Extremum seeking control for soft landing of an electromechanical valve actuator

Many electromagnetic actuators suffer from high velocity impacts. One such actuator is the electromechanical valve actuator, recently receiving attention for enabling variable valve timing in internal combustion engines. impacts experienced by the actuator are excessively loud and create unnecessary wear. This paper presents an extremum seeking controller designed to reduce the magnitude of these impacts. Based on a measure of the sound intensity at impact, the controller tunes a nonlinear feedback to achieve impact velocities of less than 0.1 m/s while maintaining transition times of less than 4.0 ms. The control strategy is implemented with an eddy current sensor, to measure the valve position, and a microphone. (C) 2004 Elsevier Ltd. All rights reserved.