Sumitesh Majumder1， T K Maiti2
（1. Dept. of Applied Electronics and Instrumentation Engineering, Netaji Subhash Engineering College, Kolkata 700152, India；2. Dept. of Instrumentation Engineering, Central Institute of Technology Kokrajhar, Assam 783370, India）
Abstract： In this research paper, we have presented variable area type capacitive sensor signal conditioning system for angular displacement measurement and for this purpose we have used timer LM555 based astable multivibrator and universal frequency to digital converter (UFDC). Due to variation in angular displacement in the variable area type capacitor which is connected in the timer based astable circuit, capacitance changes which in turn changes the time period of the timer circuit output. The time period of the timer output waveform is linear with the capacitance and hence linear with angular displacement. The timer output is further processed with UFDC for the measurement. The experimental results show that the time period is linear with the angular displacement in the range of 0- 180° and the uncertainty we should associate it with this average time period value is the standard deviation of the mean, often called the standard error (SE), which is ± 0.023 μs. Because of the simplicity, this measurement system can be used in both electronic and industrial instrumentation.
Key words： variable area type capacitive sensor; timer circuit; sensor interfacing; astable multivibrator; universal frequency to digital converter (UFDC)
CLD number： TP761 Document code： A
Article ID： 1674-8042（2019）01-0049-06 doi： 10.3969/j.issn.1674-8042.2019.01.007
References
［1］ Pallas-Areny R，Webster J G. Sensor and signal conditioning, 2nd edtion. John Wiley & Sons, USA, 2000.
［2］ Doeblin E O, Manik D N. Measurement Systems-Application and Design, 5th edtion. Tata-McGraw Hill , New Delhi, 2007.
［3］ Patranabis D. Principles of industrial Instrumentation, 2nd edtion. Tata-McGraw Hill, New Delhi, 2008.
［4］ Ferrari V, Ghisla A, Marioli D, et al. Capacitive angular-position sensor with electrically floating conductive rotor and measurement redundancy, IEEE Transactions on Instrumentation & Measurement, 2006, 55(2): 514-520.
［5］ Sauter T, Nachtnebel H, Kero N. A smart capacitive angle sensor, IEEE Transactions on Industrial Informatics, 2005, 1(4): 250-258.
［6］ Gasulla M, Li X J, Meijer G C M, et al. A contact less capacitive angular-position sensor. IEEE Sensors Journal, 2003, 3(5): 607- 614.
［7］ Brasseur G, Fulmek P L, Smetna W. Virtual rotor grounding of capacitive angular position sensors. IEEE Transactions on Instrumentation & Measurement, 2000, 49(5): 1108-1111.
［8］ Massa D P. Choosing an ultrasonic sensor for proximity or distance measurement, part 1: acoustic considerations. Sensors, 1999, 6(2): 34-37.
［9］ Massa D P. Choosing an ultrasonic sensor for proximity or distance measurement, part 2: optimizing sensor selection. Sensors, 1999, 6(3): 28-42.
［10］ Brasseur G. A capacitive 4 turn angular position sensor. IEEE Transactions on Instrumentation & Measurement, 1998, 47(1): 275-279.
［11］ Bramanti M. A high sensitivity measuring technique for capacitive sensor transducer. IEEE Transactions on Industrial Electronics, 1990, 37(6): 584-586.
［12］ Coughlin R F, Driscol F F. Operational amplifiers and linear integrated circuit, 6th edtion, PHI, New Delhi, 2012.
［13］ Stanley W D. Operational amplifiers with linear integrated circuit, 6th edtion. Pearson, USA, 2012.
［14］ Universal frequency-to-digital converters UFDC-1 and UFDC-1M-16 . ［2018-05-07］. http:∥www.sensorsportal.com/HTML/E-SHOP/PRODUCTS_4/UFDC_1.htm.
［15］ International Frequency Sensor Association. Universal frequency-to-digital converters (UFDC-1) specification and application note. ［2018-05-07］. http:∥www.sensorsportal.com/DOWNLOADS/UFDC_1.pdf.
［16］ Yurish S Y. Digital sensors design based on universal frequency sensors interfacing IC. Sensors and Actuators A: Physical, 2006, 132(1): 265-270.
［17］ Ghosh A K. Introduction to measurements and Instrumentation, 3rd edtion. PHI, New Delhi, 2010.
信号调制系统实现角位移测量
Sumitesh Majumder1， T K Maiti2
（1. 内达斯·苏巴斯工程学院 应用电子与仪器工程系， 加尔各答 700152, 印度；2. 科克拉贾尔中央理工学院 仪器工程系， 阿萨姆 783370, 印度）
摘 要: 采用基于定时器LM555的非稳态多谐振荡器和通用频数转换设计了一种变面积式电容传感器信号调制系统用于角位移测量。 变面积式电容器连接在基于定时器的非稳态电路内， 其角位移的变化引起电容的变化， 进而引起定时器电路输出时间周期的变化。 定时器电路输出波形的时间周期与电容呈线性关系， 因而与角位移也是线性关系。定时器输出经通用频数转换器进一步处理后可用于测量。实验结果显示， 时间周期与角位移在 0-180° 范围内呈线性关系， 将不确定度与平均时间周期相关联， 即为平均标准差， 亦称为标准误差， 其值为 ± 0.023 μs。该测量系统使用简单， 可用于电子和工业仪器中。
关键词: 变面积式电容传感器； 定时器电路； 传感器连接； 非稳态多谐振荡器； 通用频数转换器
引用格式： Sumitesh Majumder, T K Maiti. Development of capacitive sensor signal conditioning system for angular displacement measurement using timr IC LM555 and UFDC. Journal of Measurement Science and Instrumentation, 2019, 10(1)： 49-54. ［doi： 10.3969／j.issn.1674-8042.2019.01.007］
[full text view]
