Frequency readout gyroscope

An electromechanical system, comprising:

• a mechanical resonator having a non-zero average frequency difference between oscillations of said mechanical resonator in a first mode of vibration and a second mode of vibration, wherein angular rate of motion input couples energy between said first mode of vibration and said second mode of vibration;
• sensors and actuators for each of the first mode and the second mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• sustaining circuitry connected to the sensors and actuators to maintain substantially constant, non-zero velocity amplitude vibrations in the first mode at a first oscillation frequency and the second mode at a second oscillation frequency;
• phase and frequency control circuitry coupled with the mechanical resonator and at least one sensor for controlling phase difference, frequency difference, or a combination of phase and frequency difference between said first mode and said second mode;
• output circuitry to estimate angular rate of motion from instantaneous frequencies, mechanical velocity, or displacement of said first mode or said second mode, or both said first mode and said second mode;
• a second mechanical resonator having a third mode of vibration and an associated third natural frequency, and a fourth mode of vibration having an associated fourth natural frequency, wherein energy from the third mode is coupled to energy from the fourth mode;
• additional sensors and additional actuators for each of the third mode and the fourth mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• additional sustaining circuitry for each of the third mode and the fourth mode connected to the additional sensors and additional actuators to maintain substantially continuous, non-zero velocity amplitude vibrations of the third mode at a third oscillation frequency and the fourth mode at a fourth oscillation frequency;
• and
• additional output circuitry to determine angular rate of motion from instantaneous frequency, mechanical velocity or displacement of said third mode or said fourth mode, or both said third mode and said fourth mode;
• wherein said first mode, second mode, third mode and said fourth mode have equal velocities.

An electromechanical system, comprising:

• a mechanical resonator having a first mode of vibration and an associated first natural frequency, and a second mode of vibration having an associated second natural frequency, wherein angular rate of motion input couples energy between said first mode of vibration and said second mode of vibration;
• sensors and actuators for each of the first mode and the second mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• sustaining circuitry connected to the sensors and actuators to maintain substantially constant, non-zero velocity amplitude vibrations in the first mode at a first oscillation frequency and the second mode at a second oscillation frequency;
• output circuitry to infer an angular rate of motion from mechanical velocity or displacement of said first mode or said second mode, or both said first mode and said second mode;
• wherein said output circuitry comprises at least one frequency demodulator receiving a frequency modulated signal from at least one of said sensors, and generating a demodulated output;
• and
• wherein said output circuitry further comprises a rate reference detector which generates a rate reference having a constant-envelope signal of known amplitude, in-phase with the sine of phase difference between two displacement vibrations associated with the first mode and the second mode.

An electromechanical system, comprising:

• a mechanical resonator having a first mode of vibration and an associated first natural frequency, and a second mode of vibration having an associated second natural frequency, wherein angular rate of motion input couples energy between said first mode of vibration and said second mode of vibration;
• sensors and actuators for each of the first mode and the second mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• sustaining circuitry connected to the sensors and actuators to maintain substantially constant, non-zero velocity amplitude vibrations in the first mode at a first oscillation frequency and the second mode at a second oscillation frequency;
• output circuitry to infer an angular rate of motion from mechanical velocity or displacement of said first mode or said second mode, or both said first mode and said second mode;
• a second mechanical resonator having a third mode of vibration and an associated third natural frequency, and a fourth mode of vibration having an associated fourth natural frequency, wherein energy from the third mode is coupled to energy from the fourth mode;
• additional sensors and additional actuators for each of the third mode and the fourth mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• additional sustaining circuitry for each of the third mode and the fourth mode connected to the additional sensors and additional actuators to maintain substantially continuous, non-zero velocity amplitude vibrations of the third mode at a third oscillation frequency and the fourth mode at a fourth oscillation frequency;
• additional output circuitry to determine angular rate of motion from mechanical velocity or displacement of said third mode or said fourth mode, or both said third mode and said fourth mode;
• an additional tuner for transduction of electrical signals into a change in natural frequency of the first mode, the second mode, the third mode, and the fourth mode;
• and
• phase and frequency control circuitry coupled with at least one mechanical resonator, the additional tuner and at least one sensor;
• wherein said phase and frequency control circuitry comprises a phase difference detector connected to sensing means of the first resonator and a negative feedback controller connected to a tuning means of the first resonator, wherein said negative feedback controller adjusts one or more natural frequencies of one or both modes in order to control phase difference between said first and second oscillations with respect to a first phase reference;
• wherein said phase and frequency control circuitry further comprises a phase difference detector connected to a sensor of said second resonator, and a negative feedback controller connected to a tuning means of the second resonator;
• wherein said negative feedback controller adjusts one or more natural frequencies of one or both modes in order to control the phase difference between the third and fourth oscillations with respect to a second phase reference;
• wherein said first phase reference is +90° and the second phase reference is −90°;
• wherein the output circuitry comprises at least two frequency measurement units, wherein the first measured frequency outputs of the first frequency measurement unit are representative of oscillation frequencies of the first and second modes of vibration, and the second measured frequency outputs of the second frequency measurement unit are representative of oscillation frequencies of the third and fourth modes of vibration;
• and
• wherein said output circuitry further comprises either (a) a subtractor connected to outputs of said first frequency measurement unit and second frequency measurement unit to generate a subtractor output signal as a difference between said first and second measured frequencies;
• or (b) one or more phase demodulators in which said output circuitry derives integrated angular rate from determining a phase difference between vibrations of said first mechanical resonator and said second mechanical resonator;
• or (c) a combination of (a) and (b) above.

