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A system and method for monitoring position of a piston within a fluid-actuated cylinder by radiating microwave energy into the actuator cylinder and measuring axial position of the piston as a function of microwave resonances and the frequencies at which such resonances occur. Separate microwave tr

A system and method for monitoring position of a piston within a fluid-actuated cylinder by radiating microwave energy into the actuator cylinder and measuring axial position of the piston as a function of microwave resonances and the frequencies at which such resonances occur. Separate microwave transmitting and receiving antenna probes are mounted on one end cap of the actuator cylinder, which has a fixed diameter and an axial dimension which varies as a function of piston position. The transmitting probe is coupled to an oscillator which is controlled to sweep a predetermined frequency range for generating one or more TM01q resonant modes within the cylinder cavity. A threshold detector and a peak detector are coupled to the receiving probe for detecting occurrence of cavity resonances. Latches store oscillator control signals associated with occurrence of up to eight such resonance events, with the stored control signals thus being an indication of resonant frequencies. A microprocessor is programmed to determine cavity length and piston position as a combined function of such resonant frequencies and the corresponding orders q of each frequency.

대표청구항 ▼

Apparatus for monitoring position of a piston within a cylinder comprising means for generating microwave radiation over a preselected swept frequency range, antenna means coupled to said generating means and positioned in said cylinder to inject said microwave energy into said cylinder such that re

Apparatus for monitoring position of a piston within a cylinder comprising means for generating microwave radiation over a preselected swept frequency range, antenna means coupled to said generating means and positioned in said cylinder to inject said microwave energy into said cylinder such that resonances of differing axial order and constant radial and circumferential orders of a single normal cylindrical mode of microwave propagation are developed within said cylinder as said generating means sweeps said frequency range, occurence-detecting means coupled to said antenna means for detecting occurrence of said resonances, and position-determining means responsive to said detecting means and to said generating means for determining position of said piston within said cylinder as a function of frequency of said microwave signal at which said resonances occur, characterized in that said position-determining means comprises means for identifying axial order of one said resonance, means coupled to said generating means for identifying microwave frequency associated with said one resonance, and means for determinig position of said piston within said cylinder as a combined function of said axial order and said frequency of said one resonance.