Speed control experiments for commercial heavy vehicles with coordinated friction and engine compression brakes

In this paper we describe the development and experimental validation of a simple coordination scheme between friction and engine compression brakes for a Class 8 Freightliner truck used as a development platform in the California PATH program. The coordination scheme is tuned to minimize the use of friction brakes while maintaining the speed tracking performance of the closed-loop braking controller that utilizes the friction (service) brakes only. Through the coordination scheme, a PID controller command is interpreted as a braking torque demand and split into a friction brake command and compression brake command. The split is based on the models for the compression braking torque and friction braking torque developed and identified from "field" experiments performed in Crow's Landing. The results of closed-loop experiments show that the integration of the compression brake into the speed control framework reduces the usage and wear of the conventional friction brakes.