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The paper presents a failsafe strategy conceived for a Vehicle Dynamics Control (VDC) system developed by the Vehicle Dynamics Research Team of Politecnico di Torino. The main equations used by the failsafe algorithm are presented, especially those devoted to estimate steering wheel angle, body yaw rate and lateral acceleration, each of them fundamental to correctly actuate the VDC. The estimation is based on redundancy; each formula is considered according to a weight depending on the kind of maneuver. A new recovery algorithm is presented, which does not deactivate VDC after a sensor fault, but substitutes the sensor signal with the virtually estimated value. The results obtained through simulation are satisfactory. First experimental tests carried out on a ABS/VDC test bench of the Vehicle Dynamics Research Team of Politecnico di Torino confirmed the simulation results.

In vehicle dynamics, simple and fast vehicle models are required, especially in the framework of real-time simulations and autonomous driving software. Therefore, a trade-off between accuracy and simulation speed must be pursued by selecting the appropriate level of detail and the corresponding simplifying assumptions based on the specific purpose of the simulation. The aim of this study is to develop a methodology for map and parameter estimation from multibody simulation results, to be used for simplified vehicle modelling focused on handling performance. In this paper, maneuvers, algorithms and results of the parameter estimation are reported, together with their integration in single track models with increasing complexity and fidelity. The agreement between the multibody model, used as reference, and four single track models is analyzed and discussed through the evaluation of the correlation index.

Chassis Control Systems development methodology is nowadays strongly based on analyzing performance by using PC vehicle dynamics simulation. Generally, the overall design, test bench and road validation process is continuously accompanied by simulation. The Base Model Simulator was developed by the Vehicle Dynamics Group at the Department of Mechanics of Politecnico di Torino both to satisfy this requirement and for educational purposes. It considers a complete vehicle dynamics mathematical model, including driver, powertrain, driveline, vehicle body, suspensions, steering system, brakes, tires. The Base Model Simulator takes in account the suspensions system elastokinematics, including, for example, automatic computation of camber variation during the vehicle roll motions. Tire model considered are either Pacejka's models or experimental data.

The paper presents the research activity managed to investigate the dynamics of a 4WD vehicle equipped considering drivelines with different layout. The procedure developed required to conceive an on purpose simulator to compare performance through virtual experimentation. Drivelines mechanical main characteristics and performance increasing due to control strategy were evaluated. Preliminary road test were performed with a single driveline layout, to evaluate simulation reliability and limits. The paper presents the 4WD vehicle simulator, the main equations applied to model open, torque sensing and limited slip differentials, some preliminary road test results showing torque sensing driveline performance.

The aim of this paper is the conception of a tire model which allows a good fit with the physical experimental behavior of the component. In the meanwhile, the model should be simple enough to permit real time vehicle dynamics simulation, in the same way as the diffused Pacejka's model. The paper discusses the influence of the model for the estimation of contact patch properties on the overall tire forces and moments. It demonstrates that unrealistic models of the contact patch can lead to a good fit with the experimental data (in terms of forces and self-aligning moment), even if the real physics of the tire is not reproduced. A realistic model implies a significant reduction of the stiffness of the brushes as a function of the vertical load between the tire and the road surface.

In automotive market, today more than in the past, it is very important to reduce time to market and, mostly, developing costs before the final production start. Ideally, bench and on-road tests can be replaced by multi-body studies because virtual approach guarantees test conditions very close to reality and it is able to exactly replicate the standard procedures. Therefore, today, it is essential to create very reliable models, able to forecast the vehicle behavior on every road condition (including uneven surfaces). The aim of this study is to build an accurate multi-body model of a heavy-duty truck, check its handling performance, and correlate experimental and numerical data related to comfort tests for model tuning and validation purposes. Experimental results are recorded during tests carried out at different speeds and loading conditions on a Belgian blocks track. Simulation data are obtained reproducing the on-road test conditions in multi-body environment.

The aim of this paper is to study in deep the peculiar test-rigs and experimental procedures adopted to the fulfilment of the principal requirements of automotive steel wheels, in particular regarding fatigue damaging. In the discussion, the standard requirements, the OEM specifications and the dimensional and geometric tolerances are approached. As result of an increasingly necessity to improve the performance of the components, innovative virtual test benches are presented. Differently from their traditional precursors, virtual test-rigs give an extended view of the physical behaviour of the component as the possibility to monitor stress-strain distribution in deep. In the first section, the state of the art and the specifications are listed. Secondly, the adopted hardware test-rigs as the experimental tests are described in detail. In the third one, proposed virtual test-rig is discussed.

The superior mobility of a military vehicle provides the combat crew with a tactical advantage through increased cross country speed. The suspension system plays a fundamental role in evaluating a vehicle mobility. A mathematical model that allows realistic simulations of vehicles operating in a wide spectrum of environmental conditions may help to lower costs and time required during their development. The paper concerns with vehicle-terrain interaction modeling, for a military tracked tank, through multi-body and block-oriented approaches. It is focused on the consequences that the suspension system has got on the comfort and on the performance. Thus through a multi-body software a realistic three dimensional model of a tracked fighting vehicle is developed. This virtual model confirms some experimental data available on its longitudinal dynamics. In order to simplify the multi-body simulations, a block-oriented approach is adopted to develop a model of the same vehicle.