A preliminary study for H∞ control of parallel cable-driven manipulators

Abstract

This paper reports preliminary investigations for H∞ control of cable-driven parallel robot. This methodology specially suits for multi-input multi-output systems including flexible modes, which is the case of cable robots with flexible cables. A nonlinear model is first developed accounting for flexible cables for the case where actuators are speed controlled. A first method based on a rigid model is proposed as an adaptation for speed-controlled actuators of the well-known Jacobian-based method. A low-pass filter is tuned in order to increase the reachable bandwidth. The H∞ controller is derived from a linear dynamic model. One interest is that one single controller manages both the position of the end-effector and the cable tension. The simulation results show that improvements are possible in the bandwidth thanks to the H∞ control.