Robust Assist for Conveyance of Flexible Structures Taking Account of Structured Uncertainties and Vibration Influence to Operators

Abstract

Power assist systems have been introduced to reduce workers' load in industrial production. The authors have studied on control systems for power assisted conveyance of flexible structures. Generally, the systems include influences of various kinds of uncertainties. One of them is vibration influence of controlled objects to operators. Another one is structured uncertainties such as nonlinear friction or parameter variations. This paper shows a robust assist system design by taking these uncertainties into account. It consists of an impedance controller, a disturbance accommodating optimal controller, a disturbance observer and a reaction force controller. The first and second elements have already been applied to the authors' previous paper. In addition, the disturbance observer is needed for eliminating the influence of the structured uncertainties. Moreover, taking the characteristic of the controlled object model into account, the simple reaction force controller is applied in order to eliminate the influence of the reaction force from the vibration reduction actuator. As a controlled object example, this paper adopts a power assist cart with a vibration system. The effectiveness of the proposed control system is verified by experiments and their corresponding simulations.