In this report, we develop nonlinear dynamical models and longitudinal control algorithms that coordinate variable compression brake mechanism with service brakes for a Class-8 commercial heavy vehicle. For the coordination and full use of these retarding actuators, we model the multivariable system based on physics-based principles and experimental data. We show that, for one specific critical braking maneuver, the coordination of compression and service brakes reduces the use of the service brakes by a factor of 45, and that it reduces the settling time by a factor of 2. Key words: Advanced Vehicle Control Systems, Brakes, Commercial Vehicle Operations. Speed Control, Vehicle Dynamics

In this report, we extend our previous work within MOU 372 on modeling and longitudinal speed control design for heavy commercial vehicles equipped with variable compression braking mechanisms. Previously, we developed a detailed crankangle based simulation model for a six cylinder, 350 hp diesel engine with a continuously varying compression brake that is capable of describing the intrinsic interactions between individual cylinder intake and exhaust processes, turbocharger dynamics during combustion and braking modes, and the transition between those modes. Moreover, for control design and analysis purposes we derived a low-order approximation of that model. In this report we present our new results on developing longitudinal control algorithms that coordinate the variable compression brake with conventional service brakes and gear selection. Specifically, we integrate the compression brake actuator with the service brakes and design a PI-controller that emulates the driver's actions on long grades. The controller uses the engine speed measurement to activate the service brakes only when retarding power of the compression brake is insufficient. We also employ robust linear control technique using the concept of structured singular values to design a controller that is robust to parameter variations and model uncertainty in the CHV. Finally, we compare the performance of this robust controller with the performance of an adaptive control scheme that we have derived within MOU 393. The performance of all the controllers is demonstrated through extensive simulations on the 24th order nonlinear vehicle model developed in our previous work within MOU 372.

This report describes the development and experimental validation of a coordination scheme between friction and discretely variable compression brakes for a Class 8 Freightliner truck used as a development platform in the California PATH program. The coordination scheme that we developed maintains the speed tracking performance of the nominal PID controller which was originally designed by the UCLA team for the case of friction brakes only. Through the coordination scheme, the command of the nominal PID controller is split into a friction brake command and compression brake command. The integration of the compression brake into the speed control framework reduces the usage and wear of the conventional friction brakes. This report describes the experimental hardware and software setup; open-loop experiments that were conducted to identify the models for the friction brake and the compression brake; the identification procedure of the friction brake and compression brake characteristics and the identification results; the development of the coordination scheme for the friction and compression brakes and the results of closed loop experiments that were used to validate the coordination scheme performance.

This report describes the development and experimental validation of a coordination scheme between friction and discretely variable compression brakes for a Class 8 Freightliner truck used as a development platform in the California PATH program. The coordination scheme that we developed maintains the speed tracking performance of the nominal PID controller which was originally designed by the UCLA team for the case of friction brakes only.....