Passive Versus Active Control of Weight-on-Bit for an Ultrasonic Percussive Drill

Abstract

Multiple ultrasonic percussive drill cross-drilling anchoring helps to achieve long-term, secure attachment of sampling platforms in extreme environments. Ultrasonic percussive drills require less weight-on-bit (WOB) and lower power than conventional drills, making them more suitable for asteroid anchoring mission. Choosing a suitable WOB control method is one of the key factors to ensure rapid and stable drilling, but there is little research on the effect of WOB control method on ultrasonic drilling performance. To address the technical challenges of drilling, this paper investigates the effects of passive and active WOB control on ultrasonic drilling performance. Firstly, the mechanical configuration of an ultrasonic percussive drill is presented and a full-wavelength piezoelectric transducer is designed using impedance analysis (IA) and Experimental Modal Analysis (EMA). Then, passive control of WOB is implemented using suspended weights, and active control is implemented using a linear actuator. Finally, the effect of the WOB control method on drilling performance is experimentally verified on rocks with different compressive strengths. Our results show that active control is better suited to WOB variation and rock compressive strength variation. When the WOB is 5 N, the drilling rate of passive control is slightly higher than that of active control, but the difference is not significant. When the WOB is 10 N and 15 N, the drilling rate of active control surpasses that of passive control. The ultrasonic percussive drill's power consumption is less than 60 W. This paper provides a technical reference for selecting the WOB method for ultrasonic percussive drills in planetary exploration.