JP2857091B2 - Gyro device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gyro device used as an azimuth detecting means for detecting a change in a traveling direction, for example, in a navigation device mounted on a vehicle for providing route guidance to a driver.

[0002]

2. Description of the Related Art Conventionally, in navigation devices, G
In addition to the method of absolutely detecting the current position and heading of the vehicle with PS, etc., the method of estimating the relative current position by self-contained navigation based on the change in the running direction of the vehicle and the running distance is used in parallel. ing. GPS radio wave reception is not always possible under good conditions, and even when an absolute position or an absolute direction can be detected, the error sometimes increases. In order to detect the relative orientation, a gyro device using a vibrating gyroscope or the like is suitably used, and the orientation can be always detected. Direction detection using a gyro sensor involves multiplying the difference between the output value of the gyro sensor and the gyro offset value output when the vehicle does not rotate in the running direction by a gyro sensitivity coefficient, and integrating the result. Done by However, the offset changes with time due to temperature drift or the like, and needs to be corrected appropriately. In particular, at the time of startup, a deviation of several tens of degrees may occur in 5 minutes. The prior art for correcting a gyro sensor for temperature drift and the like is disclosed in, for example,
95407 and JP-A-4-235310. Japanese Patent Application Laid-Open No. 3-95407 discloses a technique of assuming that a drift component continuously changes with time, and performing offset correction in consideration of a change. Japanese Patent Application Laid-Open No. Hei 4-235310 discloses a technique of increasing the number of times of sampling for calculating an offset correction value when the apparatus is started up and calculating a required offset value in a short time.

[0003]

In a gyro device such as a vibrating gyro, a temperature drift is likely to occur due to an increase in the ambient temperature due to heat generated by the gyro vibrator itself and heat generated by a peripheral circuit for signal processing, and high accuracy is required. If required, the fluctuation of the offset becomes so large that it cannot be ignored. Therefore, even if the offset correction is performed in a short time immediately after the start-up of the apparatus as in the prior art of JP-A-4-235310, the subsequent temperature drift and the like cannot be avoided.

In order to correct an offset from a temperature drift or the like, it is necessary to actually detect an offset component and perform an appropriate offset correction. Generally, the detection of the offset value is performed at the time of a stop or at the time of straight traveling with a small change in the traveling direction of the vehicle. However, when traveling on a mountain road or a highway, the vehicle continues to travel for a long time, and travels straight ahead for a relatively short time. The offset value of may be greatly different.

[0005] An object of the present invention is to provide a gyro device capable of accurately and appropriately performing offset correction.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a gyro device which is mounted on a vehicle, detects a change in the traveling direction of the vehicle by a gyro sensor, and estimates the traveling direction during traveling. Offset detecting means for detecting an offset component from the output of the gyro sensor when detecting the running state, storage means for storing an offset for correcting the output of the gyro sensor, time measuring means for measuring the time elapsed since the power-on, A degree determining means for determining a degree of correction from the output of the timing means, an offset component of the offset detecting means, and a correction value correcting means for correcting the offset stored in the storage means using the degree of the degree determining means. Correcting the output from the gyro sensor using the offset correction value corrected by the correction value correcting means. A gyro device, characterized in that it comprises a offset compensation means. According to the present invention, the offset detecting means detects an offset component from the output of the gyro sensor when detecting a stop or straight-ahead state of the vehicle determined to have a stable traveling direction. The detected offset is stored in the storage means. The correction value correction means corrects the offset stored by the storage means using the offset component of the offset detection means and the degree of the degree determination means. The offset correction means corrects the output from the gyro sensor using the offset correction value corrected by the correction value calculation means. Since the degree of offset correction during the period from power-on to the predetermined time is greater than the degree of correction during other periods, large offset fluctuations at power-on are properly corrected, and changes in bearing are detected accurately. can do.

Further, in the present invention, the offset correction means increases the degree of the offset correction when a predetermined time or more has elapsed from the previous offset correction with reference to the timing means. According to the present invention,
The offset correction means increases the degree of the offset correction when the elapsed time from the previous offset correction has elapsed for a predetermined time or more. If the condition of the offset correction is not satisfied and the elapsed time from the previous offset correction becomes long, it is assumed that the offset is largely deviated due to the temperature rise due to continuous running. Corrections can be made.

