Abstract: A method and apparatus are described for using a computer to compensate for zero point and span errors as well as other non-linearities in the operation of strain gauge transducers. The apparatus comprises a semiconductor strain gauge transducer with a quasi stable voltage supply, two strain gauges and two precision resistors which form a voltage divider network; a scanner for scanning the strain gauges and precision resistors; an analog-to-digital converter for digitizing the output of the scanner; and a microprocessor for calculating a corrected output representing the phenomenon that is monitored by the strain gauge transducer. The microcomputer contains a memory in which are stored a set of bridge completion constants, a table of correction constants and a set of temperature compensation and signal conditioning algorithms.

Abstract: The voltage drops across a series-connected pair of strain gauges and arbitrary resistance are measured at zero and maximum stresses at three temperatures. The appropriate resistance for span compensation at the two extreme temperatures is then calculated from these values. The span compensation resistance is then distributed between a first resistor connected in series with one of the strain gauges and a second resistor connected in series with the other strain gauge. Initially, the first resistor is assigned a value of one ohm and the second resistor the remainder. With these values the series/parallel resistances required for temperature compensation at zero stress are calculated for the two extreme temperatures. The outputs at zero stress are then calculated for both the maximum temperature and the intermediate temperature and the difference between these outputs is obtained.