Dynamic modeling and vibration properties study for flexible-joint space manipulators

Joints flexibility will lead to the vibration of the manipulator´s end-effector, not only affecting the execution of the task but also creating the safety problems. In order to achieve high accuracy and stability control, it is required to study the vibration properties of flexible-joint manipulators. First, we create the dynamics and kinematics models and analyze the effect of the joints flexibility on the end-effector´s pose (position and attitude). Then, the dynamics model is simplified and is used to derive the analytical expressions for joint vibration equation under driving torques, free-motion and residual vibration equation. The relationship of the vibration amplitude and frequency versus the structure parameters is also obtained. At last, we analyzed the vibration properties for different stiff and length based on the derived results, supplying the basis for structure optimization design, vibration suppression control, and so on. The simulation results are fully consistent with the theoretical derivation.