A Robust Control Approach for Hydraulic Excavators Using μ-synthesis

• Published in: International journal of control, automation, and systems Vol. 16; no. 4; pp. 1615 - 1628
• Main Authors: Kim, Seunghyun, Park, Jaemann, Kang, Seonhyeok, Kim, Pan Young, Kim, H. Jin
• Format: Journal Article
• Language: English
• Published: Bucheon / Seoul Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers 01.08.2018; 제어·로봇·시스템학회
• Subjects: Control; Engineering; Mechatronics; Regular Papers; Robotics; 제어계측공학; synthesis; robust control; Hydraulic excavators; robust performance
• ISSN: 1598-6446; 2005-4092
• DOI: 10.1007/s12555-017-0071-9

In this work, a robust control is applied to the automation of a hydraulic excavator. Hydraulic excavators exhibit complex nonlinear behavior due to the inherent nonlinearity of the hydraulic servo system. Furthermore, the hydraulic excavator is subject to large disturbance forces during interaction with the environment. As a result, conventional feedback control techniques, such as a proportional-integral-derivative (PID) control, fail to provide consistent performance over the whole operation region of the excavator. Especially, when phase-offset errors vary between joints, undesirable motions are generated in the workspace, which evidently degrades the overall performance of the controller. With this in mind, we apply a robust control approach to the autonomous hydraulic excavators. By handling the nonlinearities and disturbances as uncertainties within the joint dynamics, a robust controller is designed by means of μ -synthesis that guarantees robust stability and performance within the given uncertainty bounds. Furthermore, by adopting a common model reference for each joint, we seek to increase the overall performance of tracking the digging trajectory in the workspace. Experimental results of the robust controller conducted on an industrial 21-ton class hydraulic excavator are presented.