Gilberto Burgio

A Model-Based Traction Control Strategy Non-Reliant On Wheel Slip Information

A traction control system (TCS) for two-wheel-drive vehicles can conveniently be realised by means of slip control. Such a TCS is modified in this paper in order to be applicable to four-wheel-drive vehicles and anti-lock braking systems, where slip information is not readily available. A reference vehicle model is used to estimate the vehicle velocity. The reference model is excited by a saw-tooth signal in order to adapt the slip for maximum tyre traction performance. The model-based TCS is made robust to vehicle modelling errors by extending it with (i) a superimposed loop of tyre static curve gradient control or (ii) a robust switching controller based on a bi-directional saw-tooth excitation signal. The proposed traction control strategies are verified by experiments and computer simulations.

A switching traction control strategy based on tire force feedback

The paper presents a novel concept of switching traction control (or ABS) strategy which does not rely on wheel slip information. The core of the strategy includes a driven wheel speed control loop and a reference vehicle model in the wheel speed target path. The reference model is fed by a bidirectional sawtooth-like tire force input signal, in order to keep the longitudinal tire force close to its maximum value. The switching criterion for transition between adhesion and slipping region of the tire static curve is based on comparing the applied wheel force with the tire force that can be obtained by estimation or direct measurement. The proposed 4WD traction control strategy is verified by means of computer simulations and partly by experiment.

Estimation of tire static curve gradient and related model-based traction control application

This paper presents an adaptive Kalman filter for estimation of longitudinal tire static curve gradient, based on the driven wheel speed measurement. The static curve gradient estimator is used along with a model-based traction control (or ABS) strategy that does not require wheel slip information. More specifically, the estimator is used to establish a superimposed gradient control loop, in order to compensate for the reference vehicle model errors and make the overall control strategy more robust. The proposed estimator and the related traction control strategy are verified by means of computer simulations and partly by experiments.