Electro-hydrostatic actuator (EHA) has backdrivability and is suitable for a robot system that cooperates with human. However, its design methodology to miniaturize and to generate high pressure has not been established. We develop a robotic arm, all joints of which are actuated by EHAs. This paper reports the development of the vane motor type EHA and a wrist mechanism using the EHA. We employ a single vane motor for a wide motion range. In order to suppress internal leakage, we carefully set the clearance of the EHA and made the rigid casing by using ceramics disks. It is confirmed that the internal leakage of the new EHA is significantly reduced compared to that of the previous model. The wrist mechanism has three degrees of freedom, consisting of three vane motors in series. The flow path between a hydraulic pump and a vane motor is designed using metal pipings, swivel joints and manifolds are presented for a compact wrist mechanism. We validated the fundamental performance of the developed wrist mechanism through experiments. GRAPHICAL ABSTRACT

中文翻译：

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静液压驱动机械臂三自由度手腕机构的研制

静液压执行器（EHA）具有反向驱动能力，适用于与人类协作的机器人系统。然而，其小型化和产生高压的设计方法尚未建立。我们开发了一个机械臂，它的所有关节都由 EHA 驱动。本文报告了叶片马达型 EHA 和使用 EHA 的腕式机构的开发。我们采用单叶片电机来实现广泛的运动范围。为了抑制内部泄漏，我们仔细设置了 EHA 的间隙，并使用陶瓷盘制作了刚性外壳。经证实，与之前的型号相比，新 EHA 的内部泄漏显着减少。腕机构具有三个自由度，由三个串联的叶片马达组成。液压泵和叶片马达之间的流动路径使用金属管道设计，旋转接头和歧管用于紧凑的腕式机构。我们通过实验验证了开发的手腕机构的基本性能。图形概要