Design methods for mobility

This paper is conceived to optimize the design of the thermodynamic cycle of a turbine (Brayton cycle) that uses a modern common rail diesel engine as an "active" combustion chamber. In this case the "active" combustion chamber produces the mechanical energy that drives the fan. The incoming air is compressed by the compressor, then is cooled (aftercooler) and inputted in the diesel engine. A high pressure common rail system optimizes the combustion in the diesel combustion chamber and the expansion begins inside the diesel engine. At the exhaust of the combustion chamber a turbine completes the expansion of the hot gases. A nozzle accelerates the exhaust from the turbine to increase the overall thrust. The mechanical energy from the diesel and from the turbine engizes the compressor and the fan. The system can be seen as a turbocharged diesel engine with the turbocharger that outputs energy to the turbofan, increasing the output power and or the efficiency. A diesel-turbine compound can be realized in this way. The coupling of the two system may be obtained in several different ways. The simplest is to put on the same shaft the compressor, the diesel crankshaft and the turbine. In front of the compressor a speed reducer drives the fan. A second example is to connect the turbine and the diesel on to electric generators. Electric engines are connected to the compressor and to the fan. The traditional turbo-diesel has the compressor coupled to the turbine, and the diesel engine that moves the fan. In this latter case, however, the turbine does not energize the fan. Many other hybrid and non hybrid solution are possible. The problem is to optimize temperatures, pressures and rpm to the different machines that form the compound. The availability of many experimental data for diesel and turbines makes it possible to obtain a design of a "true" feasible optimum Diesel-Brayton cycle. The high efficiency justifies the huge manufacturing and development costs of these turbocompound engines.

Common rail systems are conventionally employed in diesel and gasoline engines. Pressure, precision and velocity are key factors for correct engine power management. Current systems are based on digital computers and PID control systems. When anomalies occur, recovery strategies are used and engine performance is significantly reduced. Then technical assistance is required to restore normal condition. For safety reasons this approach cannot be used in aeronautical, naval and energy-supply applications. In some cases it is necessary to utilize all the possible energy from the power unit causing significant life-reduction of the engine. In this case a progressive reduction strategy should be used and injection law should be reduced accordingly. For this purpose injection control based on fuzzy logic is more effective . In this case, traditional PID control systems are substituted by fuzzy logic control. A reference map is introduced in the Full Authority Digital Electronic Control, this map is interpreted by the fuzzy logic control system that adapts the injection law to the current engine situation. For example, if fuel temperature tends to increase over the normal level, injection pressure is reduced by the fuzzy control system and injection time is increased to obtain the maximum possible power output. This approach can be easily implemented with very simple and effective fuzzy logic controllers. This method has been experimented on a commonrail test bed and results are compared with traditional "binary recovery strategy" FADEC. Maximum power output is slightly reduced since fuzzy controllers are less effective than PID in "near reference" conditions. However, when anomalies take place or are simply beginning to appear the fuzzy FADEC behaviour is more effective and preserves engine performance more effectively. Aim of this paper it to define rules and fuzzy controllers to optimize the performance of a diesel engine in various operating conditions with particular attention to the power output.

A main problem in aircraft engines is the evaluation of residual life to TBO. The algorithm described in this paper calculates with good reliability the residual life to TBO of a petrol piston engine. The method was tested on small last-generation naturally-aspirated-avio piston engine, and has demonstrated to be effective in several experimental tests. This method is implemented directly in the FADEC or ECU of the engine with very few lines of C-Code. The method can be used also in many industrial engines. This innovative method assumes that only two main factors (load and wear) affect engine durability or Time Between Overhauls (TBO). These two factors are considered as separate and combined with the worst case criteria. The load is assumed to follow a logarithmic law and a formula similar to the Miner's law for material fatigue is used, making possible to calculate the "load curve" with die knowledge of only two points. The "wear" curve is related to elapsed engine cycles, and is easy to implement since it is related to technological. The resulting algorithm is very simple and can be implemented in very few software lines with data collected from the already existing sensors.

