• Journal of Electrical Engineering and Technology
• /
• 제13권2호
• /
• pp.1008-1020
• /
• 2018

In this paper, the dynamic compliance and its compensation control of the force control system on the highly integrated valve-controlled cylinder (HIVC), the joint driver of the hydraulic drive legged robot, is researched. During the robot motion process, the outer loop dynamic compliance control is applied on the base of hydraulic control inner loop and most inner loop control are the force or torque closed loop control. While the dynamic compliance control effectiveness of outer loop can be affected by the inner loop self-dynamic-compliance. Based on this problem, the dynamic compliance series composition theory of HIVC force control system as well as the analysis of its self-dynamic-compliance is proposed. And then the paper comes up with the compliance-enhanced control, which is a compound compensation control method of dynamic compliance with multiple series branches. Finally, the experiment results indicate that the control method mentioned above can enhance the dynamic compliance of HIVC force control system observably. This provides the compensation control method of inner loop dynamic compliance for the outer loop compliance control requiring the high accuracy and high robustness for the robot.

• Journal of Biosystems Engineering
• /
• 제43권4호
• /
• pp.379-385
• /
• 2018

Purpose: Postharvest handling of onions (harvesting, cleaning, grading, cooling, storing, and transport) should be performed continually to reduce costs and improve quality. The purpose of this study is to a) determine the design parameters and operating conditions of anion auto-dumping that constitutes a key component of the postharvest bulk handling machinery system, and b) to perform a performance test with the auto-dump prototype system. Methods: Kinematic analyses and computer simulations of the auto-dump mechanism were applied to analyze the operating conditions and design parameters. Results: The optimum working condition for the auto-dump was determined from kinetic analyses. In addition, the interaction between the velocity of the hydraulic cylinder and the angular velocity of the auto-dump were analyzed in order to control the bulk handling machinery system. The acting forces and optimum operating conditions of the hydraulic cylinder were determined by analyzing the forces related to the mass of inertia of the auto-dump assembly during rotation. The method of controlling the feeding rate of onions in terms of the uniformity of the stacking pattern and the control of the entire system was better than the two-stage method of controlling the rotational speed of the auto-dump. Based on the performance test with the prototype for the auto-dump, the stacking pattern and rigidity of the system were analyzed. Conclusions: These results would be of great importance in the postharvest bulk handling machinery system for onions.

• 터널과지하공간
• /
• 제33권5호
• /
• pp.339-347
• /
• 2023

TBM 추진잭이 경사면에 접촉하거나 편심하중이 발생할 때 추진잭의 페데스탈 및 로드 부위에 횡하중에 의한 휨변형이 발생할 수 있다. 이는 추진잭 모듈의 고장을 유발할 우려가 있으므로, 추진잭 모듈 전체에 대한 좌굴 안정성을 검증할 필요가 있다. 본 연구는 추진잭 좌굴 안정성 분석을 위한 좌굴 압축시험방법을 조사하고, 압축시험 시스템을 구성하였다. 추진잭의 전체 부품을 모델링하여 수치해석을 통해 응력집중 파트를 분석하였다. 경사도 0도 조건에서 최대하중을 가압하여 압축시험을 수행하였다. 로드의 변형과 씰의 누유는 관측되지 않아서 0도 조건에서 추진잭의 좌굴 안정성을 검증하였다.

• 한국항공우주학회지
• /
• 제41권1호
• /
• pp.25-30
• /
• 2013

집적형 하이브리드 구동장치는 적층형 압전재료(압전스택)를 이용한 마이크로 펌프에서 토출되는 유체로 피스톤을 구동시키는데 크기는 작으면서도 큰 구동력과 높은 속도를 동시에 출력할 수 있는 새로운 개념의 통합 구동장치로서 현재 소형화 및 고출력을 요구하는 항공 우주, 유도무기 등 다양한 분야에서 광범위하게 연구되고 있다. 본 연구에서는 이러한 하이브리드 구동장치의 구동원리 및 성능 시험에 대해 소개하였다. 우선 구동장치의 주 동력인 압전 스택의 성능 시험을 수행함으로써 압전 스택의 구동전력과 구동시간에 따른 성능 변화를 관찰하였고 다음 구동장치의 성능 시험을 통해 구동장치의 최대 이송속도와 최대 구동력을 측정하였다. 구동장치의 최대 이송속도는 53.3 mm/s로, 최대 구동력은 240.7 N으로, 최대 일률은 3.2 W로 측정되었다.

