Earticle

This paper presents the development of a collocated capacitance sensor and its application to the controller design for magnetic bearing supported rotor systems. The main feature of the sensor is that it is made of a compact printed circuit board(PCB) so that it can be built into the actuator coil of the magnetic bearing unit. The singnal processing unit hax been also developed. The experi- mental results of the sensor performance evaluation on sensitivity, bandwidth and resolution are presented. Then, simulation study shows the advantages of the collocated sensor for magnetic bearings over the nonco- llocated sensor. Finally, the experimental result on the performance of the collocated sensor based contrl- ler for a magnetic bearing rotor system is presented.

본 논문에서는 적외선 센서, 레이저 센서, 초음파 센서, 정전용량 센서로 실험을 통해 수위의 변화를 선형적으로 감지할 수 있는 수위센서를 이용한 액적 토출 시스템을 연구하였다. 전원 공급으로 SMPS, 레귤레이터 5V, LDO 3.3V를 설계하였으며 수위 센서 입력부 ADC 회로와 마이크로프로세서를 이용하였다. 또한 솔레노이트 밸브 제어, 양압/음압 발생을 위한 펌프 출력 제어부와 산업용 통신을 위한 CAN 통신, 이터넷 통신, UART 통신, USB를 사용하였다. 수위의 변화를 통해 압력의 변화를 확인하였으며, 압력의 변화를 최소화하여 액적 토출을 위한 시스템을 구현하였다.

In this paper, This paper is a liquid droplet discharge system using a water level sensor that can linearly detect changes in water level through experiments with an infrared sensor, a laser sensor, an ultrasonic sensor, and a capacitance sensor. SMPS, regulator 5V, and LDO 3.3V were designed for power supply. A water level sensor input ADC circuit and microprocessor were used. Solenoid valve control, pump output control unit for positive/negative pressure generation, CAN, Ethernet, UART communication, and USB for industrial communication were used. The change in pressure was confirmed through the change in water level, the change in pressure was minimized, and a system for discharging liquid droplets was implemented.

In this paper we focused on mathematical formulation for capacitive pressure sensor. The most important parameter of every sensor are deflection on the application of applied pressure, variation of capacitance on deflection and sensitivity. Here we mathematically drive equation for every parameter. This article help researcher to develop MEMS based capacitive pressure sensor for particular application. For that purpose we also vary the thickness of sensing diaphragm. Our study in this article is mainly consider only case of pressure sensor in normal mode. Mostly researcher use FEM method for design and simulation of capacitive pressure sensor but using these equation they can easily design any sensor by changing the parameter of equation. The material for diaphragm is Si and for insulation layer is SiO₂ is taken in this article.

Sensitivity field distribution of the sensor in ECT system is affected by the distribution of the mixture, The "soft field" property of sensitive field bring great difficulty in image reconstruction, on the basis of analyzing capacitance tomography sensitive mechanism, by analyzing that sensor structure parameters in ECT system have influence on the uniformity of the sensitive field, this paper proposed a structural parameters optimization algorithm based on the ant colony algorithm. The algorithm first determines the parameter optimization design evaluation function, and then rapidly identifies several suboptimal paths by using particle swarm optimization and initializes the pheromones in the path, Ant colony algorithm finds the optimal solution according to the initialization pheromones and using the characteristics of rapid convergence. The experimental results show that, compared with the orthogonal algorithm, the performance of the sensor designed by using the structure parameters obtained by ant colony optimization algorithm is obviously improved, Alleviate the difficulty of data acquisition circuit design and improve the accuracy and uniformity of the sensitive field, the quality of image reconstruction is improved, the relative error of image reconstruction is reduced.

One of major errors in flow rate measurement for two-phase flow using an Electrical Capacitance Sensor (ECS) concerns sensor sensitivity under temperature raise. The thermal effect on electrical capacitance sensor (ECS) system for air-water two-phase flow monitoring include sensor sensitivity, capacitance measurements, capacitance change and node potential distribution is reported in this paper. The rules of 12-electrode sensor parameters such as capacitance, capacitance change, and change rate of capacitance and sensitivity map the basis of Air-water two-phase flow permittivity distribution and temperature raise are discussed by ANSYS and MATLAB, which are combined to simulate sensor characteristic. The cross-sectional void fraction as a function of temperature is determined from the scripting capabilities in ANSYS simulation. The results show that the temperature raise had a detrimental effect on the electrodes sensitivity and sensitive domain of electrodes. The FE results are in excellent agreement with an experimental result available in the literature, thus validating the accuracy and reliability of the proposed flow rate measurement system.

