Robust variable structure control for stabilisation of articulated steer vehicles by torque vectoring

In this work, a Variable Structure Control (VSC) system is developed to remove the instability of an articulated steer vehicle during the snaking mode. First, by using a linearised model of the vehicle, the equations of motion are derived in the state-space form. The uncertainties in the tyre-road contact parameters introduce some unknown and time-varying but bounded terms to these equations. This will be a basis for designing a robust VSC system to stabilise the vehicle during the snaking by a torque vectoring device. The robustness of the resulting controller is examined for different driving conditions in terms of the road surface, forward speed and vehicle parameters, based on the linearised model. The control system is also incorporated into a virtual prototype of the vehicle in ADAMS, and its operation is investigated. The results from the linear model analysis and simulations in ADAMS show that the controller can eliminate the instability effectively.