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Triet Hung Ho,Kyoung Kwan Ahn 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
A newly assisted hydraulic circuit is proposed for a hydraulic transformer to improve energy saving potential of the system. The use of three directional controlled valves with the designed controller forces the transformer and the cylinder work in proper conditions, which contributes to improve energy utilization of the system. A model of hydraulic transformer including energy losses of the pump/motor is used to estimate energy consumption in different situations. A switching method based on desired load is also designed to select a feasible operating mode of the system. Simulation results indicate that saving energy is significantly improved by the proposed circuit.
Ho Triet Hung,Kyoung Kwan 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
A hydraulic cylinder drive using a hydraulic transformer, which is considered as secondary controlled unit, is studied here. Using hydraulic transformer for driving a hydraulic cylinder should avoid energy loss via controlled valves and get benefit from recovery of the load potential. Position control, an important issue of the cylinder control is investigated in this paper. To obtain robust position control in spite of external load disturbance and variation of parameters in the system, a two degree of freedom robust controller based on disturbance observer is designed. he controller includes a mixed ?- sensitivity H∞ controller and a high order disturbance observer. Weights for controller synthesis and filter in the disturbance observer are fixed in their structure but vary in values of the coefficients. Genetic algorithm is used to tune parameters of the weights and time constants of the filter. In this manner, a controller with its structure based on robust analysis and parameters depended on performance of nominal plant is design. Simulation results indicate that the system guarantees the robustness with external load disturbance, variation in parameters and sensor noise.
Speed Control of a Hydraulic Pressure Coupling Drive Using an Adaptive Fuzzy Sliding-Mode Control
Ho, Triet Hung,Ahn, Kyoung Kwan IEEE 2012 IEEE/ASME transactions on mechatronics Vol.17 No.5
<P>In this paper, an adaptive fuzzy sliding-mode control (AFSMC) was proposed for speed control of a hydraulic pressure coupling drive. The AFSMC combined a direct adaptive fuzzy scheme and a fuzzy sliding scheme in a new structure to reduce the tracking error and the chattering of the control effort. The input nonlinearity of the secondary unit, the input dead zone, was taken into account during the speed controller synthesis and analysis of the stability of the closed-loop system. The stability of a system was proven from Lyapunov's sense. Experiments were performed with different controllers, the AFSMC, the traditional sliding-mode control, and the PID controllers, and under different operating conditions. Then, the experimental results were brought into comparison to evaluate the effectiveness of the AFSMC controller from the viewpoints of stability, performance, and robustness of the closed-loop system.</P>
Ho, Triet Hung,Ahn, Kyoung-Kwan 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.5
A new hydraulic closed-loop hydrostatic transmission (HST) energy-saving system is proposed in this paper. The system improves the efficiency of the primary power source. Furthermore, the system is energy regenerative, highly efficient even under partial load conditions. It can work in either a flow or pressure coupling configuration, allowing it to avoid the disadvantages of each configuration. A hydraulic accumulator, the key component of the energy regenerative modality, can be decoupled from or coupled to the HST circuit to improve the efficiency of the system in low-speed, high-torque situations. The accumulator is used in a novel way to recover the kinetic energy without reversion of fluid flow. Both variable displacement hydraulic pump /motors are used when the system operates in the flow coupling configuration so as to enable it to meet the difficult requirements of some industrial and mobile applications. Modeling and a simulation were undertaken with regard to testing the primary energy sources in the two configurations and recovering the energy potential of the system. The results indicated that the low efficiency of traditional HSTs under partial load conditions can be improved by utilizing the pressure coupling configuration. The round-trip efficiency of the system in the energy recovery testing varied from 32% to 66% when the losses of the load were taken into account.
유압 트랜스포머를 이용한 에너지 절감형 유압시스템에 관한 기초연구
이민수(M. S. Lee),안경관(K. K. Ahn),조용래(Y. R. Cho),Ho Triet Hung 유공압건설기계학회 2008 유공압건설기계학회 학술대회논문집 Vol.2008 No.10
In order to reduce energy consumption, secondary controlled system has been applied to many types of equipments. In lifting equipments or press machines using hydraulic cylinder, a hydraulic transformer is used as a control component instead of a valve for motion control and a component for recovering potential energy of load. The transformer is combination of a variable displacement pump/motor as a secondary controlled element and a fixed displacement pump/motor. Based on the nominal model derived from mathematical model, the feedback type two-degree-of-freedom controller is designed and implemented. From simulation results, the disturbances including nonlinear friction torque, leakage flow and load force can be compensated and good positioning accuracy is obtained. It show that the proposed controller is effective.
A STUDY ON HYDRAULIC LOAD SIMULATOR USING ONLINE SELF TUNING FUZZY PID TECHNIQUE
Dinh Quang Truong,Ahn Kyoung Kwan,Yoon Hong Soo,Ho Triet Hung 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Nowadays, hydraulic actuator has a wide range of application fields where controlled forces or pressures with high accuracy and fast response are the most significant demands. This paper presents a new kind of hydraulic load simulator for conducting performance and stability test for control force of hybrid systems. In order to improve the control performance of loading system an online self tuning fuzzy PID controller is designed. Experiments are carried out to evaluate the effectiveness of the proposed controller applied for load simulator with varied external disturbance.
유압 트랜스포머를 이용한 에너지 절감형 유압시스템에 관한 기초연구
이민수(Lee Min-Su),안경관(Ahn Kyoung-Kwan),조용래(Cho Yong-Rae),조우근(Jo Woo-Keun),Ho Triet Hung 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
In order to reduce energy consumption, secondary controlled system has been applied to many types of equipments. In lifting equipments or press machines using hydraulic cylinder, a hydraulic transformer is used as a control component instead of a valve for motion control and a component for recovering potential energy of load. The transformer is combination of a variable displacement pump/motor as a secondary controlled element and a fixed displacement pump/motor. Based on the nominal model derived from mathematical model, the feedback type two-degree-of-freedom controller is designed and implemented. From simulation results, the disturbances including nonlinear friction torque, leakage flow and load force can be compensated and good positioning accuracy is obtained. It show that the proposed controller is effective.