• 드라이브 ㆍ 컨트롤
• /
• 제17권3호
• /
• pp.26-32
• /
• 2020

In modern society, the energy-saving problem of industrial vehicles is economically and environmentally critical. Energy savings using the potential energy of forklifts are one of the viable solutions to resolving this problem. The basic concept of this study is to operate the hydraulic motor and recharge the battery using the flow rate from the cylinder when loading heavy objects and lowering the fork. To save energy, the torque and rotational speed of the generator should be optimized according to the load and descent speed to increase efficiency. To this end, we propose a system that optimizes energy saving efficiency by controlling the swashplate angle of the variable hydraulic motor through the GA(Genetic-Algorithm). The results were verified by building and comparing fixed motor models and variable motor models using the AMEsim. The results of the study show that the proposed optimized swashplate angle increases the energy saving efficiency by approximately 6%-8%, depending on the working conditions.

• 한국공작기계학회논문집
• /
• 제11권6호
• /
• pp.75-82
• /
• 2002

Design for a quiet operation of fluid power system requires the understanding of noise and vibration characteristics of the system. It's not easy to analyze noise problem in hydraulic cylinder used in typical actuator Because they've got complex fluid dynamics. One of the fundamental problems associated with the hydraulic system is the pulsating flow in pipe lines, which can be tackled by the analysis under simplifying assumptions. The present study focuses on theoretic analysis and experimental study on the dynamics of laminar pulsating flow in a circular pipe. We analyze the propagation characteristics of the pressure pulse within a hydraulic pipe line taking into account the pulsating flow frequency variation. We also measure instantaneous pressure pulses within pipe line to identify the transfer functions. We conduct series of experiments to investigate the propagation characteristics of pressure pulse for various pressure of pulsating flow. The working fluid of the present study is ISO VG46 and the temperature ranges from 20 to $60^{\circ}$ with normal pressure at 4000kPa. The flow rate is measured by using an ultrasonic flow meter. Pressures at fixed upstream and downstream positions are measured concurrently. The electric signals of the pressure sensor are stored and analyzed using a system analyzer(PKE 983 series). The frequency is varied in the range of 10~500Hz. The Reynolds number is kept below 2,000. In the present study, boundary condition was varied by installing a surge tank and an orifice at the end of pipe. Experimental and theoretical results were compared each other under various boundary conditions.

• 전력전자학회논문지
• /
• 제7권1호
• /
• pp.55-64
• /
• 2002

인버터를 적용한 유압식 시스템은 펌프의 마찰과 실린더 패킹 및 탑승 카와 레일의 마찰특성으로 인하여 PID 제어기로는 제어가 되지 않는 데드 존이 생기게 된다. 본 논문에서는, 우선 유압시스템으로 구동되는 유압식 시스템의 극저속 속도영역(zero-crossing)에서 속도가 제어되지 않는 원인이 되는 실린더의 마찰특성을 고찰하고, 이러한 실린더의 마찰특성으로 인하여 기존의 PID 속도제어기로 제어 시 발생되는 문제점을 해결하기 위한 줌잉 퍼지 룰을 포함한 퍼지제어기를 설계한다. 마지막으로, 설계된 퍼지제어기와 기존의 PID 제어기를 결합하여 보다 성능이 향상된 하이브리드 퍼지제어기를 설계한다. 제안된 하이브리드 퍼지제어기는 정속주행구간에서는 정상상태제어성능이 우수한 PID 제어기를 적용하고 PID제어기로 제어되지 않는 극저속 속도구간에서는 퍼지제어기를 적용하여 유압식 시스템이 실린더의 마찰특성으로 인하여 극저속 속도영역(zero-crossing)에서 속도가 제어되지 않는 문제를 해결하고, 극저속 영역에서 뿐 아니라 정상상태를 포함한 전 운전영역에서의 제어성능이 우수함을 시뮬레이션과 실험을 통하여 보인다.

