Institute of Natural and Technical Systems, RF, Sevastopol, Lenin St., 28
It is shown that the use of bridge circuits for switching on strain gauge sensors in traditional hydrostatic pressure meters significantly increases the total nonlinearity error. To reduce it, within the framework of the principle of constructing invariant systems, it is proposed to use several separate strain gauge sensors, having different conversion functions, approximated by the product of polynomials of degree m for pressure and degree n for temperature, the formation of a system of linear algebraic equations from the transformation functions and relative changes in the resistance of strain gauge sensors.
Methods for identifying the parameters of the transformation functions of strain gauges by pressure calibration at a given initial temperature and by temperature calibration at a given initial pressure are considered. Further use of different transformation functions in the system of equations guarantees its unique solution.
It is possible to calibrate the entire meter according to the specified reference pressures with the determination of coefficients for the measured relative changes in the resistance of strain gauges.
The measured pressure is determined by solving this system of equations with respect to one unknown – pressure. It is not necessary to measure the temperature of the strain gauges.
The proposed method is implemented by a multichannel device for interrogating strain gauges by a direct current or alternating current generator with an output voltage proportional to the relative change in the resistance of strain gauges, constituting a column of free terms in the formed system of linear algebraic equations.
Keywords: pressure, strain gauge, conversion functions.
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