A Robotic Concept for the NASA Asteroid-capture Mission

摘要

This paper proposes an approach for capturing and despinning a tumbling asteroid using a space robot. The capturing and despining approach consists of four phases. In the first phase, the capturing system is controlled to match the linear and angular velocities of the asteroid while the path of its center of mass (CM) is made to follow the path of the asteroid’s CM. The second phase is divided into two subphases. In the first subphase, a robotic manipulator is deployed until a camera mounted at the end effector (EE) faces the target landing location. During the second phase, the EE of manipulator approaches a chosen point on the surface of the asteroid. Attitude controllers driving the thrusters at the base of the spacecraft ensure that the matching velocity errors remain bounded while the robotic arm is deployed. Cameras mounted on the arm time such a deployment in order to minimize the impact forces to be experienced at contact. In the third phase a rigid connection between the asteroid and the end-effector is established. In the last phase, the position of the base of the spacecraft relative to contact point is autonomously adjusted to minimize the energy consumption required to despin and stabilize the joint system by maximizing the torque’s arm. This procedure relaxes the need for accurate estimates of the inertial properties of the asteroid. The concept proposed is illustrated by simulating the capture of a rigid asteroid subject to a one axis rotation with no precession or nutation.