Meeting Abstract
Animals like snakes use traveling body bends to move in multi-component terrestrial terrain. Previously we studied [Schiebel et al., PNAS, 2019] a desert specialist (Chionactis occipitalis) traversing sparse rigid obstacles and discovered that passive body buckling, facilitated by unilateral muscle activation, allowed obstacle negotiation without additional control input. In this poster, we explore the benefits and limitations of this obstacle negotiation strategy using a novel robophysical model designed to capture muscle morphology and activation patterns in snakes. Most snake robots have one motor per joint whose positions are precisely controlled. In contrast, the actuation in our robot is modeled after biological snakes; pairs of muscles, one on each side of the spine, create body bends by unilaterally contracting. The robot snake has 8 joints and 16 motors, one motor with a pulley on each side. Each pulley is connected to a wire that, when shortened, bends the robot toward that side. Inspired by snake muscle activation patterns [Jayne, J. Morph., 1988], we programed the motors to be unilaterally active and propagate a sine wave down the body. Opposite an active motor, the pulley is completely unspooled so that the joint can be bent toward the active pulley without tension force from this passive wire. These pairs of motors can thus resist forces which attempt to lengthen active wires but not those pushing them shorter, resulting in mechanical passivity. Preliminary tests demonstrate that the robot can move on hard ground when drag anisotropy is large, achieved via wheels attached to each segment on the robot’s belly.
