Nonlinear Full-Model-Based Controller for Unactuated Joints in Vertical Plane

Articulated multiple degrees-of-freedom (DOF) hydraulic manipulators are used in many industry tasks. These hydraulic manipulators can be used to move heavy loads, such as logs and containers. The grasping tool of these manipulators is often connected at the tip of the manipulator by using unactuated revolute joints, which are not directly controllable. Currently, work performed efficiently by commercial hydraulic manipulators depends on the driver, and the automation level of these manipulators is relatively low. The Virtual Decomposition Control (VDC) is the nonlinear model-based control theory, which performs subsystem-based control design and stability analysis for complex multiple DOF redundant hydraulics manipulators. In this paper, we present a VDC approach based nonlinear full-model-based anti-sway controller for a redundant manipulator in vertical plane. The experimental results, with a full-size redundant hydraulic manipulator, verify that the proposed anti-sway control efficiently damps load swaying in the vertical plane motions.