This paper reports a method for regulating the internal forces during in hand manipulation of an object with soft robotic fingers. It is known that for the case of multifingered manipulation, a part of the forces applied by the fingers result in the motion of the object, whereas the other part is considered to be an internal force. The internal forces do not result in the motion of the object but are used to improve the grip on the object. For an object with unknown shape, the internal forces are regulated to ensure that the object does not slip off during manipulation. To develop the control algorithm, the property of soft fingers, conforming to the shape of the rigid object is utilized. It is shown that if soft fingers show bounded conformity and the finger-object interface does not have relative slip (or a bounded slip), then the relative angular velocity between the object and the fingertip frame in contact is bounded. This allows definition of a new metric of slip, which is used to design a sliding mode control algorithm. The robotic fingers are assumed to be under virtual rigidity constraint, that is, the distance between the fingers do not change. The control algorithm is attractive as it skirts requirement of information of the shape of the shape of the object or to solve optimization problems. The methodology is simulated for the case of one spherical object and one conical object, as a demonstrator. 


A Sliding-Mode Control Algorithm to Enhance In-Hand Motion Capabilities

Division / Sponsors: 
Design Engineering Division and Computers & Information In Engineering Division


Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2020/volume/83907

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