Analysis and control of high sideslip manoeuvres

This paper presents simple analytical techniques that are used to understand and control high sideslip drift manoeuvres of road vehicles. These are manoeuvres in which a skilled driver stabilises a vehicle beyond its limits of handling, an operating regime responsible for major safety concerns in everyday driving. An analysis of the equilibria of a bicycle model with nonlinear tyres reveals the existence of unstable ‘drift equilibria’ corresponding to cornering at high sideslip angle in a countersteer configuration. Equipped with this information, linearisation about a desired drift equilibrium is used to design a controller that stabilises the vehicle at the equilibrium. The controller is subsequently implemented on a steer- and drive-by-wire testbed and successfully used to achieve autonomous drifts.