In the shipbuilding industry, the manufacturing of large yacht hulls is a complex process. Metal hulls are traditionally manufactured by welding pre fabricated large steel panels to form the external superstructure. A surface finishing process is then carried out in order to obtain a final target surface having a smooth curvature. The methodologies manly rely on manual processes based on the measurement of the as built hull shape through simple testing instrumentation. Well-experienced workers are required, and a great amount of time is usually wasted, thus affecting the overall shipyard competitiveness. This paper introduces a methodology for automating the measurement process of as built hull yacht shapes. The methodology, which is based on the integration of a robotic system with an optical scanner, provides accurate non contact 3D full field measurements of the hull surface. The placement of the robotic system around the hull shape is determined by a laser total station thus allowing the automatic multi view data registration into a common reference frame. The proposed approach represents the basis for the automation of the whole surface finishing process of large yacht hulls. In this paper, the methodology has been tested by measuring a large broadside area of a 59 m hull assembled within a shipyard. © 2012 Elsevier Ltd. All rights reserved.

Keywords: Laser tracking , Mechanical tracking , Optical 3D measurement , Shipbuilding

The search for safe vehicles is increasing with both diffusion of high traffic density over the world and availability of new technologies providing sophisticated tools previously impossible to realize. Design and development of the necessary devices may be based on simulation tests that reduce cost allowing trials in many directions. A proper choice of the arrangement of the drive simulators, as much as of the parameters to be monitored, is of basic importance as they can address the design of devices somehow responsible for the drivers safety or, even their lives. This system setup, consisting of a free car simulator equipped with a monitoring system, collects in a nonintrusive way data of the car lateral position within the road lane and of its first derivative. Based on these measured parameters, the system is able to detect symptoms of drowsiness and sleepiness. The analysis is realized by a fuzzy inferential process that provides an immediate warning signal as soon as drowsiness is detected with a high level of certainty. Enhancement of reliability and minimisation of the false alarm rate are obtained by operating continuous comparison between learned driver typical modalities of operation on the control command of the vehicle the pattern recorded. © 2012 Pasquale Sena et al.

This article presents multidisciplinary optimization methods applied to the design and performance evaluation of a magneto-mechanical energy scavenger for automotive wireless tire sensors. Optimal performance strictly depends on source characteristics, volume, weight and power density targets, energy scavenger typology, technological and manufacturing capabilities, optimization and reliability of performance, environment requirements, and so on. Thus an optimization study has been conducted on equivalent viscous damping due to strong magneto-electrical-mechanical coupling. To do this, an optimization tool has been developed that maximizes the power output in specific working conditions by varying the number and size of coils. © The Author(s) 2011.

Keywords: damping optimization , electromechanical device , energy harvester , nonlinear dynamic

This article presents a very compact electromechanical wideband energy harvester optimized for tire applications. The device exploits an asymmetric magnetic spring to be adaptive and effective at almost any vehicle speed. The device has been simulated through an experimentally validated SIMULINK block-oriented model. The simulation takes into account nonlinear dynamic and adaptive resonant behavior of the seismic mass, electromagnetic, and magnetostatic coupling between floating magnetic mass and coils, and the transfer of the generated power to an external load by means of a nonlinear circuit interface. A particular focus on the pneumatic effect on the floating magnet has been made. A convenient choice of clearance between moving and fixed parts can be used to create an effective air brake preventing or softening shocks with end stops and to modify system dynamic. A nonlinear equivalent spring dashpot model of the pneumatic effect and a method to estimate its parameters from geometry have been proposed. An analysis of different nonlinearities of the system at different vehicle speed and a study on the combined effect of softening and hardening behavior of the device have been performed and discussed. © SAGE Publications 2011.

