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Electric vehicles with multiple motors permit continuous direct yaw moment control, also called torque-vectoring. This allows to significantly enhance the cornering response, e.g., by extending the linear region of the vehicle understeer characteristic, and by increasing the maximum achievable lateral acceleration. These benefits are well documented for human-driven cars, yet limited information is available for autonomous/driverless vehicles. In particular, over the last few years, steering controllers for automated driving at the cornering limit have considerably advanced, but it is unclear how these controllers should be integrated alongside a torque-vectoring system. This contribution discusses the integration of torque-vectoring control and automated driving, including the design and implementation of the torque-vectoring controller of an autonomous electric vehicle for a novel racing competition. The paper presents the main vehicle characteristics and control architecture.

This paper presents an experimental methodology which can be adopted to measure the friction torque of the bearings in the wheel hubs of passenger vehicles. The first section of the paper highlights the reasons why an experimental device is necessary to have an objective evaluation of the performance of the bearing in terms of friction. In particular, the high level of approximation of the current formulas for the estimation of the friction inside a single bearing is discussed and demonstrated. An analytical methodology for the evaluation of the distribution of the axial load between the two bearings of the wheel hub is presented. However, its practical application for the precise calculation of the distribution of the load has to be checked through experimental tests.

Active Roll Control (ARC) is one of the most promising active systems to improve vehicle comfort and handling. This paper describes the simulation based procedure adopted to conceive a double-channel Active Roll Control system, characterized by the hydraulic actuation of the stabilizer bars of a sedan. The first part of the paper presents the vehicle model adopted for this activity. It is Base Model Simulator (BMS), the 14 Degrees-of-Freedom vehicle model by Politecnico di Torino. It was validated through road tests. Then the paper describes the development of the control algorithm adopted to improve the roll dynamics of the vehicle. The implemented control algorithm is characterized by a first subsystem, capable of obtaining the desired values of body roll angle as a function of lateral acceleration during semi-stationary maneuvers.

The paper deals with the virtual and experimental analysis of two commercial Mechanical Brake Assist systems. They are described in detail, then modeled and experimentally evaluated through a Hardware-In-the-Loop test bench and road tests. Three different kinds of drivers are compared, from the point of view of the performance increase promised by Brake Assist during an emergency brake maneuver. The three driver types are based on the measurement of the behavior of real drivers, as it is presented in specific research activities in literature.

The paper shortly describes an ABS/ESP Hardware-In-the-Loop (HIL) test bench built by the Vehicle Dynamics Team of the Department of Mechanics of Politecnico di Torino. It consists of a whole brake system, integrated through specific interface (e.g. wheel pressures signals) with a vehicle model running in real time on a dSPACE® board. Different commercial ABS strategies are compared, in a large spectrum of manoeuvres: slow brake apply manoeuvres, panic brake manoeuvres, μ-split brake manoeuvres, brake manoeuvres with a sudden variation of the friction coefficient between tyres and ground. The paper deals with the generation of all the signals required for activating a commercial ESP: steering wheel angle, body yaw rate, body lateral acceleration, engine control, etc… Some of them are transmitted by CAN. Typical handling manoeuvres are used to test the ESP: step steer, double step steer, ramp steer, etc… Several brake manoeuvres are simulated while turning.

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 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.

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 paper presents a 4-wheel-steering (4WS) control strategy devoted to reduce the turn diameter for small longitudinal speed values and to obtain a yaw rate damping effect in dynamic manoeuvres. Moreover, the 4WS active system conceived produces compensation both for lateral wind and road irregularities. The main results obtained through a functional vehicle model are presented. 4WS was integrated with a Vehicle Dynamics Control (VDC), which was improved for turn while braking manoeuvres. The results due to integration were very good, with a reduction of both systems interventions. Finally, a VDC-4WS-Active Roll Control (ARC) integration was tried, based on only one reference body yaw rate for all the active systems. The main results obtained are presented and discussed.

The paper deals with the elaboration of an Active Roll Control (ARC) oriented both on comfort and handling improvement. The ARC determines hydraulically the variation of the equivalent stiffness of the anti-roll bars. The control strategies conceived were extensively validated through road tests managed on an Alfa Romeo sedan. The first part of the paper deals with comfort improvement, mainly consisting in an absence of bar effect during straight-ahead travel and in a modification of the roll characteristic of the car. To increase driver's handling feeling, it was necessary to optimise the ratio between front and rear roll stiffness. This purpose can be reached through control strategies based exclusively on lateral acceleration. Some control strategy corrections were necessary to optimise roll damping and front/rear roll stiffness balancing.