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ABSTRACT: Texture evolution and physical properties are studied to investigate effects according to recrystallization treatment and
the reduction ratio of temper rolling. Cold rolling texture can be decided by the deformation criteria and slip systems. Texture
components develop by different deformation hysteresis in the surface and center layer of low-C flat rolled steels. Predominant
γ-fiber is developed by cold rolling in center layer and (α+γ)-fibers which α-fiber is strong are developed in surface layer.
This is the result of the different deformation hysteresis of the surface and center layer. After recrystallization the intensity
of γ-fiber is clearly developed. γ-fiber is well developed in IF steel, but strong α-fiber together with γ-fiber is developed
in AK steel. This is because textures having orientation scattering from γ-fiber are developed from recovery detention by
the reaction between carbon and dislocations, inhomogeneity of slip behavior by carbon atoms, and plastic deformation mechanism
like slip bands, etc. High permeability and low coercivity can be obtained by developing texture parallel to magnetic easy
axis {hkl}〈100〉. Factors having effects on magnetic properties are grain size, chemical composition, texture, etc.
KeywordsTexture-Recrystallization-Deformation hysteresis-Temper rolling-Low-C steel
International Journal of Precision Engineering and Manufacturing 05/2012; 11(3):445-452. · 1.14 Impact Factor
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ABSTRACT: To open and close the breech-block of a tank automatically, we used a switched reluctance motor (SRM) which has the characteristics
of high speed, high torque, high efficiency, durability, and environmental robustness. For the stable operation of a tank’s
automatic breech system, a new type of SRM encoder with a simple configuration is proposed.
Key wordsSwitched reluctance motor-Encoder-Tank-Breech
Artificial Life and Robotics 04/2012; 7(4):205-209.
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ABSTRACT: Several types of detector, such as ultraviolet, infrared, visible light, differential pressure, flame rod, and others, are
employed to detect fire flame in power generation plants. However, these flame detectors have some performance problems. This
article describes the image-processing method of fire detection as well as neural network modeling. Nowadays, the image-processing
technique is broadly applied in industrial fields. The neural network model has strong adaptability and learning capability,
and is suitable for pattern classification. The Ulsan Steam Power Generation Plant in Korea was employed as the test field.
If this technique can be implemented, boilers will be able to operate more economically and effectively.
Key wordsFlame detection-Neural networks
Artificial Life and Robotics 04/2012; 8(2):202-207.
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ABSTRACT: Torque ripple control of brushless DC motor has long been the main issue of the servo drive systems in which the speed fluctuation,
vibration and acoustic noise need to be minimized. The vast majority of the methods for suppressing the torque ripple require
the Fourier series analysis and either the iterative or least mean square minimization. In this paper, a novel approach based
on thed-q-o reference frame that achieves ripple-free torque control with maximum efficiency is presented. The proposed method optimizes
the reference phase current waveforms including even the case of 3-phase unbalanced condition, and the motor winding currents
are controlled to track the optimized current waveforms by the delta modulation technique. As a result, the proposed approach
provides a simple and yet effectine means for obtaining the optimal motor excitation currents. The validity and applicability
of the proposed control scheme are verified through simulations and experimental investigations.
Key WordsBrushless DC Motor-Torque Ripple-Maximum Efficiency-Optimal Current
Journal of Mechanical Science and Technology 04/2012; 15(7):831-838. · 0.45 Impact Factor
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ABSTRACT: In this paper, an integration system is proposed to improve the positioning performance of a mobile robot by fusing a Pseudolite
Ultrasonic System (PUS), an absolute position measurement system using direct ultrasonic waves, with a Dead Reckoning (DR)
odometer. As an integration algorithm of the absolute position measurement system and DR, two methods are proposed. In the
loosely coupled method, the PUS and the DR calculate the position independently and a Kalman filter estimates the position
using position information from the PUS and the DR. In the tightly coupled method, the PUS provides the distance between the
ultrasonic transmitters and receivers without calculating the position directly and the DR provides the translational and
rotational displacement of the mobile robot. The Kalman filter then estimates the position using information from the PUS
and the DR. In addition, to improve the positioning performance in case the line-of-sight (LOS) between the ultrasonic transmitter
and receiver is blocked due to obstacles, a positioning failure detection algorithm and reckoning methods are proposed. The
positioning performances of the proposed PUS/DR integrated systems and the validity of the positioning failure detection algorithm
are verified and evaluated by experiments.
