Nonlinear Pressure Control for BBW Systems via Dead-Zone and Antiwindup Compensation

In the automotive field, brake-by-wire (BBW) systems are electronically regulated actuators, which are capable of applying a desired braking torque to the vehicle's wheel. Specifically, the electrohydraulic technology is the most widely used in commercial vehicles, as it offers a good tradeoff in terms of size, weight, and cost. However, control of BBW actuators in such a configuration is a challenging problem for many reasons, among which the most critical are the dead zone due to the fluid reservoir and the input saturation limits of the electric motor that moves the pump. In this paper, a complete control architecture accounting for this nonlinear behavior is presented, where the main components are a linear controller, a dead-zone compensator, and an antiwindup block, designed in a cascade fashion. With such a configuration, the achieved equilibrium point is guaranteed to be globally asymptotically stable, and the overall system shows to be robust with respect to variations of the position-pressure curve. Simulation and experiments on a production prototype are proposed to show the effectiveness of the proposed strategy.