Compact Tensegrity Robotic Inchworm with Superior Locomotion Ability

Robotic inchworms have extensive applications in various areas, including pipe inspection, planetary surface exploration, and disaster relief. The challenges inherent in designing such a type of robots are to achieve high adaptability in a compact configuration and to enhance locomotion velocity without compromising load-bearing capability. In this article, we propose a novel approach to cutting-edge robotic inchworm technology that exploits the tensegrity's specific high stiffness-to-mass ratio and robust compliance. Our robotic inchworm can feature excellent maneuverability, with actuation achieved by contracting internal components and specifying differential forward-backward frictions. The robotic inchworm's superior locomotion abilities are systematically demonstrated through both theory and simulation, yielding perfectly consistent results. Based on the theoretical design, we constructed a physical prototype that showcased a locomotion velocity of up to 30.0 BL/min (BL: body length) at a load-to-mass ratio of 4.1 (the fastest untethered robot in the literature under this payload, to the best of our knowledge). The prototype's locomotion performance was further evaluated on surfaces with varying frictional properties, showing consistent stable and efficient propulsion. Moreover, the present robotic inchworm can actively regulate height to traverse confined passageways and maintain its mounting platform horizontal when navigating on slopes, showing highly commendable adaptability.