Novel Multipoint-drive Rotary Actuator for Extraterrestrial Celestial Ultrasonic Driller

Abstract Ultrasonic drilling has emerged as a prominent technique in extraterrestrial environments due to its advantageous features. However, its application in extraterrestrial sampling missions is constrained by challenges such as drilling, chip removal efficiency, and high and low temperature adaptability. Addressing these limitations, this study introduces a novel multi-point driven rotary helical longitudinal torsion horn. The initial phase involved a detailed analysis of the actuator’s structure and operational principle. Subsequently, the actuator’s vibration mode and elliptical motion trajectory were validated through finite element simulation. The study further explores a methodology for adjusting the parameters of the helical groove and the displacement amplitude of the impact head. Following the theoretical analysis, prototypes of the actuator and drill were fabricated. Their adaptability to high and low temperatures, as well as their output characteristics, were rigorously tested. Experimental results demonstrate that with an increase in temperature, the dynamic impedance of the actuator initially rises before decreasing, while the mechanical quality factor exhibits the opposite trend. Notably, the concurrent activation of points P 1 and P 2 significantly enhances the no-load speed, achieving a maximum of 506 revolutions per minute (r/min). Under conditions of power below 35 W and a drilling pressure of 10 N, the drilling speed achieved in basalt is 6.2 millimeters per minute (mm/min). The proposed multipoint-driven actuator can effectively improve the drilling and chip removal efficiency of the driller, which is an important application prospect in future extraterrestrial drilling missions.