Feedforward Control Techniques to Achieve Fast Settling Time in Robots

Robots experience vibration problems when commanded to perform rapid motions which excite system resonances. To reduce the time required to arrive and stop at the commanded position, both move time and settling time must be reduced. The control scheme presented in this paper is designed to achieve these objectives using a modified state-variable feedback controller. The conventional controller is modified with the addition of a suitably-shaped feedforward forcing function which is designed to minimize both move time and residual vibration amplitudes. This modified control system is described and performance evaluations are presented on a typical flexible dynamic system.