A computer program processes signal data in the instrument described in “Current- Signature Sensor for Diagnosing Solenoid Valves” (KSC-12152), NASA Tech Briefs, Vol. 25, No. 9 (September 2001), page 30. Ten-bit samples of the electric current in a solenoid valve are acquired at a rate of 10 kHz and fed to a digital signal processor that executes the present software, which performs buffering, filtering, identification of features, and general assessment of the “health” of the valve. The identified signal features include the time of beginning of a transition, the time of maximum change in current, the time when the poppet begins to move, the amplitude of the current needed to initiate movement, the time of travel of the poppet to final seating, the time when the current reaches the steady state, the amplitude of the steady-state current, the minimum current needed to hold the poppet against unseating, and the time required for the poppet to unseat. The software can generate indications of impediment or jamming of the poppet; burnt or short-circuited solenoid windings; buildup of friction; faulty valve spring; incorrect operating voltage, temperature, or pressure; bounce during seating of the poppet; and failure of anti-arcing circuitry.
This program was written by Bradley M. Burns of Dynacs, Inc., for Kennedy Space Center.