A practical approach for minimum-time trajectory planning for industrial robots

Purpose - The purpose of this paper is to maximize the speed of industrial robots by obtaining the minimum-time trajectories that satisfy various constraints commonly given in the application of industrial robots. Design/methodology/approach - The method utilizes the dynamic model of the robot manipulators to find the maximum kinematic constraints that are used with conventional trajectory patterns, such as trapezoidal velocity profiles and cubic polynomial functions. Findings - The experimental results demonstrate that the proposed method can decrease the motion times substantially compared with the conventional kinematic method. Practical implications - Although the method used a dynamic model, the computational burden is minimized by calculating dynamics only at certain points, enabling implementation of the method online. The proposed method is tested on more than 40 different types of robots made by Hyundai Heavy Industries Co. Ltd (HHI). The method is successfully implemented in Hi5, a new generation of HHl robot controller. Originality/value - The paper shows that the method is computationally very simple compared with other minimum-time trajectory-planning methods, thus making it suitable for online implementation.