Sensorless Reaction Torque Regulation of Multi-DoF Industrial Manipulator Using Gated Recurrent Unit-Based Virtual Environment Quarrier

Disturbance observers (DOb) are widely used to estimate disturbances, enabling robust position control through additional compensation currents and environmental force estimation. However, non-linear friction and gear compliance must to be excluded from the estimated disturbances torques for effective reaction force observation. Previous research has proposed an environment quarrier to estimate these torques by using an additional robot identical to the target. However, replicating the same robot is challenging due to cost and production variability. In this research, we used a gated recurrent unit to construct a virtual environment quarrier. This virtual environment quarrier was trained on free-motion data and applied to a reaction torque observer. We implemented the proposed method a 6-DoF manipulator and successfully regulated reaction torque.