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In the first two chapters of this report, the development of discrete compression brake and transmission models is explained. In the vehicle model development, special efforts have been put in transmission shifting scheduling. Transmission up-shift and down-shift scheduling are separated in the modelling. Hysteresis during shifting is introduced to reduce chattering. A compression brake effect on transmission shifting is identified and considered in the modelling. The new transmission shifting model has been validated through experimental data. The transmission shifting model is combined with the compression brake model and the model of the longitudinal vehicle dynamics for a high-fidelity predictive simulation software tool. Power-width-modulation (PWM) actuation for brake coordination is proposed to further exploit the capacity of the compression brake and reduce the usage of service brake. Simulation results indicates that the PWM actuation strategy will have the same speed regulation performance as the direct torque split strategy, while the usage of the service brake is significantly reduced, and the compression brake can handle a down slope of -4 when tracking a speed of 56 mile per hour. Simulation results also indicated the importance of vehicle mass and road grade estimation in controller performance. The estimation problem is addressed in detail next. In the third chapter, a recursive least square scheme with multiple forgetting factors is proposed for on-line estimation of road grade and vehicle mass. The estimated mass and grade can be used to robustify many automatic controllers in conventional or automated heavy-duty vehicles. We demonstrate with measured test data from the July 26-27, 2002 test dates in San Diego, CA, that the proposed scheme estimates mass within 5% of its actual value and tracks grade with good accuracy. The experimental setup, signals, their source and their accuracy are discussed. Issues like lack of persistent excitations in certain parts of the run or difficulties of parameter tracking during gear shift are explained and suggestions to bypass these problems are made. In the final part of this work, an adaptive model predictive control scheme is designed for speed control of heavy vehicles. The controller coordinates use of compression brakes and service brakes on downhill slopes. The advantage of model predictive control (MPC) scheme over PI design is its ability to explicitly handle the constraints on service brake and compression command. MPC minimizes use of service brakes based on constrain optimization techniques. Given a perfect model, good performance was obtained in closedloop. We showed with simulation analysis that model uncertainties due to uncertainty in vehicle mass result in degraded and sometimes poor oscillatory closed-loop response. Unknown road disturbance (grade) was another limiting factor to the performance of the controller. It is shown that accurate estimate of mass is necessary for safe and comfortable operation in closed-loop. Also knowledge of the road grade can improve the results further by contributing in feedforward control. Therefore the estimation method presented in the third chapter of the report is used in parallel with the controller to update the estimates of mass and road grade. We show that adaptation allows robust speed tracking even if initial mass is 300 percent over or underestimated.

In the first two chapters of this report, the development of discrete compression brake and transmission models is explained. In the vehicle model development, special efforts have been put in transmission shifting scheduling. Transmission up-shift and down-shift scheduling are separated in the modelling. Hysteresis during shifting is introduced to reduce chattering. A compression brake effect on transmission shifting is identified and considered in the modelling. The new transmission shifting model has been validated through experimental data. The transmission shifting model is combined with the compression brake model and the model of the longitudinal vehicle dynamics for a high-fidelity predictive simulation software tool. Power-width-modulation (PWM) actuation for brake coordination is proposed to further exploit the capacity of the compression brake and reduce the usage of service brake. Simulation results indicates that the PWM actuation strategy will have the same speed regulation performance as the direct torque split strategy, while the usage of the service brake is significantly reduced, and the compression brake can handle a down slope of -4 when tracking a speed of 56 mile per hour. Simulation results also indicated the importance of vehicle mass and road grade estimation in controller performance. The estimation problem is addressed in detail next. In the third chapter, a recursive least square scheme with multiple forgetting factors is proposed for on-line estimation of road grade and vehicle mass. The estimated mass and grade can be used to robustify many automatic controllers in conventional or automated heavy-duty vehicles. We demonstrate with measured test data from the July 26-27, 2002 test dates in San Diego, CA, that the proposed scheme estimates mass within 5% of its actual value and tracks grade with good accuracy. The experimental setup, signals, their source and their accuracy are discussed. Issues like lack of persistent excitations in certain parts of the run or difficulties of parameter tracking during gear shift are explained and suggestions to bypass these problems are made. In the final part of this work, an adaptive model predictive control scheme is designed for speed control of heavy vehicles. The controller coordinates use of compression brakes and service brakes on downhill slopes. The advantage of model predictive control (MPC) scheme over PI design is its ability to explicitly handle the constraints on service brake and compression command. MPC minimizes use of service brakes based on constrain optimization techniques. Given a perfect model, good performance was obtained in closedloop. We showed with simulation analysis that model uncertainties due to uncertainty in vehicle mass result in degraded and sometimes poor oscillatory closed-loop response. Unknown road disturbance (grade) was another limiting factor to the performance of the controller. It is shown that accurate estimate of mass is necessary for safe and comfortable operation in closed-loop. Also knowledge of the road grade can improve the results further by contributing in feedforward control. Therefore the estimation method presented in the third chapter of the report is used in parallel with the controller to update the estimates of mass and road grade. We show that adaptation allows robust speed tracking even if initial mass is 300 percent over or underestimated.

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.

In this report a recursive least square scheme with multiple forgetting factors is proposed for on-line estimation of road grade and vehicle mass. The estimated mass and grade can be used to robustify many automatic controllers in conventional or automated heavy-duty vehicles. We demonstrate with measured test data from the July 26-27, 2002 test dates in San Diego, CA, that the proposed scheme estimates mass within 5% of its actual value and tracks grade with good accuracy. The experimental setup, signals, their source and their accuracy are discussed. Issues like lack of persistent excitations in certain parts of the run or difficulties of parameter tracking during gear shift are explained and suggestions to bypass these problems are made. Finally, the steps taken for developing the compression brake map, transmission map and tuning a controller for coordinated use of service and compression brake are explained. Using the data from the July 26-27, 2002 test dates in San Diego, CA, we show in simulation that the inclusion of the splitting torques scheme resulted in a service brake use decrease of 90 percent.

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.....

In this report, we develop a detailed crank angle based diesel engine model and a low order engine torque model for a Class 8 commercial heavy vehicle (CHV) as well as longitudinal control algorithms that coordinate the variable compression brake mechanism with service brakes and gear ratios. In particular, we have developed a detailed crank angle based simulation model for a six cylinder, 350Hp diesel engine equipped with a compression brake.

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