工業(yè)測量中的精度挑戰(zhàn)

　　骯臟、嘈雜、雜亂的工業(yè)工廠環(huán)境似乎是人們期望找到高科技的最后地方。平凡的功能，如壓力、溫度、流量和在現(xiàn)代工廠的環(huán)境包括水、石油、油漆、果汁、面包面團(tuán)中材料的無限多樣，或鋼鐵需求不斷增加為了更準(zhǔn)確改善成本和效率的要求在一個(gè)非常具有挑戰(zhàn)性的環(huán)境–測量準(zhǔn)確度驚人的水平，并減少對環(huán)境的影響。

　　首先，考慮到許多傳感器技術(shù)由于其自身的物理特性和由于周圍環(huán)境的影響而導(dǎo)致的整體測量精度不到0.1%。熱電偶傳感器非線性負(fù)載細(xì)胞蠕變，應(yīng)變計(jì)的零點(diǎn)漂移，和其他誤差源都總計(jì)達(dá)降解在偏移的測量對。

　　同時(shí)，觀察到大多數(shù)流行的傳感器技術(shù)提供了在輸出電壓輸出（只有分?jǐn)?shù)在10 V或更少的勵(lì)磁電壓熱電偶或應(yīng)變計(jì)的MV，和數(shù)萬）體積?。憫?yīng)時(shí)間快，體積小，和最小的對被測介質(zhì)的影響）在非常高的阻抗結(jié)果（零電流），或高靈敏度由于偏置電流通過傳感器誤差補(bǔ)償。

　　Finally， observe that in most cases the physical arrangement of the process itself imposes numerous challenges， including long cable lengths which incur electrical interference， difficult packaging due to the environment involved， and of course the aforementioned dirty， noisy mess of a factory floor filled with motors， solenoids， contactors， AC heaters， and so on.

　　If we desire to preserve the accuracy of our sensor in this environment， we must take into account the influence of a wide variety of error-producing factors. They include the operating temperature range， which is in the range of 100°C and， therefore， requires careful temperature compensation. Offset errors， due to bias currents causing voltage drops across connectors and long lead lengths （including thermoelectric effects at bimetal interfaces） and induced noise is addressed by utilizing techniques such as two-wire， differential sensing， and ratiometric circuit configurations which take advantage of the CMRR （Common-Mode error Rejection Ratio） of a carefully-designed measurement circuit. Supply variations must also be considered， demanding a circuit designed to provide a high PSRR （Power Supply error Rejection Ratio）.