Energy-based Residual for Collision Detection Using aVelocity Observer

Robot collision detection is addressed with an energy monitoring residual signal that uses only joint position measurements. The residual is evaluated by estimating joint velocity with a reduced-order observer. The observer uses in turn the momentum-based residual as additional input, acting as a virtual sensor of the external torque. We show the effectiveness of this method by comparing it in simulation with numerical differentiation of encoder measurements under nominal and uncertain conditions.