• International Journal of Precision Engineering and Manufacturing
• /
• 제8권3호
• /
• pp.8-13
• /
• 2007

A hybrid fuzzy PID controller for a pneumatic chamber is proposed in this paper. First, a mathematical model of a pneumatic pressure servocontrol system was developed where separate implementations of a PID controller and a fuzzy controller were made. The experimental results using a step input signal revealed that the PID controller accurately controlled the steady-state pressure but did not robustly handle parameter variations in the system while the fuzzy controller provided a fast rise time and low overshoot of the pressure in the system. In order to attain the advantages of both the fuzzy and PID controllers, a hybrid control scheme was developed. The experimental results show that the hybrid fuzzy PID controller proposed in this study does indeed possess the advantages of both PID and fuzzy controllers. Hence, it can be concluded that the hybrid fuzzy PID controller is suited for high-precision control of pressure in a pneumatic chamber.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2004년도 ICCAS
• /
• pp.326-329
• /
• 2004

In this paper, we show a new form of blood pressure controller combined PI control with $H_{\infty}$ loop-shaping. Hypertensive patients or post-operative patients need to maintain normally blood pressure. Exact regulation of blood pressure is needed for maintaining variable blood pressure of preventing complications. The regulation of blood pressure is achieved by injecting drugs, and usually sodium nitroprusside is used as those kinds of drugs. It is necessary to control the infusion rate sodium-nitroprusside carefully to achieve the desired blood pressure. It has been known that regulation of blood pressure by automatic controller is more effective than regulation of blood pressure by human operators. The control of blood pressure has many constraints and uncertainties. Most of biological system has the time-varying variables and the side effects such as increased risk of sepsis and organ failure. To solve such a problem, we design a new robust PI controller using $H_{\infty}$ loop-shaping to decrease noise effects that come out from human body and errors for time delay. The system with designed controller shows more stable control of mean blood pressure and more robust performance for uncertainties. Validation methods for the control performance are confirmed to computer simulations.

• 동력기계공학회지
• /
• 제5권4호
• /
• pp.90-96
• /
• 2001

In this study, a robust controller to control pressure in a pneumatic pressure vessel considering dynamic characteristics of pneumatic transmission line is proposed. Dynamic characteristics of transmission line using compressible fluid is changed by the flowing states of the fluid. So, if the fixed gain controller is designed based on a fixed model, the performance of the control system could be destabilized or degraded. The controller designed in this study is composed of two parts. The one is to reject modelling error based on the disturbance observer, the other is to obtain the control performance. The control results with the designed controller show that the robustness of the control system is achieved regardless of the change of the model of the transmission line. Therefore, the designed controller can be utilized for the performance improvement of the pressure control system using compressible fluid such as air and gas

• International Journal of Control, Automation, and Systems
• /
• 제5권6호
• /
• pp.643-651
• /
• 2007

The various blood pressure simulators have been proposed to evaluate and improve the performance of the automatic sphygmomanometer. These have some problems such as the deviation of the actual blood pressure waveform, limitation in the blood pressure condition of the simulator, or difficulty in displaying the blood flow. An improved simulator using disturbance observer is proposed to supplement the current problems of the blood pressure simulator. The proposed simulator has an artificial arm model capable of feeding appropriate fluids that can generate the blood pressure waveform to evaluate the automatic sphygmomanometer. A controller was designed and thereafter, simulation was performed to control the output signal with respect to the reference input in the fluid dynamic model using the proposed proportional control valve. To minimize the external fluctuation of pressure applied to the artificial arm, a disturbance observer was designed on the plant. A hybrid controller combined with a proportional controller and feed-forward controller was fabricated after applying a disturbance observer to the control plant. Comparison of the simulations between the conventional proportional controller and the proposed hybrid controller indicated that even though the former showed good control performance without disturbance, it was affected by the disturbance signal induced by the cuff. The latter exhibited an excellent performance under both situations.

• 대한의용생체공학회:의공학회지
• /
• 제28권6호
• /
• pp.768-776
• /
• 2007

A new type of the fluid circulation blood pressure simulator was proposed to enhance the blood pressure simulator used for the development and evaluation of automatic sphygmomanometers. Various pressure waveform of fluid flowing in the pipe was reproduced by operating the proportional control valve after applying a pressure on the fluid in pressurized oil tank. After that, appropriate fluid was supplied by operating the proportional control valve, which enabled to reproduce various pressure wave of the fluid flowing in the tube. To accomplish this work, the mathematical model was carefully reviewed in cooperating with the proposed simulator. After modeling the driving signal as input signal and the pressure in internal tube as output signal, the simulation on system parameters such as internal volume, cross-section of orifice and supply pressure, which are sensitive to dynamic characteristic of system, was accomplished. System parameters affecting the dynamic characteristic were analyzed in the frequency bandwidth and also reflected to the design of the plant. The performance evaluator of fluid dynamic characteristic using proportional control signal was fabricated on the basis of obtained simulation result. An experimental apparatus was set-up and measurements on the dynamic characteristic, nonlinearity, and rising and falling response was carried out to verify the characteristic of the fluid dynamic model. Controller was designed and thereafter, simulation was performed to control the output signal with respect to the reference input in the fluid dynamic model using the proposed proportional control valve. Hybrid controller combined with an proportional controller and feed-forward controller was fabricated after applying a disturbance observer to the control plant. Comparison of the simulations between the conventional proportional controller and the proposed hybrid simulator indicated that even though the former showed good control performance.

