• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 심포지엄 논문집 정보 및 제어부문
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• pp.120-122
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• 2004

Wearable input device that can make free-space typewriting possible is introduced. We named this device as $SCURRY^{TM}$. To measure the angular velocity of hand and the acceleration rates at the ends of fingers, we buried MEMS inertial sensors in this keyboard. We processed sensor signals to get the information on hand movement and finger-click motion. With this signal processing, apparent finger movements were depicted over the virtual keyboard shown on output device of a target computing system. In this paper, a finger-click recognition method is proposed to improve the recognition performance for finger clicking of $SCURRY^{TM}$. The proposed method is composed of three parts including feature extraction part, valid click part, and cross-talk avoidance part. The experiments were conducted to verify the effectiveness and efficiency of the proposed algorithms.

• 반도체디스플레이기술학회지
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• 제23권2호
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• pp.33-37
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• 2024

Recently, wearable virtual reality devices are widely used. These instruments include a 3-axis accelerometer. User's heart rate information in virtual reality contents can be useful for measuring user experience. In this paper, we propose a method to measure the heart rate through a 3-axis accelerometer based on the principle of ballistocardiography without additional sensors. The angular velocity was successively measured in a time series by the 3-axis accelerometer mounted to the head. The frequency of the maximum magnitude is determined as the heart rate through frequency transform and band pass filtering of the time series signal. For verification, the heart rate calculated from photoplethysmography sensors acquired at the same time was compared as ground-truth. In the virtual reality, the user's heart rate information can be extracted without additional heart rate sensor, and the emotional state and fatigue can be measured.

• 대한기계학회논문집A
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• 제29권2호
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• pp.311-317
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• 2005

NC controller parameters are fixed when the controller is combined with a machine. However, the characteristics of controller could be changed as it has being used by the machine or other environmental conditions. Ultimately, it results in tool positioning accuracy changing. The loading torque in servo motor also influences on the positioning accuracy. This study focus on a measuring and analysing method for verifying the angular positioning accuracy of NC servo motor. We used a high resolution A/D converter for acquiring analogue signal of rotary encoder in servo motor. Generating tool path by the combination of axial movements (X,Y,Z) is compared with the encoder signals with the servo motor torque. The current variation signal is also read from the servo motor power using a hall sensor and converted to the motor torque. The method of analysing proposed in this study will be used for determining the gains (tuning) of parameter in NC controller, when the controller is set up at a machine initially or the controller condition is changed during the work.

• 한국정보통신학회논문지
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• 제15권4호
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• pp.886-890
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• 2011

유도전동기는 상대적으로 저가이며 보수가 용이하여 산업 및 여러 분야에서 많이 사용되고 있는 전동기이다. 유도전동기의 정확한 속도 및 토크 제어를 위해서 회전자의 속도 및 위치정보가 요구된다. 회전자의 위치 및 속도 센서들은 경제성 및 주위 환경에 따른 센서의 신뢰도 감소 문제를 가져온다. 최근에는 이러한 경제성 및 신뢰성 향상을 위하여 속도 및 위치센서를 사용하지 않는 센서리스 제어방식의 연구가 많이 이루어지고 있다. 대부분의 센서리스제어 방식에서 위치 및 속도추정은 전동기 전압방정식으로부터 계산된다. 따라서 파라미터 오차는 센서리스 제어성능에 큰 영향을 미치게 된다. 본 논문에서는 유도전동기의 속도 추정에서 회전자 저항 오차에 의해 발생하는 속도 오차를 보상하기 위하여 회전자 저항 보상방식을 제안한다. 본 논문에서 제안한 방식은 컴퓨터 시뮬레이션 및 실험을 통하여 검증한다.

• 한국산업융합학회 논문집
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• 제3권2호
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• pp.131-139
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• 2000

Gear train in the automobile to be used for controlling gas flow in automobiles consists of spur gears with involute tooth type in multiple stages. This spur gear is designed considering to the high power transfer efficiency, bending stress and contact stress in the static and dynamic analysis. The torque has been increased simultaneously the angular velocity has been decreased through the stages after being supplied by AC synchronous motor. This apparatus is controlled by electrical devices such as the PIC microprocessor, hall sensor and other electric components. By comparing the preset data of PIC microcomputer which is supplied by external DC electric power with the value set of hall sensor which detects the rotation angle position, PIC microcomputer thus controls AC motor and gear train according to the program algorithm which includes the on-off control and PWM motor driving method. As the result of the experiment such as performance, fatigue, torque test, we can conclude that this system is superior to the same and familiar foreign systems.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.923-928
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• 2003