KeywordsAbsolute position measurement system–dead reckoning (DR)–positioning failure detection algorithm–pseudolite ultrasonic system (PUS)–PUS/DR integrated systems
International Journal of Control Automation and Systems 04/2012; 9(2):339-347. · 0.75 Impact Factor
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ABSTRACT: In this paper, the thermodynamic modeling of a vapor-compression cycle, based on a neural network approach is presented. A
generalized radial basis function is used for the network, which takes previous control inputs and previous states as the
network input and generates the predicted current state as the network output. The trained network is validated by non-trained
data and shows all the process characteristics of a vapor-compression cycle for an air-to-water heat pump to a satisfactory
degree.
KeywordsAir-to-water heat pump–dynamic simulation–neural network–vapor-compression cycle
International Journal of Control Automation and Systems 04/2012; 8(6):1241-1249. · 0.75 Impact Factor
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ABSTRACT: In this paper, estimability measures and their properties are introduced for a discrete linear system. The degrees of estimability
of both a system and its subspaces can be examined with these measures for multi-input/multi-output time-varying systems.
The relations among estimability, error covariance, and information matrix are presented. The effects of the initial error
covariance, system model perturbation, and the transformation of state variable on the measures are also given. The estimability
measures are applied to GPS/INS to confirm the estimability analysis results.
Journal of Mechanical Science and Technology 04/2012; 22(5):905-913. · 0.45 Impact Factor
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ABSTRACT: This paper considers the control model identification andH∞ controller design for a tandem cold mill (TCM). In order to improve the performance of the existing automatic gauge control
(AGC) system based on the Taylor linearized model of the TCM, a new mathematical model that can complement the Taylor linearized
model is constructed by using the N4SID algorithm based on subspace method and the least squares algorithm based on ARX model.
It is shown that the identified model has dynamic characteristics of the TCM than the existing Taylor linearized model. TheH∞ controller is designed to have robust stability to the system parameters variation, disturbance attenuation and robust tracking
capability to the set-up value of strip thickness. TheH∞ servo problem is formulated and it is solved by using LMI (linear matrix inequality) techniques. Simulation results demonstrate
the usefulness and applicability of the proposedH∞ controller.
Key WordsTandem Cold Mill-N4SID (Numerical algorithms for Subspace State Space System IDentification)-LMI-basedH∞ Control-Taylor Linearized Model-Interstand Interference
Journal of Mechanical Science and Technology 04/2012; 15(7):847-858. · 0.45 Impact Factor
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ABSTRACT: In this paper, we present a new approach to visual feedback control using image-based visual servoing with stereo vision.
In order to control the position and orientation of a robot with respect to an object, a new technique is proposed using binocular
stereo vision. The stereo vision enables us to calculate an exact image Jacobian not only around a desired location but also
at other locations. The suggested technique can guide a robot manipulator to the desired location without providing a priori
knowledge such as the relative distance to the desired location or the model of an object even when the initial positioning
error is large. This paper describes a model of stereo vision and how to generate feedback commands. The performance of the
proposed visual servoing system is illustrated by experimental results and compared with conventional control methods for
an assembly robot.
Key WordsVisual Feedback-Image-Based Visual Servoing-Intelligent Robot-SCARA Robot
Journal of Mechanical Science and Technology 04/2012; 14(7):782-788. · 0.45 Impact Factor
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ABSTRACT: In the autonomous vehicle, the reference lane is continually detected by machine vision system. And then the vehicle is steered
to follow the reference yaw rates which are generated by the deviations of lateral distance and the yaw angle between a vehicle
and the reference lane. To cope with the steering delay and the side-slip of vehicle, PI controller is introduced by yaw rate
feedback and tuned from the simulation where the vehicle is modeled as 2 DOF and 79 DOF and verified by the results of an
actual vehicle test. The lateral control algorithm by yaw rate feedback has good performances of lane tracking and passenger
comfort.
