Path Planning of Space Robot Based on hp-Adaptive Pseudospectral Method

For the problem that the motion of the space robot will cause a large disturbance to the attitude of the base, a path planning method based on hp-adaptive Gauss pseudospectral method is proposed, in which the minimum reaction torque of the base is taken as the objective function. Firstly, the path planning problem of the space robot is regarded as an optimal control problem which meets the boundary condition and a series of path constraints including joint angle constraint, joint angular velocity constraint, control torque constraint and initial and terminal state constraints, and simultaneously minimizes a special performance index. Secondly, the optimal problem with boundary constraints and path constraints is solved by combining the hp-adaptive Gauss pseudospectral method (hp-AGPM) and the nonlinear programming technique, and a space robot trajectory satisfying the constraints and the optimal performance index is obtained. Finally, a planar two degree-of-freedom space manipulator is taken as an example to simulate and verify the designed method, and different pseudospectral methods are compared and analyzed. The simulation results show that the proposed method can generate an optimal trajectory satisfying all constraints in 10.6 s with the tolerance less than 10^-6, and is better than other pseudospectral methods both in computation speed and the number of collocation points.