High resolution IOC drive and method for driving fiber optic gyroscopes
AssigneeHoneywell International Inc.
InventorsGregory W. Keith, Thomas C. Greening, Lee K. Strandjord
Life of this patent
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Abstract
Methods and system are provided for driving light through a sensing coil of an optical gyro. The system includes a photodetection circuit having an input for receiving an optical output from the sensing coil and having an output, and a signal processing circuit having an input coupled to the output of the photodetection circuit and having an output for supplying an output signal to modulate the sensing coil. The photodetection system produces a digital signal from the optical output. The signal processing circuit produces a feedback signal from the digital signal and adds a random number to the feedback signal to produce the output signal.
Claims16
A system for driving a sensing coil, the circuit comprising:
- a photodetection circuit having an input for receiving an optical output from the sensing coil and having an output, said photodetection system producing a digital signal from said optical output;
- a signal processing circuit having an input coupled to said output of said photodetection circuit and having an output for supplying an output signal to modulate said sensing coil, said signal processing circuit configured to produce a feedback signal from said digital signal and further configured to add a random number to said feedback signal to produce said output signal;
- a digital-to-analog converter (DAC) having an input for receiving said output signal and having an output;
- and
- an amplifier having an input coupled to said output of said DAC and having an output for coupling with said sensing coil,
- wherein said DAC has a first resolution, wherein said signal processing circuit has a second resolution greater than said first resolution, and wherein said random number has a size corresponding to a difference between said second resolution and said first resolution.
An optical gyro comprising:
- a sensing coil circuit having an input and an output and configured to produce an optical output having a phase difference proportional to a rotational rate of the optical gyro;
- a photodetection circuit having an input coupled to said output of said sensing coil circuit and having an output, said photodetection circuit configured to produce a digital signal representing said optical output;
- and
- a signal processing circuit having an input coupled to said output of said photodetection circuit and having an output coupled to said input of said sensing coil circuit, said signal processing circuit configured to produce a feedback signal from said digital signal and further configured to transmit an output signal to said sensing coil circuit for canceling said phase difference of said optical output, said output signal derived from a combination of said feedback signal and a random number,
- wherein said signal processing circuit comprises a digital-to-analog converter (DAC) having a first resolution, and wherein said signal processing circuit is further configured to determine with a second resolution a modulation signal for canceling said phase difference of said optical output, said second resolution greater than said first resolution, and wherein said random number has a size corresponding to a difference between said second resolution and said first resolution.
A method for operating an optical gyro having a sensing coil, the sensing coil for circulating light and producing an optical output having a phase difference during rotation of the sensing coil, the method comprising the steps of:
- generating a rate signal from the optical output of the sensing coil;
- accumulating the rate signal to produce a first accumulated signal;
- deriving a modulation signal from a combination of the first accumulated signal and a random noise signal;
- and
- applying the modulation signal to the sensing coil to cancel the phase difference,
- wherein said deriving step comprises:
- determining the modulation signal to cancel the phase difference, the modulation signal having a first resolution;
- producing a ramp signal from the combination of the first accumulated signal and the random number;
- and
- converting the ramp signal to an analog signal at a second resolution, the random number having a size of a difference of the first resolution and the second resolution.
Dependencies are inferred from the claim text.