Design and Dynamics of a Tendon-Actuated Flexible Crawling Robot

Abstract Flexible crawling robots have extensive applications in various fields, including on-orbit modular assembly, space transportation, and spacecraft surface maintenance. This article designs a tendon-actuated flexible crawling robot with the advantages of light weight, compact form factor, simple drive, versatile maneuverability, all-round movement, and capabilities of accomplishing intricate crawling tasks for detection, searching, and on-orbit service. First, the structures of the crawling robot are designed via the topology optimization approach, which reduces the total mass of the crawling robot by up to 70%. The dynamic model of the flexible crawling robot is established based on the natural coordinate formulation (NCF) and the absolute nodal coordinate formulation (ANCF) in the framework of arbitrary Lagrange–Euler (ALE). Second, various gaits of the crawling robot are designed via the variations in tendon lengths and verified via dynamic simulations. Finally, a prototype of the crawling robot is manufactured by using eight servo motors to actuate the tendons, thereby controlling the movement of the crawling robot. The designed gaits, i.e., standing, rotating in place, and wriggling forward gaits, are tested across diverse terrains. Several technical indexes of these gaits are analyzed, including standing height, turning angle, and crawling displacement, thereby confirming the viability of the tendon-actuated locomotion patterns exhibited by the flexible crawling robot.