Mirrored piezo servo hydraulic actuators for use in camless combustion engines and its Control with mirrored inputs and MPC

In this paper a model of a hybrid actuator is proposed. It consists of two mirrored piezo-mechanical structures (each including a hydraulic transmission ratio) and a hydraulic aggregate. A cascade control strategy based on a Model Predictive Control (MPC) is proposed to track periodic valve trajectory signals. The duality is based on the concept to maintain invariant the summation of the two piezo input voltage to a suitable value. The proposed cascade control structure consists of an internal and an external MPC controller. The secondary, internal controller is needed to accomplish a Soft Landing. The MPCs is combined with two feed forward control actions, one for the hydraulic aggregate model and one for the piezo-mechanic part of the model. Simulation results carried out the suitability of the control approach.