An asteroid anchoring method based on cross-drilling geometric force closure of ultrasonic drill

Asteroid anchoring is the premise for the spacecraft to conduct in-situ scientific exploration on the surface of a weak gravitational asteroid. There is not any precedent for successful anchoring on the asteroid surface all over the world. Ultrasonic drill actuated by the piezoelectric ceramic is especially suitable for drilling on the surface of a weak gravitational asteroid, showing outstanding advantages such as low power consumption, low required drilling pressure and wide temperature range. In order to solve the technical problem of anchoring, a novel anchoring device based on multiple ultrasonic drill cross-drilling geometric force closure is proposed. Firstly, the structure and working principle of the anchoring device are introduced. Then the EDEM software based on the Discrete Element Method is used to simulate the influencing factors of the anchoring force. Finally, the effectiveness of the anchoring device is proved by experiments. The results show that the ultrasonic drill is effective for the anchoring device; the anchoring device can provide an anchoring force of 60–250 N for the spacecraft; its structure is simple, compact and adaptable.