| 摘要 |
<p>A servo loop control for the dither drive of a Coriolis rate sensor is provided. The dither drive includes a pair of electromagnetic coils (70), which are alternately energized to dither a parallelogram frame (50), on which first and second accelerometers (20 and 22) are mounted with their sensitive axes antiparallel to each other. An LVDT position sensor (106) provides a feedback signal indicating the relative position of the two accelerometers or displacement of the parallelogram frame as it is dithered back and forth. The position signal is summed with a driving signal, amplified and summed with a velocity aiding signal and a velocity signal derived by differentiating the position signal. The resulting sum is amplified and again summed with an acceleration aiding input that includes compensation for a phase shift in the motion of the parallelogram frame relative to the driving force applied by the electromagnet coils, and for (I2 and 1/D2) nonlinearities where I is the current and D is the pole gap dimension (114). The sum of these signals is used to energize the electromagnetic coils, driving the parellelogram frame with a signal that causes it to dither in a pure sinusoidal fashion. Each of the critical frequencies used in the servo loop is phase locked to a common stable crystal reference frequency, and all components of the servo loop are powered by a common power supply. The servo loop provides improved frequency and phase stability and insensitivity to voltage fluctuations.</p> |
