Data processing: measuring – calibrating – or testing – Calibration or correction system – Sensor or transducer
Reexamination Certificate
2002-03-07
2004-04-20
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Calibration or correction system
Sensor or transducer
C702S060000, C702S065000, C702S092000, C702S107000, C073S488000, C073S504020, C073S504120
Reexamination Certificate
active
06725169
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to rate sensing systems, and more particularly, to gyro motors and start up sequences for gyro motors.
During a startup phase of certain known gyro motors, a transient signal such as a pulse or a noise burst is used to excite the very lightly damped motor structure of the gyro motor. The motor responds with a very small and slowly decaying sinusoidal pick-off signal. This pick-off signal is typically applied to a gain circuit, which applies a large gain to the pick-off signal in an attempt to provide a constant amplitude sinusoidal signal to a motor control loop. The motor control loop tries to acquire the sinusoid signal with a phase-locked loop (PLL), which provides a motor drive signal at an appropriate frequency, magnitude, and phase. When the PLL “catches” and the correct motor drive signal is applied, the amplitude of the motor pick-off signal suddenly increases by orders of magnitude, and can overwhelm an analog-to-digital converter (ADC) in the motor control loop. Therefore, in known motor control loops, the large variations in the pick-off signal prevent a constant amplitude sinusoidal signal from being generated.
BRIEF SUMMARY OF THE INVENTION
In one aspect, an apparatus for controlling an amplitude of a signal generated from a digitized sinusoid signal of rapidly and widely varying amplitude is provided. The apparatus comprises a two stage gain adjuster which produces a gain adjusted signal and a phase shifter which converts the gain adjusted signal into two gain adjusted output signals separated in phase by 90 degrees. The apparatus further comprises a power estimation unit to estimate the power of the gain adjusted signal and an adjusting unit to adjust a gain of the gain adjuster according to a power estimate from said power estimation unit and a desired output signal power.
In another aspect, a method for controlling the amplitude of a signal generated from a digitized sinusoid signal of rapidly and widely varying amplitude is provided. The method comprises producing a gain adjusted signal from the sinusoid signal utilizing a two stage gain adjuster and converting the gain adjusted signal into two gain adjusted output signals separated in phase by 90 degrees utilizing a phase shifter. The method also comprises estimating the power of the gain adjusted signal and adjusting the gain of the gain adjuster according to the estimated power and a desired output signal power.
In yet another aspect, a control circuit for a gyro is provided. The control circuit comprises a phase-locked loop configured to supply a motor control signal, and a motor signal conditioning circuit which converts the motor control signal to an analog motor drive signal. The phase-locked loop further comprises an analog-to-digital converter configured to receive a gyro pick-off signal, an automatic gain control circuit to provide amplitude control to an output of the analog-to-digital converter, and a numerically controlled digital dual frequency oscillator.
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Thielman Leroy O.
White Stanley A.
Armstrong Teasdale LLP
Barlow John
Honeywell International , Inc.
Luxton, Esq. Matthew
Walling Meagan S
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