On-line minimum-time trajectory planning for industrial manipulators

In this paper, a method for the on-line minimum-time trajectory planning for industrial manipulators was proposed assuming that the path is specified and the maximum allowable actuator torques are limited. The typical on-line trajectory planning strategy in industry is to find polynomials that follow the given path while satisfying the kinematic constraints. Although this traditional method is widely used in industry, it has a major shortcoming, which is, by using the constant kinematic constraints that neglect the manipulator dynamics, it lowers the global efficiency of the manipulator´s dynamic capability. We demonstrated that this existing shortcoming of the traditional method could be overcome considerably by taking the manipulator dynamics into consideration. In the proposed method, the dynamic calculation was performed only at certain points on the given path, which is effectively utilized to determine the kinematic constraints. The experimental results implied that this method could improve the traditional trajectory planning method for industrial manipulators.