Flatness-Based Tracking of an Electromechanical Variable Valve Timing Actuator With Disturbance Observer Feedforward Compensation

A comprehensive control strategy for an automotive solenoid variable valve timing actuator is presented that addresses the issues of feedback sensors, soft seating or landing control, disturbance rejection and feedforward design. In particular, the motion control of the engine exhaust valve actuator subject to large cycle-to-cycle gas force variations is successfully demonstrated in simulation and on an experimental test-bench. Also provided is a method of characterization and online cycle-to-cycle identification of combustion gas force disturbances. The identified gas forces are used in energy-based feedforward and flatness-based landing algorithms. Simulated and experimental results indicate the proposed control methodology is capable of compensating for the combustion gas force disturbances experienced by exhaust valve solenoid actuators.