• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.152-155
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• 2004

Effects of sliding speed, applied load, counterpart radius and thickness of PMMA (Poly Methyl Methacrylate) coating layers on their dry sliding frictional and wear behavior were investigated. Sliding wear tests were carried out using a pin-on-disk wear tester. The PMMA layer was coated on Si wafer by a sol-gel technique with two different thicknesses, $1.5{\mu}m\;and\;0.8{\mu}m$. AISI 52100 bearing steel balls were used as a counterpart of the PMMA coating during the wear. Normal applied load and sliding speed were varied. Wear mechanisms were investigated by examining worn surfaces by an SEM. Under most of sliding test conditions, the thicker layer with the thickness of $1.5{\mu}m$ showed lower fiction coefficient than the thinner layer. Effects of sliding speed and counterpart's radius on the frictional behavior were varied depending on the thickness of the coating layer.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2004년도 춘계학술대회 학술발표 논문집 제14권 제1호
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• pp.153-156
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• 2004

This Paper deals with speed control of DC servo motor using a Fuzzy-Sliding observer. Speed sensor detect a speed of rotor continuously. But It have a limit as a driving speed to detect speed precisely. So it is problem to improve the performance of the driving system To solve the problem, it is studied to detect a speed of DC motor without sensor In particular, study on the method to estimate the speed using the observer is performed a lot. In this parer, the gain of the observer is properly set up using the fuzzy control and sliding observer that have a superior transient characteristic and is easy to implement compared the exist ing method is designed. It estimate the derivative of the armature current directly using the armature current measured in the DC motor. It estimate the speed of the rotor using the differentiation. It is Proposed speed sensor less control method using the estimated speed. Optimal gain of Luenberger observer is set up using the fuzzy control and adapted speed control of DC servo motor. It is proved excellence and feasibility of the presented observer from the comparison tested a case with a speed sensor and a case without a speed sensor which used a highly efficient drive and 200W DC servo motor start ing system.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권5호
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• pp.271-279
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• 2006

In this paper, a new speed sensorless control based on an adaptive sliding mode observer is proposed lot the interior permanent magnet synchronous motor(IPMSM) drives. With using voltage equation only, the adaptive sliding mode observer was investigated. Since the parameter of the dynamic equation such as machine inertia or viscosity friction coefficient are not well known and these values can be easily changed during normal operation, there are many restrictions in the actual implementation. The proposed adaptive sliding mode observer applied to overcome the problem caused by using the dynamic equation. Furthermore, the Lyapunov function is used to prove the system stability included speed estimate and speed control. The effectiveness of the proposed algorithm is confirmed by the experiments.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권1호
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• pp.52-58
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• 2003

The application of a sliding mode control for improving the dynamic response of an induction motor based speed control system is presented in this paper and provides attractive features, such as fast response, good transient performance, and insensitivity to variations in plant parameters and external disturbance. However, chattering is a difficult problem for which the sliding mode control is a popular solution. This paper presents a new fuzzy-sliding mode controller for a sensorless vector-controlled induction motor servo system to practically eliminate the chattering problem for traction applications. A DSP based implementation of the speed control system is employed. Experimental results are presented using a propulsion system simulator. The performance of the drive is shown to be practically free from chattering.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.340-342
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• 2005

This paper describes the speed-sensorless vector control system of a three-phase induction motor using sliding mode flux/speed observer. The sliding mode observer estimates the rotor speed. The error between the actual and observed currents converges to zero which guarantees the accuracy of the flux observer. The convergence of nonlinear time-varying observer along with the asymptotic stability of the controller was analyzed. To define the control action which maintains the motion on the sliding manifold, an "equivalent control" concept was used. It was simulated and implemented on a sensorless indirect vector drive for 750[W] three-phase induction motor. The simulation and experimental results demonstrated the effectiveness of the proposed estimation method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.215-218
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• 1995

