Analysing the interaction between braking control and speed estimation: The case of two-wheeled vehicles

The availability of actuators capable of a very fine-grained modulation of both traction and braking torques makes the design of slip-based braking control strategies for two-wheeled vehicles a real possibility. As the wheel slip cannot be directly measured, one has to use some estimate of the vehicle speed. The most commonly used speed estimate for two-wheeled vehicles is the fastest wheel speed. This paper investigates the interaction between control and estimation in braking control design for two-wheeled vehicles. Specifically, it is shown that a slip controller can be designed which guarantees global asymptotic stability under perfect knowledge of the vehicle speed. Conversely, when such a controller is fed by the fastest wheel speed stability is lost.