• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2002년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.251-253
• /
• 2002

We have fabricated a novel Vertical Trench Hall-Effect Device sensitive to the magnetic field parallel to the sensor chip surface for non-contact angular position sensing applications. The Vertical Trench Hall-Effect Device is built on SOI wafer which is produced by silicon direct bonding technology using bulk micromachining, where buried $SiO_2$ layer and surround trench define active device volume. Sensitivity up to 150 V/AT is measured.

• 한국전문물리치료학회지
• /
• 제10권3호
• /
• pp.63-70
• /
• 2003

The purpose of this study was to compare the difference of joint position sense between measurements. Fourteen healthy male subjects were recruited for this study. The elbow joint position senses were measured using angle reproduction test. The elbow joint position sense was assessed with three experimental conditions: ipsilateral reproduction test in open-chain condition, contralateral reproduction test in open-chain condition, ipsilateral reproduction test with weight in open-chain condition and ipsilateral reproduction test in closed-chain condition. The angular difference between stimulus position and the reproduced position (angular error) was calculated in all testing conditions to examine the accuracy of the joint position sense. One way ANOVA was used to compare the error angles in all experimental conditions. The error angles between measurements were significantly different in elbow joint. The error angles was smallest in ipsilateral reproduction test with weight in open-chain condition and was greatest in the contralateral reproduction test in open-chain condition. Findings of this study indicate that testing methods, types of task, existence of resistance should be considered in clinical assessment for the joint position sense.

• 조명전기설비학회논문지
• /
• 제22권3호
• /
• pp.66-73
• /
• 2008

This paper presents a position sensorless control system of SRM over wide speed range. Due to the doubly salient structure of the SRM, the phase inductance varies along with the rotor position. Most of the sensorless control techniques are based on the fact that the magnetic status of the SRM is a function of the angular rotor position. The rotor position estimation of the SRM is somewhat difficult because of its highly nonlinear magnetizing characteristics. In order to estimate more accurate rotor position over wide speed range, Neural Network is used for this highly nonlinear function approximation. Magnetizing data patterns of the prototype 1-hp SRM are obtained from locked rotor test, and used for the Neural Network training data set. Through measurement of the flux-linkage and phase currents, rotor position is able to estimate from current-flux-rotor position lookup table which is constructed from trained Neural Network. Experimental results for a 1-hp SRM over 16:1 speed range are presented for the verification of the proposed sensorless control algorithm.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
• /
• pp.103-107
• /
• 2006

At present, most efforts tend to develop a INS which is only based linear accelerometers, because of the low cost micro-machining gyroscopes lack of the accuracy needed for precise navigation application and possible achieving the required levels of precise for micro-machining accelerometer. Although it was known in theory that a minimum of six accelerometers are required for a complete description of a rigid body motion, and any configuration of six accelerometers (except for a "measure zero " set of six-accelerometer schemes) will work. Studies on the feasible configuration of GF-INS indicate that the errors of angular velocity resolved from the six accelerometers scheme are diverged with time or have multi solutions. The angular velocity errors are induced by the biases together with the position vectors of the accelerometers, therefore, in order to treat with the problem just mentioned, researchers have been doing many efforts, such as the extra three accelerometers or the magnetometers may be taken as the reference information, the extended Kalman filter (EKF) involved to make the angular velocity errors bound and be estimated, and so on. In this paper, the typical configurations of GF-INS are introduced; for each type GF-INS described, the solutions to the angular velocity and the specific force are derived and the characteristic is indicated; one of the corresponding extend Kalman filters are introduced to estimate the angular errors; parts of the simulation results are presented to verify the validity of the equations of angular velocity and specific force and the performance of extend Kalman filter.

• 한국정밀공학회지
• /
• 제13권2호
• /
• pp.76-83
• /
• 1996

We have developed the unconventional robot arm which is composed of the two main parts, one is a ball screw and the other is a robot arm. The dynamic systems of the robot arm and ball screw are unstable systems coupled with each other. The ball screw mechanism is unstable system but controllable system. The robot arm's dynamics is quasi stable system when ball screw's angular position is zero, else, unstable system. Our system has the duality between stability and controllability at the view point of control. This duality causes difficulty to control of the robot arm using normal control law. We have investigated the location of the characteristic roots of the dynamic equation. And we have found out that the best condition for the control of the arm is quasi stable state. In this paper, we have proposed multiple control laws which are consist of three components to guarantee the stability and controllability simultaneously. The computer simulations were carried out based on VSC about the angular position control of the robot arm, and it is confirmed that the good performances could be obtained by using new controller.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2003년도 추계학술대회논문집
• /
• pp.418-423
• /
• 2003

The balancing performance of an automatic ball balancer (ABB) in the vertical or horizontal position is studied in this paper. Considering the effects of gravity and angular velocity profiles, a physical model for an ABB installed on the Jeffcott rotor is adopted. The non-linear equations of motion for the rotor with ABB are derived by using Lagrange's equation. Based on derived equations, dynamic responses for the rotor are computed by using the generalized-u method. From the computed responses, the effects of gravity and angular velocity profiles on the balancing performance are investigated. It is found that the rotor with ABB can be balanced regardless of the gravity effect. It is also shown that a smooth velocity profile yields relatively smaller vibration amplitude than a non-smooth velocity profile.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.852-857
• /
• 2004

In this paper, an angular self-sensing algorithm is proposed and implemented to a Lorentz force type integrated motor-bearing system. It is based on the principle that the flux linkages of stator windings, calculated from the voltage and torque control current, are the functions of the rotor angle. The tracking angular position error is proven to vanish using the Lyapunov stability method, and the experimental results show that the initial error decays within about 5 seconds. It is found that the resolution of the algorithm remains about 1º over the speed range of 100 to 1000 rpm.