An electromechanical system, comprising:

• a mechanical resonator having a non-zero average frequency difference between oscillations of said mechanical resonator in a first mode of vibration and a second mode of vibration, wherein angular rate of motion input couples energy between said first mode of vibration and said second mode of vibration;
• sensors and actuators for each of the first mode and the second mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• sustaining circuitry connected to the sensors and actuators to maintain substantially constant, non-zero velocity amplitude vibrations in the first mode at a first oscillation frequency and the second mode at a second oscillation frequency;
• phase and frequency control circuitry coupled with the mechanical resonator and at least one sensor for controlling phase difference, frequency difference, or a combination of phase and frequency difference between said first mode and said second mode;
• output circuitry to estimate angular rate of motion from instantaneous frequencies, mechanical velocity, or displacement of said first mode or said second mode, or both said first mode and said second mode;
• a second mechanical resonator having a third mode of vibration and an associated third natural frequency, and a fourth mode of vibration having an associated fourth natural frequency, wherein energy from the third mode is coupled to energy from the fourth mode;
• additional sensors and additional actuators for each of the third mode and the fourth mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• additional sustaining circuitry for each of the third mode and the fourth mode connected to the additional sensors and additional actuators to maintain substantially continuous, non-zero velocity amplitude vibrations of the third mode at a third oscillation frequency and the fourth mode at a fourth oscillation frequency;
• and
• additional output circuitry to determine angular rate of motion from instantaneous frequency, mechanical velocity or displacement of said third mode or said fourth mode, or both said third mode and said fourth mode;
• wherein the output circuitry comprises at least two frequency measurement units, wherein the first measured frequency outputs of the first frequency measurement unit are responsive to oscillation frequencies of the first and second modes of vibration, and the second measured frequency outputs of the second frequency measurement unit are responsive to oscillation frequencies of the third and fourth modes of vibration;
• wherein each frequency measurement unit is comprised of at least one frequency demodulator;
• and
• wherein the output circuitry further comprises a subtractor connected to outputs of said first frequency measurement unit and second frequency measurement unit to generate a subtractor output signal as a difference between said first and second measured frequencies.

