압전 밸브용 압력 레귤레이터

윤소남,김찬용,서우석,박중호,함영복 사단법인 유공압건설기계학회 2006 드라이브·컨트롤 Vol.3 No.2

The pressure regulator which is used for controlling the reducing pressure in the piezoelectrically driven pneumatic valve has been studied. The pneumatic valve of this study object is 2-stage type and consists of a piezoelectric actuator, a controller, a poppet valve and a pressure regulator. Nominal flow of 50 1pm, maximum operating pressure of 0.9MPa and frequency characteristic of 10Hz and over are required in this pneumatic valve, but the pressure regulator is needed because piezoelectric actuator has no ability to control the pressure of 0.9MPa directly. In this study, bimorph type PZT actuator of 25.2 mm(L)x7.2 mm(W)x0.5 mm(H) with constant of -220x10-12 CN-1 was proposed and investigated. Maximum operating force of 0.052 N and maximum displacement of 63 ㎛ were gotten from the fabricated PZT actuator. From the analysis results, the orifice diameter or 0.6mm for a piezoelectric actuator was derived and then the pressure regulator which can be operated under 0.15 MPa easily was designed and manufactured. Performance and effects of design parameters were simulated by the Simulink of Matlab software, and it was confirmed that the performance characteristics of manufactured pressure regulator are superior in the common use pressure of 0.5 MPa to 0.7MPa, The results show that the proposed pressure regulator is suitable for the pneumatic valve with a PZT actuator.

유공압 회로를 이용한 자전거 포크용 가변댐퍼-공압스프링 서스펜션의 해석

장문석,최영휴,김수태,최재일 사단법인 유공압건설기계학회 2019 드라이브·컨트롤 Vol.16 No.1

The objective of this study was to present a damped pneumatic suspension, a bike fork suspension, which can adapt itself to incoming road excitations is presented in this paper. It consists of a hydraulic damper and a pneumatic spring in parallel with a linear spring. The study also proposed a variable and switchable orifice, in the hydraulic damper, to select appropriate damping property. Hydraulic-pneumatic circuit model for the bike fork suspension was established based on AMESim, in order to predict its performance. In addition, elastic-damping characteristics of the fork such as spring constant and viscous damping coefficient were computed and compared, for validation, with those evaluated by experiment using the universal test machine. Through simulation analysis and test, it was established that the hydraulic-pneumatic circuit model is effective and practical for development of future MTB suspensions.

Backstepping Sliding Mode-based Model-free Control of Electro-hydraulic Systems

Hoai Vu Anh Truong,TRINH HOAI AN,안경관 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.1

This paper presents a model-free system based on a framework of a backstepping sliding mode control (BSMC) with a radial basis function neural network (RBFNN) and adaptive mechanism for electro-hydraulic systems (EHSs). First, an EHS mathematical model was dedicatedly derived to understand the system behavior. Based on the system structure, BSMC was employed to satisfy the output performance. Due to the highly nonlinear characteristics and the presence of parametric uncertainties, a model-free approximator based on an RBFNN was developed to compensate for the EHS dynamics, thus addressing the difficulty in the requirement of system information. Adaptive laws based on the actor-critic neural network (ACNN) were implemented to suppress the existing error in the approximation and satisfy system qualification. The stability of the closed-loop system was theoretically proven by the Lyapunov function. To evaluate the effectiveness of the proposed algorithm, proportional-integrated-derivative (PID) and improved PID with ACNN (ACPID), which are considered two complete model-free methods, and adaptive backstepping sliding mode control, considered an ideal model-based method with the same adaptive laws, were used as two benchmark control strategies in a comparative simulation. The simulated results validated the superiority of the proposed algorithm in achieving nearly the same performance as the ideal adaptive BSMC.

식용 풋옥수수 수확 시험장치 설계 및 성능평가

강나래,최일수,김영근,최용,유승화,우제근,현창식,김성국 사단법인 유공압건설기계학회 2019 드라이브·컨트롤 Vol.16 No.4

In this study, an edible fresh corn harvest testing machine was designed and manufactured. And harvesting performance was analyzed through the field test. The testing machine is of the tractor attached type. It is connected to the tractor PTO shaft to transfer power to the each part of the harvesting machine. And it harvests fresh corn by one row through the processes of cutting, stem crushing, detaching, and collecting. The performance test was performed at PTO speed (540, 750, 1050 rpm, respectively), working speed (0.1, 0.15, 0.2 m/s, respectively), and cropping cultivation (row spacing·hill spacing 70·25 cm, 70·40 cm, 90·30 cm, respectively). The performance test was repeated three times in the 15 m section. The detachment loss ratio, uncollected crop ratio, damage ratio, and harvest ratio were analyzed. As a result of the performance test, it was analyzed that the PTO speed 540 rpm, running speed of 0.1 m/s, and row spacing·hill spacing 70·40 cm were the optimal condition.

