In the absence of vision, grasping an object often relies on tactile feedback from the fingertips. As the finger pushes the object, the fingertip can feel the contact point move. If the object is known in advance, from this motion the finger may infer the location of the contact point on the object, and thereby, the object pose. This paper primarily investigates the problem of determining the pose (orientation and position) and motion (velocity and angular velocity) of a planar object with known geometry from such contact motion generated by pushing. A dynamic analysis of pushing yields a nonlinear system that relates through contact the object pose and motion to the finger motion. The contact motion on the fingertip thus encodes certain information about the object pose. Nonlinear observability theory is employed to show that such information is sufficient for the finger to "observe" not only the pose, but also the motion of the object. Therefore, a sensing strategy can be realized as an "observer" of the nonlinear dynamical system. Two observers are subsequently introduced. The first observer, based on the work of Gauthier, Hammouri, and Othman (1992)
Jia and Erdmann REF investigate a dynamic analysis of pushing but assume that the pusher and the object interact through a frictionless contact.