FLOW VS. PRESSURE CONTROL SERVOVALVES IN FORCEBASED POSITION CONTROL APPLICATIONS

Abstract

In teleoperation applications torque controlled joints are often required. If hydraulic actuator is driven by flow control servovalve, a force-based position control requires tuning of inner loop force controller and force or pressure sensor. An alternative for flow control servovalves are pressure servovalves which are seldom used in industrial applications. Advantage of this technology should be that tuning of inner force-control loop should be avoided and also more importantly addition of pressure and/or force feedback sensors should not required. Sensors are often the most likely component to fail while working in hazardous environments. Our aim is to compare three kinds of inner loop force controls. First, we use pressure servovalve in position control application without inner loop pressure or force sensors. In remaining two cases we use force control in the inner control loop with flow and pressure control servovalve. Three controller alternatives are compared and the results are discussed.