An expanded impedance control scheme for slosh-free liquid transfer by a dual-arm cooperative robot

The use of robots has been rapidly spreading in different daily applications. The transport of liquids by robot arms without causing any slosh is one of such applications which has recently taken the attention of researchers. Liquid transfer by dual-arm robots causes challenging problems because, in the process of dual-arm cooperation, a closed kinematic chain is formed and a set of constraints appears in motion, which increases the complexity of the process. In this study, an expanded impedance control was proposed for a dual-arm cooperative robot to achieve high speed for the transfer of a liquid-filled cylindrical container without sloshing. The impedance control method provides efficient results in controlling multi-robot interactions. However, a conventional impedance control is incapable of suppressing the slosh during liquid transfer. Therefore, in this study, we expand the impedance control by introducing a slosh suppression term, which leads to suppressing the slosh successfully during the transport of a liquid container. The effectiveness of the proposed controller was demonstrated for liquid transfer in a 2-D plane.