| 摘要 |
<p>A monitoring device comprises an SAW resonator means being a pair of SAW resonators (201), each with different non-related resonant frequencies, mounted on a rotating shaft such that their axes are substantially perpendicular to one another and substantially at 45 degrees to the rotation axis of the shaft. By measuring the variation in the resonant frequency of each of the SAW resonators (201) the torque applied to the shaft can be determined. A frequency agile signal generating means (202) is also mounted on the shaft and is arranged to generate and apply to the SAW resonator means a signal at the resonant frequency of a selected one of the SAW resonators (201) such as to excite it. The signal generating means (202) is also operable to receive the relaxation oscillation signals output by said SAW resonator (201) and to act as an interface means to pass the signals to a signal processing means (203) also mounted on said shaft. The signal processing means (203) is operable to process the signals output by said SAW resonator (201) and to output a signal indicative of the variation in frequency of these signals from the resonant frequency of the SAW resonator (201) and/or to further process the signals output by the SAW resonator (201) and thereby output a signal indicative of either the strain applied to said SAW resonator (201) or the torque applied to the shaft. By generating signals for input to the SAW resonators on the shaft and by processing signals output from the SAW resonator means on the shaft, noise in the signals resulting from imperfect coupling is reduced and thus more accurate monitoring of the shaft can be achieved.</p> |