• 한국정보통신학회논문지
• /
• 제11권12호
• /
• pp.2352-2360
• /
• 2007

인버터를 적용한 유압시스템은 펌프의 마찰과 실린더 패킹 및 탑승 카와 레일의 마찰특성으로 인하여 PID 제어기로는 제어가 되지 않는 데드존이 생기게 된다. 본 논문에서는, 우선 유압시스템으로 구동되는 엘리베이터의 극저속 속도영역(zero-crossing)에서 속도가 제어되지 않는 원인이 되는 실린더의 마찰특성을 고찰하고, 이러한 실린더의 마찰특성으로 인하여 기존의 PID 속도제어기로 제어시 발생되는 문제점을 해결하기 위한 줌잉 퍼지룰을 포함한 퍼지제어기를 설계한다. 설계된 퍼지제어기와 PID 제어기의 출력을 비선형과 선형구간으로 나누어 각 제어기가 각각 동작하는 하이브리드 퍼지제어기를 설계한다. 제안된 하이브리드 퍼지제어기는 정속주행구간에서는 PID 제어기를 적용하고 PID제어기로 제어되지 않는 극저속 속도구간에서는 퍼지제어기를 적용하여 유압식 엘리베이터가 실린더의 마찰특성으로 인하여 극저속 속도영역(zero-crossing)에서 속도가 제어되지 않는 문제를 해결하고, 극저속 영역에서 뿐 아니라 정상상태를 포함한 전 운전영역에서의 제어성능이 우수함을 시뮬레이션과 실험을 통하여 보인다.

• 대한기계학회논문집A
• /
• 제25권4호
• /
• pp.685-694
• /
• 2001

In this study, a transfemoral prosthesis system of which both stance phase and swing phase are controllable has been developed for the recovery of the biomechanical function of the amputated leg. It consists of a 5 bar link mechanism, a hydraulic-rubber knee damper for stance phase control and a pneumatic cylinder controlled via a microprocessor for stance phase control. The mechanical characteristics of the knee damper which absorbs the impact energy generated at the heel contact were investigated. The characteristics of the pneumatic cylinder essential for the speed adaptation of the prosthesis during swing phase were also studied for its mechanical characteristics. The prosthesis was subject to the clinical tests, and the gait characteristics obtained were very close to those of normal subjects. The stance and swing controlled prosthesis that were developed in this study showed good stability during the stance phase and showed good controllability during the swing phase.

• International Journal of Advanced Culture Technology
• /
• 제7권1호
• /
• pp.209-215
• /
• 2019

In order to provide a safe free-weight-training environment to people without workout trainers, we suggest a smart bench press machine with an automatic weight control system sensitive to user tiredness. Physical weight plates on the machine are replaced with a hydraulic cylinder as a press load and the cylinder knob is coupled with a step motor to change its tensile force automatically in-between lifting exercises. Three subjects participated to verify the usability of the smart bench press machine. They were asked to lift a 6-RM press load 10 times with 3 different lifting conditions: 1) no assistance, 2) a human assistance, and 3) the automatic weight control. All subjects were not able to complete the 10 sets without assistance due to tiredness, but they finished the full sets under the two assistive conditions. Average lifting speeds under the automatic weight control condition showed the most consistent level. Normalized quasi-tension data based on surface electromyogram signals of both Pectoralis Majors revealed that the subjects maintained the target muscle activation level above 50% but not more than 80% throughout the 10 sets. Therefore, the smart bench press machine is expected to both keep pace with the lifting exercise and reduce risk of injuries due to excessive muscle tensions.