Abstract: Hydraulic actuated quadruped robots have bright application prospects and significant research values in unmanned area investigation, disaster rescue, material transport and other scenarios, due to their discrete landing positions and large payloads. As the most critical movement unit of a quadruped robot, the mass distribution of limb leg unit directly affects the dynamic performance of the robot, calling for a compact and lightweight design. This study focuses on the problem of excessive redundant weight in the thigh structure of the limb leg unit of Spurlos Ⅱ robot. The solid isotropic material with penalization algorithm is adopted to the thigh structure topology optimization, and the optimized mesh model is reconstructed using a method based on B-spline fitting approach for two-dimensional cross-sectional profiles. Then, to solve the problem of local stress concentration caused by model reconstruction, lattice filling structures are introduced to achieve further optimization. After optimization, the weight of the thigh structure component reduces by 36.01% to 1007.19 g, and its maximum equivalent stress decreases by 1.41%. Finally, the optimized leg limb unit demonstrated better dynamic performance in trajectory tracking experiments with different frequencies, proving the effectiveness of the proposed lightweight design method.

Key words: hydraulic quadruped robot, topology optimization, lattice filling, model reconstruction, lightweight design