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백스테핑 기법을 이용한 항공기용 이중화 비대칭형 직렬 전기-정유압 구동기의 위치제어
김대연,박형준,김상석,김대현,김상범,이준원,최종윤 항공우주시스템공학회 2021 항공우주시스템공학회지 Vol.15 No.3
전기-정유압 구동기(EHA)는 독립적으로 유압 동력원을 운용할 수 있고, 효율이 높다는 장점으로 다양한 산업분야에서 사용되고 있다. 특히 항공분야에서는 고장 대비 및 장착공간의 최소화를 위해 이중화 비대칭형 직렬 구동기 형태로 설계된 EHA를 주로 사용하고 있다. 하지만 이중화 비대칭형 직렬 구동기 형태로 설계된 항공용 EHA는 포스 파이팅(force fighting)현상이 발생하여 내구성능이 감소한다는 단점이 있다. 본 논문에서는 항공용 EHA의 제어성능 향상 및 포스 파이팅 문제를 해결하기 위해 대표적인 비선형 제어 기법인 백스테핑을 기반으로 제어기를 설계하였고, 제어에 필요한 상태를 추정하기 위해 추가 상태 관측기를 제안하였다. 시뮬레이션을 통한 성능 검증으로 제안한 제어기는 일반적인 PI제어기에 비해 제어성능이 우수하고, EHA의 포스 파이팅 현상을 현저히 감소시킨다는 것을 확인할 수 있었다. The electro-hydrostatic actuators (EHA) are widely used in various industrial fields since they can independently execute the function of the hydraulic power source and have high efficiency. Particularly, in the aviation field, the EHA is mainly designed as dual redundant asymmetric tandem actuator to mitigate failure and minimize installation space. However, aviation EHAs designed in the form of dual redundant asymmetric tandem actuator have the disadvantage of decreased durability performance due to the occurrence of force fighting. In this paper, the controller is designed based on backstepping technique to improve control performance and reduce force fighting for aviation EHA. The augmented state observer is proposed to estimate the states required for control. Through simulation, it was verified that the proposed controller had superior control performance and significantly reduces the force fighting compared to the general PI controller.
항공기용 이중화 비대칭형 직렬 전기-정유압 구동기의 Force Fighting 억제 기법
송우근,김상석,최정석,이정운,이종철,이준원,최종윤 항공우주시스템공학회 2022 항공우주시스템공학회지 Vol.16 No.5
EHA(Electro-Hydrostatic Actuator)는 기존의 중앙집중식 유압시스템에 비해 높은 에너지 효율을 가진다. 특히 항공기용 EHA는 고장상황에 대비하여 이중화 설계가 일반적이다. 또한 장착공간의 한계로, 구동기 길이를 최적화 하여야 한다. 따라서 양로드형 실린더와 단로드형 실린더의 직렬 구성이 유리하다. 하지만 피스톤 수압부 면적의 비대칭성으로 인해, 일반적인 제어 기법으로 이중화 구동 시 두 실린더 사이에 Force Fighting 현상이 발생하게 된다. 본 논문에서는 이중화된 EHA의 시뮬레이션을 통해 Force Fighting 현상을 확인하였다. 이를 억제하기 위한 방법으로 Load Compensation 제어기와 힘 제어 기반 위치 제어기를 적용하였고 시뮬레이션을 통해 각각의 성능을 비교 분석하였다.
전기-정유압 구동기의 확장 상태 관측기 기반 비선형 서보 제어
전기호(Gi Ho Jun),안경관(Kyoung Kwan Ahn) 유공압건설기계학회 2017 드라이브·컨트롤 Vol.14 No.4
In this study, an extended-state-observer (ESO) based non-linear servo control is introduced for an electro-hydrostatic actuator (EHA). Almost hydraulic systems not only are highly non-linear system that has mismatched uncertainties and external disturbances, but also can not measure some states. ESO that only use an output signal can be used to compensate these uncertainties and estimate unmeasurable states. To improve the position tracking performance, the barrier Lyapunov function (BLF) that can guarantee an output tolerance is introduced for the position tracking error signal of back stepping control procedures. Finally, the proposed servo control is compared with the proportional-integral (PI) control.
전기호(G. H. Jun),하태욱(T. W. Ha),정근희(K. H. Jeong),안경관(K. K. Ahn) 유공압건설기계학회 2017 유공압건설기계학회 학술대회논문집 Vol.2017 No.11
Hydraulic systems have highly nonlinearities and uncertainties which decrease its performance. In this paper, output feedback nonlinear servo control is proposed for an electro-hydrostatic actuator (EHA). The proposed controller can compensate nonlinearities and uncertainties by using an extended-state-observer (ESO) and backstepping control approach. ESO estimates not only unmeasurable states but also system uncertainty. After that, the estimated uncertainty is compensated in control law design procedure as a feedforward term. In backstepping procedure, a maximum error tolerance is introduced to achieve the servo control. In experimental results in EHA system, the proposed controller is compared with PI controller which is commonly used in industry.
소형 외접기어펌프를 사용하는 EHA의 시스템 효율 분석
김종혁,홍예선 사단법인 유공압건설기계학회 2019 드라이브·컨트롤 Vol.16 No.2
In this study, the maximum system efficiency of the electro-hydrostatic actuators was experimentally investigated, where small size external gear pumps with volumetric displacement under 1.3 cc/rev were combined with a 400W servomotor as the prime mover. Since the efficiency data of the servomotor, gear pumps and hydraulic cylinder were not provided by the suppliers, experimental apparatuses for their efficiency measurement were extra built up. When a gear pump with a volumetric displacement of 1.27cc/rev was used on an electro-hydrostatic actuator system, the maximum system efficiency was not higher than 70%. This was because the most effective operation ranges of the motor and pump did not coincide each other. In order to match their operation ranges as one of the most crucial design factors, a speed reduction mechanism can be used, such as a timing belt. It was shown in the study that the maximum system efficiency could be increased from 70% to 76% in that way.
이성렬(Seong Ryeol Lee),홍예선(Yeh Sun Hong) 유공압건설기계학회 2016 드라이브·컨트롤 Vol.13 No.2
In this paper, an elementary force fighting problem was investigated. The problem is encountered when a double-rod type EHA(electro-hydrostatic actuator) is combined with a single-rod type EHA to build a redundant actuator system with synchronized motion. When the rod-side chambers of the two different types of EHAs have the same effective piston areas and are simultaneously pressurized by an external load, the two EHAs behave identically, sharing the external load equally. However, when the piston head-side chamber of the single rod type EHA, having a larger effective area than the rod-side chamber, is pressurized by the external load, an abnormal force fighting between the two EHAs occurs, unless their pump speeds are properly decoupled. In this study, the output drive forces of each EHA were obtained from the cylinder pressure signals and applied to the position control for each EHA to maintain the balance between their pump speeds. Adding minor force difference feedback loops to the position control, the force fighting phenomena could be eliminated and steady state synchronization errors were reduced. The power consumption of the pumps also could be remarkably reduced, avoiding unnecessarily high load pressures to the pumps.
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.