Analysis of Contouring Error for Articulated Robot Arm and Determination of Operational Condition

Mechanism of locus error for contour following control of industrial articulated robot arms was analyzed and the locus error was derived theoretically. Main causes of locus error were found in the nonlinear transformation between kinematics and the inverse kinematics, and the delay of dynamics. The derived equation of the locus error was assured by simulation and experimental studies. Besides, the relationship between locus error and objective velocity was obtained by using the analyzed equation. As a result, objective velocity can be decided based on the maximum locus error and position loop gain of the servo controller. Moreover, optimal ratio of length of links was obtained by use of the derived relationship.