Hydraulic actuators for flexible robots : a flatness based approach for tracking and vibration control

This paper deals with an application of the differential algebraic flatness approach to hydraulic drives. Here, an elastic robot arm driven by a differential cylinder is investigated. The task is to design a suitable control law which not only tracks a given trajectory but also allows the damping of the flexible arm. In general, the flatness-property of a dynamical system enables a simple approach to solve a given tracking control problem. Although the model of the differential cylinder is not flat, the tracking control in terms of flatness is possible if some of the state variables are measured. Furthermore, the control law is supplemented with a damping component, based on model matching. This approach to control is confirmed to be suitable through simulation results