Active driveline and suspension control to improve vehicle handling

Abstract

This research focuses on the integration of roll moment distribution control and variable torque distribution control to improve vehicle handling and dynamics. A survey of the literature determines the current state of the art and directs the research toward undeveloped areas. The work is carried out with the racing environment in mind. The most promising control systems prove to be roll moment distribution and variable torque distribution. The control objectives are to both improve the driveability of the vehicle and ensure the stability. The driveability is measured by the ability to track a linear reference yaw rate. This aims to linearise the yaw rate response to the steering input and gives the driver predictable handling. Vehicle stability is determined by the sideslip behaviour of the vehicle, where the controllers aim to minimise the sideslip. The testing is achieved by computer simulation. An eight degree of freedom nonlinear vehicle model is developed to model the University of Leeds Formula Racing Car. Initially independent controllers are developed for both roll moment distribution and variable torque distribution to control the driveability and stability individually. The independent controllers are able to enhance the vehicle behaviour with respect to each of these goals. However, the roll moment distribution is more suited to the stability control while the variable torque distribution achieves the yaw rate tracking more effectively. The independent controllers are combined to determine any interactions between them before a final integrated control strategy is developed. This integrated control strategy integrates the variable torque distribution driveability control and the roll moment distribution stability control to give a complete vehicle control strategy. The integrated controller shows improved yaw rate tracking as well as the ability to stabilise the vehicle at limit handling