Research On Mechanism Of Active Vibration Suppression For A Smart Flexible-joint-and-link Space Manipulator

Against the background of the great development of space technology, an ever increasing number of high-tech sophisticated manipulators are coming into use in the fields of space station technology and deep space exploration. As a consequence, it's essential to study the dynamic and control characteristics of flexible space manipulators. In this paper, the under actuated model of a smart space manipulator with flexible links and joints is established based on the Lagrange equation and assumed model method. Afterwards, considering the fact that the rigid-body motion and the flexible vibration take place in two time scales, the system is decomposed into a slow subsystem and a fast subsystem with the use of singular perturbation method,, which describe the rigid-body motion and flexible vibration, respectively. Besides, multi-body dynamics analysis software ADAMS is used to carry out the kinematic simulation of a space manipulator with flexible links and a space manipulator with flexible joints, respectively. Then, by comparing the results from ADAMS and those computerized with singular perturbation theory, the validity and superiority of singular perturbation method in analyzing the dynamic characteristics of flexible space manipulators are demonstrated.A modified computed torque controller based on the under actuated model is put forward to realize trajectory tracking of joints. In the meantime, the joint flexibility is compensated real-timely by the motors while the real-time suppression of the link vibration is realized by the embedded piezoelectric actuators. The results from the simulations for the smart space manipulator with flexible links and elastic joints indicate that the proposed composite control strategy can realize the trajectory tracking rapidly and in the same time suppress the vibration caused by flexible joints and links efficiently.