高精度温度测量装置的设计--外文翻译及论大学生写作能力.docx

附录A Design of a High Precision Temperature Measurement System 1 Introduction Sensors are one of the most important elements used in many instrumentation circuits. They are used in many industrial applications and take a certain form of input (temperature, pressure, altitude, etc.) and convert it into readings that can be interpreted. Many types of sensors are nonlinear in nature from which a linear output is desired. There are many different sensors for temperature measurement and thermocouples are the most commonly used . They are preferred in industrial applications due to their low cost, wide operation range, fast response time and accurate when their peculiarities are understood. Thermocouples have also outputs nonlinearly related to temperature. Therefore, sensor modeling and linearization techniques are necessary. To solve the linearization problem of a sensor, there are generally two methods proposed. The first one requires nonlinear analog circuit and the second uses numerical methods that are computed by microprocessor or computer . Analog circuits are frequently used for improving the linearity of the sensor characteristics, which implies additional analog hardware and typical problems associated to analog circuits such as temperature drift, gain and offset error. Using the second method, sensor nonlinearities can be compensated by means of arithmetic operations, if an accurate sensor model is available (direct computation of the polynomials), or use of a multidimensional look-up table. Direct computation of the polynomial method is more accurate but takes a long time for computation, while the look-up table method, though faster, is not very accurate . In recent years, application of ANNs has emerged as a promising area of research in the field of instrumentation and measurement . It provides a neurocomputing approach for solving complex problems especially in nonlinear system modeling which the network itself is a nonlinear system. This is extre