Research on the Application of Polynomial Direct Fitting to Platinum High-precision Temperature Measurement

Abstract

Although many methods can be used to conduct platinum resistor non-linear rectification, they cannot be put into wide use because of shortcomings such as narrow temperature range and complicated calculation of rectification. This article 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 distributiongraph is also demonstrated. The maximum error is only ±0. 003°C when applying quartic multinomial fittingalgorism within the range of 0-650°C. Finally, the advantages of multinomial direct fitting is further testified ananalysis of C language calculation precision and data instances.