A Novel Articulated Manipulator Design With Mechanism Doublet

摘要

The manipulators with circular bending ability, represented by continuum robots, prevail in constrained and unstructured environments, earning broad applications including inspection, search and rescue, and minimally invasive surgery. However, their distal maneuvers get forceless and inaccurate in the long-distance transmission of tiny strain. This article introduces a novel articulated manipulator assembled of serially connected mechanism doublet (MD)—mechanism with symmetric kinematic inputs and outputs. The outputs of one MD serve as the inputs of the next. Based on the transmission property of MDs, the manipulator holds circular bending ability, yet stands out of the continuum robot communities and excels in several aspects. First, it reaches a larger bending range with extreme curvature, unlimited by the material deformation that continuum robots rely on. Second, this structure transmits the small rotations based on geometric constraints among MDs. No more need for driven tendons or other appendices for actuation. This structure can be directly driven by packed motors. Third, the motions are copied along parallel mechanisms, promising better position accuracy. Experimental evaluation was performed on a three-dimensional printed prototype of this articulated manipulator, reporting a mean repeatability of 0.42 mm and a maximum payload of 1.5 N, equivalent to 420% of the structure weight. The MD-based manipulator provides a new solution for operation in constrained environments.