[0008] In the present invention, the offset correction means includes:
The offset value is corrected by multiplying the correction value from the correction value calculation means by a weight coefficient, and the degree of the offset correction is adjusted by changing the value of the weight coefficient. According to the present invention, the correction by the offset correction means multiplies the correction value from the correction value calculation means by the weight coefficient to correct the output from the gyro sensor. Since the degree of correction may be adjusted by changing the value of the weight coefficient, the degree of offset correction according to various conditions can be easily changed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic electrical configuration of a navigation device including a gyro device as a form on which the present invention is based. The gyro sensor 1 includes a vibration gyro 2 and an electric processing circuit 3 for processing the gyro 2.
including. The vibrating gyroscope 2 is mounted on a vehicle and detects a change in azimuth accompanying a change in the traveling direction of the vehicle. The vibrating gyroscope 2 receives Coriolis force accompanying a change in the traveling direction, and the vibration component changes according to the direction. A change in the vibration component corresponding to the change in the direction is electrically detected by the processing circuit 3, and an electrical output corresponding to the change in the direction is generated. The running speed of the vehicle is detected by a vehicle speed sensor 4. The absolute position of the vehicle and the absolute direction of the traveling direction can be detected by the GPS receiver 5. Information about the road on which the vehicle is traveling is stored in a storage medium provided in the map data storage device 6, such as a CD-ROM. The current position of the vehicle and the like are displayed on the display device 7 in association with the map data in the map data storage device 6.

The processing device 10 responds to input signals from the gyro sensor 1, the vehicle speed sensor 4, the GPS receiving device 5, the map data storage device 6 and the like, and displays the current position on the display device 7 and guides the driving route. I do. Processing device 10
Inside, a signal indicating an azimuth indicating a traveling direction from the gyro sensor 1 is input, an offset correction unit 11 that detects a timing at which offset correction is performed, calculates a correction value for offset correction, and sets an offset correction value. The current position of the vehicle is estimated using the azimuth correcting means 12 for correcting the azimuth using the corrected azimuth and a signal indicating the traveling distance from the vehicle speed sensor 4, and the absolute value from the GPS receiver 5 is obtained. Current position estimating means 13 for estimating the current position in combination
And a map matching means 14 for performing a map matching of the current position estimated for the road stored in the map data storage means 6, and data for calculating an offset value from an output of the gyro sensor 1. It includes a storage unit 15, a clock unit 16 for counting the time corresponding to the offset correction interval, and a power supply 17. Power supply 17
Turns on the power switch 18 and turns on the onboard battery 19.
When power is supplied from such as, the timer operation of the timer unit 16 is started.

FIG. 2 shows the operation of the processing apparatus 10 of FIG. When the power switch 18 is turned on in step a1,
In step a2, the timekeeping operation of the timekeeping means 16 is started. At step a3, an offset reference value G _off0 and weighting coefficients α1, α2, α3 (α1>α2> α3) are set. In step a4, a detected value of a change in direction is detected from the output of the gyro sensor 1 at a constant sampling cycle and stored in the storage unit 15. In step a5, it is determined whether the vehicle has started running. If the traveling is not started and the vehicle is stopped, the process returns to step a4. Whether or not the vehicle has started traveling can be determined by, for example, an output from the vehicle speed sensor 4. Gyro sensor 1
In the azimuth detection using, for example, the azimuth detected by the gyro sensor at time T _n is D _n , the output value of the gyro sensor 1 is G _n , the offset value of the gyro sensor output is G _off , and the sensitivity coefficient of the gyro sensor 1 is Is K, there is the following relationship of the first formula.

[0012] _{D n = K (G n -} G off) + D n-1 ... (1) where, D _n-1 represents the orientation in one sampling period before time T _n-1. The offset of the gyro sensor 1 is
Generally, it is obtained by taking the average of the output of the gyro sensor 1 in a stationary state. This is because the output value _Gn should be a constant value when stationary, but a variation due to an error occurs. Assuming that the number of data samples in the stationary time is N, the average value G _ave can be obtained by the following second equation.

[0013]

(Equation 1)

In practice, a method of updating the gyro sensor 1 with appropriate weights in consideration of variations in the output value of the gyro sensor 1 is used. Offset value G of new gyro sensor 1
_off is calculated based on the average value G _ave of the gyro sensor 1 and the offset value G _{off0 at} that time as in the following third equation.

G _off = (1−α) G _off0 + αG _ave (3) When it is determined in step a5 that the traveling is to start, an offset correction value G _off is calculated in step a6 according to the above-described third equation. At step a7, calculates the azimuth D _n of the first equation by using the calculated offset correction value, performs offset correction.

In step a8, after the vehicle starts running,
It is again determined whether or not the timing at which offset correction can be performed has been reached. The offset correction according to the present embodiment can be performed not only in a stationary state at the time of stop, but also in a state in which the traveling direction of the vehicle is somewhat stable. When it is determined that the correction timing has come, the average value G _ave is calculated in step a9 as shown in the above-described second equation. In step a10, it is determined whether or not the correction timing is within a predetermined time after activation. The predetermined time is, for example, 30 minutes. If the offset correction timing is reached during this time, the largest value α1 is selected as the weight coefficient α in step all. If it is determined in step a10 that the time is not within the predetermined time after the activation, it is determined in step a12 whether the time elapsed since the previous offset correction has exceeded the reference time. When it is determined that the time exceeds the reference time, in step a13, the next largest value α2 is selected as the weighting coefficient α. If it is determined in step a12 that the elapsed time is less than or equal to the reference time, step a14
, The smallest value α3 is selected as the weighting coefficient α. In step a3, α1 is set to, for example, about twice α3.