굴착기 내구시험 모니터링을 위한 작업부하 지표 개발

조재홍,나선준,김민석,박명관 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

In this paper, we developed a workload index for monitoring the durability test using operation information of an excavator. First, the acceleration and cylinder pressure were selected as load factors by analyzing operation data. Through load correlation analysis according to each load factor, Root Mean Square (RMS) and Work Load Range (WLR) were respectively derived as a load feature representing mechanical load. In addition, the workload index was used to quantify load features. For applying the workload index to monitoring, a real-time monitoring system consisting of sensors and embedded controller was installed on the excavator and the system was integrated with a remote monitoring environment using a wireless network. Results of load monitoring and analysis verified that the developed workload index was effective from the viewpoint of the relative comparison of the workload.

제조 로봇용 서보모터의 양산성능 평가 연구

류경하,이태현,박종원,권혁성,강보식 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

The performance and reliability of foreign servomotors and domestic servomotors for manufacturing robots were compared and verified. The mass productivity was confirmed by satisfying the requirements of the demanding companies. The servomotor was designed in consideration of mass productivity while satisfying the requirements of the demanding company. It was mounted on a real robot to check its performance and reliability. To secure mass-production performance, we designed and manufactured easy-to-manufacture parts and jigs to manufacture servomotors and achieved the goal of the mass-production evaluation of servomotors through individual performance evaluation, robot mounting test evaluation, and supplementation.

디스펜서를 이용한 차량용 연료 탱크 수소 충전 모델링에 관한 연구

최지아,지상원,장지성 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.2

Hydrogen energy as an alternative source of energy has been receiving tremendous support around the world, and research is being actively conducted accordingly. However, most of the studies focus on hydrogen storage tanks and only are few studies on interpreting the hydrogen filling system itself. In this study, with reference to SAE J2601, a hydrogen fueling protocol, a simulation model was developed that can confirm the behavior of the vehicle's internal tank during hydrogen fueling. With respect to factors such as fuel supply temperature, ambient temperature, and pressure increase rate, the developed model can check the change of temperature and pressure in the tank and the state of hydrogen charging during hydrogen fueling. The validity of the developed simulation model was confirmed by comparing the simulation results with the experimental results presented in SAE J2601.

지게차 마스트 작동내구를 위한 실차 기반 무인시험장치 개발

조재홍,나선준,김민석,박명관 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

In this paper, we develops an unmanned test system for the purpose of realizing an actual forklift-based test-bed for the operation durability of the forklift mast. First, two robot actuators were applied to the lever to replace lever manipulation of the operator. For detecting the height of the fork and the tilt angle of the mast, the laser displacement sensor and the inclinometer were installed to the forklift. Next, the embedded control system was used to control the robot actuator with reference to test mode. Experimental evaluation verified that developed test system was effective and practical for the viewpoint of the repeatability of the test mode.

학습제어를 이용한 지게차 자동변속기 상향 변속품질 개선

정규홍 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.2

Recently, automatic transmissions caused a good improvement in the shift quality of a forklift. An advanced shift control algorithm, which was based on TCU firmware, was applied with embedded control technology and microcontrollers. In the clutch-to-clutch shifting, one friction element is released and the other friction element is activated. During this process, if the release and application timings are not synchronized, an overrun or tie-up occurs and ultimately leads to a shift shock. The TCU, which measures only the speed of the forklift, inevitably applies the open-loop shift control. In this situation, the speed ratio does not change during the clutch fill. The torque phase occurs until the clutch is disengaged. In this study, an offline shift logic of the learning control was proposed. It induced a synchronous shift when the learning control progressed. During this process, the reference current trajectory of the release clutch was corrected and applied to the next upshift. We considered the results of the overrun/tie-up characteristics of the upshift performed immediately before. The vehicle test proved that the deviation in shift quality, which was caused by the difference in the mechanical characteristics of the clutch, could be improved by the learning control.

속도제어-유압펌프에 의하여 구동되는 사출성형 실린더의 궤적추적제어

조승호 사단법인 유공압건설기계학회 2007 드라이브·컨트롤 Vol.4 No.2

This paper deals with the issue of trajectory tracking control of a clamping cylinder for injection moulding machine, which is directly driven by speed controlled hydraulic pump in combination with AC servomotor. As a fundamental step prior to tracking controller design, feedback control system is developed by implementing a position control loop parallel with a system pressure control loop. A sliding mode controller combining velocity feedforward scheme is developed for enhancing the tracking performance. Consequently a significant reduction in tracking error is achieved for both position and pressure control applications.