• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.1104-1109
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• 1991

Recently, Pneumatic Actuation System (PAS) has been used increasingly as a high performance fin-control servo actuation systems because of the special advantages of pneumatic units: primarily their low cost, small size, light weight, and tolerance to broad temperature extremes. In this study, a nonlinear model of PAS is derived through the detailed analysis of the major components in the typical system. The model includes nonlinear flow-pressure relationships of the flow through the solenoid valve openings and orifices, PWM algorithm for driving two solenoid valves as a closed-center 3-way valve for minimum gas consumption, solenoid valve dynamics, saturation, and friction. Simulation results are compared with the experimental ones for square and sinusoidal inputs to see the validity of the model. Independent of the shape and magnitude of the input signals, both results are in good agreements with minor difference.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1640_1641
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• 2009

Dynamic friction and force ripple are the most predominant factors that affect the positioning accuracy of permanent magnet synchronous motor(PMSM) servo drives system, and it is desirable to compensate them in finite time with a continuous control law. In this paper, based on LuGre dynamic friction model, a robust adaptive skidding mode controller is proposed to compensate the nonlinear effect of friction and force ripple. The controller scheme consists of a PD component and a robust adaptive sliding mode controller for estimating the unknown system parameter. Using Lyapunov stability theorem, asymptotic stability analysis and position tracking performance are guaranteed. Simulation results well verify the feasibility and the effectiveness of the proposed scheme for high0precision motion trajectory tracking.

• 제어로봇시스템학회논문지
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• 제7권6호
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• pp.509-517
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• 2001

To deal with non-linearities and time-varying characteristics of hydraulic systems, in this paper, the neuro-fuzzy controller has been introduced. This controller does not require and accurate mathematical model for the nonlinear factor. In order to solve general fuzzy inference problems, the input membership function and fuzzy reasoning rules are used for determining the controller parameters. These parameters are determined by using the learning algorithm. The control performance of the neuro-fuzzy controller is evaluated through a series of experiments for the various types of inputs while applying disturbances to the hydraulic system. The performance of this controller was compared with those of PID and PD controllers. From these results, We observe be said that the position tracking performance of neuro-fuzzy is better those of PID and PD controllers.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.228-228
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• 2000

To deal with non-linearities and time-varying characteristics of hydraulic systems, in this paper, the neuro-fuzzy controller has been introduced. This controller does not require an accurate mathematical model for the nonlinear factor. In order to solve general fuzzy inference problems, the input membership function and fuzzy reasoning rules are used for determining the controller Parameters. These parameters are determined by using the learning algorithm. The control performance of the neuro-fuzzy controller is obtained through a series of experiments for the various types of input while applying disturbances to the cylinder. .and performance of this controller was compared with that of PID, PD controller. As a experimental result, it can be proven that the position tracking performance of the neuro-fuzzy is better than that of PID and PD controller.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제14권2호
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• pp.136-144
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• 2014

The existing conventional motion controller does not perform well in the presence of nonlinear properties, uncertain factors, and servo lag phenomena of industrial actuators. Hence, a feasible and effective fuzzy self-tuning proportional integral derivative (PID) and feed-forward control scheme is introduced to overcome these problems. In this design, a fuzzy tuner is used to tune the PID parameters resulting in the rejection of the disturbance, which achieves better performance. Then, both velocity and acceleration feed-forward units are added to considerably reduce the tracking error due to servo lag. To verify the capability and effectiveness of the proposed control scheme, the hardware configuration includes digital signal processing (DSP) which plays the main role, dual-port RAM (DPRAM) to guarantee rapid and reliable communication with the host, field-programmable gate array (FPGA) to handle the task of the address decoder and receive the feed-back encoder signal, and several peripheral logic circuits. The results from the experiments show that the proposed motion controller has a smooth profile, with high tracking precision and real-time performance, which are applicable in various manufacturing fields.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.242-244
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• 1992

Conventionally in the industrial control, PlD controller has been used because of its robustness, and nonlinear characteristic of a system under control. Although the PlD controller produce suitable parameter of the each system and also variable of PlD controller should be changed according to environment, disturbance, load. In this paper, the convergence and learning accuracy of the back-propagation(BP) method in neural network are investigated by analyzing the reason for decelerating the convergence of BP method. and examining the rapid deceleration of the convergence when the learning is executed on the part of sigmoid activation function with the very small first derivative. The modified logistic activation function it proposed by defining the convergence factor based on the analysis and applied to the position and speed control of a DC-servo motor. This paper revealed for experimental, a neural network and a PD controller combined off-line system using developed the position and speed characteristics of a DC-servo motor.

