Multirate closed-loop system identification of a variable valve timing actuator for an internal combustion engine

This paper applies the multi-rate closed-loop system identification (ID) technique to a continuously variable valve timing (VVT) actuator system. Limited by the sample rate of the crank-based cam position sensor, function of engine speed, the actuator control sample rate is different from that of cam position sensor. Multi-rate system identification is a necessity for this application. On the other hand, it is also difficult to maintain the desired actuator operational condition with an open-loop control. Therefore, system identification in a closed-loop is required. In this study, PRBS q-Markov Cover identification is used to obtain the closed-loop model, and the open-loop system model is calculated based upon information of closed loop controller and identified closed-loop system model. Both open and closed-loop identifications are performed in an HIL simulation environment with a given reference model as a validation process. An intake VVT actuator system test bench is used to conduct the proposed multi-rate system identification using PRBS as excitation signals.