• 한국시뮬레이션학회:학술대회논문집
• /
• 한국시뮬레이션학회 2005년도 춘계학술대회 논문집
• /
• pp.149-153
• /
• 2005

In the cardiovascular system, the waveform of the pulsatory blood pressure appears variously due to the cardiac impulse and compliance of blood vessels and arm tissue. We have constructed a blood pressure simulator to investigate effects of mechanical properties of artery walls and tissue on blood pressure measurements. The blood pressure simulator is designed to reproduce wave forms of blood pressure in human arteries. To minimize tracking error, we use a linear control valve, and adapt a hybrid control scheme which consists of a feedback controller and a feedforward controller. Any form of the pressure wave can be reproduced, changing function of the wave form in the computer connected to the simulator for control. From experiments, it has been shown that the simulator reproduces wave forms very well, and that the hybrid scheme adapted is superior to the feedback controller.

• 유공압시스템학회논문집
• /
• 제2권4호
• /
• pp.7-13
• /
• 2005

This paper presents modeling and ostimator/controller design for the hydraulic system in Vehicle Stability Control(VSC) system. A nonlinear mathematical model of the VSC hydraulic system is proposed and its accuracy is experimentally verified. A brake pressure estimator is then designed based on the derived mathematical model of VSC hydraulic system. And a disturbance observer, which compensates the estimation error between the brake pressure and the computed brake pressure is also designed to enhance the accuracy of the estimator. The proposed controller has the form of a feedback controller and determines explicitly the on/off ratio of valves' driving PWM signals by means of making use of the simplified mathematical model in the VSC hydraulic system. The performance of the designed controller whose feedback signal is generated by the brake pressure estimator is validated through experimental results.

• Journal of Advanced Marine Engineering and Technology
• /
• 제37권4호
• /
• pp.404-408
• /
• 2013

본 연구에서는, 대형 증기유량이 요구되는 플랜트에서 정밀한 압력제어의 요구를 충족시키기 위한 다른 방법으로 3단계의 다중 제어밸브 구조를 이용하여 압력을 제어하는 제어기를 설계하는 내용이다. 본 연구의 핵심은 전기 유압시스템 외부에 별도의 PID 제어기를 이용하여 제어밸브의 위치를 정확하게 제어하는 것이다. 시뮬레이션 및 실험을 통해 제어기의 성능을 검증한다.

• 센서학회지
• /
• 제16권1호
• /
• pp.44-51
• /
• 2007

A hybridized simulator for generating blood pressure waveform is proposed to study the remedy and/or evaluation of the conventional sphygmomanometer utilizing the oscillometric method which is widely applied. The blood pressure of a flowing fluid was controlled for the blood vessel's condition caused by a rhythmical and periodical contraction/relaxation because of the special excitatory and conductive system of the heart. In this study, a hybridized controller composed of the PI feedback controller and the feedforward controller. The inverse dynamics function is proposed to operating the control valve while the pressure is applied in an oil pressure tank. The proposed hybrid simulator reproducing the blood pressure waveform in an artificial blood vessel has kept the control performance consistent over all range. Based on these results, the proposed simulators could be applied to the development and compensation of the non invasive sphygmomanometer type as well as to study the characteristics of the blood pressure and blood vessel.

• 대한기계학회논문집A
• /
• 제27권4호
• /
• pp.567-576
• /
• 2003

In this study, a robust controller to control pressure in a pneumatic pressure vessel with a long transmission line is proposed. Frequency response of transmission line using compressible fluid is changed by the flowing state of the fluid. So, it a fixed gain controller designed based on a model supposed the flowing state to a specific state, the performance of the control system could be degraded because of the modelling error. The controller designed in this study is composed of two parts. One is a feedback controller to improve a feedback characteristics and to compensate the influence of the variation of transfer characteristics of a transmission line owing to the change of flowing state and the other is a feedforward controller to regulate command fallowing performance. The experimental results with the designed controller show that the robustness of the control system is achieved regardless of the change of the model or the transmission line. Therefore, the designed controller can be utilized for the Performance improvement of a Pressure control system with a long transmission line using compressible fluid.