Toward Autonomous Free-Climbing Robots

The goal of this research is to enable a multi-limbed robot to climb vertical rock using techniques similar to those developed by human climbers. The robot consists of a small number of articulated limbs. Only the limb end-points can make contact with the environment—a vertical surface with small, arbitrarily distributed features called holds. A path through this environment is a sequence of one-step climbing moves in which the robot brings a limb end-point to a new hold. The robot maintains balance during each move by pushing and/or pulling at other holds, exploiting contact and friction at these holds while adjusting internal degrees of freedom to avoid sliding. The paper first considers a planar three-limbed robot, then a 3-D four-limbed robot modeled after a real hardware system. It proposes an efficient test of the quasi-static equilibrium of these robots and describes a fast planner based on this test to compute one-step climbing moves. This planner is demonstrated in simulation for both robots.