Design and Fabrication of a Small Climbing Platform inspired by a Cockroach

Abstract

Small mobile robots are required in rescue missions and military task. Milli-scale robots can pass a narrow gap within a collapsed building and carry out the reconnaissance mission without being detected by enemies. The issue of a small robot is that it might get stuck in obstacles that are bigger than itself. The ability to overcome obstacles is important to small robot. Climbing can make it overcome tens of times larger than itself. In this research, three principles of cockroach climbing are defined and integrated with planar mechanism. Small cockroach can rapidly climb vertical walls with a rough surface. First principle inspired by a cockroach is stable walking with an alternating tripod gait. This gait makes stable locomotion possible thanks to the support of at least three feet. Planar transmission using a single actuator is designed for alternating tripod gait. Second principle is reducing the impact during the attachment process. Cockroach use compliant foot called tarsus structure. This can reduce the amount of normal reaction force during the interaction between spines and surface. Compliant foot are modelled based on Pseudo-rigid-body model (PRBM). Hind leg is designed to reduce the pitch-back moment at the front limb without tail. Third principle is the phase overlap. Phase overlap is an overlapping of the set of feet on the ground. Cockroaches have the phase overlap during climbing at 5body-lengths/sec. Planar quick-return leg is designed to have the phase overlap during alternating tripod gait. In this research, three key principles are extracted and integrated with planar fabrication for a small climbing robot. A new method using laminating film and fabric is developed for fast prototyping as well as for high structural strength. Fabricated robot is 8.5cm long and 6g in weight. This robot can climb on three different kinds of surfaces at around 0.1body-lengths/sec. The research suggest the possibility that a new approach based on biomimetics and planar design can solve the scale issue of small mobile robots thanks to a novel and simple mechanism.