Contact Information from Proprioception

This paper presents a method to derive estimates of contact properties for the case of a planar robot interacting with unknown objects by means of propri-oceptive information (joint angles and torques). In a rst stage, two kinematic observations, based on the instantaneous velocities and the displacement between two consecutive postures, are used to obtain an estimate of the location with an associated uncertainty. This is then fused over time by tracking using a linear observer, resulting in a nal position estimate. A second step then uses torque domain evidence and the location estimates to decide the existence of the contact and to compute a corresponding contact force estimate. This approach allows the detection of multiple contact points on diierent links and provides estimates for the contact location, velocity, surface normal and contact force, using general manipulator motions.