Design, Analysis, and Verification of an Electro Hydrostatic Actuator for Distributed Actuation System In order to provide a simplified and lowcost solution of the terminal for a distributed actuation system, this paper proposes an electrohydrostatic actuator (EHA) based on the linear drive principle. The proposed actuator is directly driven by a linear pump with a collaborative rectification mechanism, whose performance relies on the collaboration of the internal two units. A pair of linear oscillating motors are employed to drive the two pump units respectively. The control of the actuator is based on the modulation of the oscillating amplitude, frequency, and phase difference of the two motors. The advantage of this actuator is that no more valve control is needed to rectify the linear pump besides the high efficiency of the direct pump drive. In this paper, both schematic and detailed structure of the actuator is presented. The kinematic and dynamic characteristics are analyzed and modeled, based on which the control method is proposed. The experiments verify the validity of the actuator structure and control.

Simulation and Analysis of a FullActive ElectroHydrostatic Powered Ankle Prosthesis This paper presents the design and control architecture of a novel fullactive powered ankle prosthesis which uses integrated forcecontrollable electrohydrostatic actuator (EHA) to provide both initiative compliance and sufficient positive power output at terminal stance to assist walking in whole gait cycle. A 100W brushless DC motor driving a 0.45 ccrev bidirectional gear pump operates as the power kernel. Based on finitestate machine (FSM), a hierarchical controller was designed to ensure the control system performance while different control strategies were implemented on each individual gait phase. Three independent force sensing resistor (FSR) mounted under sole, two pressure transducers and a displacement sensor used as ankle rotation sensor provide feedback signal for both state detection and lowlevel impedance control. A simulation model of the ankle prosthesis system was established with the help of MatlabSimulink to validate its feasibility. Using presampled biomechanics profile as input variable and matched group, the conceptual ankle prosthesis turns out to be able to restore the dynamic interaction response of a wholesome anklefoot to a great extent.