Energy Optimal Tracking Control with Discrete Fluid Power Systems using Model Predictive Control

For Discrete Displacement Cylinder (DDC) drives the control task lies in choosing force level. Hence, which force level to apply and thereby which pressure level each cylinder chambers shall be connected to. The DDC system is inherently a force system why often a force reference is generated by a tracking controller and translated into a discrete force level in a Force Shifting Algorithm (FSA). In the current paper the tracking controller and the FSA are combined in a Model Predictive Control algorithm solving the tracking problem while minimizing the energy use. Two MPC algorithms are investigated and compared to a PID like tracking controller combined with a FSA. The results indicate that the energy efficiency of position tracking DDC systems may be improved significantly by using the MPC algorithm.