Model-free joint torque control strategy for hydraulic robots
Woongyong Lee, Minjun Kim, Wan Kyun Chung
Abstract
This paper proposes a simple model-free joint torque control strategy for hydraulic robots. The undesirable effect called “natural velocity feedback effect” is discussed by introducing mechanical impedance of the system. The proposed model-free joint torque control consists of internal-loop control and external-loop control (2 degrees of freedom (DOF)). Based on a mechanically represented hydraulic robot joint, the first-order internal-loop control is designed to reduce the mechanical impedance of a hydraulic robot joint in a passive manner. To improve joint torque tracking performance, a simple proportional-integral-derivative external-loop control is applied to the modified system by the internal-loop control. Robustness to external disturbance is demonstrated by transforming the proposed 2DOF control structure to the disturbance observer form. The proposed joint torque control strategy is validated on a 1DOF rotary hydraulic robot joint.
BibTeX
@inproceedings{icra2016_modelfreejointto,
title = {Model-free joint torque control strategy for hydraulic robots},
author = {Woongyong Lee and Minjun Kim and Wan Kyun Chung},
booktitle = {ICRA 2016},
year = {2016}
}