Stability Control Method And Dynamics Modeling Of Space Manipulator

With the deep exploration of Space, On-orbit space station as extremely important experimental platform is gradually moving in large, complex direction. The important work of the next phase of China’s manned spaceflight is building a large space station, during the process, the large space manipulator will play a very important role for the construction and routine maintenance. Based on this background, this paper studies the stable control strategy of 7Dof space manipulator carrying massive load, to provide some reference for motion control of space manipulator in the future. The main contents and results are as follow:First, based on the configuration analysis of the 7Dof space manipulator, this paper established a D-H coordinate, analyzed and solve the forward kinematics and Jacobian matrix of 7Dof space manipulator, and this paper optimized the trajectory aiming at the redundant degrees of freedom of space manipulator. This paper used five interpolation planning process to ensure that the joint motion acceleration is not mutation, used functional analysis optimization method to rational allocate the velocity of each joint. In this way, this paper ensured the stability of space manipulator motion control from the trajectory planning level.Second, for the characteristics of space environment, this paper established a dynamic model of 7Dof space manipulator under floating base, got the coupling relationship between the space manipulator, load and the base, and laid a foundation for the feedforward control of this system.Third, for the space manipulator joints using PMSM, this paper established the dynamics model of PMSM, given the mapping relation of load torque and motor current, and the motor current and motor voltage. Besides, this paper proposed parameter identification algorithm of dynamics model, provided the conditions to the feedforward control of joints.Fourth, considered of that there is a wide range change of joint torque during the work process, this paper proposed a kind of multi-feedforward control strategy based on the multisystem dynamics and joint dynamics. This strategy can ensure the joint position, velocity and acceleration is continuous, reduce the torque shocks and accelerate the response speed of space manipulator with heavy load in the end and improve the stability of arm movement.Finally, in order to verify the control strategy on the ground, this paper designed a semi-physical simulation system. This system can verify the stability control effect of space manipulator with heavy load in the end. The simulation and experimental results demonstrate the effectiveness of space manipulator stability control algorithm.