This paper presents the motion control of a mobile robot with arc sensor for lattice type welding. Its dynamic equation and motion control method for welding speed and seam tracking are described. The motion control is realized in the view of keeping constant welding speed and precise target line even though the robot is driven along a straight line or comer. The mobile robot is modeled based on Lagrange equation under nonholonomic constraints and the model is represented in state space form. The motion control of the mobile robot is separated into three driving motions of straight locomotion, turning locomotion and torch slider controls. For the torch slider control, the proportional integral derivative (PID) control method is used. For the straight locomotion, a concept of decoupling method between input and output is adopted and for the turning locomotion, the turning speed is controlled according to the angular velocity value at each point of the comer with range of $90^{\circ}$ constrained to the welding speed. The proposed control methods are proved through simulation results and the results have proved that the mobile robot has enough ability to apply the lattice type welding line.

• Journal of Mechanical Science and Technology
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• 제17권5호
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• pp.629-636
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• 2003

This paper introduces the developed geometry PIG (Pipeline Inspection Gauge), one of several ILI (In-Line Inspection) tools, which provide a full picture of the pipeline from only single pass, and has compact size of the electronic device with not only low power consumption but also rapid response of sensors such as calipers, IMU and odometer. This tool is equipped with the several sensor systems. Caliper sensors measure the pipeline internal diameter, ovality and dent size and shape with high accuracy. The IMU (Inertial Measurement Unit) measures the precise trajectory of the PIG during its traverse of the pipeline. The IMU also provide three-dimensional coordination in space from measurement of inertial acceleration and angular rate. Three odometers mounted on the PIG body provide the distance moved along the line and instantaneous velocity during the PIG run. The datum measured by the sensor systems are stored in on-board solid state memory and magnetic tape devices. There is an electromagnetic transmitter at the back end of the tool, the transmitter enables the inspection operators to keep tracking the tool while it travels through the pipeline. An experiment was fulfilled in pull-rig facility and was adopted from Incheon LT (LNG Terminal) to Namdong GS (Governor Station) line, 13 km length.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.933-934
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• 2006

High level perceptual tasks such as context understanding, SLAM and object recognition are essential for intelligent robot to provide services for human supports. Those intelligent robots often use camera sensor for vision information, sonar or laser sensor for range information, encoder for angular velocity of wheel and so on. The information is generated at different time intervals by the different H/W devices and S/W algorithms. The generation of high level information requires the specific mixture of low level information. And the information should be represented to be useful for robots to use in their ecological niche. In conventional robot systems, perceptual module requires the resource to use by tightly coupling whenever it is needed. So the resource and information cannot be easily shared and even could be invalid for the delayed information. In this paper, we propose a synchronization system of robot-centered information for context understanding. Our system represents information for the robot capacity and synchronizes the information that is asynchronously generated, where is employed the black-board architecture.

• 제어로봇시스템학회논문지
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• 제21권7호
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• pp.615-620
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• 2015

DOB (Disturbance Observer) is an useful control method for estimating the disturbance applied to dynamic systems. Disturbance observer can be used to implement a robust control system to generate a control input for rejecting the disturbance, and it can be also used to estimate the disturbance to obtain information. The system that uses disturbance estimation is investigated for high performance control such as automatic door systems, walking robot and electric power steering system in vehicles. In this paper, a novel disturbance observer which is called disturbance and current observer for estimating load torque in the motor system is proposed. The difference between the DOB for disturbance rejection and DCOB is mathematically verified. Current and angular velocity are required for estimating the load torque of the motor in DOB. However, the DCOB can estimate load torque and current without current sensor. DCOB is designed based on modeling of the motor system. Appropriate Q-filter is selected and the applicability of DCOB is verified by simulation. The estimated disturbance and current of the electric motor can be verified without current sensor, as experiments of the actual motor system.

• Journal of Mechanical Science and Technology
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• 제19권12호
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• pp.2205-2212
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• 2005

In this paper, the cutting torque of a CNC machine tool during machining is monitored through the internet. To estimate the cutting torque precisely, the spindle driving system is divided into two parts: electrical induction motor part and mechanical part. A magnetized current is calculated from the measured three-phase stator currents and used for the total torque estimation generated by a spindle motor. Slip angular velocity is calculated from the magnetized current directly, which gets rid of the necessity of a spindle speed sensor. Since the frictional torque changes according to the cutting torque and the spindle rotational speed, an experiment is adopted to obtain the frictional torque as a function of the cutting torque and the spindle rotation speed. Then the cutting torque can be calculated by solving a $2^{nd}$ order difference equation at a given cutting condition. A graphical programming method is used to implement the torque monitoring system developed in this study to the computer and at the same time monitor the torque of the spindle motor in real time through the internet. The cutting torque of the CNC lathe is estimated well within an about $3\%$ error range in average in various cutting conditions.