Acceleration-Based Disturbance Observer for Hybrid Control of Redundant Systems

This study proposes a method for simultaneous implementation of performance improvement, decoupling of null space and workspace, and suppressing operational force for a hybrid control system with a redundant degree of freedom (RDOF). Hybrid control systems with RDOF are necessary for motion control systems to achieve future applications for human support systems and robots in unknown and open environments. This article shows that the acceleration controller performs decoupling of task (modal) spaces in the redundant system. Additionally, this article proposes a novel method based on the extension of an acceleration-based disturbance observer in modal space for position/force hybrid controllers to the redundant systems. The proposed method contributes to the suppression of operating (inertia) force and interference from the null space with the simplification of inverse kinematics. Experiments of the scaled bilateral control, which is one of the hybrid control systems for the master and slave systems with RDOF, are conducted to validate the proposed method.