Fusing force and vision feedback for manipulating deformable objects

This article describes a framework that fuses vision and force feedback for the control of highly deformable objects. Deformable active contours, or snakes, are used to visually observe changes in object shape over time. Finite-element models of object deformations are used with force feedback to predict expected visually observed deformations. Our approach improves the performance of large, complex deformable contour tracking over traditional computer vision tracking techniques. This same approach of combining deformable active contours with finite-element material models is modified so that a vision sensor, i.e., a charge-coupled device (CCD) camera, can be used as a force sensor. By visually tracking changes in contours on the object, material deflections can be transformed into applied stress estimates through finite element modeling. Therefore, internal object stresses due to object manipulation can be visually observed and controlled, thus creating a framework for deformable object manipulation. A pinhole camera model is used to accomplish vision and force sensor feedback assimilation from these two sensing modalities during manipulation, (C) 2001 John Wiley & Sons, Inc.