최근 편리함과 측정의 정확성으로 인해 Capacitance sensor가 토양수분 연구나 물관리에 국제적으로도 널리 이용되고 있다. 이 연구는 Capacitance sensor (EnviroSCAN, Sentek Ltd.)가 화산회토양이 많이 분포하는 제주도 지역에서도 활용성이 있는 지를 알아보기 위해 유기물함량이 다른 제주도의 대표적인 토양 종류를 이용하여 Calibration 시험을 수행하였다. 시험 결과 화산회토양에서는 비화산회토양과 달리 센서의 Scaled frequency와 토양의 용적수분함량 간에 Calibration식이 로그식 형태로 나타내는 것이 일반적으로 적용되는 지수식 형태로 나타내는 것보다 상관이 더 높게 나타났다. 또한 화산회토양이 많이 분포하는 지역에 서는 토양수분함량이 높아 습하거나 매우 적어 건조할 경우에는 Capacitance sensor에 의한 수분함량 측정값이 건조기를 이용한 수분함량 값보다 과소하게 측정될 수 있었다. Capacitance sensor를 이용하여 화산회토양에서 토양 수분함량을 정확하게 측정하기 위해서 Calibration식에 적용될 수 있는 현실적인 계수값을 제시하였다. 또 현재 이용되는 EnviroSCAN capacitance probes의 활용성을 제고하기 위해서 계수값을 유기물함량별로 추정하는 식을 제시 하였다. Capacitance sensor를 이용하여 토양수분함량을 정확하게 측정하기 위해서는 사전에 토양의 공극분포, 유기물함량, EC 등 측정여건을 파악하여 조절하는 것이 필요하였다.

Capacitance soil moisture sensor is extensively used by soil research and irrigation management with its convenience and accuracy. This experiment was conducted to evaluate the acceptability of capacitance soil moisture sensor, named EnviroSCAN made by Sentek Ltd., in Jeju Island where volcanic ash soils are widely distributed, and to calibrate it to various soils with different amount of soil organic matter. For sensor calibration equation of volcanic ash soils, a logarithm function is better than a typical power function of non-volcanic ash soils. So there are possibilities of under evaluated in soil water contents in very wet and very dry conditions by using typical power function with volcanic ash soil areas. We suggested practical coefficients of typical calibration equation for using capacitance sensor in volcanic ash soils, also suggested equations for estimation of them with soil organic matter contents. The measurement of soil water content with a capacitance sensor can be affected by some soil characteristics such as porosity, soil organic matter content, EC, etc. So those factors should be controlled for improving the accuracy of measurement.

We designed capacitance sensor in order to examine characteristics of W/O type emulsified fuel, so it concluded the following conclusions. The capacitance value of emulsified fuel, using with capacitance sensor, increases as water content increases due to the coalescence. When surfactant increases, the capacitance value decreases, the condition of W/O type emulsified fuel was maintained stably. There was revealed the capacitance value difference of W/O type emulsified fuel in in according to water content. We checked the phase separation of emulsified fuel with the capacitance value difference. The surfactant(HLB=5.4) had better stable condition than surfactant(HLB=4.3). Also, we confirmed that two mixture surfactants were better than one surfactant.

In this study, a method of using a capacitance sensor was investigated as a means to measure the mass fraction of a type of harmful substance. Using MEMS process, we developed a capacitance sensor and studied the real time mass fraction with harmful substance mixture liquid.

We designed capacitance sensor for measuring capactance of W/O type emulsified fuel. Capacitance sensor consists of two conductors isolated by an insulator. The characteristics nature of a capacitance sensor is its ability to accept and store an electric charge. From using this concept, we carried out With manufacturing of capacitance sensor, the test results for validity of sensor and stability of 6 emulsified fuel conclude the followings. The result of capacitance measurement fur 6 test fuels indicates design error range is within 4% max, so this fact proves the validity of capacitance sensor. Capacitance value of 6 emulsified fuel, with the aid of capacitance sensor, increases as water volume increases, but it decreases as surfactant increases when water is given equally. As a result, cylindrical type capacitance sensor proves validity of sensor and emulsified fuel which produce seperation ratio proves the stability of capacitance value

근래의 코로나 시대로 인해 접촉에 의한 감염을 방지하기 위해 다양한 방법들을 강구하고 있다. 그중 생활 속에서 많은 접촉이 일어나고 있는 엘리베이터에서의 감염 방지를 위해 비접촉 버튼을 개발하였다. 본 연구에서는 능동 차폐(active shield) 방식의 정전용량(capacitance) 센서를 이용하여 손가락이 접근했을 때의 커패시턴스 변화를 감지한다. 정전 전력 소모(static power consumption)가 없으며, 아날로그 멀티플렉서를 사용하여 일정 시간마다 돌아가면서 버튼을 센싱 하는 방식을 사용하여 상대적으로 가격이 비싼 센서칩을 하나만 사용하였다. 엘리베이터 버튼뿐만 아니라 터치 버튼, 자동문 등 일상에서 많은 사람들이 접촉하는 버튼을 높은 비용 추가 없이 대체 가능하다.

