Contact Force Sensing and Control for Inserting Operation During Precise Assembly Using a Micromanipulator Integrated With Force Sensors

Abstract

This paper proposes a novel contact force sensing and control method for the inserting operation during precise assembly process, which is based on a micromanipulator integrated with force sensors. At first, theoretical analysis is carried out to calculate the admissible contact force between the gripped holes and the pegs. The contact force thresholds which are smaller than the admissible contact forces are adopted in the control algorithm to avoid the rotating of the gripped holes during assembly process. The force sensors are calibrated using an ATI force sensor and the conversing coefficients are calculated. The admissible contact forces are tested when different contact distance and preload force are adopted. The performance of the proposed contact force sensing and control method is verified by carrying out the task of applying contact force on the surface of the gripped holes with different contacting speeds. The results indicate that the contact force can be adjusted to be smaller than the threshold 1 and the peg-in-hole assembly can be completed successfully. <i>Note to Practitioners</i>&#x2014;This paper proposes a novel contact force sensing method during the inserting operation. Compared with the traditional contact force sensing method, this paper adopts the force sensor integrated into the micromanipulator instead of commercial force sensor to detect the contact force between two parts. To ensure the assembling precision, the theoretical analysis is conducted to calculated the admissible contact force to avoid the sliding and rotating of the gripped micro part during assembling. This work efficiently simplifies the contact force sensing and control process, where complex calibration process needn&#x2019;t to be carried out to eliminate the influence of the mass of the micromanipulator on the testing results. In addition, the assembling costs are reduced by replacing commercial force sensors with strain gauges.