Stiffness Optimisation and Kinematics Modelling of a Cable‐Stayed Flexible Manipulator for Endoscopic Surgery

BACKGROUND: Cable-driven continuum robots face an inherent trade-off between stiffness and flexibility, with stiffness enhancement representing a critical challenge in the field. METHODS: This study presents a stiffness-optimised cable-stayed notched manipulator (CSNM). The Bernoulli-Euler beam theory models elastic beam (EB) deformation for stiffness optimisation, while a simplified piecewise constant-curvature assumption based on tendon lengths is used for kinematics. An evolution-based EB optimisation algorithm achieves uniform stress distribution and enhanced load capacity. RESULTS: Experiments show that the maximum variance of the EB bending angle after optimisation is 0.5°. The maximum motion error of the manipulator on the x-axis and y-axis is 0.21 and 0.32 mm, respectively. Benefitting from the uniform distribution of stress, the load capacity of the manipulator increases by 100% after optimisation. CONCLUSION: These results validate the structural optimisation and kinematic modelling, highlighting the CSNM's potential for endoscopic applications needing flexibility and high load capacity.