Output feedback H∞ preview control of an electromechanical valve actuator

In an electromechanical valve actuated engine, solenoid actuators drive the valves that control airflow into the cylinders, allowing elimination of the camshaft and flexible control of the valve timing. Individual control of the valves provides flexibility in valve timing over all engine operating conditions and fully enables the benefits of variable valve timing. This-paper describes a closed-loop preview control of an electro-mechanical valve actuator that achieves quiet, robust, and reliable operation in the presence of significant delays in an electromagnetic system associated with eddy current losses. In this case, the desired trajectory of the armature position is known a priori. It is well known that preview control can greatly enhance disturbance rejection and tracking performance, when future information about the desired output is available. A detailed model is developed for the mechanical actuator system, the power electronics, and electromagnetic system. Illustrative experimental results are also presented.