Apparatus and method for determining the linear position of a hydraulic cylinder

Reference Number: N 01-03

Inventors: Allen, William E.; Bitar, Ali A.; Herold, Robert A.

Owner: NISTAC

USPTO Link: 5471147

Invention Summary

In one aspect of the present invention, an apparatus for detecting a linear position of a piston and a piston rod is provided. The piston and piston rod are movable within a housing and form first and second coaxial resonant cavities. The apparatus includes RF sections for determining the resonant frequencies of the cavities and a sensor controller for determining the position of the piston and piston rod.

In another aspect of the invention, a method for detecting a linear position of a piston and a piston rod is provided. The piston and piston rod are movable within a housing and define first and second coaxial resonant cavities. The method includes the steps of determining the resonant frequency of one of the cavities and responsively determining a first location of the piston. If the first location is invalid then the resonant frequency of the other cavity is determined and a second location is responsively determined.