The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 25, 1987
Filed:
Apr. 12, 1985
Mark L Haddox, Ann Arbor, MI (US);
Jodon Engineering Associates, Inc., Ann Arbor, MI (US);
Abstract
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 TM.sub.01q 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.