Traveling wave rotary ultrasonic motors (TRUMs) are widely used in various industrial processes due to their attractive features, such as compact structure, high accuracy, and fast response. However, the major limiting factors of the operational performance of TRUMs under high-voltage excitation are the nonlinear behavior caused by the nonlinearities of the piezoelectric materials and the friction between the stator and rotor of the motor. In this study, a nonlinear dynamics model and an identification method are presented to directly design the driver circuit for suppressing the nonlinear behavior under high voltage excitation. Firstly, by studying the time–frequency characteristics of the isolated electrode voltage, a single-sided Hertzian contact forced oscillator model of TRUMs is established, involving the nonlinearities of the piezoelectric material and friction. Secondly, a harmonic balance nonlinear identification is proposed in the time domain for TRUMs. The influence of the voltage and preload on the nonlinear phenomena is discussed. Lastly, a novel driver circuit is proposed to suppress the nonlinearities using feedback from the isolated electrode. Experiments showed that the total harmonic distortion decreased by 89.4% under 500 Vpp. The proposed drive circuit design method is used to find a high excitation voltage and preload to achieve greater motor output power.
Drilling extra-terrestrial planets can be difficult, which is restrained by the payloads, power, and requirements of low axial force of rover posed by low environmental gravity, and drill bits can be trapped at a large depth, due to the accumulated spoils resulted from the low efficiency removal rate. This can cause motor to stall and draw excessive power. This work explores the opportunity of superposition of ultrasonic vibration on a vertical rotating auger in a variety of granular media. Ultrasonic vibration is known to facilitate direct penetration of granular materials, and it is anticipated that any related reduction in the contact friction force might improve augering performance.Experimental results suggest that, compared to the nonultrasonic scenario, ultrasonically assisted augering process has significantly promoted the flow of granular media and has moderately reduced the torque required to operate the device. Furthermore, it was discovered that particle size and auger speed also affect the performance of the auger system in different ways as the ultrasonic amplitude is adjusted.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.