Robotic valve turning: axial misalignment estimation from reaction torques

In this work, we present a simplified quasi-static model of a two-point contact gripper turning a circular valve to predict the reaction torques produced at the base of the valve as a function of the axis misalignment. Specifically, we learned that geometric features such as (i) the misalignment vector being tangent to the reaction torques, (ii) length of the misalignment vector being directly proportional to the magnitude of the reaction torques and (iii) small axial misalignments resulting in well defined ‘double-loops’ in the 2D reaction torques space are indicative of axis misalignment.