Minimum heat loss control of fluid-powered systems

We address the problem of minimizing heat loss in the control of fluid-powered systems. We argue that minimizing the heat loss rate is more physically meaningful than, e.g., power consumption, pressure, time, or input forces, and is also closely correlated with minimizing friction. Focusing on hydraulic systems, we first construct an analytical model of heat loss in a fluid-powered system, and formulate an associated optimal control problem together with a computational algorithm for its solution. Numerical case studies involving a one degree-of-freedom hydraulic cylinder model and a three degree-of-freedom hydraulic excavator are presented. Minimum heat loss trajectories are shown to exhibit far less oscillatory behavior than, e.g., minimum power consumption or input force trajectories, and share similar qualitative features with minimum time trajectories.