|A Robust Control Approach for Hydraulic Excavators Using m-synthesis
Seunghyun Kim, Jaemann Park, Seonhyeok Kang, Pan Young Kim, and H. Jin Kim*
International Journal of Control, Automation, and Systems, vol. 16, no. 4, pp.1615-1628, 2018
Abstract : "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 m-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."
Hydraulic excavators, m-synthesis, robust control, robust performance.