Research on Motion Characteristics of a Space Flexible Joint Manipulator

Research on motion characteristics of the space flexible joint manipulator is investigated. A general dynamic model of the manipulator is established by using the Lagrange method to obtained the simplified nonlinear mathematical model of a three-arm manipulator composed of shoulder, elbow and wrist joints. The desired multi-curve path is generated by quintic interpolation polynomials. The feedback linearization technique is used to establish input-output linear state space equations. The trajectory tracking control of the three-flexible-joint manipulator is realized through the energy-optimized linear quadratic LQR and state feedback control. Motion simulations of the manipulator with different paths and joint stiffnesses are then carried out. The results show that the steady vibrations of the elbow joint, evolved from the configuration and flexibility, can be suppressed significantly by increasing the joint stiffness or damping, and reasonable trajectory planning can optimize the dynamic response of the system. It lays the foundation for designing flexible joints of the space manipulator.