Due to the recent COVID-19 pandemic, various methods have been devised to prevent infections caused by physical contact. Among them, a non-contact button was developed to prevent infections in elevators, where many contacts occur in daily life. In this study, an active shield type capacitance sensor is used to detect changes in capacitance when a finger approaches. There is no static power consumption, and the relatively expensive ADC and MCU are reduced to one by sensing buttons every time using analog switches. In addition to the elevator buttons, this technology is expected to replace push-type buttons that many people contact in everyday life.

This paper analysised Oil-Mist-Detector applied Capacitance Sensor which protects Diesel engine & human from explosion by detecting density of oil mist distribution. Assuming that distance between oil mists is same, Capacitance sensor plates & all oil mists could be analogized to capacitors. From equivalent circuit of Oil-Mist-Detector, variation of Capacitance which is related to Oil Mist's diameter & density of oil mist distribution is obtainable.

The design and performance verification of collocated capacitance sensor system for magnetic bearing is presented. Noncollocation between actuators and sensors may cause unstable rotor behavior. The capacitance sensor is not affected by magnetic field. PCB type capacitance sensor is installed between magnetic bearing polse. so, collocation of sensors and actuators can be achieved. Experiment of sensor's static and dynamic charactistics is conducted. Modeling of the rotor system supported by magnetic bearing is made. And performance comparison between simulation and experiment is showed.

This paper presents the development of a collocated capacitance sensor and its application to the decentralized PID controller design for 4-axis magnetic bearing system. The main feature of the sensor is that it is made of a compact printed circuit board (PCB) so that it can be built in to the actuator coil of the magnetic bearing unit. The signal processing unit has been also developed. Then, decentralized PED controller is designed using simplified rotor system model. Finally, the experimental results on the performance of the collocated sensor based decentralized PID controller for a magnetic bearing rotor system is presented.

We estimated on the stability of W/O type emulsified fuel using by capacitance sensor, so it concluded the following conclusions. For the first 24 hours, prepared emulsified fuel reveals phase separation ratio of 5%, maintains stable status which verifies the stability of emulsified fuel. Adding more water increases the phase separation ratio rapidly, and adding more surfactant displays stable emulsification. Adding water causes larger size of water droplet diameter, and adding surfactant mixture causes smaller size of water droplet diameter. In conclusion, the size of W/O type emulsified fuel water droplet diameter is directly related to the volume of surfactant, and density of water droplet diameter changes thedistribution according to water contents.

금속 평행판 전극 사이에 주입된 액체 유전체의 움직임에 의해서 발생되는 차동 전기용량 변화를 이용하여 기울기 측정센서를 개발하였다. 기울기 $0^{\circ}{\sim}{\pm}90^{\circ}$의 범위에서 직선에 대한 상관계수가 0.999 99로 분석이 되어 우수한 선형성을 보였다. 센서의 전극구조를 완벽한 3-전극형 전기용량기로 설계하였기 때문에 외부로부터의 전자기 잡음 및 전기장의 영향에 관계없이 기울기를 정밀하게 측정할 수 있었다. 또한 안정된 디지털 출력을 이용하여 기울기의 정밀측정 뿐만 아니라 장치나 구조물 등의 기울기를 원격조정 또는 monitoring에도 적용이 가능하다.

This paper discusses several design factors of a capacitance displacement sensor with a numerical method and several experiments and describes guide lines of the design of this type sensor. We introduce the charge density method for the analysis of this type sensor, which has feasible accuracy and efficiency. The analysis of this type sensor with the charge density method agrees with displacement sensitivity experiments of a circular plate capacitance sensor with the sensor amp based In the charge transfer principle.

In this paper, an actively controlled aerostatic bearing is studied to overcome the defects of air bearing such as low stiffness and damping coefficients. The actively controlled aerostatic bearing is composed of aerostatic bearings, non-contact type of displacement sensors, piezoelectric actuators and controllers. The cylindrical capacitance sensor (CCS) is used as the displacement sensor. The reason for using CCS instead of the commercial gap sensor is that it can give us the pure error motion of the spindle because it removes the roundness error or the geometric errors in the spindle. The controller is designed by the state space equation and quadratic optimal control theory. The characteristic data of the actively controlled aerostatic bearing system in the frequency domain are presented and the stiffness and damping coefficients of the bearing are mentioned. This paper shows the possibility to reduce the motion error up to 6000 rpm.