Near time-optimal collision-free motion planning of robotic manipulators using an evolutionary algorithm

A technique for open-loop minimum time planning of time-histories of control torques for robotic manipulators subject to constraints on the control torques using evolutionary algorithm is presented here. Planning is carried out in joint space of the manipulator and the path is represented as a string of via-points connected by cubic spline polynomial functions. Repeated path modification is done by using the evolutionary algorithm to search for a time-optimal path. Time taken to traverse over a particular path is calculated by reducing the dynamic equations of motion over that path in terms of a path parameter and then calculating the time optimal-control over that path. This time is included in the fitness function of the evolutionary algorithm to guide the search for the time-optimal trajectory. Simulation results for 2-DOF and 3-DOF dual-arm systems are presented.