摘要 |
A two-gyro four-gimbal attitude sensing system having gimbal lock avoidance is provided with continuous azimuth information, rather than roll information, relative to the magnetic cardinal headings while in near vertical attitudes, thereby to allow recovery from vertical on a desired heading. The system is comprised of means (48) for stabilizing an outer roll gimbal (14) that is common to a vertical gyro (12) and a directional gyro (10) with respect to the aircraft platform (50) which is being angularly displaced about an axis substantially parallel to the outer roll gyro axis, and means (38) for producing a signal indicative of the magnitude of such displacement (62, 64) as an indication of aircraft heading. Means are provided to cause stabilization of the outer roll gimbal (14) whenever the pitch angle of the aircraft passes through a threshold prior to entering vertical flight and destabilization of the outer roll gimbal (14) upon passing through the threshold when departing vertical flight.
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