A nN⋅m level micromotor holding torque measurement method

Efficient and high-precision torque measurement methods for micromotors are globally critical, impeding the advancement of microsystems, particularly ultrasonic micromotors, known for their small size, high speed and high resolution. This paper proposes a novel torque measurement method for ultrasonic micromotors, establishing a torque measurement device that utilizes a parallelogram flexible hinge as the force transmission element. This approach can measure torque at the nano-Newton-meter (nN⋅m) level. The system demonstrates high measurement accuracy, robust anti-interference capability, and a wide measurement range. When the 18 V voltage is applied to the motor, the holding torque is 234.66 nN⋅m, the repeatability error of the system is 1.25%, and the combined standard uncertainty is 5.36 nN⋅m. The proposed method is a pivotal step towards filling the existing technological void, offering a substantial impact on the development of ultrasonic micromotors and the broader field of microsystems. •A nN-m level method to measure holding torque is proposed.•A parallelogram mechanism is proposed.•High measurement stability.•Low uncertainty. [Display omitted]