Self-Compensating Variable Resistance Displacement Measurement
Original Publication Date: 1988-Nov-01
Included in the Prior Art Database: 2005-Feb-15
The hardware and algorithm described present a technique for making displacement measurements with a variable resistance element which are independent of resistivity changes and the wiper resistance. This yields higher accuracy and permits looser tolerances on the components. A technique for the elimination of wiper resistance is explained in conjunction with the figure, where: Resistance from point 1 to the wiper = R1p, and Resistance from the wiper to point 2 = R2p. The resistance with relay 1 closed is equal to R2p plus the wiper resistance, Rw. The resistance with relay 2 closed and relay 1 open is equal to R1p plus the wiper resistance. The following equations result: 1) R1 = R2p + Rw = the resistance measured with relay 1 closed and relay 2 open.