A Triarc Planning Method for Concentric Cable-Driven Manipulators With Three Segments Working in Throat Examinations

The flexibility of concentric cable-driven manipulators with more segments is significantly enhanced. However, some specific methods can only efficiently solve the configuration planning for manipulators with one or two segments; other general methods have extremely low efficiency in configuration planning for concentric cable-driven manipulators with multiple segments. This article proposes an efficient triarc planning method for concentric cable-driven manipulators with three segments working in throat examinations. In this article, the reasonable triarc configuration for these three segments can be planned simultaneously by considering six input parameters, i.e., proximal and distal control points, tangent vectors, and centers of curvature circle. The proposed method has three features as follows. First, the proportion of each segment can be adjusted by the free control point to optimize the triarc configuration. Then, the relative direction of rotation between proximal and distal tangent vectors can be set to predetermine the triarc configuration. Furthermore, the suitable triarc configuration of the concentric cable-driven manipulator for throat examinations can be optimized by simultaneously considering the bending coefficient. Finally, the proposed triarc planning method is validated by simulations and experiments. Results show that the designed concentric cable-driven manipulator can reach the target point according to planned triarc configurations with an average error of 1.41 mm.