Spatial stiffness study of parasitic mechanism-based wheel-legged robots

ObjectiveTo address the problems of low computational efficiency and significant deviation from test results in the stiffness analysis of complex spatial multi-link mechanisms, a parallel decoupled multi-link wheel-legged robot was designed based on the host-parasitic mechanism, aiming to achieve efficient and accurate spatial stiffness modeling and analysis.MethodsFirstly, the configuration of the wheel-legged robot was constructed according to the host-parasitic mechanism to provide a structural basis for subsequent stiffness modeling; secondly, a spatial fitting stiffness distribution (S-FSD) model composed of very few computational units was established using Matlab software to simplify the stiffness calculation process; then, reference data were obtained through static simulation with Ansys software, and the model parameters were fitted by the Monte Carlo method to improve the computational accuracy of the model; finally, physical tests were conducted to verify the correctness of the established model.ResultsThe results show that the computational efficiency of the S-FSD model is significantly improved, with the computation time reduced by more than 99.35%. The maximum deviation for a single pose is 4.06%, the maximum deviation after comprehensive multi-pose fitting is 19.66%, and the maximum deviation from the measured stiffness is only 14.5%. Meanwhile, the differential regularity of stiffness distribution in the x, y, and z directions of the robot is revealed, providing a reference for the structural optimization and trajectory planning of wheel-legged robots.