Design methods for mobility

Road accidents represent the primary cause of death among young drivers. To understand the emerging issue of young drivers' involvement in traffic accidents abroad, risk-taking behaviors were investigated in familiar and unfamiliar driving situations. Twenty-two young Chinese drivers completed a road regulation test followed by a simulated test drive. The number of traffic violations and accidents in familiar and unfamiliar driving intersections were correlated to road regulation knowledge, risk perception scores and to self-assessment of driving skills. Significant number of mistakes was found in risk-taking situations, regardless of the familiarity of the situation, especially for drivers that presented high ratings of self-assessed driving skills. Results show that risk-taking behaviors while driving in unfamiliar conditions are mediated by psychological factors, like self-assessment of being a good driver, more than the actual knowledge of road regulation rules. Implications for international driving can be considered for future research development.

Keywords: Driving skills , International driving , Knowledge of traffic laws , Risk perception , Road intersection , Road violations and accidents , Young drivers

An impulsive thruster propulsion system that could be used in a multi-modal UAV capable of sustained aerial flight, locomotion in water and deployment from a tube filled with compressed air is under development. This paper covers the design and optimisation process of the propulsive system, as well as its modelling with analytical and CFD simulations to predict the performances. The system is designed to fulfil vehicle mission requirements in terms of altitude and velocity after water/air transition. The thruster uses a common CO2 cartridge available off-the-shelf to accelerate water stored inside a water chamber along with an inflator to activate and regulate the mechanism remotely for efficient and sustained thrust. Water is chosen as vectorial fluid since it is available from the surroundings. Water chamber sizing process uses an analytical model calibration through CFD approach to refine an analytical model and predict propulsion performances. After thruster sizing, an experimental prototype was fabricated and tested for model validation. A comparison and discussion of the results as future work is also proposed with areas for improvement and development.

A multi-modal UAV capable of sustained aerial flight, locomotion in water and deployment from a tube filled with compressed air is under development. This paper covers the design and integration process of a CO 2 thruster previously designed in a vehicle designed to fulfil mission requirements in terms of altitude and velocity after water/air transition. The thruster uses a common CO 2 cartridge available off-the-shelf to accelerate water stored inside a water chamber for efficient and sustained thrust. Water is chosen as vectorial fluid since it is available from the surroundings. Analytical model, described in the paper, evaluates water to air transition phase in terms of trajectory, reached altitude and velocity. After thruster performances evaluation thanks to the analytical model, an experimental prototype was fabricated and tested for model validation. High speed camera is used to track vehicle transition and Kinovea software exports resulting data from a recorded video to spreadsheet formats for scientific study and post-processing. A comparison and discussion of the results as future work is also proposed with areas for improvement and development.

Keywords: Bimodal vehicle , Bio-inspired vehicle , Testing , Transition , Unmanned vehicle

A servo-hydraulic road simulator test rig (aka four-poster) can play a key role in testing and development of road vehicles. Its use for durability testing, NVH analysis, suspension setup optimization etc. is widespread. Engineers often make use of four-poster testing to validate their dynamic simulation models as well. The use of a so-called four poster is normally restricted to four-wheeled vehicles, typically passenger cars and light commercial vehicles. Motorbikes might also require similar R&D activities, even more so now that the market appears to be interested in electronically adjustable and semi-active suspension systems, especially for adventure/touring bikes; however, there are not many specific rigs around. This work proposes a method to retrofit a four-poster into a two-poster dedicated to motorbikes by means of a simple auxiliary structure: the so-called BikeShake. A case study has been reported at the end of the paper to validate the project.

