Research on the Application of Polynomial Direct Fitting to Platinum High-precision Temperature Measurement
WU Zhi-xian · Automation and Instrumentation · 2014
Although many methods can be used to conduct platinum resistor non-linear rectification,they can not be put into wide use because of shortcomings such as narrow temperature range and complicated calculation of rectification. This paper conducts fitting algorism based on three temperature ranges of platinum resistor within temperature range and obtains cubic and quartic polynomial coefficients via the method of adjusting weight function using least square method after a brief summary of the regular method and problems existing in platinum resistor non-linear function inversion calculation. Meanwhile,fitting algorism error distribution graph was also demonstrated. The maximum error was only ±0.003 ℃ when applying quartic multinomial fitting algorism within the range of 0~650 ℃. Finally,the advantages of multinomial direct fitting was further testified an analysis of C language calculation precision and data instances.