Collision-free trajectory planning of redundant space manipulators based on pseudo-distance

In this paper, we proposed a unified framework to model the obstacles, and a method to plan the 3-D collision-free trajectory for a redundant space manipulator. Firstly, the exterior contour of an obstacle was enveloped by one or several geometric primitives, such as cylinder, sphere, cone, cube, and so on. Secondly, the surface of its envelope was represented by a super-quadratic function, whose parameters can be adjusted to describe different shapes and dimensions. Combining with the pose and motion describing, the complete properties of an obstacle were included in a unified framework. Thirdly, a trajectory planning method based on gradient projection was presented to avoid the obstacles moving in the 3-D workspace. Instead of Euclidean distance, the normalized pseudo-distance was addressed and used as the objective function to be optimized. Finally, simulation studies of typical on-orbital missions with different obstacles were performed. Simulation results verified the unified obstacle model and 3-D collision-free trajectory planning method.