| 摘要 |
A method and apparatus for determining a change in velocity of a body following a power disruptive event. An accelerometer (10, 50) includes quartz crystals (16 and 18, 60 and 62), which produce output signals indicative of the acceleration to which a body connected to the accelerometer is subjected. The acceleration measured is directed along the sensitive axis of the accelerometer. The quartz crystals are selected to have different scale factors, K1 and K2, which define the change in frequency of the quartz crystal from its no-load resonant frequency as a force is applied to it. The quartz crystals are connected between a supporting case (14) and a proof mass (12) so that a given acceleration applied to the proof mass along its sensitive axis causes one of the crystals to experience a tension force and the other to experience a compression force. A processor (86) determines the change in velocity of the body as a function of the change in phase of the signals produced by the quartz crystals at a time, t1, and a subsequent time, t 2, and further in response to the scale factors, K1 and K2. Since the quartz crystals continue to oscillate during a brief interruption of their driving signal, the change in velocity of the body during a time interval from t1 to t2 can be determined after recovery from a brief power disruptive event that has occurred during that interval.
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