Key WordsLateral Control-Yaw Rate Control-Machine Vision
Journal of Mechanical Science and Technology 04/2012; 16(3):338-343. · 0.45 Impact Factor
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ABSTRACT: This paper describes the development of the obstacle sensing and collision avoidance for Adaptive Cruises Control(ACC) system with an automated vehicle using the laser scanner and RTK - DGPS(Real Time Kinematic - Differential Global Positioning System) system for autonomous navigation. The real scale vehicle for experiment is constructed using RTK-DGPS and laser scanner. Laser scanner is detects the obstacle of the vehicle front. The controller applies to RTK-DGPS and laser scanner based real scale autonomous vehicle, and the performance of the controller and the results of experiments are suggested.
Industrial Electronics, 2008. ISIE 2008. IEEE International Symposium on; 08/2008
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ABSTRACT: In this paper, two observability measures are introduced for a discrete linear system. The degrees of observability of both the system and its subspaces can be examined with these measures. The measures are well conditioned to perturbation and applicable to multi-input/multi-output time-varying systems. The relations among observability, observability measures, error covariance, and the information matrix are presented. It is shown that the measures have direct connections with the singular value decomposition of the information matrix. In contrast to the error covariance, the measures are determined by the system model and independent of the initial error covariance. An example of the observability analysis of the Global Positioning System/inertial navigation system is given. The measures are confirmed to be less sensitive to the system model perturbation. It is also shown that the vertical component of the gyro bias can be considered unobservable with a tactical-grade inertial measurement unit for a horizontal constant-speed motion.
IEEE Transactions on Vehicular Technology 02/2008; · 1.92 Impact Factor
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ABSTRACT: The industrial network, often referred to as fieldbus, becomes an indispensable component for intelligent manufacturing systems. Thus, in order to satisfy the real-time requirements of field devices such as sensors, actuators, and controllers, numerous fieldbus protocols have been developed. But, the application of fieldbus has been limited due to the high cost of hardware and the difficulty in interfacing with multivendor products. As an alternative to fieldbus, the Ethernet (IEEE 802.3) technology is being adapted to the industrial environment. However, the crucial technical obstacle of Ethernet is its nondeterministic behavior that cannot satisfy the real-time requirements. Recently, the switched Ethernet becomes a very promising alternative for real-time industrial application due to the elimination of uncertainties in Ethernet. This paper focuses on the application of the switched Ethernet with multiple levels (that is, cascade structure with multiple switching hubs) for real-time industrial networking. More specifically, this paper presents an analytical performance evaluation of the switched Ethernet with multiple levels from timing diagram analysis, and experimental evaluation from an experimental testbed of networked control system
IEEE Transactions on Industrial Electronics 11/2006; · 5.16 Impact Factor
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ABSTRACT: Lever-arm uncertainty can be an important error source in the integration of the Global Positioning System (GPS) and inertial navigation system (INS). This paper presents both numerical and experimental studies on the estimation of the lever arm in the integration of a very-low-grade inertial measurement unit (IMU) with an accurate single-antenna GPS measurement system. Covariance simulation results showed that maneuvers play an important role on the estimation of the lever arm and attitude. The length of the lever arm has a rather insignificant effect on the estimation of these. Experimental tests conducted with a low-cost microelectromechanical system (MEMS) IMU and a carrier-phase differential GPS (CDGPS) measurement system showed that the lever arm can be estimated with centimeter-level accuracy. The test results confirmed that angular motions and horizontal accelerations improve the estimates of the lever arm and yaw angle, respectively.
IEEE Transactions on Vehicular Technology 04/2006; · 1.92 Impact Factor
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ABSTRACT: Several types of detectors such as ultraviolet (UV), infrared (IR), visible light (VL), different pressure, flame rod, and others are employed to detect a fire flame in power generation plants. However, these flame detectors have some performance problems. Therefore, this paper describes the image-processing method of fire detection as well as the neural-network modeling. Nowadays, the image-processing technique is broadly applied in the industrial fields. An extracted image information is taken into the inputs of the neural-network model. The neural-network model has strong adaptability and learning capability; therefore, this model can be suitable for pattern classification. The Ulsan Steam Power Generation Plant in Korea is employed as the test field. If this technique can be implemented in physical plants, the boilers can be operated economically and effectively.
