Detection of a plunger position in an irrigation control device

摘要

Some embodiments provide irrigation valve control apparatuses comprising: a solenoid configured to cooperate with a plunger; an input stimulus source coupled with the solenoid and configured to apply an input stimulus while a plunger drive signal is not being applied and that is sufficiently small to not cause the plunger to move; sampling circuitry configured to measure one or more voltage measurements corresponding to one or more voltages across the solenoid, wherein the one or more voltage measurements are dependent upon the current position of the plunger relative to the solenoid; and control circuitry cooperated with the sampling circuitry to receive the one or more voltage measurements from the sampling circuitry, wherein the control circuitry is configured to determine whether the plunger is in one of the open and closed positions based on the one or more voltage measurements.

主权项

1. An irrigation valve control apparatus comprising:
a solenoid configured to cooperate with a plunger and to receive a plunger drive signal from plunger activation circuitry, wherein the plunger drive signal is configured to induce a magnetic field relative to the solenoid that causes the plunger to change positions between open and closed positions; an input stimulus source coupled with the solenoid and configured to apply an input stimulus into the solenoid at a time while the plunger drive signal is not being applied to the solenoid, wherein the input stimulus is sufficiently small that the input stimulus applied to the solenoid does not cause the plunger to move from a current position, and wherein the input stimulus comprises multiple input stimulus signals having different resonant frequencies that are sequentially applied into the solenoid; sampling circuitry configured to measure one or more voltage measurements corresponding to one or more voltages across the solenoid, wherein the one or more voltage measurements are dependent upon the current position of the plunger relative to the solenoid in response to applying the input stimulus to the solenoid; and control circuitry cooperated with the sampling circuitry to receive the one or more voltage measurements from the sampling circuitry, wherein the control circuitry is configured to determine whether the plunger is in one of the open and closed positions based on the one or more voltage measurements.