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When the human operator manually conveys a flexible part, vibration may occur in the flexible part. If the vibration occurs, the conveyance efficiency is reduced. To solve this problem, this paper proposes a semi-active operation assist handle, which is referred to an assist-handle, for manual conveyance of a flexible part. The assist-handle can be easily attached to a general hand cart. A human operates the hand cart through the assist-handle. The assist-handle consists of a handle, a variable damper, a mechanical spring and its controller. In order to suppress the vibration of the flexible part, the operating force is shaped by changing the viscous damping coefficient of the variable damper. The viscous damping coefficient of the variable damper is changed by the proposed controller. The controlled model is represented as a bilinear system, in which the inputs are the human force applied to the hand cart and the viscous damping coefficient of the variable damper, and the output is the relative position between the handle and the hand cart. The semi-active operation assist control is designed by using the bilinear optimal control theory. The effectiveness of the proposed assist handle is verified by simulations. From the comparative studies, the vibration suppression effect is seen in the proposed method. Moreover, the vibration suppression mechanism is considered. The proposed controller changes the viscous damping coefficient of the variable damper, by which the hand cart decelerates like step-shape. Then the anti-phase vibration generates in the flexible part and suppresses the vibration.

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We previously proposed a semi-active operation assist handle for manual conveyance of flexible part. The assist handle consists of a handle, a variable damper and a mechanical spring. The assist-handle can be attached to a general hand cart, through which a human operates the hand cart. In this paper we verified the work efficiency of manual conveyance of flexible part by using the assist-handle. For this purpose, a one-degree of freedom force display device was used to simulate the behavior of the assist-handle, the cart and the flexible part. Furthermore, we considered the work efficiency by evaluating the attenuation of the residual vibration of the flexible part and the conveyance time.