Force Sensorless Force Control Using Notch-Type Dual Disturbance Observer

Abstract

This paper proposes force sensorless force control using a notch-type dual disturbance observer. The force control is structured by acceleration and speed controllers. The reaction force estimation system reduces the effect of the static friction using a dither signal. The proposed notch-type dual disturbance observer combines notch- type zero-order friction-free disturbance observer (FF - DOB) and notch-type first-order FFDOB. The proposed disturbance observer has the disturbance suppression characteristics of a notch-type zero-order FFDOB on the high-frequency side and a notch-type first-order FFDOB on the low-frequency side. It has a wide estimation band and allows the improvement of the suppression characteristics against low frequency disturbances. The validity of the proposed notch-type dual disturbance observer is verified through experimental results using an actual industrial robot.