Linear position sensor using a coaxial resonant cavity
Reference Number: N 01-03
Inventors: Bitar, Ali A.; Bowman, Charles W.; Morgan, Denny E.
Owner: NISTAC
USPTO Link:5491422
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 define a variable length coaxial resonant cavity. A transmitting section
produces an electromagnetic signal and delivers the electromagnetic signal into the
resonant cavity. The electromagnetic signal has a frequency which varies between predetermined
minimum and maximum values. A receiving section senses an electromagnetic wave signal
within the coaxial cavity and detects a slope intercept condition of the electromagnetic
wave signal. A sensor controller determines the position of the piston and piston
rod as a function of the slope intercept condition.
In another aspect of the present 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 a variable length coaxial resonant cavity. The method includes
the steps of delivering an electromagnetic signal into the coaxial resonant cavity,
receiving electromagnetic wave signals from said coaxial resonant cavity, detecting
a slope intercept condition and responsively determining the position of the piston
and piston rod.