Adaptive Voltage-based Control of Direct-drive Robots Driven by Permanent Magnet Synchronous Motors

Abstract

Tracking control of the direct-drive robot manipulators in high-speed is a challenging problem. The Coriolis and centrifugal torques become dominant in the high-speed motion control. The dynamical model of the robotic system including the robot manipulator and actuators is highly nonlinear, heavily coupled, uncertain and computationally extensive in non-companion form. In order to overcome these problems, this paper presents a novel adaptive control for direct-drive robot manipulators driven by Permanent Magnet Synchronous Motors (PMSM) in tracking applications. The novelty of this paper is that the proposed adaptive law is free from manipulator dynamics by using the Voltage Control Strategy (VCS). Additionally, a state space model of the robotic system driven by PMSM is presented. The VCS differs from the commonly used control strategy for robot manipulators the so called torque control strategy. The position control of the PMSM is effectively used for the tracking control of the robot manipulator. This idea takes the control problem from the manipulator control to the motor control resulting in a simple yet efficient control design. Compared with the torque control, the control design is simpler, easier to implement with better tracking performance. The control method is verified by stability analysis.  Simulation results show superiority of the proposed control to the torque control applied by field oriented control on the direct-drive robot driven by PMSM.