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수압 기반 EHA의 동역학적 특성 해석 및 시스템 식별
송하권(Ha-Gwon Song),임동원(Dong-Won Lim) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
The EHA (Electro-Hydraulic Actuator) is a compact and reliable hydraulic system. It consists of a hydraulic pump, a power cylinder, connecting tubes, and other accessories. The EHA has merits such as its high weight-to-power ratio. In this reason, EHAs have potential to be used for various engineering applications. Due to the possibility of leakage of its working fluid, the mineral oil, the water-based EHA has been developed. Water has different characteristics apart from oil, the dynamic characteristics of the water-based EHA need to be studied for its proper control scheme. This paper deals with analyzing the dynamic behavior of the water-based EHA as a whole system so that the system identification can be made for the control logic. To this end, the experiment set-up has been constructed using a DC motor, water pump, power cylinder, pressure gage, encoder, potentiometer, and torque transducer. When the pressure and the velocity of the payload is the input and output, respectively, the simplified transfer function was formulated. From the results, it was found that the experimental transient behavior cannot be clearly predicted by the transfer function itself. This implies that the nonlinear characteristics of the fluid circuit are important as well, and so the coupled analysis of fluid and mechanical systems will be studied in the future. Therefore, the water-based EHA system needs more dynamic analysis in detail for the accurate control logics.
수압 기반 EHA의 동역학적 특성 해석 및 시스템 식별
송하권(Ha-Gwon Song),임동원(Dong-Won Lim) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
The EHA (Electro-Hydraulic Actuator) is a compact and reliable hydraulic system. It consists of a hydraulic pump, a power cylinder, connecting tubes, and other accessories. The EHA has merits such as its high weight-to-power ratio. In this reason, EHAs have potential to be used for various engineering applications. Due to the possibility of leakage of its working fluid, the mineral oil, the water-based EHA has been developed. Water has different characteristics apart from oil, the dynamic characteristics of the water-based EHA need to be studied for its proper control scheme. This paper deals with analyzing the dynamic behavior of the water-based EHA as a whole system so that the system identification can be made for the control logic. To this end, the experiment set-up has been constructed using a DC motor, water pump, power cylinder, pressure gage, encoder, potentiometer, and torque transducer. When the pressure and the velocity of the payload is the input and output, respectively, the simplified transfer function was formulated. From the results, it was found that the experimental transient behavior cannot be clearly predicted by the transfer function itself. This implies that the nonlinear characteristics of the fluid circuit are important as well, and so the coupled analysis of fluid and mechanical systems will be studied in the future. Therefore, the water-based EHA system needs more dynamic analysis in detail for the accurate control logics.
수압 기반 소형 EHA(electro-hydraulic actuator) 시스템을 위한 플라스틱 액셜 피스톤 사판식 수압펌프 설계
송하권(Ha-Gwon Song),임동원(Dong-Won Lim) 대한기계학회 2024 大韓機械學會論文集A Vol.48 No.3
In this study, we focus on the design and verification of an axial piston swash-plate pump for the small water-based electro-hydraulic actuator (EHA). By utilizing water as the working fluid, the proposed EHA compensates the downsides of conventional oil-based EHAs, keeping the environmental benefits. The proposed compact hydraulic pump, with a size of 20 mm × 20 mm × 40 mm, is almost capable of the theoretically-calculated pressure of 0.237 MPa and flow rate of 1,449.6 mm³/s. The proposed pump, made of appropriate plastic materials for water as the working fluid, ensures a lightweight and rust-proof design. Therefore, the compact EHA concept was attained. Experimental validation confirmed the design validity that the pump could exert the experimental pressure of 0.19 MPa and flow rates of 914 mm³/s (lifting) and 1,127.6 mm³/s (lowering).
