Propriety of Linear Model of Servo System for Industrial Articulated Robot Arms and Evaluation of Its Linearization Error

In this paper, propriety of the linearized servo system model for an industrial articulated robot arm was discussed. Industrially, the contour control of the robot arm has been implemented in such a way that an objective trajectory of the robot arm is divided into small segments and actuators of the servo motors have been controlled to pursue the divided segments, sequentially. In the conventional controller, the model of the robot arm control system has been regarded as the linear dynamic model in working coordinates. We consider this problem and analyzed the error of the linearized model. Based on the error analysis, we derive the permissible working region where the linearization error is negligibly small. In the permissible region, the robot arm dynamics can be expressed by a linear dynamic model in working coordinates.