• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.1127-1128
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• 2008

In this paper, we propose a control method to improve control performance for a Quad-rotor Unmanned Aerial Vehicle's stabilization. The proposed method is the Fuzzy+I control that contains a fuzzy controller which processes signals from the error and the change of error, and generates the control signal by summing up fuzzy output signal and integral signal. We simulated and experimented on the fuzzy+I control method by implementing Quad-rotor UAV that is able to hovering, for the purpose of verifying the effectiveness of the proposed fuzzy+I control method in comparison with general PID control, and we found out that fuzzy+I controller improved control performance of the system.

• 한국항공우주학회지
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• 제33권3호
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• pp.47-56
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• 2005

본 논문에서는 마이크로 자이로스코프를 위한 폐루프 제어기를 설계하여 그 성능이 개선됨을 보였다. 마이크로 자이로스코프는 높은 Q값을 가지는 시스템으로 그 특성상 공진 영역에서 동작하게 되는데, 개루프로 동작할 경우 선형성, 대역폭 등의 성능에 제약이 있게 된다. 폐루프 제어기는 개루프 동작시의 이러한 제약을 극복하고 성능을 개선할 수 있도록 한다. 본 연구에서는 PD 제어기를 적용하였으며 실험 대상이 된 마이크로 자이로스코프는 서울대에서 설계하고 Bosch foundry에서 제작한 SNU-Bosch MEMS 자이로스코프를 사용하였다. 실험을 통해 폐루프 제어기의 성능을 검증한 결과 대역폭은 35Hz에서 78Hz로, 선형성은 2.07%에서 0.504%로, 바이어스 안정도는 0.066deg/sec에서 0.043deg/sec로 개선되는 것을 확인할 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권5호
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• pp.563-569
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• 2015

A chemical reaction occurring in CSTR (Continuous Stirred Tank Reactor) is significantly affected by the concentration, temperature, pressure, and reacting time of materials, and thus it has strong nonlinear and time-varying characteristics. Also, when an existing linear PID controller with fixed gain is used, the performance could deteriorate or could be unstable if the system parameters change due to the change in the operating point of CSTR. In this study, a technique for the design of a fuzzy PD plus I controller was proposed for the temperature control of a CSTR process. In the fuzzy PD plus I controller, a linear integral controller was added to a fuzzy PD controller in parallel, and the steady-state performance could be improved based on this. For the fuzzy membership function, a Gaussian type was used; for the fuzzy inference, the Max-Min method of Mamdani was used; and for the defuzzification, the center of gravity method was used. In addition, the saturation state of the actuator was also considered during controller design. The validity of the proposed method was examined by comparing the set-point tracking performance and the robustness to the parameter change with those of an adaptive controller and a nonlinear proportional-integral-differential controller.

• 전자공학회논문지SC
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• 제45권1호
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• pp.1-8
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• 2008

자유롭고 빠르게 이동할 수 있도록 도와주는 개인 이동 수단인 two-wheel balancing vehicle은 inverted pendulum 시스템의 원리를 이용한 것으로, 최근 들어 많은 연구가 이루어지고 있고 이를 이용한 제품이 실제 사용되고 있다. 본 논문에서는 일반적인 PID 제어이론을 이용한 two-wheel balancing vehicle에 대한 제어성능을 개선시키는 새로운 제어방식을 제안한다. 제안한 방식은 퍼지 PD+I 제어방식으로 향상된 PID 제어의 일종으로 2개의 입력과 1개의 출력을 가진 퍼지시스템에 적분 신호를 더함으로써 출력신호를 만든다. 퍼지시스템의 비선형성은 시간공정에서 비례신호와 미분신호의 가중치를 변화함으로써 최적의 출력제어신호를 만들어낸다. 제안한 퍼지 PD+I 제어방식의 유용성을 알아보기 위해 two-wheel balancing mobile robot에 대해 시뮬레이션과 실험의 결과를 통해, 제안한 퍼지 PD+I 제어방식이 일반적인 PID 방식보다 우수한 성능을 가지고 있음을 알 수가 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.572-575
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• 2005

A novel pneumatic artificial muscle actuator (PAM actuator), which has achieved increased popularity to provide the advantages such as high strength and high power/weight ratio, low cost, compactness, ease of maintenance, cleanliness, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks, has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators. In order to realize satisfactory control performance, a variable damper Magneto Rheological Brake (MRB), Is equipped to the Joint of the manipulator. Superb mixture of conventional PID controller and a phase plane switching control method brings us a novel controller. This proposed controller is appropriate for a kind of plants with nonlinearity, uncertainties and disturbances. The experiments were carried out in practical PAM manipulator and the effectiveness of the proposed control algorithm was demonstrated through experiments, which had proved that the stability of the manipulator can be improved greatly in a high gain control by using MRB with phase plane switching control method and without regard for the changes of external inertia loads.

