Time-varying internal model-based control of a camless engine valve actuation system

This paper focuses on the motion control of a camless engine valve actuation system during both steady state and transient engine operation. The precise tracking performance obtained using controllers based on the internal model principle for the constant speed case motivates the investigation under engine speed transients. The cyclic but aperiodic reference signal to be tracked is modeled using two different methods, i.e., as a combination of frequency varying sinusoids in the time domain or as a repetitive (periodic) signal in the rotational angle domain. The recently developed time-varying internal model-based controller is ideally suited for both the approaches. The details associated with the design of the controller for each of the approaches are first documented. A quantitative analysis comparing various performance metrics for both the approaches helps to highlight the relative advantages of each method. The experimental results from a prototype camless engine valve actuation system are then presented to help in validating the overall effectiveness of the proposed control method.