Tumbling and hopping locomotion control for a minor body exploration robot

This paper presents the modeling and analysis of a novel moving mechanism "tumbling"for asteroid exploration. The system actuation is provided by an internal motor and torque wheel; elastic spring-mounted spikes are attached to the perimeter of a circular-shaped robot, protruding normal to the surface and distributed uniformly. Compared with the conventional motion mechanisms, this simple layout enhances the capability of the robot to traverse a diverse microgravity environment. Technical challenges involved in conventional moving mechanisms, such as uncertainty of moving direction and inability to traverse uneven asteroid surfaces, can now be solved. A tumbling locomotion approach demonstrates two beneficial characteristics in this environment. First, tumbling locomotion maintains contact between the rover spikes and the ground. This enables the robot to continually apply control adjustments to realize precise and controlled motion. Second, owing to the nature of the mechanical interaction of the spikes and potential uneven surface protrusions, the robot can traverse uneven surfaces. In this paper, we present the dynamics modeling of the robot and analyze the motion of the robot experimentally and via numerical simulations. The results of this study help establish a moving strategy to approach the desired locations on asteroid surfaces.