• 전력전자학회논문지
• /
• 제11권6호
• /
• pp.551-557
• /
• 2006

교류 전동기는 전류의 측정오차와 데드타임(dead time) 등의 영향으로 전기각주파수에 동기된 주기적인 토크리플이 발생한다. 본 논문에서는 주기적인 토크리플 보상알고리즘을 제안한다. 보상기는 토크리플에 의해 생성된 속도리플의 크기을 관측하는 속도리플 관측기와 관측한 양으로 토크리플을 보상하는 토크리플 보상기로 나누어진다. 본 논문에서는 토크리플 보상기의 해석을 통해 정상상태에서 속도리플이 제거되고 새롭게 제안된 속도리플 관측기을 적용하여 성능이 향상됨을 보였다. 제안한 주기적인 토크리플 보상알고리즘에 의해 토크리플 성분이 보상됨을 모의 실험과 실험을 통해 검증하였다.

• Journal of Electrical Engineering and Technology
• /
• 제1권3호
• /
• pp.327-331
• /
• 2006

This paper presents the analysis method for the torque characteristic of the 1-phase induction motor considering space harmonics in the air gap. The equivalent circuit method is used, where the circuit constants are obtained by classic theory. In addition, the space harmonic components in air gap magneto motive force are analyzed and added to the equivalent circuit to obtain accurate torque characteristics in low speed regions. Each torque component due to the harmonics is calculated and the total torque characteristic is obtained and compared with the measurement result.

• 한국정밀공학회지
• /
• 제33권10호
• /
• pp.789-796
• /
• 2016

The weight of an antenna system pointing satellite on the mobile platform is restricted by the weight limit of the mobile platform. The maximum power of the actuator driving the antenna system is thus limited because a high power actuator needs a heavier weight. Thus, a drive system is designed to have a low torque requirement by reducing the gravitational torque depending on gravity or acceleration of the mobile platform, including vibration, shock, and accelerated motion. To reduce the gravitational torque, the mathematical model of the gravitational torque is preferentially obtained. However, the method to directly estimate the mathematical model in an antenna system has not previously been reported. In this paper, a method is proposed to estimate the gravitational torque as a mathematical model in the antenna system. Additionally, a method is also proposed to calculate the optimal weight of the balancing weight to compensate for the gravitational torque.

• 한국공작기계학회논문집
• /
• 제13권2호
• /
• pp.88-93
• /
• 2004

The main objective of the research is to Propose an algorithm that to estimate the screwing torque from parameters of DC motor current without using any stain gage and torque cell. The auto screw drive system is divided into two parts, one is the DC motor ind the other is mechanical part in which the friction torque and damping ratio are a function of rotational of spindle electro motive force constant. The torque is estimated from the friction torque. The research is concerned with applying the method to an auto screw drive and the advantages and limitations are also discussed in this paper.

• 한국자동차공학회논문집
• /
• 제4권3호
• /
• pp.1-9
• /
• 1996

This study investigated torque characteristics for Couette flow experimentally under circumstaces that ferrofluids were between two coaxial spheres. Torque measurement was obtained for the situation where the inner sphere was rotating while the outer sphere was kept stationary. The magnetic field was imposed on the fluid, using a bar magnet which was inserted in the inner sphere. In the laminar flow region the torque increase when the magnetic field is applied and the critical Reynolds number is increased. However, in the transition regime, the effect of the magnetic field on the torque characteristics decrease as Reynolds number increases. The value of torque were the same as those of glycerine solution beyond the cirtical Reynolds number. We also made experimental equation which could obtain coefficient of torque within critical Reynolds number in terms of sphere spacing Reynolds number and magnetic properties of ferrofluid.