Keywords: Four-poster , Indoor testing , Motorcycle testing , Motorcycle vertical dynamics , Road reproduction , Two-poster

Purpose: Currently, the reduction of weight in automotive is a very important topic in order to lower the air pollution. In this context, the purpose of the present paper was to analyze a real case study through a comparison of the environmental sustainability between a conventional steel crossbeam for light commercial vehicles and an innovative lightweight aluminum one. Methods: For both scenarios, a cradle-to-grave life cycle assessment methodology and a sensitivity analysis has been used through the study of the following phases: mineral extraction, component manufacturing, use on vehicle, and end of life. In particular, many primary data and a complete vehicle model simulation with three different European driving cycles have been used in order to reach the highest possible level of accuracy during the analysis. Results and discussion: Regarding the manufacturing phase, the aluminum component's production gave the highest impact because of the high energy required in the mineral reduction. Anyway, this stage of the analysis had a low effect on the entire LCA, because the benefit of weight reduction during vehicle use showed a strongly higher contribution. The urban driving cycle had the most relevant impact, as a consequence of the frequent start and stop operations and the longest time with engine at idle speed, while the extra-urban cycle is the less demanding due to its higher average speed and no start and stop. Conclusions: In conclusion, the present research demonstrated the environmental importance of the lightweight for an actual case study in the commercial vehicles field.

Keywords: Aluminum , Automotive , Commercial vehicles , Life cycle assessment (LCA) , Lightweighting , Steel

Race car performance is strongly affected by aerodynamics. Due to downforce generated by the vehicle floor (i.e. diffuser), vehicle ride heights are key parameters to improve performance, and the coupling of aerodynamics and suspension is one of the key points of race car setting. This work focuses on the suspension and aerodynamic coupling from the vertical dynamics point of view. Besides road holding performance, for race cars, aerodynamic performance and stability are major factors. Downforce decreases laptime (the main performance target) but pitch instability is a non-desired effect that can happen in high downforce race cars. A new vertical dynamic performance index is proposed through the use of simulation to improve aerodynamic performance and understand the pitch instability phenomenon. This new index uses all relevant vehicle nonlinearities related to vertical dynamics and can handle a specific track profile and vehicle speed range, allowing the analysis be conducted according to a circuit specification. A previously validated Formula 3 car model was used as an example.

Keywords: Aerodynamics , stability analysis , suspension systems

In this work, a reliable and effective method to predict the vehicle side-slip angle is given by means of an artificial neural network. It is well known that artificial neural networks are a very powerful modelling tool. They are largely used in many engineering fields to model complex and strongly non-linear systems. For this application, the network has to be as simple as possible in order to work in real-time within built-in applications such as active safety systems. The network has been trained with the data coming from a custom manoeuvre designed in order to keep the method simple and light from the computational point of view. Therefore, a 5-10-1 (input-hidden-output layer) network layout has been used. These aspects allow the network to give a proper estimation despite its simplicity. The proposed methodology has been tested by means of the CarSim® simulation package, which is considered one of the reference tools in the field of vehicle dynamics simulation. To prove the effectiveness of the method, tests have been carried out under different adherence conditions.

Typical active safety systems that control the dynamics of passenger cars rely on the real-time monitoring of the vehicle sideslip angle (VSA), together with other signals such as the wheel angular velocities, steering angle, lateral acceleration, and the rate of rotation about the vertical axis, which is known as the yaw rate. The VSA (also known as the attitude or "drifting" angle) is defined as the angle between the vehicle's longitudinal axis and the direction of travel, taking the centre of gravity as a reference. It is basically a measure of the misalignment between vehicle orientation and trajectory; therefore, it is a vital piece of information enabling directional stability assessment, such as in transience following emergency manoeuvres, for instance. As explained in the introduction, the VSA is not measured directly for impracticality, and it is estimated on the basis of available measurements such as wheel velocities, linear and angular accelerations, etc. This work is intended to provide a comprehensive literature review on the VSA estimation problem. Two main estimation methods have been categorised, i.e., observer-based and neural network-based, focussing on the most effective and innovative approaches. As the first method normally relies on a vehicle model, a review of the vehicle models has been included. The advantages and limitations of each technique have been highlighted and discussed.

