Design of Novel Untethered Hydraulically Driven Soft Crawling Robots

To satisfy the demands of operating in various unstructured environments, soft robots have gained wider applications due to their high degrees of freedom and soft materials. However, existing soft robots typically use external power sources. For example, pneumatic soft robots require a separate air pump to supply pressure, which significantly limits their practical applications. To solve this problem, in this paper, an untethered hydraulically driven soft crawling robot (UHDSCR) is proposed, in which an internal hydraulic gear pump enables tetherless operation. UHDSCRs consist of two hydraulic gear pumps, a set of PU plastic hoses, two brushless DC motors (BLDC) and four three-dimensional deformation soft actuators, etc. Three-dimensional deformation soft actuators bend under pressure from hydraulic pumps. The deformation of all four three-dimensional deformation soft actuators provides both support and driving force for UHDSCRs. UHDSCRs are designed for the first time using three-dimensional deformation soft actuators and a hydraulically driven system based on hydraulic gear pumps, accompanied by the development of a crawling gait design. Finally, an experimental platform for UHDSCRs is independently constructed, and the effectiveness of design concepts and experimental methods are validated through experiments.