An experimental study of the characteristics of hydrostatic transmission systems

In the field of robotics, mechanical power transmission systems are fundamental and critical components. In recent years, hydrostatic transmission systems (HSTs) have begun to receive attention as power transmission systems for robotic applications. The primary goal of this study is to identify the inherent properties of HSTs. In this article, we first introduce experimental methods for determining the characteristics of HSTs and then discuss the experimental results. Our findings from the experiments suggest that the commercial external gear pump in an HST cannot entirely convert mechanical power to hydraulic power because of its internal leakage and friction behavior. These physical behaviors are mathematically modeled and experimentally identified. It is also found that a long transmission line not only results in low-pressure rise rates but also flow friction loss. We strongly believe that the results discussed in this article will provide helpful guidance for the design and control of robotic systems.