Angular Velocity Calculating Device, Offset Determination Method for the Same, and Vehicle Stopping Detecting Device

• US 20080027601A1
• Filed: 06/01/2007
• Published: 01/31/2008
• Est. Priority Date: 07/31/2006
• Status: Active Grant

• Current Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.)
• Original Assignee: Alpine Electronics Incorporated (Alps Alpine Co., Ltd.)
• Inventors: Sewaki, Koji
• Granted Patent: US 8,131,418 B2
• Time in Patent Office: Days
• US Class Current: 701/29
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: G01C 19/42 for indicating rate of turn; for integrating rate of turn

Abstract

Minimum and maximum values of an angular velocity signal output from a gyro while a vehicle is stationary are detected. A range of the angular velocity signal is set that is used to determine when the vehicle is stationary. When the angular velocity signal output from the gyro exceeds the range, the vehicle starts to move, offset values calculated within a set time from a movement start detection time are discarded, and an average angular velocity signal having been calculated and stored the set time before, is output as the offset value. Thus, even when the vehicle does not have a vehicle speed sensor, the stopping and starting of the movement of the vehicle can be accurately detected using the output signal from the gyro and the accurate offset value can be output.

Claims

1. An angular velocity calculating device operative to determine an offset value based on an angular velocity signal that is output from a gyro while a vehicle is stationary and to determine an angular velocity while the vehicle is moving based on the offset value, the angular velocity calculating device comprising:

a stationary range determiner configured to detect a minimum value and a maximum value of an angular velocity signal for a predetermined period T1 while a vehicle is stationary and to determine a range of the angular velocity signal used to identify when the vehicle is stationary;

a stopping/starting determiner configured to determine that the vehicle starts to move when the angular velocity signal from a gyro exceeds the range and to determine that the vehicle is stationary when the angular velocity signal from the gyro is within the range;

an angular velocity averager configured to calculate an average angular velocity value based on the angular velocity signal output from the gyro at predetermined time intervals;

an angular velocity storage configured to store the average angular velocity output from the angular velocity averager; and

an offset value determiner configured to determine an offset value based on the angular velocity stored at a set time before the stopping/starting determiner detects that the vehicle starts to move.

2. The device according to claim 1, further comprising:

an angular velocity signal outputter configured to sample a voltage signal output from the gyro at predetermined intervals to determine rotation angles, and to add the rotation angles sampled for a predetermined number of times to output an angular velocity signal.

3. The device according to claim 1, wherein the stationary range determiner determines and updates the range of the angular velocity signal, wherein the range of the angular velocity signal is used to determine whether the vehicle is considered to be stationary at time intervals T2 that is shorter than the predetermined period T1.

4. The device according to claim 1, wherein the range used to determine whether the vehicle is considered to be stationary is a predetermined percentage that is greater than a range defined by the minimum value and the maximum value.

5. A vehicle stopping detecting device for detecting when a vehicle stops, comprising:

a gyro configured to output an angular velocity signal of the vehicle;

a stationary range determiner configured to detect a minimum value and a maximum value of the angular velocity signal for a predetermined period T1 while the vehicle is stationary and to determine a range of the angular velocity signal used to determine whether the vehicle is stationary; and

a stopping/starting determiner configured to determine that the vehicle starts to move when the angular velocity signal from the gyro exceeds the stationary range and to determine that the vehicle is stationary when the angular velocity signal from the gyro is within the range.

6. The device according to claim 5, further comprising:

an angular velocity signal outputter configured to sample a voltage signal output from the gyro at predetermined intervals to determine rotation angles, and to add the rotation angles sampled for a predetermined number of times to output an angular velocity signal.

7. The device according to claim 5, wherein the stationary range determiner determines and updates the range of the angular velocity signal, wherein the range of the angular velocity signal is used to determine whether the vehicle is considered to be stationary at time intervals T2 that is shorter than the predetermined period T1.

8. The device according to claim 5, wherein the range used to determine whether the vehicle is considered to be stationary is a predetermined percentage that is greater than a range defined by the minimum value and the maximum value.

9. An angular velocity calculating device comprising:

a vehicle stop determiner configured to determine whether or not a vehicle is stationary based on a vehicle speed pulse generated by a vehicle speed sensor;

an angular velocity averager configured to calculate an average value of an angular velocity signal based on a gyro output signal at predetermined time intervals; and

an offset fetcher configured to fetch and output an offset value based on the angular velocity output from the angular velocity averager when at least one of a variation of the average angular velocity is within a set range, the vehicle is stationary, and a difference between the angular velocity and a previously-fetched offset value is within an allowable range.

10. The device according to claim 9, further comprising:

an angular velocity signal outputter configured to sample a voltage signal output from the gyro at predetermined intervals to determine rotation angles, and to output an angular velocity signal based on the sampled rotation angles.

11. The device according to claim 9, further comprising:

a correspondence table storage configured to store information on a correspondence between an elapsed time from a last offset fetch time and the allowable range;

an elapsed time monitor configured to monitor the elapsed time; and

an allowable range determiner configured to supply information on the allowable range corresponding to the elapsed time to the offset fetcher.

12. The device according to claim 11, wherein the correspondence table is determined based on time-output voltage characteristics of the gyro.

13. An offset determination method comprising the steps of:

detecting a minimum value and a maximum value of an angular velocity signal for a predetermined period T1 while a vehicle is stationary and determining a range of the angular velocity signal used to determine when the vehicle is stationary;

determining that the vehicle starts to move when the angular velocity signal from a gyro exceeds the range and determining that the vehicle is stationary when the angular velocity signal from the gyro is within the range; and

determining an offset value based on the value of the angular velocity of the gyro at predetermined time intervals.

14. The method according to claim 13, further comprising the step of:

sampling a voltage signal output from the gyro at predetermined intervals to determine rotation angles, wherein the angular velocity signal output from the gyro is based on the sampled rotation angles.

15. The method according to claim 13, further comprising the step of:

determining and updating the range of the angular velocity signal at time intervals T2 that is shorter than the predetermined period T1.

16. The method according to claim 13, wherein the range of the angular velocity signal is a predetermined percentage greater than a range defined by the minimum value and the maximum value.

17. An offset determination method comprising the steps of:

determining whether or not a vehicle is stationary based on a vehicle speed pulse generated by a vehicle speed sensor;

calculating an average value of an angular velocity signal based on a value of a gyro output signal at predetermined time intervals; and

fetching and outputting an offset value based on the average angular velocity signal when at least one of a variation of the average angular velocity is within a set range, the vehicle is stationary, and a difference between the angular velocity and a previously-fetched offset value is within an allowable range.

18. The method according to claim 17, further comprising the step of:

sampling a voltage signal output from the gyro at predetermined intervals to determine rotation angles, wherein the output angular velocity signal is based on the sampled rotation angles.

19. The method according to claim 17, further comprising the step of:

storing a correspondence table containing a relation between an elapsed time from a last offset fetch time and the allowable range; and

determining the allowable range based on the elapsed time from the correspondence table.

20. An angular velocity calculating device comprising:

a stationary range determiner configured to detect a minimum value and a maximum value of an angular velocity signal for a predetermined period T1 while a vehicle is stationary and to determine a range of the angular velocity signal used to identify when the vehicle is stationary;

a stopping/starting determiner configured to determine that the vehicle starts to move when the angular velocity signal exceeds the range and to determine that the vehicle is stationary when the angular velocity signal is within the range; and

an offset value determiner configured to determine an offset value based on the angular velocity signal at predetermined time intervals.