Time-Optimal Elbow Robot Motion

G. Giese, R.W. Longman, and H.G. Bock



The use of time-optimal path planning can speed up robots on assembly lines and allow them to run faster, increasing their productivity. This paper develops a more complete understanding of the nature of time-optimal point-to-point trajectories for elbow coordinate robots. It also demonstrates the effectiveness of direct optimal control solution methods, and demonstrates the way in which direct methods bypass the issues of determining the optimal switching structure. In time-optimal robot point-to-point motion there is generically one robot axis that has the hardest time reaching its endpoint, and then, to whatever extent other axes have extra freedom, it must be used to help the axis with the hardest task, whenever possible. Such assistance makes use of different mechanical interaction forces and effects. In this paper we examine one basic type of robot, the elbow coordinate robot, and analyze all types of forces during optimal motions, in order to develop an understanding of optimal manoeuvres.

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