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A microwave method and apparatus for detecting the position of a piston of a pneumatic cylinder. While the piston is being moved by fluid pressure a microwave signal is applied to a cavity defined by the piston and interior of the cylinder and the reflected microwave signal is detected. The reflecte

A microwave method and apparatus for detecting the position of a piston of a pneumatic cylinder. While the piston is being moved by fluid pressure a microwave signal is applied to a cavity defined by the piston and interior of the cylinder and the reflected microwave signal is detected. The reflected microwave signal is processed to determine piston position.

대표청구항 ▼

A method of determining the position of a piston movable in a cylinder of a hydraulic actuator, the steps comprising, applying a microwave signal to a cavity defined by the piston and the interior of said cylinder and detecting a reflected microwave signal while the piston is being moved in the cyli

A method of determining the position of a piston movable in a cylinder of a hydraulic actuator, the steps comprising, applying a microwave signal to a cavity defined by the piston and the interior of said cylinder and detecting a reflected microwave signal while the piston is being moved in the cylinder by the application of fluid pressure to the cylinder, repeatedly varying the frequency of the microwave signal applied to the cavity between two values that are of such a magnitude that the reflected microwave signal has one or more resonant amplitude variations the number of which are a function of the position of the piston relative to an end of said cylinder, developing data from said reflected microwave signal that is indicative of the number of resonant amplitude variations that occur and the frequency of the microwave signal applied to the cavity at the time at least one of said resonant amplitude variations occurred and converting said data to piston position information.