Analysis of the interpolation parameters to estimate the errors at specific force values in continuous calibration

The Euramet project 18SIB08 “ComTraForce” developed research to improve the continuous calibration procedures intended to be added to the under review standards that traditionally deals with static force calibration, such as ISO 376 and ISO 7500-1. Among these procedures is the description of a method for the adequate synchronous correlation between the force signals of the reference and the device under test to estimate the indication error for a specific force target value. This method describes the necessity to carry out a double interpolation sequence, using linear least squares adjustments. This paper presents a study on the impact of selecting different ranges of points on the estimation of the interpolation coefficients and the consequent impact on the calculation of the indication errors. The statistical parameters of these curves are also discussed. Experimental data was obtained from measurement series with different force rates carried out in an assembly with a testing machine and a reference sensor.