System for generating an angular rate signal from an angular position signal utilizing a constant amplitude-variable carrier phase signal

Abstract

The instant invention relates to turn-rate signal generating circuitry for interrupting slaving of the directional gyro and roll erection of the vertical gyro in a heading, attitude and reference system whenever the turn-rate of the vehicle on which the system is mounted exceeds a predetermined rate. Cutoff of slaving and roll erection eliminates acceleration induced dynamic errors produced by excessive turn rates and is effectuated in response to a turn-rate signal (i.e., an angular rate signal) generated indirectly from angular position (i.e., shaft position) information. The angular position information is in the form of carrier signals amplitude modulated as a function of the sine and cosine of the angle .theta.. These signals are converted to modify the carrier phases so that they are respectively sinusoidal and cosinusoidal functions of the carrier frequency. The sinusoidal and cosinusoidally varying carrier signals are combined to produce a constant amplitude, variable carrier-phase signal, the phase of which is directly proportional to the shaft angle .theta.. The constant amplitude variable phase carrier is processed in a phase-to-pulse width converter to produce an output pulse which is proportional to the angle .theta.. This signal is differentiated and filtered to produce a varying DC signal proportional to the angular rate of change (d.theta./dt). The rate signal is compared with a reference signal to determine when the rate of angular change exceeds a predetermined value to actuate turn-rate cutoff. By virtue of this novel arrangement, which does not require demodulation of the amplitude modulated carrier signal which represents angular position, the system is insensitive to variations in the excitation voltages for the electromechanical devices, such as synchros or the like, which produce the angular position signals.

Dependencies are inferred from the claim text.