When step a11, step a13 or step a14 is completed, an offset correction value is calculated in accordance with the above-described third equation in step a15. Then calculates the azimuth D _n of performing an offset correction according to the first equation by using the offset values calculated in step a5 in step a16. In step a17, the offset correction value G _off calculated in step a15 is _substituted as a new offset reference value G _off0 . Next, at step a18, the timer is reset, and the process returns to step a8. Thereafter, each time the offset correction timing is reached, the operations from step a9 to step a18 are repeated.

FIG. 3 shows, as one embodiment of the present invention, an operation of changing the weight coefficient in accordance with the magnitude of the stop time in step a6 of FIG. The operation starts from step b1, and in step b2, the average value G _ave of the gyro sensor output during the stop time is calculated in the same manner as in the above-described second equation.
At step b3, it is determined whether or not the stop time exceeds a predetermined time set in advance. The predetermined time is set to a time that is assumed to elapse between the start of the normal vehicle and the start of traveling. If the stop time exceeds the predetermined time, a predetermined value α10 is set as the weighting coefficient α in step b4. If the stop time is equal to or shorter than the predetermined time, a value α11 larger than the predetermined value α10 is set as the weighting coefficient α in step b5. When the stop time is short, sufficient idling operation or the like is not performed, and the subsequent offset fluctuation is assumed to be large. Therefore, the degree of correction is increased. Step b4 or step b5
When the setting of the weighting factor α is completed, the correction value G _off is calculated in step b6 according to the above-described third equation, and the correction value G _off is calculated in step b7.
To end the operation.

In the operation shown in FIG. 2, the value of the weight coefficient α is changed depending on whether or not the elapsed time from the previous offset correction exceeds the reference time after a lapse of a predetermined time after activation. In step b8, the weighting factor α
May be adjusted. For example, when the straight traveling section is short on a mountain road or the like, but the engine output is large and the temperature rise around the vibrating gyroscope 2 becomes large, the condition for performing the offset correction is relaxed,
Instead of increasing the frequency of the offset correction, it is preferable to use a method in which the weight coefficient is reduced to prevent an increase in the error per operation.

[0020]

As described above, according to the present invention, the degree of offset correction is increased at power-on, so that an offset value having a large fluctuation can be appropriately adjusted.
After the period from power-on to the predetermined time,
Since the degree of the offset correction is smaller than the degree of the offset correction immediately after the power is turned on, it is possible to prevent the offset value from fluctuating by performing excessive correction in a range where the offset value fluctuates little.

Further, according to the present invention, when the condition of the offset correction is not satisfied for a long time and the interval of the offset correction becomes large, the degree of the offset correction is increased to effectively use the opportunity of the offset correction. Thus, an appropriate correction can be made.

Further, according to the present invention, the weight coefficient for the offset correction value is adjusted to change the degree of the offset correction, so that the degree adjustment for appropriately performing the correction can be easily performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic electrical configuration as a form on which the present invention is based;

FIG. 2 is a flowchart showing an operation of the processing device 10 of FIG.

FIG. 3 is a flowchart showing an operation of the processing apparatus 10 of FIG. 1 as one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gyro sensor 2 Vibration gyroscope 3 Processing circuit 4 Vehicle speed sensor 5 GPS receiving device 6 Map data storage device 7 Display device 10 Processing device 11 Offset correction means 12 Direction correction means 13 Current position estimation means 15 Storage means 16 Clocking means 17 Power supply 18 Power supply switch

Continuation of front page (56) References JP-A-3-144309 (JP, A) JP-A-4-295714 (JP, A) JP-A-3-191812 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) G01C 19/56 G01C 21/00 G01P 9/04

Claims (3)

(57) [Claims] 1. A gyro device mounted on a vehicle for detecting a change in the traveling direction of a vehicle by a gyro sensor and estimating the traveling direction during traveling, wherein the gyro sensor detects a stop or straight traveling state of the vehicle. Offset detection means for detecting an offset component from the output; storage means for storing an offset for correcting the output of the gyro sensor; timer means for measuring an elapsed time from power-on; and correction degree from the output of the time measurement means. Correction value correction means for correcting the offset stored in the storage means using the offset component of the offset detection means and the degree of the degree determination means, and correction by the correction value correction means. Offset correction means for correcting the output from the gyro sensor using the offset correction value obtained. A gyro device, comprising: 2. The offset correction unit according to claim 1, wherein the offset correction unit refers to the clock unit and increases the degree of the offset correction when a predetermined time or more has elapsed since the previous offset correction. Gyro device. 3. The offset correction means multiplies the correction value from the correction value calculation means by a weight coefficient to correct the offset, and adjusts the degree of the offset correction by changing the value of the weight coefficient. The gyro device according to claim 1 or 2, wherein