Delay compensated pneumatic brake controller for heavy road vehicle active safety systems

Performance enhancement of typically sluggish pneumatic brake actuators in Heavy Commercial Road Vehicles (HCRVs) is necessary for the efficacious operation of active safety systems. This study develops a robust Proportional Integral Derivative (PID) controller using the Kharitonov theorem for pneumatic brakes. To account for the inherent time delay present in pneumatic brakes, Padé approximation and state prediction methods were used. The efficacy of the brake controller when used for active safety system operation has been investigated by conducting Hardware-in-Loop (HiL) experiments. It was found that state prediction based design turned out to be a better choice for handling time delays in the brake actuator. This controller was then compared with a Sliding Mode Control (SMC) based brake controller and the performance of both controllers was comparable. Further, the state prediction based PID brake controller was found to be robust up to 100% variation in system time constant and 40% variation in time delay for different road and load conditions.