| 摘要 |
PCT No. PCT/US91/07313 Sec. 371 Date Oct. 3, 1991 Sec. 102(e) Date Oct. 3, 1991 PCT Filed Oct. 3, 1991 PCT Pub. No. WO93/07444 PCT Pub. Date Apr. 15, 1993.An apparatus (102) and method for detecting the position of a piston and piston rod (104,106) within a housing (108) of a hydraulic cylinder (110). The piston (104), piston rod (106), and housing (108) form first and second coaxial resonant cavities (114,116). A first location of the piston and piston rod (104,106) is determined as a function of the resonant frequency of one of the coaxial cavities (114,116). A second location of the piston and piston rod (104,106) is determined as function of the resonant frequency of the other cavity if the first location is invalid.
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