A cable-based synergy drive approach for variable curvature snake-like robots

Abstract Cable-driven snake-like robots have been widely applied in various fields. However, some of these robots may have poor operational precision and payload capacity. Moreover, an excessive number of motors would increase the complexity of motion control, and the configuration of driving cables at the distal joints is severely limited by the drive system. Therefore, this study introduces a driving model of cable-driven rolling joints through coordinate-based analysis, and proposes a novel two-degree-of-freedom planar synergy drive system to enable variable curvature at the distal joints. A prototype was designed based on the proposed system, which was put into a precision experiment. Two quantifiable parameters were proposed to demonstrate the advantages of the proposed system. The distal joint precision and the driving model precision were employed as indicators to quantify the performance of the prototype. The maximum mean absolute error of the two indicators was 1.52% and 1.88 $^{\circ }$ , respectively, and the maximum root mean square error was 1.66% and 2.02 $^{\circ }$ , respectively. The experimental results demonstrate the feasibility of our approach, which offers increased flexibility in the cable configuration at the distal joints.