Goal-oriented planning and path parameterization for time-optimal spacecraft reorientation

The fast attitude reorientation maneuver capability of spacecraft is required in many space missions. It is difficult to solve time-optimal attitude reorientation with respect to pointing constraints and bounds on control torques and angular velocities, because the solution is related to a complex nonlinear programming problem. This paper addresses the problem of time-optimal spacecraft reorientation under bounded and pointing constraints. A two-step procedure is developed to avoid the piecewise rest-to-rest process. First of all, an efficient goal-oriented planning method based on random obstacle avoidance is proposed to obtain a feasible attitude maneuver trajectory subject to all constrains. In order to reduce the generation of unnecessary paths and decrease the number of random extensions, the rotation towards the final target will be solved at the start of the planning procedure and after each random obstacle avoidance. Random obstacle avoidance will be adopted if any pointing constraint is violated. The incremental eigenaxis rotation is utilized as the uniform trajectory generation approach for solving all rotations towards the final goal or the random intermediate target. At each shortcut iteration subsequently, the time-optimal path parameterization algorithm is used to minimize the maneuver time along the trajectory. Simulation results demonstrate the effectiveness of the proposed two-step method. The proposed goal-oriented planning method can efficiently process multiple complex constraints. The computation of the minimum time reorientation with the shortcut iteration technique leads to the near-optimal solution.