An Ultrasonic Drilling System for Fast Drilling Speed With Uncertain Load

China's first asteroid exploration project plans to use ultrasonic drilling solutions to achieve asteroid anchoring. The uncertain rock strength on the asteroid and the high and low temperatures pose challenges to the drilling speed and stability of an ultrasonic drill. Therefore, we propose a design method for the ultrasonic drilling system to tackle this issue. First, a novel percussive ultrasonic drill is designed based on theory and experiments. Then, an ultrasonic drive power with resonance frequency tracking, electrical matching, and constant amplitude control is developed to improve the adaptive ability of an ultrasonic drill in an uncertain load environment. Finally, the drilling performance of an ultrasonic drill on rocks with different compressive strengths at different temperatures is verified by experiments. Our results show that when the temperature range is -60 to 120 ^{\circ }C and the rock strength is 200 MPa, the drilling speed is 8-28 mm/min, and the power consumption is less than 50 W, the stable working time of a single operation exceeds 2 min. Herein, we provide a technical reference for the application of ultrasonic drilling in planetary exploration.