INDIRECT METHOD OF TUNING OF STRAIN GAUGES WITH BRIDGE MEASUREMENT CIRCUIT BY MULTIPLICATIVE TEMPERATURE ERROR WITH ACCOUNT OF NEGATIVE NON-LINEARITY OF TEMPERATURE CHARACTERISTIC OF OUTPUT SIGNAL OF SENSOR Russian patent published in 2015 - IPC G01B7/16 

FIELD: measurement equipment.

SUBSTANCE: heat-dependent technological resistor R_αm is installed into a diagonal of bridge circuit power supply, the rating of which is higher than possible values of a compensating heat-dependent resistor R_α. In parallel to the resistor R_αm they install a link. They measure initial unbalance and output signal of the sensor under normal temperature t₀, and also temperature t⁺, corresponding to upper limit of working range of temperatures, and t^-, corresponding to lower limit of the working range of temperatures. On the basis of performed measurements they calculate temperature coefficient of frequency (TCF) of strain gauges of a bridge circuit $${\alpha }_{\partial \text{ meas}}^{+}$$ and $${\alpha }_{\partial \text{ meas}}^{-}$$ at temperatures t⁺ and t^-, accordingly, and also non-linearity of TCF of strain gauges of the bridge circuit $$\left(\Delta {\alpha }_{\partial \text{ meas}}={\alpha }_{\partial \text{ meas}}^{+}-{\alpha }_{\partial \text{ meas}}^{-}\right).$$ They measure input resistance of a sensor bridge circuit. A heat-independent resistor R_i=0.5·R_inp is connected. They measure initial unbalance and output signal of the sensor at temperatures t₀, t⁺ and t^-. On the basis of completed measurements they calculate TCF of input resistance at t⁺ and t^-. The resistor R_i is disconnected, and the link is removed off the resistor R_αm. They measure initial unbalance and output signal of the sensor at temperatures t₀, t⁺ and t^-. On the basis of completed measurements they calculate TCF of a process heat-dependent resistor R_αm at temperatures t⁺ and t^-. If TCF of strain gauges of the bridge circuit and its non-linearity belong to the area of method application, they calculate the rating of the heat-dependent resistor R_α heat-independent resistor R_∂ with usage of produced values of TCF of strain gauges of a bridge circuit, TCF of input resistance and TCF of the technological heat-dependent resistor. The technological heat-dependent resistor R_αm is replaced with a resistor R_α by means of partial engagement. A resistor R_α is shunted with a heat-independent resistor R_∂.

EFFECT: increased accuracy of compensation of multiplicative temperature error with account of negative non-linearity of temperature characteristic of an output signal of a sensor with usage of widely distributed measurement equipment.

2 cl