In this paper, a sliding mode controller (SMC) which can be characterized by high accuracy, fast response and robustness is applied to speed control of AC-SERVO motor. The control input is changed to continuous one in the boundary layer to reduce the chattering phenomenon, and the boundary layer converges to zero when the state variables of system reach to steady state values. The integral compensator is added to reduce steady state error and to provide the continuous torque reference. The acceleration which is necessary to get the sliding plane is estimated by an observer. Sliding surface is included in control input to enhance the robustness and transient response without increasing sliding mode controller gain. The proposed controller is implemented by DSP(digital signal processor). The effectiveness of the proposed control scheme for speed controller is shown by the real-time experimental results in the paper.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권2호
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• pp.83-91
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• 2002

This paper presents a new speed and position sensorless control method of permanent magnet synchronous motors based on the sliding mode observer. Since the parameter of the dynamic equation such as machine inertia or viscosity friction coefficient are not well known and these values can be easily changed generally during normal operation, there are many restrictions in the actual implementation. The proposed adaptive sliding mode observer applies adaptive scheme so that observer may overcome the problem caused by using the dynamic equation. Furthermore, using the Lyapunov Function, the adaptive sliding mode observer can estimate rotor speed as well as stator resistance. The feasibility of the Proposed observer is verified cia the experiments.

• 제어로봇시스템학회논문지
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• 제16권3호
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• pp.256-263
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• 2010

The paper proposes a sensorless speed control strategy for a PMSM (Permanent Magnet Synchronous Motor) based on a new SMO (Sliding Mode Observer), which substitutes a signum function with a sigmoid function. To apply robust sensorless control of PMSM against parameter fluctuations and disturbance, the high speed SMO is proposed, which estimates the rotor position and angular velocity from the back EMF. The low-pass filter and additional position compensation of the rotor are used to reduce the chattering problem commonly found in sliding mode observer with signum function, which becomes possible by applying the sigmoid function with the control of a switching function. Also the proposed sliding mode observer with the sigmoid function has better efficiency than the conventional sliding mode observer since it adjusts the observer gain by variable boundary layer and estimates the stator resistance. The stability of the proposed sliding mode observer is verified by the Lyapunov second method in determining the observer gain. The validity of the proposed high speed PMSM sensorless velocity control has been demonstrated by real experiments.

• Tribology and Lubricants
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• 제32권6호
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• pp.195-200
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• 2016

This study examines the wear behavior of mild steel pins mated against alloyed tool steel discs in a pin-on-disc type sliding test machine and provides specific clarification regarding the effects of disc hardness on the wear behavior of a mating mild steel pin. The analysis confirms these effects through the observation of differences in the wear rates of the mild steel pins at low sliding speed ranges. These differences occur even though the hardness of the mating disc does not affect the wear characteristic curve patterns for the sliding speeds, regardless of the wear regime. In the running-in wear regime, increasing the hardness of the mating disc results in a decrease in the wear rates of the mild steel pins at low sliding speed ranges. However, in the steady-state wear region, the wear rate of a pin mated against the 42DISC is greater than the wear rate of a pin mated against the 30DISC, which has a lower hardness value. This means that the tribochemical reactivity of the mating disc, which is based on hardness value, influences the wear behavior of mild steel at low sliding speed ranges. In particular, oxides with higher oxygen contents, such as $Fe_2O_3$ oxides, form predominantly on the worn surface of the 42DISC. On the contrary, the wear behavior of mild steel pins at high sliding speed ranges is nearly unaffected by the hardness of the mating disc.

• 제어로봇시스템학회논문지
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• 제2권2호
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• pp.115-120
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• 1996

In this paper, a sliding mode controller which is characterized by high accuracy, fast response and robustness is applied to speed control of AC-SERVO motor. The control input is changed to the continuous one in the boundary layer to reduce the chattering phenomenon, and the boundary layer converges to zero when the state variables of system reach to steady state values. The integral compensator is added to reduce steady state error and to provide the continuous torque reference. The acceleration which is necessary for the sliding plane is estimated by an obsever. Sliding surface is included in control input to enhance the robustness and transient response without increasing sliding mode controller gain. The proposed controller is implemented by DSP(digital signal processor). The effectiveness of the proposed scheme is demonstrated through experimental works.