Laser gyro dither drive
First Claim
1. A direct digital dither drive apparatus for a laser gyro having a dithered gyro block with a dither motor and dither pickoff, the direct digital dither drive comprising:
- a. a means for sensing the dither pickoff connected to the dither pickoff and having a dither pickoff output;
b. a means for amplifying the dither pickoff output having an amplified dither pickoff output;
c. a means for analog to digital conversion connected to the amplified dither pickoff output having a digital dither signal output;
d. a means for digital control connected to the digital dither signal output having a pulse width modulated signal output wherein the digital control means generates the pulse width modulated signal in proportion to the digital dither output minus a reference displacement plus a predetermined amount of random noise; and
e. a means for driving the dither motor in response to the pulse width modulated signal having a dither drive signal connected to the dither motor.
1 Assignment
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Accused Products
Abstract
A direct digital dither drive for a laser gyro dither motor including a digital microcomputer which controls the dithering of a laser gyro to prevent lock in of the laser beams. The digital drive senses a dither position and schedules internal A/D conversions using an A/D conversion arbitration scheme. The period frequency and location of the minimum and maximum drive are determined using the microcontroller. Accurate dither drive is accomplished using a digital analog feedback system which compensates for real time changes in dither pickoff and dither drive components.
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Citations
64 Claims
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1. A direct digital dither drive apparatus for a laser gyro having a dithered gyro block with a dither motor and dither pickoff, the direct digital dither drive comprising:
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a. a means for sensing the dither pickoff connected to the dither pickoff and having a dither pickoff output; b. a means for amplifying the dither pickoff output having an amplified dither pickoff output; c. a means for analog to digital conversion connected to the amplified dither pickoff output having a digital dither signal output; d. a means for digital control connected to the digital dither signal output having a pulse width modulated signal output wherein the digital control means generates the pulse width modulated signal in proportion to the digital dither output minus a reference displacement plus a predetermined amount of random noise; and e. a means for driving the dither motor in response to the pulse width modulated signal having a dither drive signal connected to the dither motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A direct digital dither drive method for a laser gyro having a dithered gyro block with a dither motor and dither pickoff, the direct digital dither drive method comprising the steps of:
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a. sensing the actual displacement of the gyro block; b. reading a reference displacement of the gyro block previously stored in a memory; c. compacting the difference between the reference displacement and the actual displacement; d. forming a digital drive signal by adding random noise of a predetermined distribution to the difference; e. converting the digital drive signal into a pulse width modulation signal; and f. direct driving the dither motor with the pulse width modulation signal. - View Dependent Claims (27, 28, 29, 30, 31)
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32. A direct dither drive apparatus for a laser gyro having a dithered gyro block with a dither motor and dither pickoff, the direct dither drive comprising:
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a. a means for amplification connected to the dither pickoff having an analog dither signal output; b. means for converting the analog dither signal to a digital dither signal; c. a means for converting the digital dither signal into a digital count signal by multiplying the digital dither signal by a predetermined scale factor; d. a means for subtracting a reference displacement count from the digital count signal to generate a differential displacement signal; e. a means for injecting random noise into the differential displacement signal to generate a digital drive signal; f. a means for converting the digital drive signal into a pulse width modulated signal; and g. a means for driving the dither motor in response to the pulse width modulated signal. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
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59. A direct dither drive apparatus for a laser gyro having a dithered gyro block with a dither motor and dither pickoff, the direct dither drive comprising:
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a. a means for amplification connected to the dither pickoff having an analog dither signal output; b. a means for converting the analog dither signal to a digital dither signal; c. a means for converting a count reference displacement signal into a digital volt reference displacement signal by multiplying the digital dither signal by a predetermined scale factor; d. a means for subtracting a digital volt reference displacement signal from the digital dither signal to generate a differential displacement signal; e. a means for injecting random noise into the differential displacement signal to generate a digital drive signal; f. a means for converting the digital drive signal into a pulse width modulated signal; and g. a means for driving the dither motor in response to the pulse width modulated signal. - View Dependent Claims (60, 61)
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62. A ring laser dither pickoff sensor comprising:
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a. a first capacitor in parallel with the dither pickoff having a first terminal and second terminal; b. a first resistor in parallel with the dither pickoff and first capacitor connected between the first terminal and second terminal; c. a second capacitor connected to the first terminal and the input of a first amplifier to ac couple the dither pickoff wherein the second capacitor has a filtered dither output; d. a first amplifier means for amplifying the filtered dither output having an analog dither pickoff output, a first input and second input wherein the first input is connected to the filtered dither output and the second input is connected to the analog dither pickoff output through a second resistor and fourth capacitor connected in parallel and wherein the second input is connected to ground through a third resistor; and e. a second amplifier means for amplifying the analog dither pickoff output having a dither zero crossing detector output, a first input and second a second input wherein the first input is connected to the analog dither pickoff output and the second input is connected to the dither zero crossing detector output thought a fifth resistor and wherein the second input is also connected to ground through a sixth resistor.
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63. A direct digital dither drive apparatus for a laser gyro having a dithered gyro block with a dither motor having a dither zero crossing detector, dither pickoff, read out counter, and a system sample strobe, the direct digital dither drive comprising:
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a. an edge triggered register means for latching the read out counter value on the system sample strobe having a latched read out counter output; b. a first analog to digital conversion means connected to the dither pickoff for generating a stripper sample enabled by the system sample strobe; c. a second analog to digital conversion means connected to the dither pickoff for generating a dither drive sample enabled by the dither zero crossing detector; and d. a direct digital control means for controlling the dither motor connected to the stripper sample, and drive sample wherein the direct digital control means provides a direct digital drive signal. - View Dependent Claims (64)
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Specification