Online Monitoring Of Brake Capability for Heavy Vehicles

Abstract

The recent advancement in heavy vehicle brakes involves development of a novel fastacting electronic brake system. This brake system comprises a slip controller that aids in reducing the stopping distances and tracks longitudinal wheel slip demands accurately during extreme braking manoeuvres. The slip controller and pressure controller relies on the knowledge of the ‘brake gain’ to calculate the desired brake pressures. The brake gain is defined as a relation between applied brake pressure and received brake torque. Currently the brake gain is assumed to be known and a constant, which is far from true. In this master thesis an algorithm to measure and estimate the brake gain on-line has been developed and evaluated. The developed estimator captures the variation of the brake gain with brake fade and actuator geometry. A temperature model is developed to estimate disc temperature based on the total braking energy at each braking event. The predicted brake disc temperature is used to estimate the discpad interface friction coefficient. Further this information is used to monitor the brake capability. The developed estimator shows that the estimations converge to the reference.