Input shaping with collocated PD for vibration control of a flexible joint manipulator

This paper presents investigations into the development of collocated PD control for input tracking and vibration suppression of a flexible joint manipulator. To study the effectiveness of the controllers, a collocated PD controller is developed for tip angular position control of a flexible joint manipulator. This is then extended to incorporate input shaper control schemes for vibration reduction of the flexible joint system. The positive zero-vibration-derivative-derivative (ZVDD) and new modified specified negative amplitude zero-vibration-derivative-derivative (SNA ZVDD) input shapers are then designed based on the properties of the system for vibration control. The new SNA ZVDD is proposed to improve the robustness capability while increasing the speed of the system response. The responses of the flexible joint manipulator with the controllers are presented in time and frequency domains. The performances of the collocated PD with input shaping control schemes are examined in terms of input tracking capability, level of vibration reduction, time response specifications and robustness to parameters uncertainty. A comparative assessment of the positive ZVDD and modified SNA ZVDD shapers to the hybrid system performance is presented and discussed.