Quartz crystal based sensor head design and analysis for robot torque sensor application

Abstract

Background: Background: In recent years, with the gradual development of robot human-computer interaction, robots need to meet the precise control of more complex movements. Torque sensors play an important role. The traditional sensor uses metal strain gauge as the sensing element, which makes the sensor slow in response and low in resolution. In view of the shortcomings of strain gauge sensor, a sensor with cut quartz square as the sensing head is proposed. Methods: In order to study the quartz square sensitive head, COMSOL56 simulation modeling was first used to obtain the stress ratio relationship between the square quartz chip and the circular quartz chip. The formula for calculating the force frequency coefficient of the circular quartz chip was modified based on the ratio coefficient, and the formula for calculating the force frequency coefficient of the square quartz chip was obtained. The feasibility of the formula was verified through practical experiments; Secondly, theoretical simulation and experimental research were conducted on the buckling limit force of quartz chips, and the calculation formula for the buckling limit force during the installation process of quartz chips was revised, laying the foundation for the theoretical design of quartz sensors; Finally, the designed sensitive head is installed on the elastomer structure for verification; In order to collect frequency signals at a sampling rate of 1000Hz, the frequency signal output by the square quartz sensitive head is mixed, filtered, and amplified to form a 3.3V square wave between peaks. The frequency signal is collected by STM32. Conclusion: the test shows that the sensor with square quartz chip as the sensor head has a range of 150Nm, a sensitivity of 350 Hz / Nm, a linearity of 98.14%, a hysteresis of 0.51%, a repeatability of 98.44% and a resolution of 0.02%.