• 한국생산제조학회지
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• 제20권5호
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• pp.589-597
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• 2011

In this paper, optimal tuning of a cross-coupled controller linked with the feedforward controller and the disturbance observer is studied to improve contouring and tracking accuracy as well as robustness against disturbance. Previously developed integrated design and optimal tuning methods are applied for developing the robust tuning method. Strict mathematical modeling of the multivariable system is formulated as a state-space equation. Identification processes of the servomechanism are conducted for mechanical servo models. An optimal tuning problem to minimize both the contour error and settling time is formulated as a nonlinear constrained optimization problem including the relevant controller parameters of the servo control system. Constraints such as relative stability, robust stability and overshoot, etc. are considered for the optimization. To verify the effectiveness of the proposed optimal tuning procedure, linear and circular motion experiments are performed on the xy-table. Experimental results confirm the control performance and robustness despite the variation of parameters of the mechanical subsystems.

• 전기의세계
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• 제13권2호
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• pp.5-10
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• 1964

Some nonlinearities in feedback control systems, such as relay servo, Coulomb friction, saturating amplifier of backlash in gears cause some undesirable effects. These may be static errors, limit cycles or jump phenomena. So, linearizing method of these nonlinearities using dither signals was first suggested by Loeb. He pointed out that the addition of high frequency signal to either the input or the output of a nonlinear system would make the nonlinear performance approximate the performance of linear systems. He used high-frequency sinusoidal wave as dither signal. But, in this thesis, general method of analysis is suggested for nonlinear control systmes using various dither signals, such as noise signal of Gaussian amplitude distribution, sinusoidal dither signal and sawtooth dither signal. Also, the advantage and disadvantage of these dither signals are compared. Throughout the analysis statistical method is adopted and lastly analog computer is used for the experiment of various nonlinear systems using dither signals.

• 대한기계학회논문집
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• 제16권11호
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• pp.2011-2020
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• 1992

본 연구에서는 실용성을 중시하는 산업계의 요구에 부응하여 해석이 용이하면 서도 강인성을 갖춘 제어 알고리즘을 제안하여 실시간 제어가 가능한 시스템을 구축해 실험적으로 검토하였다. 매니퓰레이터와 서보계의 다이내믹스를 나타내는 미분방정 식은 선형요소와 비선형요소의 합으로 생각할 수 있다. 여기서 매니퓰레이터의 비선 형요소를 외란으로 간주해 슬라이딩 모드를 적용하므로 매니퓰레이터의 자유도가 높아 도 비교적 간단히 슬라이딩 모드의 존재 조건식으로 부터 절환 파라미터가 구해져 슬 라이딩 모드를 발생시킬 수 있는 알고리즘을 도출할 수가 있음을 보였다. 비선형요 소를 외란으로 간주하였을때 로보트 매니퓰레이터가 슬라이딩 모드에 들어갈 수 있도 록 외란에 대응하는 절환 제어입력을 종래의 방식대로 부가하면 이 제어입력으로 인해 채터링(chattering)이 증가하게 됨이 확인되었으며, 이러한 채터링을 줄일 수 있도록 새로운 절환 제어입력의 알고리즘을 도출하여 검토하였다.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1680-1689
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• 2002

This paper studies on the design of a looper control system for hot strip mill finisher using ILQ(Inverse Linear Quadratic optimal control) control method. The loopers are placed between each rolling stands and looper control plays an important role in regulating strip tension. The strip tension is controlled by raising and lowering the looper and by changing the speed of main work rolls. Firstly, it is shown from a nonlinear dynamic simulation that the strip tension is more influenced by difference of rolling speed than that of the looper angle. Secondly, a servo controller of the looper is designed using ILQ control method of which the characteristics and algorithms are simply introduced. Finally, the performances of the ILQ servo controller are compared with those of the LQI servo controller from computer simulation. In result, it is shown that the proposed ILQ servo controller has the better performances and robustness far parameter perturbations and disturbances than those of LQI controller.