Collision free quasi-minimum-time trajectory planning for manipulators using global search and gradient method

A method for time optimal collision free trajectory planning problem is proposed. In this paper, the dynamics of manipulator and obstacles in workspace are considered. This optimal trajectory planning problem is very difficult and complicated one because of non-linearity of manipulator dynamics and existence of obstacles. Generally, it results in a multimodal optimization problem. The proposed method is basically an iteratively improving one based on a gradient method. Firstly, two global methods (a genetic algorithm and an exact cell decomposition method) are used to search multiple initial feasible spatial paths for the gradient method. Next, the gradient method searches time optimal solution locally with the multiple initial feasible solutions. Simulation results show that this approach is effective to the time optimal collision free trajectory planning problem.