High-Precision Strain Measurement Bridge Circuit With On-line Compensation for Parasitic Capacitance Effects

This paper describes a high-precision strain measurement system using modern ADC and digital technology to provide real-time compensation for parasitic capacitance effects. In recent applications, strain gauges used for strain measurement often have to be located far from strain measuring instruments, requiring long connecting cables with associated parasitic capacitance; in such cases the parasitic capacitance degrades measurement accuracy significantly, and parasitic capacitance variation can cause measurement drift. The proposed algorithm can reliably and accurately compensate for parasitic capacitance in the digital domain both for one-gauge and two-gauge systems. We have demonstrated its effectiveness by simulation and experiments using field data.