Control Characteristics of Robust Power Assist Cart for Flexible Structures

Abstract

Power assist systems have been introduced to reduce physical burdens of workers in industrial production lines. The authors have studied on control systems for power assisted conveyance of flexible structures. The previous paper proposed a control system design consisting of an impedance controller, a disturbance accommodating suboptimal controller, a disturbance observer and a reaction force controller in order to achieve the robust assist against structured uncertainties. However, the experimental and simulation consideration in the paper adopted single operational force profile which was reserved a priori and compared control characteristics of plural control system designs. Therefore, responses by actual human operational forces have not been fully evaluated yet. Then, a subjective evaluation experiment is conducted in this paper. As an experimental task, participants push the cart about 10 m distance and position the tip of a flexible plate within 100 mm. The participants answer some questions about the operability of the cart. By using Dunnett's test as a statistical method, the effectiveness of the proposed control system is verified. Moreover, especially at the point of the effectiveness of the disturbance observer, another experiment based on the reserved operational force is conducted on moving on a flat and slope track. By the experiments in this paper in addition to the previous paper results, the control characteristics of the proposed control system design is evaluated comprehensively and multilaterally.