Synchronous FM digital detector

Claim 1

A system for determining the angular rate of rotation of a body about a rate axis, the system comprising: first and second accelerometers having their sensitive axes parallel to a sensing axis perpendicular to the rate axis, the first and second accelerometers being adapted to produce respective first and second output signals, each output signal having a frequency corresponding to the acceleration experienced by the respective accelerometer along its sensitive axis; movement means including means for producing a periodic movement signal and means responsive to the movement signal for periodically moving the accelerometers along a movement axis perpendicular to the rate and sensing axes, whereby each output signal includes a periodic Coriolis component; and processing means comprising means for producing a reference signal that is operative to define one or more first time periods during which the Coriolis components have one polarity and one or more second time periods during which the Coriolis components have the opposite polarity, the first and second time periods together comprising one or more complete periods of the movement signal, means for determining, for each output signal, a phase value representing the difference between the phase change of the output signal during the first time periods and the phase change of the output signal during the second time periods, means for adding the phase values to one another to determine a phase sum value and for subtracting the phase values from one another to determine a phase difference value, and means for linearly combining the phase sum and phase difference values to determine a value representing the angular rate of rotation of the body about the rate axis.

Claim 2

A system for determining the angular rate of rotation of a body about a rate axis, the system comprising: first and second accelerometers having their sensitive axes parallel to a sensing axis perpendicular to the rate axis, the first and second accelerometers being adapted to produce respective first and second output signals, each output signal having a frequency corresponding to the acceleration experienced by the respective accelerometer along its sensitive axis; movement means including means for producing a periodic movement signal and means responsive to the movement signal for periodically moving the accelerometers along a movement axis perpendicular to the rate and sensing axes, whereby each output signal includes a periodic Coriolis component; and processing means comprising means for producing a reference signal that is operative to define one or more first time periods during which the Coriolis components have one polarity and one or more second time periods during which the Coriolis components have the opposite polarity, the first and second time periods together comprising one or more complete periods of the movement signal, means for determining, for each output signal, a phase value representing the difference between the phase change of the output signal during the first time periods and the phase change of the output signal during the second time periods, means for adding the phase values to one another to determine a phase sum value and for subtracting the phase values from one another to determine a phase difference value, and means for linearly combining the phase sum and phase difference values to determine a value representing the angular rate of rotation of the body about the rate axis.

Claim 6

A system for determining the angular rate of rotation of a body about a rate axis, the system comprising: one or more accelerometers having their sensitive axes parallel to a sensing axis perpendicular to the rate axis, each accelerometer including means for producing an output signal having a frequency corresponding to the acceleration experienced by the accelerometer along its sensitive axis; movement means including means for producing a periodic movement signal and means responsive to the movement signal for periodically moving the accelerometers along a movement axis perpendicular to the rate and sensing axes, whereby each output signal includes a periodic Coriolis component; and processing means comprising means for producing a reference signal that is operative to define one or more first time periods during which the Coriolis components have one polarity and one or more second time periods during which the Coriolis components have the opposite polarity, the first and second time periods together comprising one or more complete periods of the movement signal, means for determining, for each output signal, a phase value representing the difference between the phase change of the output signal during the first time periods and the phase change of the output signal during the second time periods, means for generating a high frequency clock signal, counter means for counting cycles of the clock signal during fractions of a cycle of an output signal which overlaps the first and second time periods, to thereby improve the resolution of the determination of phase values, and means for determining from the phase values a value representing the angular rate of rotation of the body about the rate axis.

Claim 7

A system for determining the angular rate of rotation of a body about a rate axis, the system comprising: one or more accelerometers having their sensitive axes parallel to a sensing axis perpendicular to the rate axis, each accelerometer including means for producing an output signal having a frequency corresponding to the acceleration experienced by the accelerometer along its sensitive axis; movement means including means for producing a periodic movement signal and means responsive to the movement signal for periodically moving the accelerometers along a movement axis perpendicular to the rate and sensing axes, whereby each output signal includes a periodic Coriolis component; and processing means comprising means for producing a reference signal that is operative to define one or more first time periods during which the Coriolis components have one polarity and one or more second time periods during which the Coriolis components have the opposite polarity, the first and second time periods together comprising one or more complete periods of the movement signal, means for determining, for each output signal, a phase value representing the difference between the phase change of the output signal during the first time periods and the phase change of the output signal during the second time periods, means for generating a high frequency clock signal, counter means for counting cycles of the clock signal during fractions of a cycle of an output signal which overlaps the first and second time periods, to thereby improve the resolution of the determination of phase values, and means for determining from the phase values a value representing the angular rate of rotation of the body about the rate axis.

