Onboard Spacecraft Slew-Planning by Heuristic State-Space Search and Optimization

An attitude planning algorithm for large-angle slew of rigid-body, under multiple time-consistent and time-varying celestial constraints was studied. In three-dimensional Rodrigues parameters space, attitude motion was mapped into a directed line path, forbidden attitude zone was mapped into a boundary condition. Therefore the strategy of maneuver was transformed to a space geometry problem. The path planning was handled in a goal-directed way, which involves obstacle checking, path exploring and path modification. The algorithm is composed of two steps: a feasible path, linked by a sequence of Euler rotations, was firstly generated by random search; then an optimization procedure improves the performance of the motion. Simulation results show that the planning result is time sub-optimal. The calculation time is on the order of sub-seconds. This method is efficient for autonomous slew planning, and is probabilistically complete.