Bionic Design and Optimization on the Flow Channel of a Legged Robot Joint Hydraulic Drive Unit Based on Additive Manufacturing.

The joint hydraulic drive unit (HDU) serves as a pivotal element in enabling the high-performance movements of legged robots. Functioning as the conduit linking the oil source and the actuator, the hydraulic flow channel significantly impacts actuator performance. Hence, optimizing the HDU flow channel becomes imperative, enhancing not only HDU efficiency but also the overall system performance. This paper introduces a novel approach by aligning the hydraulic flow channel of the joint HDU with the arteriovenous layout of the cardiac vascular system, departing from the conventional machining flow channel model. Through simulations determining the optimal range of the vascular branch radius and angle, this study guides the design optimization of the joint HDU flow channel. With the primary optimization goal of reducing pressure loss, the study compares simulation outcomes of various flow channel models-linear, variable excessive radius, and the multidimensional Bessel curve-tailored to suit the arrangement specifics of the joint HDU. Further validating these designs, the flow channels are fabricated using additive manufacturing for experimental verification. The integration of simulation analyses and pressure loss testing reveals a remarkable reduction of over 40% in pressure loss for the bionic flow channel compared to the conventional machining form. This empirical evidence strongly substantiates the bionic flow channel's superior efficacy in pressure loss reduction. The findings presented herein offer valuable insights for the development of low-loss flow channels in joint HDUs, thereby presenting a new avenue for designing energy-efficient, high power-to-weight ratio legged robots.