A switched control strategy for antilock braking system with on/off valves

In this paper, a switched control strategy for an antilock braking system (ABS), which has conventional hydraulic actuators equipped with on/off valves, is presented. The investigated system contains the continuous dynamics of the vehicle and the inherent discontinuous characteristics of the on/off valves. Accordingly, a novel approach based on nonlinear state feedback and a switching strategy renders a controller that assures that the wheel slip converges into the target equilibrium set. Then, the convergence condition of the closed-loop system is analyzed using Lyapunov theory in the Filippov framework, and the influence of controller parameters on the system is also discussed. It is shown that the proposed controller has few tuning parameters, and each parameter has an explicit physical meaning. Both the illustrative hardware-in-the-loop simulation and experimental results show that the switched control approach is robust enough to guarantee a good performance, even if the uncertainties of the actuator characteristics, road-adhesion coefficient, and vehicle speed are considered.