Research On Motion Planning And Trajectory Tracking Of Space Robot

With the rapid development of aerospace, space manipulator with excellent skills is in great demand. Therefore, many countries have invested large amounts of funds in the development of the space robot with small volume, micro quality, low power consumption and high reliability. Space robot undertakes the construction of a space station, the repairation of a spacecraft, the replacement of parts, to recycle satellites, and all kinds of production and scientific experiment. Compared with the ground manipulator, it is in the harsh environment and is susceptible to disturbance. So the appropriate motion planning and accurate trajectory tracking of the robot, is of great significance to fulfill various space missions. Therefore, this paper introduces it in the following aspects in detail.This paper introduces the research situation of space manipulator in recent years, home and abroad and make a contrast between them. Then it introduces the method of path planning and trajectory tracking control theory. According to the linear momentum and angular momentum conservation principle, it establishes the motion model of free floating state by using the generalized Jacobian matrix method. On this basis, it uses the classical Lagrange method to establish the dynamics model.Space robot is different from the ground robot, so this paper uses the four element method to make a mathematical description of path planning. Parameterize the joint space trajectory by using five degree polynomial, then normalize it and solve the parameters by using the Newton iterative method. The simulation results show that the method is effective to robot's path planning which is point between point. In order to achieve continuous trajectory planning with the smoothness of joint trajectory, this paper improves the Milne-Hamming algorithm. To verify the improved algorithm, a trapezoid and a triangle trajectory planning of terminal velocity are used, the simulation results of joint trajectory are smoothing. The errors are in the scope. The ‘intermediate stage' waveform of triangular velocity planning is more ‘steeper' than trapezoid's.Finally, space robot model is established by using the virtual prototype technology. Considering the control system of space robot is nonlinear and strong coupling, it uses fuzzy control based on PID, realizing the trajectory tracking control of robotic manipulator. To reduce trajectory tracking error, base disturbance, output torque, it solves the uncertain dynamic compensation by using adaptive controller composed of regression matrix. The simulation is conducted in the known robot perturbation supremum conditions, results show that the robust adaptive PD controller can realize the precise trajectory tracking with robustness.