Keywords: adaptive resonance , electromechanical device , energy scavenger , nonlinear dynamic

The LSPE is a balloon-borne mission aimed at measuring the polarization of the Cosmic Microwave Background (CMB) at large angular scales, and in particular to constrain the curl component of CMB polarization (B-modes) produced by tensor perturbations generated during cosmic inflation, in the very early universe. Its primary target is to improve the limit on the ratio of tensor to scalar perturbations amplitudes down to r = 0.03, at 99.7% confidence. A second target is to produce wide maps of foreground polarization generated in our Galaxy by synchrotron emission and interstellar dust emission. These will be important to map Galactic magnetic fields and to study the properties of ionized gas and of diffuse interstellar dust in our Galaxy. The mission is optimized for large angular scales, with coarse angular resolution (around 1.5 degrees FWHM), and wide sky coverage (25% of the sky). The payload will fly in a circumpolar long duration balloon mission during the polar night. Using the Earth as a giant solar shield, the instrument will spin in azimuth, observing a large fraction of the northern sky. The payload will host two instruments. An array of coherent polarimeters using cryogenic HEMT amplifiers will survey the sky at 43 and 90 GHz. An array of bolometric polarimeters, using large throughput multi-mode bolometers and rotating Half Wave Plates (HWP), will survey the same sky region in three bands at 95, 145 and 245 GHz. The wide frequency coverage will allow optimal control of the polarized foregrounds, with comparable angular resolution at all frequencies. © 2012 SPIE.

Keywords: Bolometer , Cosmic microwave backgorund , Polarimeter , Polarization , Radiometer , Stratospheric balloons

Composite materials have increasingly become more common in ground transportation. As this occured thicker panels, as compared to composite panels used in aviation, become necessary in order to withstand high impact loads and day to day degradation. The effectiveness of these panels was often limited by the strength of the joint in which the panel was attached to the frame of the vehicle. Investigating methods of reducing strain concentrations within these joints would increase the effectiveness in using composite materials in ground transportation applications by increasing the load necessary for joint failure to occur. In this study, fiber optic strain gages were embedded in a composite panel along the bearing plane of a thick, single-lap, bolted joint. The gages allow for the strain profile above the hole to be determined experimentally. Several clearance values were then implemented in the bolt to determine their effect on the strain concentrations. Strain increased at every gage, by nearly the same proportion, when clearance was increased from zero to three percent. When clearance was further increased to five percent strain only continued to increase at gages three and four, with one and two remaining similar in value to what was seen at three percent clearance. Ultimately, like in thin composite panels, the zero percent clearance condition was the stiftest. ©2010 Society for Experimental Mechanics Inc.

Viscoelastic contact interfaces can be found in various robotic components that are covered with a compliant surface (pad) such as anthropomorphic hands, biomimetic haptic/tactile sensors, prostheses, and orthoses. In all these cases, it is desirable to obtain thin and resistant pads with predetermined compliance and damping properties (e.g., mimicking the human skin and pulpy tissues). In order to overcome the limits of homogeneous layers of a soft viscoelastic material, which is commonly used in the aforementioned devices, this paper suggests the adoption of soft pads that are composed of a continuous external layer (skin) coupled with an internal layer having fluid-filled voids. The process to design the pad starts with the selection of a hyperelastic medium with proper tribological features, whose constitutive parameters are determined by numerically fitting nonlinear stress-strain curves under pure homogenous deformations. The optimization of the internal layer morphology is then achieved through nonlinear finite element analysis (FEA) that provides an estimate of hardness and friction influence on the pad static compliance. Finally, the pad is filled with a viscous fluid that is chosen to modify time-dependent phenomena and to increase damping effects. The effectiveness of the procedure is proven by designing and modeling better-behaved artificial pads that mimic human-finger dynamic properties. © 2011 IEEE.

Keywords: Finite deformations , finite element analysis (FEA) , hyperelasticity , quasi-linear model , viscoelastic contact

Background: A precise placement of dental implants is a crucial step to optimize both prosthetic aspects and functional constraints. In this context, the use of virtual guiding systems has been recognized as a fundamental tool to control the ideal implant position. In particular, complex periodontal surgeries can be performed using preoperative planning based on CT data. The critical point of the procedure relies on the lack of accuracy in transferring CT planning information to surgical field through custom-made stereo-lithographic surgical guides.Methods: In this work, a novel methodology is proposed for monitoring loss of accuracy in transferring CT dental information into periodontal surgical field. The methodology is based on integrating 3D data of anatomical (impression and cast) and preoperative (radiographic template) models, obtained by both CT and optical scanning processes.Results: A clinical case, relative to a fully edentulous jaw patient, has been used as test case to assess the accuracy of the various steps concurring in manufacturing surgical guides. In particular, a surgical guide has been designed to place implants in the bone structure of the patient. The analysis of the results has allowed the clinician to monitor all the errors, which have been occurring step by step manufacturing the physical templates.Conclusions: The use of an optical scanner, which has a higher resolution and accuracy than CT scanning, has demonstrated to be a valid support to control the precision of the various physical models adopted and to point out possible error sources. A case study regarding a fully edentulous patient has confirmed the feasibility of the proposed methodology. © 2011 Frisardi et al; licensee BioMed Central Ltd.