An electromechanical system, comprising:

• a second mechanical resonator having a third mode of vibration and an associated third natural frequency, and a fourth mode of vibration having an associated fourth natural frequency, wherein energy from the third mode is coupled to energy from the fourth mode;
• additional sensors and additional actuators for each of the third mode and the fourth mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• additional sustaining circuitry for each of the third mode and the fourth mode connected to the additional sensors and additional actuators to maintain substantially continuous, non-zero velocity amplitude vibrations of the third mode at a third oscillation frequency and the fourth mode at a fourth oscillation frequency;
• additional output circuitry to determine angular rate of motion from instantaneous frequency, mechanical velocity or displacement of said third mode or said fourth mode, or both said third mode and said fourth mode;
• a mechanical resonator having a non-zero average frequency difference between oscillations of said mechanical resonator in a first mode of vibration and a second mode of vibration, wherein angular rate of motion input couples energy between said first mode of vibration and said second mode of vibration;
• sensors and actuators for each of the first mode and the second mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• sustaining circuitry connected to the sensors and actuators to maintain substantially constant, non-zero velocity amplitude vibrations in the first mode at a first oscillation frequency and the second mode at a second oscillation frequency;
• phase and frequency control circuitry coupled with the mechanical resonator and at least one sensor for controlling phase difference, frequency difference, or a combination of phase and frequency difference between said first mode and said second mode;
• and
• output circuitry to estimate angular rate of motion from instantaneous frequencies, mechanical velocity, or displacement of said first mode or said second mode, or both said first mode and said second mode;
• wherein said output circuitry further comprises one or more phase demodulators, and wherein said output circuitry derives integrated angular rate from determining a phase difference between vibrations of said first mechanical resonator and said second mechanical resonator.

An electromechanical system, comprising:

• a mechanical resonator having a non-zero average frequency difference between oscillations of said mechanical resonator in a first mode of vibration and a second mode of vibration, wherein angular rate of motion input couples energy between said first mode of vibration and said second mode of vibration;
• sensors and actuators for each of the first mode and the second mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• sustaining circuitry connected to the sensors and actuators to maintain substantially constant, non-zero velocity amplitude vibrations in the first mode at a first oscillation frequency and the second mode at a second oscillation frequency;
• phase and frequency control circuitry coupled with the mechanical resonator and at least one sensor for controlling phase difference, frequency difference, or a combination of phase and frequency difference between said first mode and said second mode;
• and
• output circuitry to estimate angular rate of motion from instantaneous frequencies, mechanical velocity, or displacement of said first mode or said second mode, or both said first mode and said second mode;
• wherein said output circuitry comprises at least one frequency demodulator receiving a frequency modulated signal from at least one of said sensors, and generating a demodulated output;
• and
• wherein said output circuitry further comprises a rate reference detector which generates a rate reference having a constant-envelope signal of known amplitude, in-phase with the sine of phase difference between two displacement vibrations associated with the first mode and the second mode.

An electromechanical system, comprising:

• a mechanical resonator having a non-zero average frequency difference between oscillations of said mechanical resonator in a first mode of vibration and a second mode of vibration, wherein angular rate of motion input couples energy between said first mode of vibration and said second mode of vibration;
• sensors and actuators for each of the first mode and the second mode for transduction of an electrical signal into a mechanical vibration and transduction of a mechanical vibration into an electrical signal;
• sustaining circuitry connected to the sensors and actuators to maintain substantially constant, non-zero velocity amplitude vibrations in the first mode at a first oscillation frequency and the second mode at a second oscillation frequency;
• phase and frequency control circuitry coupled with the mechanical resonator and at least one sensor for controlling phase difference, frequency difference, or a combination of phase and frequency difference between said first mode and said second mode;
• output circuitry to estimate angular rate of motion from instantaneous frequencies, mechanical velocity, or displacement of said first mode or said second mode, or both said first mode and said second mode;
• a tuner to transduce electrical signals into a change in natural frequency of the first mode and the second mode;
• and
• phase and frequency control circuitry coupled with the mechanical resonator, the tuner and at least one sensor;
• wherein said phase and frequency control circuitry comprises a phase difference detector connected to at least one of said sensors and a phase controller connected to the tuner, wherein said phase controller adjusts natural frequency of at least one of the first mode and the second mode to control the phase difference between the first mode and the second mode to be substantially equal to a phase reference;
• and
• wherein said phase and frequency control circuitry further comprises a frequency difference detector connected to at least one sensor and a split frequency controller connected to the tuner, wherein said split frequency controller adjusts natural frequency of at least one of the first mode and the second mode so that the frequency difference between the first mode and the second mode corresponds to a reference value.