The effects of joint and link flexibilities on the dynamic stability of force-controlled manipulators

The effects of joint and link flexibilities on the dynamic stability of two-link force-controlled manipulators are investigated. The complaint equations of motion involving joint and link flexibilities are presented. Three force control methods, which include the stiffness method, the damping method, and the hybrid method, are considered for the analysis. The linearized equations of motion about the equilibrium positions are used for stability analysis. Depending on the control method used and the distribution of system flexibility, different dynamic behaviors are predicted. Flexibility, which causes the instability problem of force-controlled manipulators, is inherent in every robotic structure. Thus, more sophisticated control strategies using different sensors which can compensate the flexibility effects are needed to improve the dynamic performance of force-controlled flexible-joint manipulators