Rising STAR: A Highly Reconfigurable Sprawl Tuned Robot

Abstract

This letter presents Rising STAR (RSTAR) a novel highly reconfigurable robot. RSTAR belongs to the family of the STAR robots with similar sprawling capabilities allowing it to run in a planar configuration, either upright or inverted and change its mechanics from the lateral to the sagittal planes. However, RSTAR is fitted with a new four bar extension mechanism (FBEM) allowing it to extend the distance between its body and legs. This combination of sprawling and extension mechanisms enables RSTAR to overcome extremely challenging obstacles, crawl over flexible and slippery surfaces and even climb vertically in a tube or between two walls. The robot can extend its height and width three-fold and move its center of mass both in the fore-aft and vertical directions. We first describe a kinematic model and the dynamical analysis conducted to improve the design of the robot and evaluate its strength and motor requirements. Based on this analysis, we designed and built a three-dimensional printed prototype and experimentally tested it. The robot can run upside down and climb over obstacles that are even higher than the diameter of its wheeled legs using a turtle-like gait. To increase its mobility, RSTAR can be fitted with wheels or spoked legs or a combination of the two, giving it superiorability to engage different terrains (see video).