# US 2008/0184770 A1 · Gyro sensor module and angular velocity detection method

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- Number: US 2008/0184770 A1
- Document ID: US20080184770A1
- Status: Published application
- Kind: A1
- Application number: 12/025,107
- Filed: 2008-02-04
- Published: 2008-08-07
- Earliest claimed: 2007-02-05
- Assignees: Epson Toyocom Corporation
- Inventors: Kenji Sato
- Web page: https://patentgrep.com/patent/US20080184770A1

## CPC

- G01C 19/56: Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C 21/12: executed aboard the object being navigated; Dead reckoning
- G01C 25/005: {initial alignment, calibration or starting-up of inertial devices}
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)

## Abstract

A gyro sensor module built into a navigation system mounted into a mobile unit includes: a first gyro sensor detecting and outputting a first angular velocity ω1 around a first detection axis; a sign determination circuit for determining a sign of the first angular velocity ω1; a second gyro sensor detecting and outputting a second angular velocity ω2 around a second detection axis intersecting the first detection axis at an acute angle θ12; a sensor output correction circuit for correcting outputs of the first and second gyro sensors; and a computation circuit for computing ω′ by equations ω′=√(ω1′2+SA2) and SA=(ω2′−ω1′ cos θ12)/sin θ12 using a first angular velocity ω1′ and a second angular velocity ω2′ obtained by a correction performed by the sensor output correction circuit, and outputting an angular velocity ω obtained by multiplying the ω′ by the sign of the first angular velocity ω′ obtained by the sign determination circuit. The sensor output correction circuit includes: a first offset adjustment circuit for outputting a value ω1″ obtained by subtracting from the ω1 a correction value B1 corresponding to an output value of the first gyro sensor at a time when the mobile unit in which the gyro sensor module is disposed is stopping; and a second offset adjustment circuit for outputting a value ω2″ obtained by subtracting from the ω2 a correction value B2 corresponding to an output value of the second gyro sensor at a time when the mobile unit in which the gyro sensor module is disposed is stopping. The angular velocity ω is an angular velocity around an axis located in a plane including the first and second detection axes and in a range between the first and second detection axes.

## Claims

### Claim 1

A gyro sensor module built into a navigation system mounted into a mobile unit, comprising:
a first gyro sensor detecting and outputting a first angular velocity ω1 around a first detection axis;
a sign determination circuit for determining a sign of the first angular velocity ω1;
a second gyro sensor detecting and outputting a second angular velocity ω2 around a second detection axis intersecting the first detection axis at an acute angle θ12;
a sensor output correction circuit for correcting outputs of the first and second gyro sensors; and
a computation circuit for computing ω′ by equations ω′=√(ω1′2+SA2) and SA=(ω2′−ω1′ cos θ12)/sin θ12 using a first angular velocity ω1′ and a second angular velocity ω2′ obtained from corrections performed by the sensor output correction circuit, and outputting an angular velocity ω obtained by multiplying the ω′ by the sign of the first angular velocity ω1 obtained by the sign determination circuit, wherein
the sensor output correction circuit includes:
a first offset adjustment circuit for outputting a value ω1″ obtained by subtracting, from the ω1, a correction value B1 corresponding to an output value of the first gyro sensor at a time when the mobile unit in which the gyro sensor module is disposed is stopping; and
a second offset adjustment circuit for outputting a value ω2″ obtained by subtracting, from the ω2, a correction value B2 corresponding to an output value of the second gyro sensor at a time when the mobile unit in which the gyro sensor module is disposed is stopping, and
the angular velocity ω is an angular velocity around an axis located in a plane including the first and second detection axes and in a range between the first and second detection axes.

### Claim 2 (depends on 1)

The gyro sensor module according to claim 1, further comprising:
a vehicle position measurement circuit for outputting an error Δθ between a traveling azimuth obtained by integrating the angular velocity ω outputted from the computation circuit and a traveling azimuth of the mobile unit computed by the navigation system; and
an adjustment factor computation circuit for computing and outputting sensitivity adjustment signals A1 and A2 from the error Δθ, the angular velocity ω outputted from the computation circuit, and a vehicle speed pulse outputted from the mobile unit, wherein
the sensor output correction circuit includes:
a first sensitivity adjustment circuit for outputting an value ω1′ obtained by multiplying the ω1″ outputted from the first offset adjustment circuit by the sensitivity adjustment signal A1; and
a second sensitivity adjustment circuit for outputting a value ω2′ obtained by multiplying the ω2″ outputted from the second offset adjustment circuit by the sensitivity adjustment signal A2.

### Claim 3

A method for detecting an angular velocity using a gyro sensor module built into a navigation system mounted into a mobile unit, comprising:
detecting a first angular velocity ω1 around a first detection axis;
determining a sign of the first angular velocity ω1;
detecting a second angular velocity ω2 around a second detection axis intersecting the first detection axis at an acute angle θ12;
performing sensor output corrections including a first offset adjustment in which a correction value B1 corresponding to an output value of the first gyro sensor at a time when the mobile unit in which the gyro sensor module is disposed is stopping is subtracted from the ω1 and a second offset adjustment in which a correction value B2 corresponding to an output value of the second gyro sensor at a time when the mobile unit in which the gyro sensor module is disposed is stopping is subtracted from the ω2; and
computing an angular velocity ω by computing ω′ by equations ω′=√(ω1′2+SA2) and SA=(ω2′−ω1′ cos θ12)/sin θ12 using a first angular velocity ω1′ and a second angular velocity ω2′ obtained from the sensor output corrections and then by multiplying the ω′ by the sign of the first angular velocity ω1 obtained by a sign determination circuit, wherein
the angular velocity ω is an angular velocity around an axis located in a plane including the first and second detection axes and in a range between the first and second detection axes.

### Claim 4 (depends on 3)

The method for detecting an angular velocity according to claim 3, further comprising:
computing an error Δθ between a traveling azimuth obtained by integrating the angular velocity ω and a traveling azimuth of the mobile unit computed by the navigation system; and
computing sensitivity adjustment signals A1 and A2 from the error Δθ and the angular velocity ω, wherein
in the step of performing the sensor output corrections, a first sensitivity adjustment in which an value ω1′ is computed by multiplying a value ω1″ after the first offset adjustment by the sensitivity adjustment signal A1 and a second sensitivity adjustment in which an value ω2′ is computed by multiplying a value ω2″ after the second offset adjustment by the sensitivity adjustment signal A2 are performed.

### Claim 5 (depends on 3)

The method for detecting an angular velocity according to claim 3, wherein
the sensor output corrections performing step is performed by a sensor output correction circuit.

### Claim 6 (depends on 3)

The method for detecting an angular velocity according to claim 3, wherein
one or more of the sensor output corrections, the angular velocity ω computation, the error Δθ computation, and the sensitivity adjustment signals A1 and A2 computations are performed using software.