Keywords: Extended Kalman Filter , GPS-aided estimation , Neural networks , Unscented Kalman Filter , Vehicle dynamics , Vehicle state estimation

This study presents a modelling system to evaluate the impact of weight reduction in light commercial vehicles with diesel engines on air quality and greenhouse gas emissions. The PROPS model assesses the emissions of one vehicle in the aforementioned category and its corresponding reduced-weight version. The results serve as an input to the RIAT + tool, an air quality integrated assessment modelling system. This paper applies the tools in a case study in the Lombardy region (Italy) and discusses the input data pre-processing, the PROPS-RIAT + modelling system runs, and the results.

Keywords: Air quality , Greenhouse gases , Lightweighting , Multi-objective optimization , Road transport , Scenario analysis

The paper presents a comparison between the emission levels produced along the most used standard driving cycles (NEDC, WLTC, CADC) by a Light Commercial Vehicle (LCV). A proven simulation tool based on real-world emission data (RDE, Real Driving Emissions) has been used instead of a demanding test campaign. Emission levels have been computed for each cycle in three conditions (urban, combined, extra-urban/highway). Then the results have been compared with Euro 5 limits and real-world emission levels to highlight each driving cycle objectivity and representativeness. Among others, the WLTC driving cycle seems to be the most plausible one yet, as expected, it is not very representative of the real world.

Keywords: Diesel Emissions , Driving Cycle , Emissions Simulation , European Driving Cycles

In this work, optimal control theory is applied to minimum lap time simulation of a GP2 car, using a multibody car model with enhanced load transfer dynamics. The mathematical multibody model is formulated with use of the symbolic algebra software MBSymba and it comprises 14 degrees of freedom, including full chassis motion, suspension travels and wheel spins. The kinematics of the suspension is exhaustively analysed and the impact of tyre longitudinal and lateral forces in determining vehicle trim is demonstrated. An indirect optimal control method is then used to solve the minimum lap time problem. Simulation outcomes are compared with experimental data acquired during a qualifying lap at Montmeló circuit (Barcelona) in the 2012 GP2 season. Results demonstrate the reliability of the model, suggesting it can be used to optimise car settings (such as gearing and aerodynamic setup) before executing track tests.

Keywords: Car , control , GP2 , lap , minimum , optimal , race , simulation , time

The steering system of a vehicle impacts on the vehicle performance, safety and on the driver's comfort. Moreover, in off-road vehicles using hydrostatic steering systems, the energy dissipation also becomes a critical issue. These aspects push and motivate innovation, research and analysis in the field of agricultural tractors. This paper proposes the modelling and analysis of a hydrostatic steering system for an agricultural tractor to calculate the performance of the system and determine the influence of its main design parameters. The focus here is on the driver's steering feel, which can improve the driver's behavior reducing unnecessary steering corrections during the working conditions. The hydrostatic steering system is quite complex and involves a hydraulic circuit and a mechanical mechanism to transmit the steering to the vehicle tires. The detailed lumped parameters model here proposed allows to simulate the dynamic behavior of the steering system and to both enhance the understanding of the system and to improve the design through parameters sensitivity analysis.

Keywords: Agricultural tractors , Hydrostatic steering system , Rotary valve analysis , Sensitivity analysis , Simulation

This paper deals with an experimental tests campaign addressed to investigate the structural behaviour of short Glass Fibre Reinforced Polymers (GFRP) plates (PA66 GF30) under Low Velocity Impact (LVI) phenomena, characterized by different impact energy levels, according to the ASTM D7136 requirement. The scope of this research activity must be found in a wider scenario, in which the experimental characterization can be the key-step to develop an established numerical model for the simulation of the experimental tests. Under a Certification by Analysis (CbA) purpose, an established numerical model can be used, rather than to virtually characterize the behaviour of specimens (reducing the costs related to the experimental tests), to simulate LVI on large structural component difficult to test in a laboratory.

