Force-torque Control Implementation for 2 DoF Manipulator

Abstract

This paper describes an approach to force control of two degrees of freedom robot manipulator. Aspects of control implementation concerning a joint torque sensor are discussed and a technique to its correction and calibration is presented. Two- level control scheme is used for the purposes of easier implementation. Such an approach has proved to be convenient in organizing general control structure and intrinsic to the two-time-scale dynamics of the system. For the fast part of system dynamics (corresponding to controlling the value measured by the torque sensor) joint model is presented. Based on this model, two variants of torque control loop are developed and their terms of application are outlined. Two types of control strategies for the slow part of system dynamics include an impedance control and force/torque control with gravity compensation as well as trajectory tracking based on the impedance control.