Key design parameters of a few types of electro-hydrostatic actuators for humanoid robots

Ko, Tianyi; Kaminaga, Hiroshi; Nakamura, Yoshihiko

doi:10.1080/01691864.2018.1545604

Cited by 17 publications

(9 citation statements)

References 7 publications

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“…The friction resistance of the bidirectional pump is an important factor for the pump-controlled system. It can greatly improve the frequency response of the hydraulic system if the friction resistance of the bidirectional pump is reduced (Ko et al, 2018; Li et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

“…A hydraulic system was developed by South Korea’s Defense Department for an exoskeleton to enhance the capabilities of soldiers, which is controlled by servo-valve and bypass valves (Kim et al, 2015). In Japan, a few types of electro-hydrostatic actuator (EHA) were used for the “Hydra” humanoid robots (Ko et al, 2018). It can be seen that the hydraulic systems of lower extremity exoskeletons mainly have two control methods.…”

Section: Introductionmentioning

confidence: 99%

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A novel pump-valve coordinated controlled hydraulic system for the lower extremity exoskeleton

Jinlin

Wang

Cao

et al. 2020

Transactions of the Institute of Measurement and Control

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In order to reduce the weight and improve the energy efficiency of the lower extremity exoskeleton, a novel pump-valve coordinated controlled (PVCC) hydraulic system is presented. This hydraulic system only uses one electro-hydrostatic unit (EHU) and two valves to drive two hydraulic cylinders at the hip and knee of the lower extremity exoskeleton. The PVCC hydraulic system has the advantage of high energy conversion efficiency of the electro-hydrostatic actuator (EHA), which consists of one EHU and one hydraulic cylinder. To meet the requirements of the moment and speed of each joint of the exoskeleton, the proportional valve and on-off valve are added to adjust the flow into two hydraulic cylinders. The performance of EHU is tested by some hydraulic experiments, and the performance of the PVCC hydraulic system is analyzed by AMESim. The results show that the novel hydraulic system can only use one EHU to drive two hydraulic cylinders simultaneously under the premise of meeting the functional requirements of the exoskeleton.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A novel pump-valve coordinated controlled hydraulic system for the lower extremity exoskeleton

Jinlin

Wang

Cao

et al. 2020

Transactions of the Institute of Measurement and Control

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show abstract

“…EHA have also been applied to robotics such as humanoid robot. The University of Tokyo developed an EHA actuated anthropomorphic hand [17,18] and humanoid robot [19,20]. The Kyushu Sangyo University designed the micro EHA's actuated robotic arm [21].…”

Section: Introductionmentioning

confidence: 99%

One Novel Hydraulic Actuating System for the Lower-Body Exoskeleton

Sun

Ouyang

Mattila

et al. 2021

Chin. J. Mech. Eng.

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The hydraulic exoskeleton is one research hotspot in the field of robotics, which can take heavy load due to the high power density of the hydraulic system. However, the traditional hydraulic system is normally centralized, inefficient, and bulky during application, which limits its development in the exoskeleton. For improving the robot’s performance, its hydraulic actuating system should be optimized further. In this paper a novel hydraulic actuating system (HAS) based on electric-hydrostatic actuator is proposed, which is applied to hip and knee joints. Each HAS integrates an electric servo motor, a high-speed micro pump, a specific tank, and other components into a module. The specific parameters are obtained through relevant simulation according to human motion data and load requirements. The dynamic models of the HAS are built, and validated by the system identification. Experiments of trajectory tracking and human-exoskeleton interaction are carried out, which demonstrate the proposed HAS has the ability to be applied to the exoskeleton. Compared with the previous prototype, the total weight of the HAS in the robot is reduced by about 40%, and the power density is increased by almost 1.6 times.

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“…Helian et al, 2019 designed an adaptive robust controller for a direct drive system, where a servomotor pump was adopted as the drive part [12]. A triple-loop feedback control strategy was developed by Tianyi et al, 2018 to extend the pressure bandwidth of the driving element in a humanoid robot [13,14]. It's also very convenient to apply adaptive control strategy, intelligent hybrid control strategy, predictive control strategy and sliding mode control strategy to the direct drive hydraulic systems with the speed mode [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Direct Drive Hydraulic System with the Torque Mode

Zhang

Jiang

2021

Energies

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The torque mode is more suitable for the direct drive 6 degree of freedom (6-DOF) parallel mechanism than the speed mode that both dynamic coupling and current coupling among motors are easily solved, but its key parameters and dynamic characteristics have never been studied, which are important and are the goals of this paper. First the hydraulic system of the direct drive 6-DOF parallel mechanism is simplified. Then the transfer function of the direct drive hydraulic system with the torque mode is deduced together with that of the speed mode. Finally, comparative experiments are conducted. Results show that the dynamic characteristics of the system with the torque mode which are generally worse than those with the speed mode, are mainly determined by the parameters of the motor-pump second-order element of the transfer function composed of two under-damped second-order elements, proportion differentiation (PD) control strategy and dynamic pressure feedback (DPF) control strategy are useful for the system with the torque mode, but practical and effective methods are still needed.

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Key design parameters of a few types of electro-hydrostatic actuators for humanoid robots

Cited by 17 publications

References 7 publications

A novel pump-valve coordinated controlled hydraulic system for the lower extremity exoskeleton

A novel pump-valve coordinated controlled hydraulic system for the lower extremity exoskeleton

One Novel Hydraulic Actuating System for the Lower-Body Exoskeleton

Experimental Study of the Direct Drive Hydraulic System with the Torque Mode

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