Keywords: composite materials , experimental tests , GFRP , Low Velocity Impact

Usually during the design of landing gear, simplified Finite Element (FE) models, based on one-dimensional finite elements (stick model), are used to investigate the in-service reaction forces involving each subcomponent. After that, the design of such subcomponent is carried out through detailed Global/Local FE analyses where, once at time, each component, modelled with threedimensional finite elements, is assembled into a one-dimensional finite elements based FE model, representing the whole landing gear under the investigated loading conditions. Moreover, the landing gears are usually investigated also under a kinematic point of view, through the multibody (MB) methods, which allow achieving the reaction forces involving each subcomponent in a very short time. However, simplified stick (FE) and MB models introduce several approximations, providing results far from the real behaviour of the landing gear. 'erefore, the first goal of this paper consists of assessing the effectiveness of such approaches against a 3D full-FE model. 'ree numerical models of the main landing gear of a regional airliner have been developed, according to MB, "stick," and 3D full-FE methods, respectively. 'e former has been developed by means of ADAMS® software, the other two by means of NASTRAN® software. Once this assessment phase has been carried out, also the Global/Local technique has verified with regard to the results achieved by the 3D full-FE model. Finally, the dynamic behaviour of the landing gear has been investigated both numerically and experimentally. In particular, Magnaghi Aeronautica S.p.A. Company performed the experimental test, consisting of a drop test according to EASA CS 25 regulations. Concerning the 3D full-FE investigation, the analysis has been simulated by means of Ls-Dyna® software. A good level of accuracy has been achieved by all the developed numerical methods.

A numerical investigation is conducted in order to identify optimum trimming attitudes for resistance reduction in the application of high performance sailing yacht hulls. A lumped parameters model based on general unsteady equations of motion is developed and implemented in combination with a numerical scheme to conduct parametric studies and predict the overall performances of a specific sailing hull. Existing semi-empirical formulas for hydrodynamic coefficients are modified and applied in order to extend the speed range of application and obtain good agreement with available experimental data. Brief discussion of the numerical results is presented with emphasis on the possible applications in the field of modern sailing yachts.

Keywords: Hull , Lumped Parameters model , Performance , Planing occurrence , Resistance , Trim

The vibrational behavior of vehicles is a crucial issue for the comfort, especially for the professional vehicles. This paper presents a simplified modelling approach for studying the vibrational behavior of a lawn tractor. The vibrational response of a real vehicle is analyzed by an extensive experimental modal analysis and Finite Element model (FE) simulating the modal behavior of the whole tractor. The FEM was then validated by the comparison with the experimental results and then used for identifying the components and connections effectively driving the modal response. Based on these results, a simplified Multi-Body (MB) model, able to reproduce the vibrational response of the studied lawn mower, was then setup, showing good correspondences with experimental results. General guidelines for defining effective vehicles Multi-Body modal models were also derived.

Keywords: Experimental modal analysis , Finite Element modal model , lawn mower , Multi-Body modal model

This paper is aimed to experimentally analyse the effectiveness of a hybrid storage system, when powering a commercial vehicle for urban use. The hybrid energy storage system is composed by two ZEBRA batteries, combined with an electric double layer capacitor (EDLC) module. The integration of those storage systems is obtained by means of a bidirectional DC/DC converter, which balances the electric power fluxes between batteries and super-capacitors, depending on the driving operative conditions. Modeling and simulations are preliminarily conducted with reference to the specific case study of an electric version of the Renault Master, supplied by the above described hybrid storage system. That theoretical activity allows the optimization of rule based energy management strategies for the hybrid energy storage system, in terms of the effectiveness in reducing the negative effects of high charging/discharging currents on battery durability. Then, the experimentation of the real power train, connected to the mentioned hybrid storage system, is carried out through a 1:1 laboratory test bench, able to perform the analysed energy management strategies on standard driving cycles, representative of the urban mission of the commercial vehicle under study. The obtained experimental results, expressed through electrical and mechanical parameters in a wide range of road operative conditions, show that the super-capacitors can improve the expected battery lifespan, with values of maximum effectiveness up to 52%, for driving patterns without negative road slopes. The procedure followed and presented in this paper definitely demonstrates the good performance of the evaluated hybrid storage system, controlled by the DC/DC power converter, to reduce the negative consequences of the power peaks associated with the urban use of commercial vehicles.

