The Singer Company

Kearfott Guidance & Navigation Corporation

Lincoln S Ferriss

Mark A Weitzner

Bo H Ljung

George F Schroeder

Jay Hoffman

John C Stiles

Robert M Hohenstein

Donald Shernoff

A piezoelectric activated dither suspension system for a ring laser gyroscope has all of the transducer elements connected in parallel to simultaneously produce sustaining torque for dither motion and respond to a back component of current produced by the vibrational motion of the gyro block. The generated current, separated from drive currents from the torquer amplifier by a transformer or, in an alternative embodiment, by sensing resistors, produces the very signal used to control and sustain the oscillations. By utilizing all transducers both as torquer and pickoff elements, economies of drive efficiency, wiring simplification and circuit redundancies are achieved.

Velocity control system using piezoelectric transducers

Electro-optical apparatus for the control of the optical path length in a laser angular rate sensor. An output of a fringe detector dual photodiode and preamplifier, normally present, is processed to recover a laser intensity component present as an amplitude modulation superimposed on the phase-modulated fringe detector signal. The laser intensity component is then provided as an input to the optical path length feedback control system.

Path length control signal derivation circuit for a laser angular rate

An electronic dither compensator for a ring laser gyroscope uses a velocity pickoff to eliminate the need for a differentiator following a displacement pick off in order to get a rate signal. The dither pickoff is converted, in a voltage to frequency converter, to a pulse train which is synchronized with the pulse train of the uncompensated input from the gyro detector. An automatic gain control with an amplitude control loop is provided. The pulses from the voltage-to-frequency converter and uncompensated inputs are synchronized and summed and differenced as selected by means of logic to produce gyro output pulses free from the effects of dither rate.

Electronic dither compensator for a ring laser gyro

A feedback control system for maintaining the intensity and spectral distribution of light at a predetermined level at a wavelength characteristic of the excited source. Control of that intensity, which exhibits a systematic but not necessarily a monotonic relation with excitation, is achieved by measuring and controlling the intensity of flux at another characteristic wavelength which is both systematic and monotonic.

Controlled light source

A signal processor which involves separation of the cell signals from a magnetic resonance gyro (MRG) using phase locked loops that also serve as frequency multipliers, phase shifting one cell output to maintain phase comparisons within the monotonic region of the phase detectors, PDM/Digital conversion of the MRG signals and finally microcomputer processing to obtain gyro angle to the required resolution and update rate.

Magnetic resonance gyro signal processor

A transimpedance amplifier is connected in a positive regenerative loop with a crystal resonator. The transimpedance amplifier includes a high gain amplifier with a parallel resistor and capacitor thereacross. A virtual ground is created at the node between the resonator and the amplifier input thereby eliminating circuit sensitivity to inherent capacitive changes between the resonator and true ground. Components are chosen to maintain oscillations at series resonance and achieve insensitivity to changes in the motional resistance of the resonator.

Transimpedance oscillator having high gain amplifier

A phase shifter of a signal processor which involves separation of the cell signals from a magnetic resonance gyro (MRG) using phase locked loops that also serve as frequency multipliers, phase shifting one cell output to maintain phase comparisons within the monotonic region of the phase detectors, PDM/Digital conversion of the MRG signals and finally microcomputer processing to obtain gyro angle to the required resolution and update rate.

Magnetic resonance gyro phase shifter

A gyro includes piezoelectric force transducers which are oscillator driven. As the gyro undergoes angular displacement, the oscillators 'follow' the instant natural frequency of the transducers and FM signals are generated at the oscillator outputs which are processed by the present invention to produce digital signals proportional to gyro angular inputs and resolved about two axes.

Signal processor for a resonator restrained gyro

A method and apparatus for phase locking the dither motions of a set of ring laser gyroscopes are shown. To prevent a variation of force from existing on a strapped-down sensor block having a plurality of ring laser gyroscopes means are provided permitting only one gyroscope to determine the frequency of oscillation of its dither suspension system. The remaining gyroscopes are slaved in both frequency and phase to the reference rather than acting independently, or locked in frequency only. The circuitry for the master and slave units have similar components, and operate substantially the same except that the signal from the variable frequency oscillator of the master unit is used as the second input to the phase detectors of the slave units rather than them using the output of their own variable frequency oscillators.

Ring laser gyroscope dither drive circuit

A piezo-electric crystal vibrating in several modes controls several frequencies generated by voltage controlled oscillators simultaneously. The output of each voltage controlled oscillator is fed to a summing amplifier which drives the crystal. The output of the crystal is fed to individual phase detectors; each phase detector is also supplied with the output of a voltage controlled oscillator and generates a voltage proportional to the phase difference between the voltage controlled oscillator and the crystal output for correcting the output frequency of each oscillator.

Multifrequency control from a single crystal

In a gyroscope including a rotor spinning about a spin axis, the rotor gimballed about two mutually perpendicular axes and including cross coupled closed loops operative on the two mutually perpendicular axes so as to be able to detect rates about said two axes, a feedback loop is provided to cause the gyroscope spin axis to nutate in a cone about its nominal, blind, spin axis at a controlled amplitude and at a frequency which is at least close to the natural nutation frequency of the gyro and the nutation detected and changes in the nutation amplitude or frequency used as a measure of the rate about the blind axis.

Three axis gyro

A digitally responsive electrostatic accelerometer having a pendulum pivotally movable about a hinge. A pair of torquer electrodes mounted on opposite sides of the pendulum are connected to a source of constant current. As the pendulum moves from its null position under the influence of acceleration forces, the displacement from null position is indicated by an increase in charge on the electrode which is in closer proximity to the pendulum. Electronic circuit means are provided to detect the direction of displacement of the pendulum from null and to apply a charge to the proper torquer electrode to force the pendulum back to null position. The principle of operation of the device is based upon the fact that the magnitude of the voltage on the torquer electrodes when charged from a constant current source contains information indicative of the position of the pendulum from null.

Electrostatic accelerometer

An instrument which performs with precision either as a pickoff or torquer and which is not subject to geometrical errors due to the electrodes going out of round. The pickoff electrodes of the instrument are mounted adjacent the end of the movable element instead of being concentric to it. Because of the location of the pickoff electrodes relative to the movable element, the device is a variable area pickoff rather than a variable gap pickoff. This provides the advantages of obtaining outputs from the X and Y axes which are a linear function of the motion of the movable element and, therefore, the displacement angle, as determined by the ratio of X and Y outputs, is independent of the amplitude of motion.

Electrostatic pickoff and torquer

An electrostatic pickoff well suited for use in a two-axis electrostatically-captured rotor rate gyroscope is shown. Displacement currents, which flow between stator electrodes and the V-shaped annular electrically conductive rotor capturing the rotor, are processed so as to produce signals related to rotor position but independent of capture currents. When closed through a 5 degree-of-freedom positional servomechanism, rotor position signals are effective in producing rotor capture with net zero rotor current without producing rotor distorting forces.

ESG Reflected impedance pickoff

An electrostatic motor which is well suited for an electrostatic gyro rotor spin up, spin down system which provides positive starting at any rotor position, choice of clock-wise or counter-clockwise rotation, spin up and spin down modes with automatic coast and stop modes, choice of full speed along with having zero induced rotor voltage and non-displacemental force generation is shown.

Growing community of inventors

Lincoln Park, NJ, United States of America

Lincoln S Ferriss