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.

By exploiting an important property of the time optimal control law structure, this paper introduces a new dynamic programming approach for X-Y robot minimum time path following problem. Compared with the conventional dynamic programming method, the proposed approach significantly reduces the computational cost. The efficiency and effectiveness of the proposed approach are demonstrated via computer simulations. In addition, via experimental studies, this paper also addresses practical difficulties in implementing the minimum-time control law.