Keywords: Dynamic test bench , Electric double layer capacitors , Electric vehicles , Energy management strategies , Hybrid storage systems , ZEBRA batteries

Human-centred design is based on the satisfaction of the user needs related to performances, aesthetics, reliability, usability, accessibility and visibility issues, costs, and many other aspects. The combination of all these aspects has been called as “perceived quality”, that is definitely a transdisciplinary topic. However, the “real” perceived quality is usually faithfully assessed only at the end of the design process, while it is very difficult to predict on 3D CAD model. In this context, digital manufacturing tools and virtual simulation technologies can be validly used according to a transdisciplinary approach to create interactive digital mock-ups where the human-system interaction can be simulated and the perceived quality assessed in advance. The paper proposes a mixed reality (MR) set-up where systems and humans interacting with them are digitalized and monitored to easily evaluate the human-machine interaction. It is useful to predict the design criticalities and to improve the global system design. An industrial case study has been developed in collaboration with CNH Industrial to demonstrate how the proposed set-up can be validly used to support human-centred design.

Keywords: Digital manufacturing , Human-centred design , Human-machine interaction , Virtual simulation

The tandem rotor configuration is particularly convenient for the lift-compound approach in helicopters. In fact, the additional wing is positioned between the two rotors in an area that is marginally interested by the airflow in vertical flight. On the contrary, in horizontal flight, the airflow accelerated by the frontal rotor directly invest the wing improving its lift. A very thin wing with a short chord and a relatively large span can be manufactured with the same technology of the rotor blades. If this wing is fixed without control surfaces, the additional weight can be extremely limited. A concaveconvex high lift airfoil can be used. This airfoil is relatively stiff due to the large bending moment of inertia. A skin stressed structure can be used for the additional wing to obtain also a large torsional stiffness. This lightweight wing can be installed on the helicopter when required and it can be optimized to a defined flight condition. In our case the optimization was performed for cruise. With a very limited weight increment and with a lift penalty within the simulation approximations, the cruise fuel consumption can be halved. The result is impressive for ferrying and long range passenger transport operations, where load capacity can be fully exploited only by increasing the fuel load. In this case a helicopter like the Chinook can perform long range missions with a significant increase in operational capability.

Keywords: Cruise , Helicopter , Lift-compound , Range , Tandem rotor

The new RPAS (remotely piloted aerial systems) are mostly video cameras with wings whose ownership isn't enshrined in any constitution. Rulers are rushing to do regulate the lack of safety and accountability for RPAS. In Italy ENAC (aviation authority) legislated against random acts of stupidity and probable failures. For the current year of 2015, there is a forecast to sell $1bn worth of RPAS product. For these reasons the installation of RPS (Recovery Parachute System) on commercial RPAS is particularly interesting. A few RPS manufacturers have manufactured specific RPS systems for "drones" both rotary and fixed wing. However, these systems are designed with the same criteria of manned aerial vehicle. This paper demonstrates that the design criteria of RPAS are sensibly different from other applications. In particular the rate of descent during recovery should be reduced from 6m/s to 2m/s. This fact poses new challenges in parachute design. In fact RPS mass depends on parachute diameter that increases with low descent rates. This paper demonstrates that it is possible to design effectively RPS for RPAS up to 80kg by using nonwoven fabric in parachutes. In this way the RPS mass is a small fraction of the RPAS one. Deployment systems are not a problem for RPAS since masses are extremely small and the power necessity are accordingly limited.

Keywords: Parachute , Recovery , Remotely piloted aerial systems , Unmanned aerial vehicles