concepts like hybrid propulsion systems require new approaches in weight and performance prediction. In this paper the application of new methods is explored to account for the changes in the governing equations when using hybrid propulsion: a design code allows predicting the performances once the hybrid propulsion architecture is chosen. Focus is on hybrid propulsion systems based on a diesel heavy fuel ICE (Internal Combustion Engine) combined with an electric motor in a parallel configuration. This study relies on simple structure and material performance indexes, neglects stability and control analysis, and uses very simple aerodynamic models.

Keywords: Aircraft sizing , Diesel , Hybrid propulsion

A significant issue in aircraft engines is quantifying residual life to overhaul. The algorithm described in this paper calculates with a good level of reliability the residual life of a petrol piston engine. The method was tested on small, latest-generation, naturally-aspirated aircraft and racing piston engines, and has been effective in several experiments. This method is implemented directly on the electronic control system of the engine with very few lines of C-code. The method can also be used in many industrial engines. This innovative method assumes that only two main factors (power level and wear) affect engine durability or time between overhauls. These two factors are considered as separate and combined with worst case criteria. The wear is assumed to follow a logarithmic law and a formula similar to the Miner's law for material fatigue is used, making it possible to calculate the power-level curve with knowledge of only two points. The wear-curve is also related to elapsed engine cycles. The algorithm is very simple and can be implemented with just a few lines of software code accessing data collected from existing sensors. The system is currently used to evaluate actual residual life of racing engines.

Keywords: Aircraft , Algorithm , Durability , Engine

The KAD (Knowledge Aided Design) tool is developed to predict the performance of an F1 car in different driving conditions and with different configurations. The regulations to put in trimming a car, also in the exasperated technology of the competitions, still demand a remarkable dose of luck and an elevated number of tests. It is then important to know a set of regulations close to the optimal trim before testing the car on the track. The difficult phase of this process is to evaluate the lap time. As a matter of fact driving style, track conditions and car behavior should be simulated. The optimisation of the fuzzy controller that simulates the pilot for an F1 racing car is difficult due to handling problems and velocity of response. For this purpose a specific Genetic Algorithm (GA) was conceived and tuned to work with a lumped mass model of an F1 racing car for the optimization of the fuzzy controller that simulates the pilot. A new mutation and a new crossover operator were defined to complement the standard crossover and mutation operators of the basic Holland's GA. This was necessary in order to increase the overall performance of the fuzzy pilot. This approach was tested on an F1 car due to the huge amount of data available (Donnarumma, 1998; Moelenbein, 1989; Lee and Takagi, 1993).

Keywords: Control , Fuzzy logic , KAD , Performance