How to make a rope climbing robot

1. Introduction A study of the sloth bear (Fig 1) in motion reveals that the bear uses both pairs of its limbs (fore limbs and hind limbs) to climb a rope or a tree. It moves both its hind limbs in one step and then both its fore limbs in another. Each pair of limbs acts as a gripper. Only one pair of limbs is used at a time for gripping the tree (while in motion) while the other pair slides over the tree. The bear uses its back as a hinge, the back being straight in one instant and bent in the other. This movement when coordinated can be a very efficient and a reliable mechanism for climbing. No wonder then, the sloth is one of the best climbers in nature. This is also the reason why it was chosen as a model for our study. In recent years, several researchers and groups have reported work on such biomimetic devices. For example, “The Robo-tuna” (Barrett [1]) is an ongoing project at MIT’s department of ocean engineering, where attempts are being made to copy the motion of a blue-fin tuna in order to develop a better propulsion system for autonomous underwater vehicles. Ayers et al [2] reported attempts being made at the Marine Science Center, Northeastern University, to copy the behavior of lobsters for the purpose of conducting autonomous investigation of both the bottom and water column of the littoral zone of an ocean. Analysis and development of snake-like devices has been reported by Hirose [3]. The ROBO-Sloth is comparatively simpler as far as its behavior is concerned. It has only to move along a pre-defined path. An improvement in design would be to enable the robot to shift between ropes, whereby the problem would become that of motion in space rather tha