Interacting with computers by using the bodily motion is one of the challenging topics in the Virtual Reality field, especially as regards the interaction with large scale virtual environments. This paper presents a device for interacting with a Virtual Reality environment that is based on the detection of the muscular activity and movements of the user by the fusion of two different signals. The idea is that through muscular activities a user is capable of moving a cursor in the virtual space, and making some actions through gestures. The device is based on an accelerometer and on electromyography, a technique that derives from the medical field and that is able to recognize the electrical activity produced by skeletal muscles during their contraction. The device consists of cheap and easy to replicate components: seven electrodes pads and a small and wearable board for the acquisition of the sEMG signals from the user's forearm, a 3 DOF accelerometer that is positioned on the user's wrist (used for moving the cursor in the space) and a glove worn on the forearm in which these components are inserted. The device can be easily used without tedious settings and training. In order to test the functionality, performances and usability issues of the device we have implemented an application that has been tested by a group of users. Specifically, the device has been used as natural interaction technique in an application for drawing in a large scale virtual environment. The muscular activity is acquired by the device and used by the application for controlling the dimension and color of the brush. Copyright © 2011 by ASME.

The paper describes a collaborative Mixed-Reality (MR) environment to support the product design assessment. In particular, we have developed a collaborative platform that enables us to improve the design and the evaluation of cars interior. The platform consists of two different systems: the 3D Haptic Modeler (3DHM) and the Mixed Reality Seating Buck (MRSB). The 3DHM is a workbench that allows us to modify the 3D model of a car dashboard by using a haptic device, while the MRSB is a configurable structure that enables us to simulate different driving seats. The two systems allow the collaboration among designers, engineers and end users in order to get, as final result, a concept design of the product that satisfies both design constraints and end users' preferences. The usability of our collaborative MR environment has been evaluated by means of some testing sessions, based on two different case studies, with the involvement of users. Copyright © 2011 by ASME.

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.

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

Ballistic requirements in the design of military aerospace components are critical for the structural assessment. Although experimental tests remain fundamental, numerical analyses allow us to simulate such a very complex scenario. However, in order to improve the consistency of such simulations, several aspects have to be considered in detail. The material behavior is a key one: constitutive laws, able to describe the material behavior in terms of hardening, strain rate, damage criteria, temperature, etc⋯, is fundamental. Moreover a detailed validation of numerical results is needed. The analysis of ballistic data (such as the residual velocity and the direction of the bullet after the impact) is only one option, but reliable simulations of damage shape and size are the real target. Therefore the paper will focus on the comparison between the experimental damage and the simulated one using a 3D acquisition of the experimental impacted area. This approach allows us not only to evaluate the damage in the macroscale field but also in the near micro-scale: shape on the border of the damage. © 2011 Published by Elsevier Ltd.

Keywords: AL-6061-T6 shaft , Ballistic impact , NATO 7.62 mm , Numerical simulations , Reversal engineering

