Valve controlled cylinder drives are an obvious choice whenever high loads are manipulated in translational motion with demanding requirements in terms of dynamic properties, accuracy, and costs. Improvements of energetic efficiency of valve control can be achieved by separating metering edges, allowing for different operating modes and thus adapting to different load scenarios.
In this paper, multiple-input-multiple-output closed loop control approaches are investigated in order to control cylinder speed and pressure in one cylinder chamber for a configuration with five 2/2-directional valves. By utilizing the flatness property of the system, the flatness-based tracking controller and the flatness based internal model controller will be described, developed and tested. They are adapted to the excessive number of command variables by introducing extended input. Based on validation on a test rig, the characteristics of both control approaches are pointed out.
The control strategy is fitted to a smooth mode switching algorithm published by the authors previously. It is shown that by making use of the degrees of freedom involved in the presented system, different operating modes can be switched smoothly in closed loop control. This contributes to the applicability of energetic potentials of independent metering.