전기 정유압 구동기를 이용한 새로운 동력 조향 시스템에 관한 연구
리쯔밍(Zhi Ming Li),이지민(Ji Min Lee),박성환(Sung Hwan Park),김종식(Jong Shik Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
In this paper, a electro hydraulic power steering system based on electro-hydraulic actuator(EHA) is proposed. A detailed steer model for proposed electro-hydrauic power steering system including mechanical subsystem and hydraulic subsystem is established. A conventional electro hydraulic power steering system is also modeled to evaluate the steering performance of hydraulic steering system based on EHA by computer simulation. Through thε computer simulation result of MATLAB/Simulink, it is concluded that the hydraulic steering system based on EHA has desirable performance with some advantages such as small size, high efficiency and no leakage.
송하권(Ha-Gwon Song),이용권(Yong-Kwun Lee),임동원(Dong-Won Lim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
In machinery, the incipient fault detection is of importance to avoid any fatal breakdown of operations. Typically, a mechanical part gradually degrades, and then its degradation accelerates as time goes. The EHA (Electro-Hydraulic Actuator) is a linear actuator which merits include its high weight-to-power ratio. The water-based EHA, which does not contaminate surrounding environment due to the leakage, employs the plastic pump, because the operating fluid is water. The plastic pump requires automatic fault detection due to its low strength of the material. In this research, the early fault detection methodology of the plastic pump is proposed based on the hardware redundancy. The residual from pressure measurements is generated, and approximately 0.005 MPa was observed. To declare the fault, the accumulated residual is used because 0.005 MPa is less than the noise level. With 1 MPa threshold, the fault could be declared using the accumulated residual which becomes greater than 1 MPa after 10 seconds of its operation.
수압 EHA 사판식 액셜 피스톤 펌프 역치법 고장탐지 알고리즘
송하권(Ha-Kwun Song),임동원(Dong-Won Lim) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.11
Early fault detection holds paramount significance in preventing catastrophic operational breakdowns. Ordinarily, mechanical components undergo a gradual degradation process, often accelerating over time. The implementation of a water-based Electro-Hydraulic Actuator (EHA), which eliminates environment contamination concerns due to leakage, relies on a plastic pump mechanism. This choice arises from the use of water as the operating fluid. However, owing to the comparatively lower material strength of plastic, the automatic detection of potential faults becomes imperative for the plastic pump. To ensure system integrity, the thresholding fault detection method was proposed based on the pressure residual integral value of the power cylinder. In this study, the thresholding for the pump fault detection was dealt mathematically. Experimental verification demonstrated that the proposed method effectively distinguished between a healthy device and a faulty pump. By comparing the pressure residual integral values, faults could be declared if the value exceeded a specified threshold. The proposed method allowed for initial fault detection within 10 seconds of pump operation, providing the opportunity to prevent abrupt system shutdowns.
Position control of Electro Hydraulic Actuator (EHA) using an Iterative Learning Control
도안녹치남,우엔민트리,박형규,안경관 사단법인 유공압건설기계학회 2014 드라이브·컨트롤 Vol.11 No.4
This paper presents the development of a compact position generator to be used for industrial purposes based on a pump controlled Electro-Hydraulic Actuator (EHA), which is closed-loop controlled by an embedded based Iterative PID controller. The controller is designed by combining the PID controller and the iterative learning scheme to perform tracking control for periodically desired references. Control algorithm is implemented on an embedded computer (AD 7011-EVA) which makes the implementation and application in industrial environments easier.
Position Control of Electro Hydraulic Actuator (EHA) using an Iterative Learning Control
D. N. C. Nam(도안녹치남),N. M. Tri(우엔민트리),H. G. Park(박형규),K. K. Ahn(안경관) 유공압건설기계학회 2014 드라이브·컨트롤 Vol.11 No.4
This paper presents the development of a compact position generator to be used for industrial purposes based on a pump controlled Electro-Hydraulic Actuator (EHA), which is closed-loop controlled by an embedded based Iterative PID controller. The controller is designed by combining the PID controller and the iterative learning scheme to perform tracking control for periodically desired references. Control algorithm is implemented on an embedded computer (AD 7011-EVA) which makes the implementation and application in industrial environments easier.