Litton Systems, Inc.

Other

Northrop Grumman Guidance and Electronics Company, Inc.

Guy Thomas Varty

Anthony Robert Matthews

David Dexter Lynch

J Scott Darling

Robert Charles Schwarz

Steven C Gillespie

Peter K Tseng

Paul C Nguyen

Jeffrey Scott Darling

Jeffrey S Darling

Chung-Ming Li

Anthony Matthews

Scott J Darling

Apparatus, systems, and methods to control the frequency of a plurality of gyroscopes are disclosed. The gyroscopes are configured such that each individual gyroscope operates independently of one another and at the same pre-determined frequency. To accomplish this, the natural frequency of each gyroscope is determined, and a reference signal is added to the output signal of its respective gyroscope such that the sum of the natural frequency and the reference signal frequency equals the pre-determined frequency. Thus, each individual gyroscope, though it may include its own individual natural frequency, operates autonomously at the pre-determined frequency.

Digital coriolis gyroscope

Apparatus, systems, and methods to control a plurality of gyroscopes utilizing intermediate frequencies are disclosed. The gyroscopes are configured to operate at the same pre-determined intermediate frequency. To accomplish this, the natural frequency of each gyroscope is determined, and a reference signal is added to the output signal of its respective gyroscope such that the sum of the natural frequency and the reference signal frequency equals the pre-determined intermediate frequency. The output signal from each gyroscope is transmitted to a common inertial data processor, and the inertial data processor outputs a directional signal. The directional signal includes a representation of angles from an X-axis, a Y-axis, and a Z-axis. Since each signal output by the gyroscopes has the same frequency, the loss of data is decreased and the accuracy of the data increased.

Methods and systems utilizing intermediate frequencies to control multiple coriolis gyroscopes

The invention is a vibratory rotation sensor comprising a housing, a resonator attached to the housing, first and second sets of electrodes, and a signal processor. One set of electrodes are attached to the housing and the other set of electrodes are attached to the resonator, the first set opposing the second set. Each set consists of one or more electrodes. The signal processor has one or more input ports capacitively connected to one or more of the first set of electrodes, the signal processor extracting from the signals appearing at the one or more input ports one or more double-frequency sinusoids having frequencies of twice the frequency of oscillation of the resonator.

Extraction of double-oscillation-frequency sinusoids in vibratory

The invention is a method and apparatus for generating a plurality of driving signals for a vibratory rotation sensor, the plurality of driving signals resulting in a plurality of readout signals from the vibratory rotation sensor. The method comprises the steps of determining a 2.times. tracking angle rate, transforming the 2.times. tracking angle rate into a trig function rate, transforming the trig function rate into a second trig function, and generating the plurality of driving signals utilizing the second trig function. The 2.times. tracking angle rate, determined from the plurality of readout signals, is the time rate of change of twice the tracking angle, the tracking angle being an angle which tracks the orientation angle of the standing-wave pattern of the vibratory rotation sensor. The trig function rate is the time rate of change of a first trig function, the first trig function being an approximation to a mathematically-exact (M-E) trig function. The M-E trig function is selected from the group consisting of the tangent of twice the tracking angle and the cotangent of twice the tracking angle. The second trig function is also an approximation to the M-E trig function.

Method and apparatus for generating driving signals for a vibratory

The invention is an apparatus for sensing rotation comprising a housing, a resonator attached to the housing, a first set of electrodes consisting of one or more electrically-connected electrodes, and a second set of N electrodes. The resonator is a rotationally-symmetric, thin-walled object capable of vibrating in at least one of a plurality of standing-wave modes. The orientation of a standing wave with respect to a reference point on the resonator is specified by an orientation angle. The first set of electrodes are attached to either the resonator or the housing. The N electrodes of the second set are attached around the circumference of either (1) the housing if the first set of electrodes is attached to the resonator or (2) the resonator if the first set of electrodes is attached to the housing. The n'th electrode of the second set is attached at angular position .theta..sub.n with respect to the reference point on the resonator, opposing one or more of the second set of electrodes. The apparatus further comprises driving electronics which supplies driving signals to one or more of the second set of electrodes and sensing electronics which receives the first-set signal appearing on the first set of electrodes as a result of the capacitive coupling between the first- and second-set electrodes. The sensing electronics also supplies one or more signals to the driving electronics.

Vibratory rotation sensor with novel electrode placements

In a vibrating rotation sensor of the hemispherical resonator gyro type (HRG), operating in the whole angle mode wherein the standing-wave components are measured to provide a measure of the pattern angle, the digital signal processor functions to control the digital to analog converter output signal in order to keep the highly amplified analog to digital input signal, the difference between the pattern angle and excitation angle, within the analog to digital converter window. The analog to digital converter window is set at n times the discrete level of the digital to analog converter. A digital feedback loop in the digital signal processor continually corrects the tracking angle to control the excitation voltage.