• 대한치과교정학회지
• /
• 제33권2호
• /
• pp.73-84
• /
• 2003

본 연구는 정모두부방사선사진 촬영시 수직적 두부회전이 방사선사진상의 계측치들에 어느 정도의 투사오차를 야기 시키는지 알아보고자 시행되었다. 임상검사를 통하여 두드러진 전후방 골격이상이나 뚜렷한 안면비 대칭을 보이지 않는 성인 25명을 대상으로 natural head position상태를 기준위치$(0^{\circ})$로 정하고 이 위치에 대해 양쪽 ear rod를 연결한 수평축을 중심으로 두부를 상, 하방으로 $5^{\circ},\;10^{\circ}$씩 회전시킨 상태에서 정모두부방사선사진을 각각 촬영하여 투사도를 작성한 다음 7개의 고경항목, 5개의 폭경항목, 6개의 각도항목을 계측하였다. 각 회전각도에서의 계측치를 비교 분석하여 다음과 같은 결과를 얻었다. 1. 고경계측항목의 투사오차가 폭경이나 각도계측항목에 비해 전반적으로 큰 양상을 나타냈다. 2. 고경계측항목 중 회전축으로부터 먼 계측점간의 거리를 나타내는 항목일수록 투사오차가 컸다. 3. 폭경 계측항목 중 비강폭경, 상악폭경, 상악 제1대구치간 폭경은 각 회전각도 간에 통계적 유의차가 없었으나 하악폭 경과 하악 제1대구치간 폭경은 통지적으로 유의차가 있었다. 4. 각도계측항목 중 menton의 편위정도를 나타내는 각도는 각 회전각도 간에 통계적 유의차가 없었으나 crista galli와 maxillare를 연결한 선이나 crista galli와 antegonion을 연결한 선과 수평기준선이 이루는 각도는 통계적으로 유의차가 있었다. 이상의 결과는 수직적 두부회전에 의해 정모두부방사선사진상에 투사오차가 발생하므로 유용한 정모두부방사선사진을 얻기 위해서는 촬영시마다 동일한 두부위치를 유지하기 위한 노력이 필요함을 시사하였다.

• 한국운동역학회지
• /
• 제15권4호
• /
• pp.153-168
• /
• 2005

The purposes of this study were to determine the influence of midsole hardness and sole thickness of sports shoes on ball flex angle and position with increment of running velocity. The subjects employed for this study were 10 college students who did not have lower extremity injuries for the last one year and whose running pattern was rearfoot striker of normal foot. The shoes used in this study had 3 different midsole hardness of shore A 40, shore A 50, shore A 60 and 3 different sole thickness of 17cm, 19cm, 21cm. The subjects were asked to run at 3 different speed of 2.0m/sec, 3.5m/sec, 5.0m/sec and their motions were videotaped with 4 S-VHS video cameras and 2 high speed video cameras and simultaneously measured with a force platform. The following results were obtained after analysing and comparing the variables. Minimum angle of each ball flex position were increased with the increment of running velocity and shoe sole thickness(P<0.05), but mid-sole hardness did not affect minimum ball flex angle. The position which minimum angle was shown as smallest was 'D'. Midsole hardness and sole thickness did not affect time to each ball flex minimum angle, total angular displacement of ball flex angle, and total angular displacement of torsion angle(P<0.05). The position which minimum angle was appeared to be earliest was similar at walking velocity, and E and F of midfoot region at running velocity. Total angular displacement of ball flex position tended to increase as shifted to heel. It was found that running velocity had effects on ball flex angle variables, but shoe sole thickness partially affected. It would be considered that running velocity made differences between analysis variables at walking and running when designing shoes. Also, it was regarded that shoes would be developed at separated region, because ball flex angle and position was shown to be different at toe and heel region. It is necessary that midsole hardness and thickness required to functional shoes be analyzed in the further study.

• 한국항해항만학회지
• /
• 제28권8호
• /
• pp.653-657
• /
• 2004

이 논문은 자유자이로의 방향보존성을 이용하여 위치를 결정하는 방법을 이론적으로 유도한 것이다. 즉, 임의 위치에서 두 대의 자유자이로 회전축의 경사각과 기준 위치로부터 측정한 경과 시간을 기본 요소로 하여 위치를 결정하는 시스템을 제시하고 이 시스템을 구축할 때 나타나는 문제점을 열거하였다.