This paper presents a new active control strategy to prevent heavy vehicle rollover and focuses mainly on cases of manoeuvre-induced rollover such as rollover in cornering and lane-change manoeuvres. The lateral acceleration at the centre of gravity of the trailer has been used in the development of the control law. A nonlinear 75,000 pound 5-axle tractor/semitrailer computer simulation model has been used to demonstrate the effectiveness of the proposed active control system. Tyre cornering stiffness characteristic variations, as possible uncertainty, were included in the controller design to prove the robustness of the system. A new nonlinear sliding mode controller has been designed and found to be effective in improving the dynamic performance and roll stability, regardless of parameter uncertainties, such as tyre cornering stiffness. The controller torque requirement is limited by the differential dynamic braking forces that the tractor drive axles are able to produce as a function of the applied dynamic loads and road surface condition. The results show that with this new controller, the vehicle lateral acceleration can be controlled to prevent rollover without significant change of the vehicle trajectory when active yaw torque is applied to the tractor drive axles. Also, simulation results indicate that the vehicle rollover might be prevented, by reducing the lateral load transfer ratio, using the lateral acceleration at the trailer centre of gravity as a control strategy. (Author/publisher)
Abstract