Engine efficiency and optimization are key aspects for automotive manufacturers. Lamborghini has particularly focus attention for reduction of time to market building up a synergic approach for new component's development using simulation, Know-how experiences, engine engineering expertise and experimental validation. In particular to reach the best results in the shortest time it is used, in the preliminary stage of development, a massive support of simulation analysis. In the Lamborghini approach analysis and simulation has become key aspects during concept and development of timing drives. This type of activity is used to support the development of better chain timing drives focusing on improving durability, lower friction, less noise and reduced cost in less time than conventional trial and processes. Even during the concept design phase it is useful to use a mathematical model to calculate dynamic forces and motions of a chain drive. These models are used to assess in detail the choice of drive layout, to check that component load limits are not exceeded and to make a first choice of the tensioner settings. Later, when the first prototype engines are available, measurements of timing drive sprocket motion, tensioner motion and tensioner force are typically taken. At this stage the model can be correlated to the measured data and then the correlated model can then be used to explore the potential for improvements to the timing drive during later phases of engine development. This paper describes the correlation of a mathematical model of a complex timing chain drive for a Lamborghini V12 gasoline engine to measurements made on a prototype engine. The depth of model required and the choice of stiffness and damping values needed to give excellent agreement between calculations and measured data are discussed. © 2011 SAE International.

The main objective of this works is to develop a wearable device to improve sport training in lower limb. The system consists of a pair of spandex shorts which embed a processor unit, 2 accelerometers, 2 vibro motors, a SD card reader\writer module and a real time clock. The accelerometers are located in proximity to the knees and are used to measure in real time the tri-axial accelerations for each leg. We present a novel algorithm to compute asymmetry from the 3 axial sensor data. We propose two applications of the system: for real time active correction and for data logging. In the correction mode, adjustment signal are sent to the user during the training by vibrations. The vibration signal is sent to the specific leg and its intensity is related to the entity of required correction. The second application of the system is as datalogger. The device stores all the training data in a SD card. Those log files can be processed using a dedicated application on a PC. This information can be very useful for long term analysis. This novel approach to sport training is very useful to athletes and sport medicine doctor in order to improve posture, efficiency and performance, but it can be also useful in other medical appliances such as rehabilitation. © 2011 IEEE.

Keywords: posture correction , sport training , vibro feedback , wearable

Active antiskid systems for high performance motorbikes are difficult to implement due to the necessity to combine performance, equilibrium, handling and safety. In order to design and optimize a fuzzy controlled antiskid system for motorbikes a fuzzy model of the pilot was applied to a lumped-mass model of the motorcycle (two different models have been considered). The fuzzy pilot acts on the steering angle to control trajectory, yaw angle, yaw velocity and roll angle. Throttle position vs. time curve, gear and an adherence model between tire and road are given as input. The fuzzy pilot is implemented with Matlab/Simulink, and simply tries to keep equilibrium. Only measurable inputs were given as input variables of the antiskid fuzzy controller. The output is the percent reduction in throttle position. The motorcycle-fuzzy-pilot model proved to be quite accurate. Motorcycle maximum velocity resulted higher than the real one due to the simplifying hypothesis. In curves the fuzzy pilot is less efficient than the real pilot. In fact there was a low frequency oscillation around the optimum steering angle. This fuzzy controlled antiskid proved to work quite well since equilibrium is attained also in critical situations where the motorcycle-fuzzy-pilot model alone fails to keep equilibrium.

The progressive increase of tire-size has concurred to a sensitive improvement of the adherence with consequent increase of car safety. However, the wide tires have problems to expel the water in excess in heavy rain condition. For this reason the phenomenon of the aquaplaning is increasingly felt and is the cause of several automotive accidents. It is not a case that nearly all tire manufacturers supply "rain" tires and adherence in wet conditions is highly advertised. A typical accident happens when aquaplaning occurs in motorway at high speed. One or more tires lose adherence and the car begins to spin. If the pilot is not able to regain the initial direction, the car may hit the guardrail or another car. In this case the modern control systems like the ESP (Electronic Stability Program) and the ASR (Anti Skid Regelung) do not have time or are not able to manage a pre-spin or spin situation at elevated slip-angles. In this paper, a fuzzy control system able to deal with these conditions is introduced. The car has been simulated with a 9 DOF lumped-mass model that does not take into account suspensions and it considers a rigid car on smooth asphalt. The model of adhesion of the tire, instead, takes into account the effect of transverse forces on the longitudinal adherence. An expert pilot controls a high-speed spin with difficulty also. In this paper, a fuzzy control system that is able to control the brake torque on each single tire has been considered. The fuzzy control system works quite well and the car does not even enter in a true spin if enough adherence is present or if the slippery zone on asphalt is limited.