Application and progress of high-efficiency electro-hydrostatic actuator technology with energy recovery: A comprehensive review

With the growing urgency of the energy crisis, hybrid power offers an advanced means of energy optimization, where electro-hydraulic hybrid systems, such as electro-hydrostatic actuators (EHAs), represent a novel opportunity for hydraulics. EHAs have gained attention in various fields due to the benefits of high efficiency and high force-to-weight ratio. In addition, energy recovery also provides ideas for reducing consumption and improving the energy efficiency of the entire machine. To facilitate the development of the technology, this paper summarizes in detail the concepts, division, and operating principles with four quadrants. Subsequently, the mechanisms of the modeling methods are comprehensively analyzed and compared. An in-depth discussion of the roles played in each area and the relevant controls is provided. Finally, the review synthesizes the progress in energy recovery, taking into account the recovery modes and energy types, and identifies the research challenges. This paper is essential for understanding EHA technology and promoting the application and popularization of EHAs.