Abstract

The development of high-performance antilock braking systems that provide reliability, steerability, and stability during braking in different road conditions, i.e., wet, icy or dry road surface, has attracted much attention in the automobile industry. This thesis addresses the controller designs for antilock braking systems (ABS) in vehicles. Simplified quarter vehicle models with special emphasis on the modeling of tire and dynamic tire-road interaction is utilized to develop and test the proposed controllers. The novelty of the present research is in the utilization and formulation of a new dynamic friction tire model for the development and testing of designed controller. Due to complex mechanics of tires, the dynamic friction tire model is significantly more realistic than that of commonly used static friction tire model. A detailed comparison of dynamic friction tire model with that of well-known magic formula and experimental data is carried out to demonstrate the effectiveness of the proposed formulation. Using this dynamic tire model, two methods for control of ABS system are proposed in this thesis, i.e., proportional-plus-integral (PI) control and the sliding mode control. Utilizing the PI controller design, the difficulty associated with on-line search of the optimal longitudinal slip can be easily overcome with the help of the dynamic friction tire model, which solves a commonly existed problem in the PI controller design. To show the advantage of the new dynamic tire model, a robust sliding mode control algorithm is also developed for the quarter vehicle model. The global stability of this control scheme is established by using the stability theory. Extensive simulation studies have been conducted for the developed controllers to demonstrate the effectiveness of the proposed control schemes. The investigation further demonstrates the effectiveness and convenience of utilizing dynamic friction tire model for the development of ABS controllers