Active Wheel Steering Research Articles

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

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.

Active wheel steering and yaw moment control combination to maximize stability as well as vehicle responsiveness during quick lane change for active vehicle handling safety

The aim of this paper is not only to present various methods for combining lateral force and yaw moment control but also to find out how the mix between them should be applied to maximize the stability limit as well as vehicle responsiveness. Approximated two-degree-of-freedom (2DOF) vehicle model responses of side-slip angle and yaw rate are used to introduce the required total lateral force and yaw moment control. Three different cases of combining lateral force and direct yaw moment control have been investigated using computer simulations. A direct yaw moment control to follow the yaw rate response only is taken as a comparison case in order to show the effect of the combined control on vehicle stability and responsiveness. A computer simulation of a closedloop driver-vehicle system subjected to quick lane change with braking is used to prove the influence of the combined control. It is found that the influence of the combined control on vehicle stability and responsiveness is significant.