Environmental force estimation for a robotic hand: Compliant contact detection

This paper presents a model based compensation method to enable environmental force estimation for a robotic hand with no tactile or force sensors. To this end, we utilize multi-joint robot dynamics and disturbance observer based friction identification methods based to account for forces that arise due to Coriolis, gravity, stiction and viscous friction. With the effective compensation of these forces, disturbance observer units, implemented for each joint, allow us to estimate environmental interaction forces. To validate the effectiveness of the force estimation with our method, experiments were conducted on an anthropomorphic robot with no haptic sensing capability. The results of these experiments showed that the force estimation was in good agreement with the actual sensor measurements. To further elaborate the effectiveness of the method, compliant contact detection task was implemented on the robot. The result of this experiment indicated that environmental force estimation performance was enough to facilitate the task, and as such our method may eliminate the need for expensive force sensors at the finger tips or the joints for dexterous manipulation.