Low quantization method and apparatus for vibratory rotation sensors

The invention is a method for reading out a vibratory rotation sensor comprising the steps of (1) driving the vibratory rotation sensor with a plurality of driving signals and (2) obtaining one or more readout signals resulting from the interaction of the driving signals and the vibratory rotation sensor. The functional dependence of all tracking-angle-dependent driving signals is expressible for a specified range of tracking-angle values as a single specific function of the tracking angle. A tracking-angle-dependent driving signal is the sum of two or more component signals where only one of the component signals is dependent on tracking angle. The single specific function specified for any one of a plurality of tracking-angle range of values can be the same as or different than the single specific function specified for any other tracking-angle range of values. In the preferred embodiment of the invention, the single specific function is the tangent of twice the tracking angle for certain tracking-angle ranges of values and is the cotangent of twice the tracking angle for other tracking-angle ranges of values. The readout signal has a functional dependence on both the tracking angle and the difference of the orientation angle of the standing wave pattern associated with the vibratory rotation sensor and the tracking angle.

Method for reading out a vibratory rotation sensor

A vibratory rotation sensor comprising a resonator, a resonator housing and a method for controlling and reading out signals from the sensor is packaged in groups of three, along with a single control and read-out electronics circuit which is either time division multiplexed, frequency multiplexed or a combination of both for the three sensors. This multiple sensor package is compact, lightweight, rugged and well suited for use as an inertial measurement instrument in several subterranean environments such as in mining, tunneling, and oil and gas drilling applications.

Multiple vibratory rotation sensors with multiplexed electronics

The invention is a vibratory rotation sensor comprising a resonator and a housing to which the resonator is attached and a method for reading out the standing-wave orientation angle utilizing a tracking angle which is maintained equal to the orientation angle on average. The resonator is a rotationally-symmetric thin-walled object that can be made to vibrate in a plurality of standing-wave modes. The method includes applying driving voltages to housing electrodes and determining the orientation of a standing wave by performing operations on the resonator signal that arrives at a single resonator output port from one or more electrodes in close proximity to the housing electrodes. A driving voltage may include either a pair of excitation voltages or a forcing voltage or both. An excitation voltage has essentially no effect on the resonator dynamics but carries information pertaining to the tracking angle and the standing-wave parameters when it arrives at the resonator output port. A forcing voltage causes forces to be applied to the resonator and thereby affects the dynamics of the resonator and the standing-wave parameters. The driving voltages applied to the housing electrodes are brought together into a single resonator signal as a result of being transmitted through the housing-electrode-resonator-electrode capacitances to the resonator output port. In order to extract the standing-wave orientation angle, the excitation and forcing voltages are designed to be separable by appropriate operations performed on the resonator signal.

Vibratory rotation sensor with whole-angle tracking

The invention is a vibratory rotation sensor comprising a resonator and a resonator housing and a method for controlling and reading out the sensor utilizing multiplex electronics. The resonator is a rotationally-symmetric thin-walled object that can be made to vibrate in a plurality of standing-wave modes. One or more electrodes are attached to a surface of the resonator and connect to a single output port The housing has a plurality of attached electrodes in close proximity to the resonator electrodes. The method for controlling and reading out the vibratory rotation sensor includes applying driving voltages to the housing electrodes and determining the parameters of the standing waves by performing operations on the resonator signal that emerges from the resonator output port. A driving voltage may include either an excitation voltage or a forcing voltage or both. An excitation voltage has essentially no effect on the resonator dynamics but carries information pertaining to the standing-wave parameters when it arrives at the resonator output port. A forcing voltage causes forces to be applied to the resonator and thereby affects the dynamics of the resonator and the standing-wave parameters. The driving voltages applied to the housing electrodes are brought together into a single resonator signal as a result of being transmitted through the housing-electrode-resonator-electrode capacitances to the resonator output port. In order to extract the standing-wave parameters, the excitation and forcing voltages are designed to be separable by appropriate operations performed on the resonator signal.

Vibratory rotation sensor with multiplex electronics

Apparatus and methods are disclosed for the time division multiplexing of fiberoptic gyros to reduce the amount of control electronics required. Each of a plurality of gyros is sampled at a rate of n.tau., where .tau. is the gyro optical transit time and n is an integer. The sampled signal is fed to a digital signal processor (DSP) for processing and used to form a rate feedback signal. The rate feedback signal is converted to analog form to drive the phase modulator drive of each gyro. In preferred embodiments the multiplexed sample rate is at least ten times the bandwidth of the gyros. The rate data can be filtered and output by the DSP and the DSP can integrate the rate data to give angle data. The use of precision analog circuits is avoided.

Multiplexed fiberoptic gyro control

A ring laser gyro having a cavity with at least one transducer-actuated mirror is controlled to conform to a preselected model of cavity operation. Control is accomplished by sampling cavity data, comparing the data to the model to generate an error signal, and controlling the mirror according to the error signal. In a preferred embodiment, at least two mirrors are dithered and the model defines an optimal amplitude of mirror dither at which theoretical lock-in error is zero. In another preferred embodiment, the sampled data corresponds to laser intensity within the cavity and the model defines an optimal intensity displaced from the maximum within an operating mode of the cavity. The model may define a plurality of operating modes of the cavity, ranked according to gyro performance for different values of a preselected environmental condition. The environmental condition is then sensed on an ongoing basis and used to select an optimal mode.

Growing community of inventors

Woodland Hills, CA, United States of America

Guy Thomas Varty