A Theoretical Conversion of Torque Controllers for Handling a Position Servo-actuated Robot Manipulator Model

Traditional robot control theory assumes implicitly that robot manipulators are equipped with ideal torque actuators (i.e., torque-driven robots). However, it is important to note that both industrial robots and economical didactic ones do not typically feature such torque actuators. In contrast, many robotics laboratories engaged in academic and research activities employ robots equipped with position servo actuators, which do not support torque control input commands. This paper aims to bridge the gap between theory and practical implementation of robot control from an automatic control perspective. To achieve this goal, a new method is introduced for converting any torque requesting control system, designed for torque–driven robots, to be directly applied to robots using proportional embedded control with position servo actuators (servo–actuated robots lack direct torque input for control). The method relies on the inverse dynamics approach, considering the comprehensive nonlinear model of a position servo–actuated robot structure. This model encompasses servos dynamics, inheriting both the advantages and disadvantages associated with model–based control algorithms.