Earticle

Practically, all properties of agricultural crops depend on moisture content. A new parallel plate capacitance sensor was built to relate the moisture content and dielectric properties of sugarcane stalks. The results revealed a relatively strong quadratic relationship between the moisture content on green weight basis of sugarcane material put through the plates of sensor and the measured voltage (mV) by capacitance sensor circuit output. The coefficient of determination (R2) was 0.91. Some other samples were used to test the results and there was a high correlation between calibrating and testing samples for the device and the coefficient of determination (R2) was found to be 0.95. More research is suggested for improving the electronic circuit and investigation about the sensor type is suggested.

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.

This paper involves the "on-line" measurement of burrs using a capacitance sensor. A non-contact capacitance gauging sensor is attached to an ultra precision milling machine which was used as a positioning system The setup is used to measure burr profiles along machined workpiece edges. Experimental procedures and results as well as the basic theoretical principles of the capacitance sensor and specifications of related equipment are presented. The proposed scheme is shown to be accurate easy to setup and with minor modifications readily applicable to automatic deburring processes.processes.

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.

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.

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.

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.

본 논문에서는 상호 유도 정전하 방식 ITO센서의 불량 여부를 판별하기 위해 ITO센서 내부의 전극막들이 이루고 있는 개별 노드에 대해 상호 유도 정전하 데이터를 이용하여 ITO센서의 정확한 분석과 검사가 가능한 방법을 제안한다. 모바일과 태블릿과 같은 소형 전자제품뿐만 아니라, 대형 전자제품에서도 입력 장치로 사용되는 상호 유도 정전하 방식 ITO센서의 구조적 특성을 분석하고 터치스크린 패널 IC를 이용해 ITO센서를 검사하기 위한 회로를 설계한다. 상호유도 정전하의 충전과 방전에 관련된 변수를 설정하고, ITO센서의 노드별 데이터를 통해 불량 발생 시 정확한 위치를 찾아 분석할 수 있도록 구현한다. 상호 유도 정전하 ITO센서의 1차 실험데이터를 통해 양품 유효 범위를 설정하고, 마지막으로 1차 실험을 통해 설정된 ITO센서 유효범위는 2차 실험을 통해 ITO센서의 노드별 측정 데이터를 이용하여 실험에 사용된 시료로 정확성과 효율성을 검증 한다.

In this paper, we propose the possible way of accurate analysis and examination of ITO sensor to discriminate whether mutual capacitance ITO sensor is defective by using mutual capacitance of data in each node which consists of electrodes inside of ITO sensor. We have analyzed the structure characteristic of mutual capacitance ITO sensor which is used as an input device for not only small size electronics like mobile phone and tablets but also big size electronics and designed the circuit to inspect ITO sensor using touch screen panel IC. Set a variable related with mutual capacitance of charge and discharge and Implement to find and analyze accurate position when defect is made through the data from each node of ITO sensor. First, we can set a yield effective range through the first experiment data of mutual capacitance ITO sensor and by using the data of each node of ITO sensor which is the result from the second experiment, we can verify accuracy and effectiveness of effective range from the first experiment as a sample which is used in this experiment.

광센서에 사용되는 TIA(트랜스임피던스 증폭기)는 포토다이오드의 기생 커패시터로 인해 안정성 문제, 대역폭 제한 등의 문제가 발생할 수 있다. 이 문제는 일반적으로 피드백 커패시터를 통하여 해결되며, 피드백 커패시턴스의 선택은 안정성에 결정적인 영향을 미친다. 기존에는 피드백 시스템 해석을 통하여 커패시턴스의 값을 결정하였는데, 이는 정확한 값을 결정하기 힘든 단점이 존재한다. 본 논문에서는 과도 응답 해석을 통한 정확한 피드백 커패시턴스 값의 결정 방법을 제시하며, 시뮬레이션을 통해 비교 검증하였다.

Transimpedance Amplifiers (TIAs) used in optical sensors can experience stability issues and bandwidth limitations due to the parasitic capacitance of photodiodes. These issues are typically resolved by incorporating a feedback capacitor, and the selection of this capacitor is crucial for stability. Traditionally, the value of the feedback capacitance has been determined through feedback system analysis, which has limitations in accurately determining the optimal value. This paper proposes a method for accurately determining the feedback capacitance value through transient response analysis and validates this approach through simulation comparisons.

작은 전하량 밖에 측정할 수 없는 MBL 전하 센서를 여러 번 사용하여 큰 전하량을 측정할 수 있는 방법에 대한 이해를 돕기 위하여 큰 원통형 용기에 담긴 물의 양을 작은 용기를 여러 번 사용하여 측정할 수 있다는 비유를 개발하였다. 용기에 담긴 물의 양은 축전기에 저장된 전하량에, 용기에 담긴 수면의 높이는 전압에 비유하였다. 큰 용기에 연결되는 작은 용기는, 큰 전기용량의 축전기에 연결되는 MBL 측정 장치 내부의 작은 전기용량의 축전기와 같은 역할을 한다. 다중 측정을 통한 수량(水量)의 측정은 작은 용기를 연결하였을 때 작은 용기로 넘어온 물의 높이는 큰 용기의 수면의 높이와 같아질 때까지 옮겨 온다는 점에 착안하였다. 이 논문에 사용된 물 비유를 활용하면, 학생들에게 전기용량과 전하량과 같은 추상적인 개념을 형성시키는데 도움을 줄 수 있을 것으로 생각된다.

We have developed analogy between multiple uses of thin cylindrical tank for measuring the quantity of water in a large tank and multiple uses of MBL charge sensor for measuring charge in a large capacitor. The cross-section area of the large cylindrical tank can be determined by measuring many times water level of small cylindrical tank with a known cross-section area. The water quantity and the water level height in the tank is corresponding to quantity of charge and voltage of the capacitor, respectively. The thin tank connected to large tank plays a role of the small capacitor inside a MBL charge sensor, which is connected to the large capacitor. The measurement of water by multiple measurements is based on the principle that the water in the large tank is transferred until the water level of both tanks connected to each other is equal. Abstract concepts like capacitance and charge will be likely to be made sense, if the water analogy proposed in this article is utilized.