High-fidelity modeling and thermal efficiency performance of an electro-hydrostatic actuator for wheel-legged robots

Research on energy efficiency is essential for enhancing energy utilization and facilitating the broader application of electro-hydrostatic actuators (EHAs) in mobile machinery. This paper presents a comprehensive investigation of the energy transfer mechanisms, efficiency characteristics, and loss patterns of EHAs based on the power bond graph. Subsequently, a high-fidelity efficiency model is developed to emulate real-world conditions. The validity is verified through both simulations and experiments, with the efficiency prediction error remaining within 5%. A full-range efficiency map is generated from the proposed model. The results indicate that the EHA exhibits high efficiency. The majority fall in the 30%-60% interval, while the maximum efficiency exceeds 70%. To provide insight into efficiency optimization strategies, the variations in electrical, volumetric, and mechanical loss contributions across different efficiency zones are clarified. Finally, the research systematically explores the influence of temperature on efficiency and the associated mechanisms from a novel perspective. This study lays the groundwork for further work on thermal effects and performance degradation in EHAs.