• 한국미생물·생명공학회지
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• 제21권4호
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• pp.354-365
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• 1993

A novel control method with automatic tuning of PID controller parameters has been developed for efficient regulation of dissolved oxygen concentration in fed-batch fermentations of Escherichia coli. Agitation speed and oxygen partial pressure in the inlet gas stream were chosen to be the manipulated variables. A heuristic reasoning allowed improved tuning decisions from the supervision of control performance indices and it coule obviate the needs for process assumptions or disturbance patterns. The control input consisted of feedback and feedforword parts. The feedback part was determined by PID control and the feedforward part is determined from the feed rate. The proportional gain was updated on-line by a set of heuristics rules based on the supervision of three performance indices. These indices were output error covariance, the average value of output error, and input covariance, which were calculated on-line using a moving window. The integral and derivative time constants were determined from the period of output response. The specific growth rate was maintained at a low level to avoid acetic acid accumulation and thus to achieve a high cell density. The specific growthe rate was estimated from the carbon dioxide evolution rate. In fed-batch fermentation, the simutaneous control of dissolved oxygen concentration (at 0.2; fraction of saturated value) and specific growth rate (at 0.25$hr^{-1}$) was satisfactory for the entire culture period in spite of the changes in the feed rate and the switching of control input.

• Smart Structures and Systems
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• 제14권3호
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• pp.327-345
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• 2014

This paper presents a composite control strategy for the active suppression of vibration due to the unknown disturbances, such as external excitation, harmonic effects and control spillover, as well as high-frequency accelerometer measurement noise in the all-clamped stiffened plate. The proposed composite control action based on the modal approach, consists of two contributions including feedback part and feedforward part. The feedback part is the well-known PID controller, which is widely used to increase the structure damping and improve its dynamic performance close to the resonance frequencies. In order to get better performance for vibration suppression, the weight matrixes is optimized by chaos sequence. Then an improved disturbance observer (IDOB) as the feedforward compensation part is developed to enhance the vibration suppression performance of PID under various disturbances and uncertainties. The proposed IDOB can simultaneously estimate the various disturbances dynamically as well as measurement noise acting on the system and suppress them by feedforward compensation design. A rigorous analysis is also given to show why the IDOB can effectively suppress the unknown disturbances and measurement noise. In order to verify the proposed composite control algorithm (IDOB-PID), the dSPACE real-time simulation platform is used and an experimental platform for the all-clamped stiffened plate active vibration control system is set up. The experimental results demonstrate the effectiveness, practicality and strong anti-disturbances ability of the proposed control strategy.

• 융합신호처리학회논문지
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• 제22권4호
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• pp.171-178
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• 2021

카라반은 외부의 물리적 요인에 쉽게 영향을 받아 탑승자에게 위험한 상황을 초래하는 경우가 많다. 따라서 탑승자의 안정성을 확보하기 위해 스웨이 현상을 사전에 예방할 수 있는 스웨이 저감 장치를 개발할 필요성이 있다. 본 논문에서는 견인차량과 카라반 사이의 Hitch angle을 최소화하는 것을 목표로 한다. 구체적으로는 견인차량과 카라반 각각에 장착된 IMU 센서를 통해 카라반의 초기 불안정성을 감지하고, PID 제어기를 이용하여 Hitch angle, Hitch yaw rate가 Desired hitch angle, Desired hitch yaw rate에 수렴할 수 있도록 제어 값을 산출한다. 산출된 제어 값에 따라 카라반 좌우 브레이크에 다른 제동토크를 생성하여 분배하고 제어한다. 주행 실험을 통해 스웨이 저감 장치의 성능을 검증한 결과, 제어하지 않은 경우보다 Hitch angle이 감소한 것을 확인할 수 있었고, 횡 방향 안정성 향상률은 제어 전에 비해 78.9% 향상된 것을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.767-771
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• 2004

In this paper the performance of some control theory-based Active Queue Management (AQM) methods are improved and investigated through simulation. The simulation scenario is considered to be closely realistic, in which the traffic is mainly due to http sessions. The results show the best performance of PID controller with respect to the others in good queue regulation as well as high link utilization and low delay metrics.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.36-41
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• 1993

The adiabatic slirn-type autoclave reactor for free radical polymerization of LDPE is represented by a two-compartment four-cell model, which is proven effective to predict the reactor behavior as well as the polymer properties. Since the temperature distribution along the reactor axis plays the central role for the properties of the polymer product, it is important in practice to regulate the temperature in each compartment. The present study aims for the application of the adaptive control algorithm not only in the period of start-up but also during the steady state operation. It is shown that the temperature control is significantly improved over the conventional PID-control and this also brings about a reduction of variations in the polymer properties. This study demonstrates the potential application of the adaptive controller for the control of the polymerization reactor operated under the adiabatic condition.