• 로봇학회논문지
• /
• 제14권4호
• /
• pp.311-317
• /
• 2019

Direct teaching is an essential function for collaborative robots for easy use by non-experts. For most robots, direct teaching is implemented only in joint space because the realization of Cartesian space direct teaching, in which the orientation of the end-effector is fixed while teaching, requires a measurement of the end-effector force. Thus, it is limited to the robots that are equipped with an expensive force/torque sensor. This study presents a Cartesian space direct teaching method for torque-controlled collaborative robots without either a force/torque sensor or joint torque sensors. The force exerted to the end-effector is obtained from the external torque which is estimated by the disturbance observer-based approach with the friction model. The friction model and the estimated end-effector force were experimentally verified using the robot equipped with joint torque sensors in order to compare the proposed sensorless approach with the method using torque sensors.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 D
• /
• pp.1780-1782
• /
• 1999

The ultrasonic motor used here is the windmill type ultrasonic motor operated by single-phase AC source. A metal-ceramic composite component was used as the stator element to generate ultrasonic vibrations. The windmill type ultrasonic motors has only three components; a stator element of two wind-mill shape slotted metal endcaps, a rotor and a bearing. In this paper we proposed a system for torque measurement of piezoelectric ultrasonic motor.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2002년도 추계학술대회 논문집
• /
• pp.12-16
• /
• 2002

This paper deals with the measurement of machine parameters of inverter-fed induction motors for an accurate torque control applications such as machine tools and tension control machines. After discussing nonlinearities of both inverter and motor, this paper suggests appropriate compensation and measurement methods. The experimental results show the validity of the proposed method in the operating conditions.

• 한국자기학회지
• /
• 제8권6호
• /
• pp.388-394
• /
• 1998

자성물질의 자기이방성을 측정하기 위해 개선된 구조의 null-type 토크마그네토미터를 설계, 제작하였다. 제작된 토크마그네토미터의 측정범위는 $0~{\pm}15\;dyne.cm$이며 조절이 가능하다. 이 범위내에서 분해능은 약 0.0005 dyne.cm 정도이며, 1회 측정시 잡음수준은 ~0.01 dyne.cm, 10회 반복측정한 경우 ~0.004 dyne.cm 이하였으며, 반복재현시 나타나는 오차는 0.5% 이하였다. 본 연구에서 제작된 토크마그네토미터는 종전의 null-type 토크마그네토미터와는 달리 영구자석을 내부에, 헬름홀쯔 코일을 외부에 위치시킨 구조의 토크미터를 포함하고 있다. 이로 인하여, 기하학적으로 등방적인 모양으로 토크미터를 설계할 수 있었으며, 헬름헬쯔 코일의 입력전선과 출력전선의 역학적 및 전기적 임피던스에 으히나 토크곡선의 왜곡을 방지할 수 있었고, 샘플막대의 관성모멘트를 줄일 수 있었다. 그 결과 토크에 대하 보다 민감하면서도 반응속도가 빠르며 토크곡선의 왜곡요인이 적은 토크마그네토미터를 제작할 수 있었다.

• 한국정밀공학회지
• /
• 제16권12호
• /
• pp.222-229
• /
• 1999

In order to regulate cutting torque in milling, monitoring system should be set to a certain threshold. Radial immersion ratio is an important factor to determine the threshold and should be estimated in process for automatic regulation. In this paper, on-line estimation of the radial immersion ration using spindle motor current in face milling is presented. When a tooth finishes sweeping, a sudden drop of cutting torque occurs. This torque drop is equal to cutting torque acting on a single tooth at the swept angle of cut and can be acquired form cutting torque signals. Average cutting torque per revolution can also be calculate form cutting torque signals. The ratio of cutting torque acting on a single tooth at the swept angle of cut to the average cutting torque per revolution is a function of the swept angle of cut and the number of teeth. Using the magnitude of this ratio, the radial immersion ratio is estimated. Identical algorithm is adopted to estimate the immersion ratio based on the spindle motor current measurement. The experiments performed under different cutting conditions show that the radial immersion ratio can be estimated within 10% error range by the proposed method using spindle motor current.