Gyro sensor module and angular velocity detection method

• US 7,814,793 B2
• Filed: 02/04/2008
• Issued: 10/19/2010
• Est. Priority Date: 02/05/2007
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Epson Toyocom Corporation (Seiko Group)
• Inventors: Sato, Kenji
• Primary Examiner(s): Kwok; Helen C.
• Application Number:
  US12/025,107
• Publication Number:
  US 20080184770A1
• Time in Patent Office: 988 Days
• Field of Search: 73/13.7, 73/13.8, 735/041.2, 735/041.6, 735/040.4, 735/10, 735/11, 702/87, 702/88, 702/104
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 21/12 executed aboard the object being navigated; Dead reckoning
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices

Abstract

A mobile navigation system gyro module comprises: first and second gyro sensors outputting angular velocities ω1, ω2 around first and second axes intersecting at an acute angle θ₁₂; a sign determination circuit determining a sign of ω1; a correction circuit correcting the first and second gyro sensor outputs; and a computation circuit computing ω′=√(ω1′²+SA²) and SA=(ω2′−ω1′ cos θ₁₂)/sin θ₁₂ using angular velocities ω1′, ω2′ from the correction circuit, and outputting angular velocity ω by multiplying ω′ by the sign of ω1, wherein the correction circuit includes: first and second offset adjustment circuits outputting ω1″ and ω2″ by respectively subtracting from ω1 and ω2, corrections B1 and B2 corresponding to the first and second gyro sensor outputs when the mobile unit stops; and the angular velocity ω is around an axis coplanar with and between the first and second axes.

Claims

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 ω

1 around a first detection axis;

a sign determination circuit for determining a sign of the first angular velocity ω

1;

a second gyro sensor detecting and outputting a second angular velocity ω

2 around a second detection axis intersecting the first detection axis at an acute angle θ

₁₂;

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

′

=√

(ω

1′

²+SA²) and SA=(ω

2′

−

ω

1′

cos θ

₁₂)/sin θ

₁₂ using a first angular velocity ω

1′ and

a second angular velocity ω

2′

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 ω

1 obtained by the sign determination circuit, wherein

the sensor output correction circuit includes;

a first offset adjustment circuit for outputting a value ω

1″

obtained by subtracting, from the ω

1, 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 ω

2″

obtained by subtracting, from the ω

2, 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.

2. The gyro sensor module according to claim 1, further comprising:

a vehicle position measurement circuit for outputting an error Δ

θ

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 Δ

θ

, 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 ω

1′

obtained by multiplying the ω

1″

outputted from the first offset adjustment circuit by the sensitivity adjustment signal A1; and

a second sensitivity adjustment circuit for outputting a value ω

2′

obtained by multiplying the ω

2″

outputted from the second offset adjustment circuit by the sensitivity adjustment signal A2.

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 ω

1 around a first detection axis;

determining a sign of the first angular velocity ω

1;

detecting a second angular velocity ω

2 around a second detection axis intersecting the first detection axis at an acute angle θ

₁₂;

performing sensor output corrections including a first offset adjustment in which a correction value B1 corresponding to an output value of a first gyro sensor at a time when the mobile unit in which the gyro sensor module is disposed is stopping is subtracted from the ω

1 and a second offset adjustment in which a correction value B2 corresponding to an output value of a second gyro sensor at a time when the mobile unit in which the gyro sensor module is disposed is stopping is subtracted from the ω

2; and

computing an angular velocity ω

by computing ω

′

by equations ω

′

=√

(ω

1′

²+SA²) and SA=(ω

2′

−

ω

1′

cos θ

₁₂)/sin θ

₁₂ using a first angular velocity ω

1′ and

a second angular velocity ω

2′

obtained from the sensor output corrections and then by multiplying the ω

′

by the sign of the first angular velocity ω

1 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.

4. The method for detecting an angular velocity according to claim 3, further comprising:

computing an error Δ

θ

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 Δ

θ and

the angular velocity ω

, wherein

in the step of performing the sensor output corrections, a first sensitivity adjustment in which an value ω

1′

is computed by multiplying a value ω

1″

after the first offset adjustment by the sensitivity adjustment signal A1 and a second sensitivity adjustment in which an value ω

2′

is computed by multiplying a value ω

2″

after the second offset adjustment by the sensitivity adjustment signal A2 are performed.

5. 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.

6. 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 Δ

θ

computation, and the sensitivity adjustment signals A1 and A2 computations are performed using software.