Trajectory and vibration control of 2-link flexible manipulator using inversion control system

Abstract

Flexible manipulators capable of high speed operations with low energy consumption have high potential uses for large-scale deployment in industrial works. However, for such systems, simultaneous control of trajectory and vibration still remains a challenge. This paper describes the development of a controller that enables trajectory and vibration control. The controller performance was tested and verified through simulations and actual experiments with a laboratory grade 3D 2-link, flexible manipulator. As a baseline, trajectory tracking using inverse kinematics was observed to have poor tracking due to self-weight deflection. Inverse kinematics results was used to acquire a model of the manipulator using canonical variate analysis system identification. Further, an inverse system was modeled for simultaneous trajectory and vibration control. Compared against the inverse kinematic and the traditional direct strain feedback (DSFB) controller, the inverse system model was found to have 9-fold decrease in trajectory error tracking as well as vibration suppression. The validation experiments on the actual manipulator showed that the inverse system based controller was superior to the inverse kinematics and DSFB method of tracking as it followed the ideal trajectory by overcoming the gravitational pull, and suppressed the link vibrations.