• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.11a
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• pp.125-128
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• 2005

This paper presents a simple methodolosy that makes a continuous-time nonlinear system chaotic using fuzzy control. The nonlinear system is represented by the T-S fuzzy model. Then, a fuzzy controller makes the T-S fuzzy model, which could be stable or unstable, bounded and chaotic. The verification of chaos in the closed-loop system is done by the following procedures. We establish an asymptotically approximate relationship between a continuous-time T-S fuzzy system with time-delay and a discrete-time T-S fuzzy system. Then, we verify the chaos in the closed-loop system by applying the Marotto theorem to its associated discrete-time T-S fuzzy system.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.4
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• pp.85-102
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• 1990

Up to now, most robot control systems are very naive. They consist of a number of independent position-servo loops to control each joint angle separately. Those control systems have constant predefined gains and do not cover the complex dynamic interactions between manipulator joints. As a result, the manipulator is severely limited in range of application, speed of operation and variation of payload. This study proposed a new method to design a robot manipulator controller capable of tracking the reference trajectories of joint angles in a reasonable accuracy to cope with actual situations of varying payload, uncertain parameters. The adaptive model following control method has been used to improve existing robot manipulator controllers. The proposed controller is operated by adjusting its gains based on the response of the manipulator in such a way that the manipulator closely matches the reference model trajectories defined by the designer. The stability of adaptive controller is based on the Second Method of Lyapunov. The coupling among joints and the nonlinearity in the dynamic equation are explicitly considered. The designed manipulator controller shows good tracking performance under various load varia- tion and parameter uncertainties.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.11
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• pp.1092-1098
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• 2007

A mobile robot localization problem can be classified into following three sub-problems as an observation likelihood model, a motion model and a filtering technique. So far, we have developed the range sensor based, integrated localization scheme, which can be used in human-coexisting real environment such as a science museum and office buildings. From those experiences, we found out that there are several significant issues to be solved. In this paper, we focus on three key issues, and then illustrate our solutions to the presented problems. Three issues are listed as follows: (1) Investigation of design requirements of a desirable observation likelihood model, and performance analysis of our design (2) Performance evaluation of the localization result by computing the matching error (3) The semi-global localization scheme to deal with localization failure due to abrupt wheel slippage In this paper, we show the significance of each concept, developed solutions and the experimental results. Experiments were carried out in a typical modern building environment, and the results clearly show that the proposed solutions are useful to develop practical and integrated localization schemes.

• Journal of Power Electronics
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• v.18 no.1
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• pp.225-233
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• 2018

This paper proposes a universal system control strategy for voltage source converter (VSC) based high voltage direct current (HVDC) systems. The framework of the designed control strategy consists of five layer structures considering the topology and control characteristics of the VSC-HVDC system. The control commands sent from the topmost layer can be transmitted to the next layer based on the existing communication system. When the commands are sent to each substation, the following transmission of commands between the four lower layers are realized using the internal communication system while ignoring the communication delay. This hierarchical control strategy can be easily applied to any VSC-HVDC system with any topology. Furthermore, an integrated controller for each converter is designed and implemented considering all of the possible operating states. The modular-designed integrated controller makes it quite easy to extend its operating states if necessary, and it is available for any kind of VSC. A detailed model of a VSC-HVDC system containing a DC hub is built in the PSCAD/EMTDC environment. Simulation results based on three operating conditions (the start-up process, the voltage margin control method and the master-slave control method) demonstrate the flexibility and validity of the proposed control strategy.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.700-703
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• 1997

A robust controller for a 6 DOF magnetically levitated fine manipulator is presented. The proposed controller consists of following two parts : a model reference controller (MRC) and a H$_{\infty}$ controller (HIC). First, the MRC stabilizes the motion of the manipulator. Then, the motion of the manipulator follows that of the reference model. Second, the HIC minimizes errors generated from the MRC due to noise and disturbance since the HIC is a kind of robust controller. The experiments of position control and tracking control are carried out by use of the proposed controller under the conditions of free disturbances and forced disturbances. Also, the experiments using PID controller are carried out under the same conditions. The results from above two controllers are compared to investigate the control performances. As the results, it is observed that the proposed controller has similar position accuracy but better tracking performances comparing to the PID controller as well as good disturbance rejection effect due to the robust characteristics of the controller. In conclusion, it is verified that the proposed controller has the simple control structure, the good tracking performances and good disturbance rejection effect due to the robust characteristics of the controller..

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.227-233
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• 2002

A vehicle longitudinal control strategy with guaranteed string stability for vehicle stop-and-go(SG) cruise control is presented in this paper. The SG cruise control systems should be designed such that string stability can be guaranteed in addition to that every vehicle in a string of SG cruise control vehicles must track any bounded acceleration and velocity profile of its preceding vehicle with a bounded spacing and velocity error. An optimal vehicle following control law based on the information of the 1311owing distance (clearance) and its velocity relative to the vehicle ahead (relative velocity) has been used and string stability analysis has been done based on the control law and constant time gap spacing policy, A validated multi-vehicle simulation package has been shown that the string stability analysis using the approximate model of the vehicle servo-loop which includes vehicle powertrain and brake control system dynamics is valid in the design of the SG cruise control law with guaranteed string stability.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.4
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• pp.27-34
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• 1989

An adaptive model following controller is designed using the theory of variable structure systems. The proposed method based on the modified condition for the sliding mode allows the designer to satisfy the requirements to speed up the reaching phase and for the magnitude of the chattering to be reduced in the sliding mode. Chattering reduction is obtained by the replacement of control input in the neighborhood of the sliding plane. The results of computer simulation show that state trajectories reach switching plane fast and chattering is reduced.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.675-679
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• 1992

In industry, the speed control of single-phase induction motor in domestic use is generally controlled by a simple ON-OFF or PID control method. However, in this case, in order to have a good speed regulating characteristics, itself should be modified in accordance with the optimum PID factors which are varied each time operating speed changes. Shortening the development time and saving the cost which are needed to modify the controller is a major problem to be solved now in industry. In order to alleviate the above difficulties, it is proposed to apply adaptive control technique using MRFAC(Model Reference Following Adaptive Control) for the speed control of single-phase induction motor which has scarcely been studied. In this paper, the above speed control technique is achieved using MCS-96 one chip micro controller with a good speed control characteristics and it is expetted to open a wide application field in the speed control of single-phase induction motor in the future.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.206-211
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• 1993

This paper presents a new identification method which utilizes fuzzy inference in parameter identification. The proposed system has an additional control loop where a real plant is replaced by a plant model. The control system to be designed is to satisfy the following specifications: 1) It has zero steady-state error. 2) It has adequate damping characteristics. 3) 1),2) satisfied, it has a shortest rise-time. Fuzzy rules describe the relationship between comparison results of the features and magnitude of modification in the model parameter values. This method is effective in auto-tuning because the response of the closed loop is verified. The proposed method is tested in simulation for several plants with high-order lags and dead-times.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.90.5-90
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• 2002

In this research, we are trying to develop an automatic sorting system, which is mostly affected by frictional forces between a veneer and plank. So we will make a suitable dynamic model and mechanism to control the velocity feedback. We will suggest stick-slip motion model which can predict the stability behavior of this system. The control system has a feedback loop, in which the following operations are included. A kind of sensor can get the velocity of the mass to adhesive veneer. The output of result signal should be passed to a filter, then to a phase shifter, which applies an adjustable phase-shift, to a variable-gain amplifier. A shaker will be attached to the mass, which ex...