• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1146-1150
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• 2000

We propose a new method to deal with the optimized auto-tuning for the PID controller which is used to the process-control in various fields. First of all, in this method, initial values are determined by the Switched Reluctance Motor of system and Ziegler-Nichols method. After deciding binary strings of parents generation using by the fitness values of genetic algorithms, we perform selection, crossover and mutation to generate the descendant generation. The advantage of this method is better than the neural network and multiple regression model method in characteristic of output, and has extent of applying without limit of initial parameters.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.496-498
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• 1998

This paper presents a mathod of reducing hunting size or steady state error occurred in the output signals via regulating the PID controllers gains. The PID controllers are widely used in industrial processes. Such processes have several inherent features like continuous operation, fixed set value, and difficulty in applyirty test signals. Thus, this paper suggests fuzzy rules of reducing hunting magnitude or steady state error using output signals only. Such an intelligent tuning technique utilizes both the experts, experience and control engineers' theortical background. For two kinds of systems such as temperature or DC motors speed control, we showed the validity of proposed method in this paper.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.795-797
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• 1995

In this paper, we present a simple auto-tuning PID controller using genetic algorithms. The basic idea of the scheme is to parameterize a Ziegler-Nichols-like tuning formula by a single parameter ${\alpha}$, then to use GA to select optimal tuning parameter. Also, simple rule mechanisms make the controller adapt against large variations in parametric and dynamics uncertainties in the plant. These scheme lead to improved performance of the transient and steady state behavior of the closed loop system, including processes with long delay-time and nonminimum phase systems.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.2
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• pp.209-214
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• 1998

In this paper, we are dealing with the problem of controlling unknown nonlinear dynamical system by using neural networks. A novel error self-recurrent(ESR) neural model is presented to perform black-box identification. Through the various outcome of the experiment, a new neural network is seen to be considerably faster than the BP algorithm and has advantages of being less affected by poor initial weights and learning rate. These characteristics make it flexible to design the controller in real-time based on neural networks model. In addition, we design an adaptive PID controller that Keyser suggested by using ESR neural networks, and present a method on the implementation of adaptive controller based on neural network for practical applications. We obtained good results in the case of robot manipulator experiment.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.8
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• pp.623-631
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• 2003

We have fabricated the two-dimensional inverted pendulum system and designed its controller. The two-dimensional inverted pendulum system, which is composed of X-Y table, is actuated through timing belt by each of two geared DC motors. And the control goal is that the rod is always kept to a vertical position to any distrubance and is quickly moved to the desired position. Because this system has generally nonlinear dynamic characteristics and X-axis and Y-axis move together, it is very difficult to find its exact mathematical model and to design its controller. Therefore, we have designed the PID controller with simple structure and excellent performance. Genetic algorithm(GA), which is blown as one of probabilistic searching methods, and human's heuristic control strategy are introduced to design an optimal PID controller. The usefulness of the proposed GA based PID coefficient searching technique is verified through the experiments and computer simulations.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.6
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• pp.11-16
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• 2004

The integral term of PID controller have the advantage of reduced steady state error and the disadvantage of accumulated errors. We proposed a method that maintains its advantage and improvs the disadvantage in transient response. The proposed PID control method with modified integral parameter accumulates errors in increment section and ignores errors in decrement section. Therefore, the proposed PID control method decreases overshoot, and makes settling time faster than conventional PID control method.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.71-74
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• 2002

본 논문에서는 유전알고리즘(GA)을 이용한 PID계수 자동조정기법에 관한 DC 서보 모터 속도 제어기 설계를 목적으로 한다. DC 서보 모터는 수많은 제어용 기계나 로봇 등의 응용분야에 사용되고 있고 이러한 분야에서 제어기 파라미터들의 선택이 사용자의 전문적인 지식을 요구하게 된다. 따라서 일반적인 공정 기술자들은 시행착오에 의해 제어기 파라미터들을 계속적으로 반복 조절해 나가야 한다. 이와 같이 동적 시스템의 변화나 외란에 대하여 파라미터 계수를 자동 조정해야 할 경우 유전알고리즘을 사용함으로써 보다 정밀하고 최적화된 파라미터 계수값을 추종함에 따라 그 성능을 높일 수 있다. 본 논문에서는 DC 모터의 동특성을 분석하여 얻은 동특성 모델링으로부터 응답 특성이 빠르고 속도 정밀도가 향상된 구동제어가 가능한 제어기를 설계하고 이를 PID제어기와 비교 평가하였다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.80-83
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• 2002

정밀한 서보기술에 바탕을 두고 있는 산업용 로봇 팔은 기계적인 강성도와 서보기구들로 인하여 정확한 제어가 가능하다 그러나 로봇팔은 동작중비 관성모멘트의 변화와 기하학적인 구조로 인하여 비선형적인 시스템이다. 특히 관성모멘트의 변화는 로봇팔의 회전속도와 로봇팔이 이동시키는 대상물의 무게 등에 따라 관성모멘트는 변할 수 있다. 이로 인하여 관성모멘트의 변화에 따라 로봇팔의 정확한 위치제어가 힘들어진다. 따라서 본 논문에서는 관성모멘트의 변화에도 불구하고 강인한 응답특성을 나타내는 제어기의 설계가 요구된다. 일반적으로 PID .제어기는 설계의 용이성으로 산업현장에서 널리 사용된다. 그러나 PIB 제어기의 각 계수값을 설정하는데 많은 어려움이 발생한다. 따라서 본 논문에서는 PID 제어기의 각 계수 값을 퍼지알고리즘을 이용하여 자동으로 설계할 수 있는 자기동조 PID 제어기를 설계한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10C
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• pp.1370-1377
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• 2004

Optimal control gain for time-delay systems is made by an optimal control gain for delay-free systems multiplied by a state transition function for the delay time. The optimal control gain for delay-free systems is obtained by pushing two zeros of the PID controller closely to a larger pole of the second order plant. Thus the optimal tuning of PID controller for time-delay second order system is able to be obtained by calculation for the state transition function.

• Journal of Ocean Engineering and Technology
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• v.15 no.1
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• pp.67-72
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• 2001

In this study, a methodology of synchronous control which can be applied to position synchronization of a two-axes driving system has been developed. The synchronous error is caused by model uncertainties and torque disturbance of each axis. To overcome these problems, the proposed synchronous control system has been composed of two speed controllers, disturbance observers, and one synchronous controller. The speed controllers, based on the PID control law are aimed at the following to speed reference. And the parameters of speed controllers have been designed in order for the speed response fo the second axis to correspond with the one of the first axis. The disturbance observer has been designed to restrain the torque disturbance. The synchronous controller eliminates the synchronous error by controlling the speed of the second axis. The effectiveness of the proposed method has been verified through simulation.