Design and Mechanical Analysis of a Cable-Driven Manta Ray-Inspired Robot

To address the limitations of conventional underwater vehicles, such as propeller-induced noise, high disturbance to aquatic ecosystems, and the inherent trade-offs in existing manta ray-inspired robots, this paper proposes a novel centralized cable-driven rigid-flexible coupled bionic manta ray robot. First, a flapping wing skeleton featuring a rigid central section and flexible rolling contact joints is developed, which relocates all power units to the fixed fuselage and enables low-inertia, continuous deformation of distal joints via a pair of antagonistic cables, eliminating the need for bulky hinges and reducing dynamic sealing risks. Second, a two-dimensional profile model is established based on the morphological characteristics of manta rays, where the leading edge is described by an exponential growth function and the trailing edge by a power function, strictly satisfying geometric boundary conditions. Third, given the under-actuated nature of single-pair cable driving, a piecewise constant curvature assumption is introduced to derive forward and inverse kinematic mappings between the driving space and task space, clarifying deterministic correlations and cable tension constraints. Finally, static analysis is conducted using ANSYS Workbench, with mesh independence verification confirming an optimal grid scheme. Results show that under an axial distributed load of 6.473 N, the maximum deformation of the skeleton is only 0.53017 mm (far below the allowable limit), and the peak stress is 5.6111 MPa with a safety factor of 15; after structural optimization reinforcing the root axial locking feature, the peak stress is further reduced by 17.75%. This study effectively balances low inertia, high load capacity, and continuous deformation requirements, providing a solid theoretical and safety foundation for the development and underwater testing of low-noise, high-maneuverability bio-inspired underwater robots.