Claim 8

A system for determining the angular rate of rotation of a body about a rate axis, the system comprising: first and second accelerometers having their sensitive axes parallel to a sensing axis perpendicular to the rate axis, each accelerometer including means for producing an output signal having a frequency corresponding to the acceleration experienced by the accelerometer along its sensitive axis; movement means including a parallelogram mechanism including a first support member secured to the first accelerometer, a second support member secured to the second accelerometer, a linkage mechanism attached to the first and second support members and secured to the body such that the first and second support members are parallel to the movement axis and such that the sensitive axes of the first and second accelerometers are parallel to the sensing axis, means for producing a sinusoidal movement signal and means responsive to the movement signal for vibrating the parallelogram mechanism such that the accelerometers are sinusoidally vibrated along a movement axis perpendicular to the rate and sensing axes, whereby each output signal includes a sinusoidal Coriolis component; and processing means comprising means for producing a reference signal that is operative to define one or more first time periods during which the Coriolis components have one polarity and one or more second time periods during which the Coriolis components have the opposite polarity, the first and second time periods together comprising one or more complete periods of the movement signal, means for determining, for each output signal, a phase value representing the difference between the phase change of the output signal during the first time periods and the phase change of the output signal during the second time periods, means for adding the phase values to one another to determine a phase sum value and for subtracting the phase values from one another to determine a phase difference value, and means for linearly combining the phase sum and phase difference values to determine a value representing the angular rate of rotation of the body about the rate axis.

Claim 9

A system for determining the angular rate of rotation of a body about a rate axis, the system comprising: first and second accelerometers having their sensitive axes parallel to a sensing axis perpendicular to the rate axis, each accelerometer including means for producing an output signal having a frequency corresponding to the acceleration experienced by the accelerometer along its sensitive axis; movement means including a parallelogram mechanism including a first support member secured to the first accelerometer, a second support member secured to the second accelerometer, a linkage mechanism attached to the first and second support members and secured to the body such that the first and second support members are parallel to the movement axis and such that the sensitive axes of the first and second accelerometers are parallel to the sensing axis, means for producing a sinusoidal movement signal and means responsive to the movement signal for vibrating the parallelogram mechanism such that the accelerometers are sinusoidally vibrated along a movement axis perpendicular to the rate and sensing axes, whereby each output signal includes a sinusoidal Coriolis component; and processing means comprising means for producing a reference signal that is operative to define one or more first time periods during which the Coriolis components have one polarity and one or more second time periods during which the Coriolis components have the opposite polarity, the first and second time periods together comprising one or more complete periods of the movement signal, means for determining, for each output signal, a phase value representing the difference between the phase change of the output signal during the first time periods and the phase change of the output signal during the second time periods, means for adding the phase values to one another to determine a phase sum value and for subtracting the phase values from one another to determine a phase difference value, and means for linearly combining the phase sum and phase difference values to determine a value representing the angular rate of rotation of the body about the rate axis.

Claim 12

A system for determining the angular rate of rotation of a body about a rate axis and the linear acceleration of the body along a sensing axis perpendicular to the rate axis, the system comprising: first and second accelerometers having their sensitive axes parallel to the sensing axis, the first and second accelerometers being adapted to produce respective first and second output signals, each output signal having a frequency corresponding to the acceleration experienced by the respective accelerometer along its sensitive axis; movement means including means for producing a periodic movement signal and means responsive to the movement signal for periodically moving the accelerometers along a movement axis perpendicular to the rate and sensing axes, whereby each output signal includes a periodic Coriolis component; processing means comprising means for producing a reference signal that is operative to define one or more first time periods during which the Coriolis components have one polarity and one or more second time periods during which the Coriolis components have the opposite polarity, the first and second time periods together comprising one or more complete periods of the movement signal, means for determining, for each output signal, a first phase value representing the difference between the phase change of the output signal during the first time periods and the phase change of the output signal during the second time periods, and a second phase value representing the phase change of the output signal during the complete period of the movement signal, and means for determining from the phase values a first output value representing the angular rate of rotation of the body about the rate axis, and a second output value representing the linear acceleration of the body along the sensing axis.

Claim 13

A system for determining the angular rate of rotation of a body about a rate axis and the linear acceleration of the body along a sensing axis perpendicular to the rate axis, the system comprising: first and second accelerometers having their sensitive axes parallel to the sensing axis, the first and second accelerometers being adapted to produce respective first and second output signals, each output signal having a frequency corresponding to the acceleration experienced by the respective accelerometer along its sensitive axis; movement means including means for producing a periodic movement signal and means responsive to the movement signal for periodically moving the accelerometers along a movement axis perpendicular to the rate and sensing axes, whereby each output signal includes a periodic Coriolis component; processing means comprising means for producing a reference signal that is operative to define one or more first time periods during which the Coriolis components have one polarity and one or more second time periods during which the Coriolis components have the opposite polarity, the first and second time periods together comprising one or more complete periods of the movement signal, means for determining, for each output signal, a first phase value representing the difference between the phase change of the output signal during the first time periods and the phase change of the output signal during the second time periods, and a second phase value representing the phase change of the output signal during the complete period of the movement signal, and means for determining from the phase values a first output value representing the angular rate of rotation of the body about the rate axis, and a second output value representing the linear acceleration of the body along the sensing axis.