Abstract: The lightweight design of hydraulic quadruped robots, especially the lightweight design of the leg joint Hydraulic Drive Unit (HDU), can improve the robot's response speed, motion speed, endurance, and load capacity. However, the lightweight design of HDU is a huge challenge due to the need for structural strength. This paper is inspired by the geometric shape of fish bones and biomimetic reinforcing ribs on the surface of the HDU shell are designed to increase its strength and reduce its weight. First, a HDU shell with biomimetic fish bone reinforcing ribs structure is proposed. Then, the MATLAB toolbox and ANSYS finite element analysis module are used to optimize the parameters of the biomimetic reinforcing ribs structure and the overall layout of the shell. Finally, the HDU shell is manufactured using additive manufacturing technology, and a performance testing platform is built to conduct dynamic and static performance tests on the designed HDU. The experimental results show that the HDU with biomimetic fish bone reinforcing ribs has excellent dynamic performance and better static performance than the prototype model, and the weight of the shell is reduced by 20% compared to the prototype model. This work has broad application prospects in the lightweight and high-strength design of closed-pressure vessel components.

Key words: Hydraulic drive unit , · Lightweight design of shell , · Biomimetic fish bone structure design , · Dynamic and static performance testing