Study on vehicle chassis control integration based on a main-loop-inner-loop design approach

Abstract

In this paper, vehicle chassis control integration has been investigated on the basis of a separated main-loop control and an optimal force distribution inner-loop design structure, as the tyre is conceptually treated as a special kind of actuator. In order to study the characteristics of the particular subsystems, i.e. longitudinal slip control of the tyres and active wheel steering during control integration, as well as the effects on vehicle-handling performance when the above two subsystems are integrated, a standard H∞ control technique is used for the main-loop design, which focuses on vehicle motion control only and a linear quadratic minimization approach is applied for achieving the optimal distribution of vehicle motion forces and moments between the wheels. Furthermore, the rotational dynamics of the wheels are considered when the resultant slip ratio control is being transformed to the actual wheel control torque that can be handled by braking and engine management systems. Simulation results and analysis indicate that both the above two subsystems have indispensable roles in the framework of integration; meanwhile a remarkable improvement in the handling performance and a large stability margin can be expected from chassis control integration and the above control structure.