IEEE Transactions on Industrial Electronics 03/2006; · 5.16 Impact Factor
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ABSTRACT: This paper presents an efficient multilevel-synthesis scheme and its application to a 27-level inverter. In the proposed multilevel scheme, this can be realized by an array of switching devices composing full-bridge inverter modules and proper mixing of each transformer terminal voltage. The most different aspect, compared to the conventional approach, in the synthesis of the multilevel output waveform is the utilization of a combination of transformers rather than the accumulation of capacitor voltage sources. A 27-level inverter consists of three full-bridge modules and their corresponding transformers. Quasi-sinusoidal voltage waves can be generated from a suitable selection of the turns ratio of the transformer. The validity of the proposed system is verified by computer-aided simulation and experimental results using a 500-W prototype, which can generate a 110-V ac output voltage from a 12-V dc input.
IEEE Transactions on Industrial Electronics 01/2006; · 5.16 Impact Factor
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ABSTRACT: This paper focuses on a quality-of-service (QoS)-based remote control scheme for networked control systems via the Profibus token passing protocol. Typically, token passing experiences random network delay due to uncertainties in token circulation, but the protocol has in-built upper and lower bounds of network delay. Thus, to ensure the control performance of networked control systems via the Profibus token passing protocol, the network delay should be maintained below the allowable delay level. As the network delay is affected by protocol parameters, such as target rotation time, we present here an algorithm for selection of target rotation time using a genetic algorithm to ensure QoS of control information. We also discuss the performance of the QoS-based remote control scheme under conditions of controlled network delay. To evaluate its feasibility, a networked control system for a feedback control system using a servo motor was implemented on a Profibus-FMS network.
IEEE Transactions on Industrial Informatics 09/2005; · 2.99 Impact Factor
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ABSTRACT: The motor is the workhorse of industry. The issues of preventive and condition-based maintenance, on-line monitoring, system fault detection, diagnosis, and prognosis are of increasing importance. This paper introduces fault detection for induction motors. Stator currents are measured by current meters and stored by time domain. The time domain is not suitable for representing current signals, so the frequency domain is applied to display signals. The Fourier transform is employed to convert signals. After signal conversion, signal features must be extracted by signal processing such as wavelet and spectrum analysis. Features are entered in a pattern classification model such as a neural network model, a polynomial neural network, or a fuzzy inference model. This paper describes fault detection results that use Fourier and wavelet analysis. This combined approach is very useful and powerful for detection signal features.
Artificial Life and Robotics 06/2005; 9(3):112-116.
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ABSTRACT: Misalignment can be an important problem in the integration of GPS/INS. Observability analysis of the alignment errors in
the integration of low-grade inertial sensors and multiantenna GPS is presented in this paper. A control-theoretic approach
is adopted to study the observability of time-varying error dynamics models. The relationship between vehicle motions and
the observability of the errors in the lever arm and relative attitude between GPS antenna array and IMU is given. It is shown
that alignment errors can be made observable through maneuvering. The change of acceleration makes the components of the relative
attitude error that are orthogonal to the direction of the acceleration change observable. The change of angular velocity
makes the components of the lever arm error that are orthogonal to the direction of the angular velocity observable. The motion
of constant angular velocity has no influence on the estimation of the lever arm.
Journal of Mechanical Science and Technology 05/2005; 19(6):1253-1267. · 0.45 Impact Factor
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ABSTRACT: Observability properties of errors in an integrated navigation system are studied with a control-theoretic approach in this paper. A navigation system with a low-grade inertial measurement unit and an accurate single-antenna Global Positioning System (GPS) measurement system is considered for observability analysis. Uncertainties in attitude, gyro bias, and GPS antenna lever arm were shown to determine unobservable errors in the position, velocity, and accelerometer bias. It was proved that all the errors can be made observable by maneuvering. Acceleration changes improve the estimates of attitude and gyro bias. Changes in angular velocity enhance the lever arm estimate. However, both the motions of translation and constant angular velocity have no influence on the estimation of the lever arm. A covariance simulation with an extended Kalman filter was performed to confirm the observability analysis.
IEEE Transactions on Vehicular Technology 04/2005; · 1.92 Impact Factor
