JP2523253B2 - Azimuth detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an azimuth detecting device having a turning angular velocity sensor offset correction function, and more particularly to stabilizing the temperature of a turning angular velocity sensor.

[0002]

2. Description of the Related Art Conventionally, a turning angular velocity sensor and a processing device for performing necessary processing on an output signal from the turning angular velocity sensor have been used as a device for detecting the azimuth of a vehicle traveling in an arbitrary portion of a road traffic network. It is proposed to obtain the current heading data of the vehicle by using the heading change amount (angular velocity) Δθ that accompanies traveling of the vehicle.

The system adopted in this azimuth detecting device is a system for calculating the current azimuth θ of the vehicle by θ = θ ₀ + Δθ based on the angular velocity data Δθ. θ ₀ is the azimuth obtained at the time of the previous sampling. Based on this azimuth data θ and traveling distance data Δl of the vehicle separately obtained, the east-west direction component Δx (= Δl × cos θ) and the north-south direction component Δy (= Δl × sin θ) of Δl at the previous vehicle position are calculated. By adding to the obtained data (P'x, P'y),
Current vehicle position data (Px = P′x + Δx, Py =
Since P′y + Δy) can be obtained, the azimuth detecting device is used for detecting the position of the vehicle.

Actually, the output of the turning angular velocity sensor is an analog value, which is converted into a digital value by an A / D converter, and the turning angle is obtained by a computer. Further, there is also a method in which an absolute azimuth is obtained by using a geomagnetic sensor and the azimuth data obtained from the output of the turning angular velocity sensor is compared and processed to obtain azimuth data with higher reliability.

However, in the turning angular velocity sensor, even when the sensor output should be 0 during straight running, there is a tendency that some output, so-called offset, is generated under the influence of temperature. Since this offset output has a property of accumulating, if the offset is left as it is, a direction gradually deviating from the actual traveling direction will be detected.

Therefore, an accurate offset value is obtained,
It is necessary to correct the detection direction. Therefore, a method is considered in which the offset amount is subtracted from the running data by utilizing that only the offset amount appears in the output of the turning angular velocity sensor when the vehicle is stopped by a signal or the like. As described above, various devices have been proposed, for example, Japanese Patent Application No. 63-245713 by the present applicant, which corrects the offset value by using the output of the turning angular velocity sensor in the stopped state.

[0007]

However, when the vehicle is stopped, the offset value of the turning angular velocity sensor is
It has the property of changing (drifting) depending on temperature regardless of whether it is running. Therefore, if the temperature when the vehicle is stopped and the temperature when the vehicle is running after starting the vehicle are different, even if the offset value is measured while the vehicle is stopped, the running offset value changes because of drift, There is an error in the azimuth.

Particularly, when the target temperature is set in the turning angular velocity sensor and the target temperature is controlled to reach the target temperature, the temperature of the turning angular velocity sensor changes even during traveling, so the offset value changes due to drift, and is found. There is an error in the azimuth.

If the time until the next stop is short while the vehicle is running, there is no problem because the correction is performed again while the drift is small, but if the continuous running time of the vehicle is long, there is less opportunity to correct the offset value. However, the error becomes large and the correction becomes difficult.

Further, the fluctuation of the offset value is a function of temperature, but the fact that there is a temperature at which the offset value is most stable has not been paid attention so far. Further, it has not been paid attention so far that this temperature is not determined uniformly, because there are individual differences among the turning angular velocity sensors.

In view of the above, the present invention can suppress the fluctuation of the offset value of the turning angular velocity sensor due to the temperature, can reduce the turning angle error due to the drift of the offset value, and can accurately estimate the bearing. For the purpose of providing.

[0012]

According to the first aspect of the present invention,
A direction detection that has a function of offset correction of the turning angular velocity sensor when the vehicle is stopped, takes in direction data obtained from the output of the turning angular velocity sensor, and obtains the current estimated direction of the vehicle from the value and past estimated direction In the apparatus, a sensor temperature detecting means for detecting the temperature t ₂ of the turning angular velocity sensor, a target temperature setting means for setting a target temperature T of the turning angular velocity sensor, a running determination means for determining whether or not the vehicle is running, a running determination Holding temperature setting means for setting the temperature t ₂ of the turning angular velocity sensor at the start of traveling detected by the sensor temperature detecting means as the holding temperature T ₁ when the means determines that the vehicle has started traveling, and when the vehicle is stopped, and the target temperature T set by the target temperature setting means, the turning angular velocity sensor which is detected by the sensor temperature detecting means and the temperature t ₂ And compare, on the basis of the comparison result,
In order to keep the temperature t ₂ of the turning angular velocity sensor at the target temperature T,
First temperature control means for controlling the temperature of the turning angular velocity sensor,
Also, when the vehicle is traveling, the holding temperature T ₁ set by the holding temperature setting means is compared with the temperature t ₂ of the turning angular velocity sensor detected by the sensor temperature detecting means, and based on the comparison result, the turning angular velocity sensor In order to keep the temperature t ₂ at the holding temperature T ₁ , a second temperature control means for controlling the temperature of the turning angular velocity sensor is included.

According to a second aspect of the present invention, in the azimuth detecting apparatus according to the first aspect, the target temperature setting means sets a target temperature T _0, which is obtained in advance, at which the offset value of the turning angular velocity sensor is most stable. It is what

According to a third aspect of the present invention, in the azimuth detecting apparatus according to the first aspect, further, there is an outside air temperature detecting means for detecting an outside air temperature, and the target temperature setting means is an outside air temperature detecting means. The target temperature T is a value obtained by raising a certain constant temperature with respect to the detected outside air temperature t ₁ .

According to a fourth aspect of the present invention, a sensor temperature detecting means for detecting the temperature t ₂ of the turning angular velocity sensor, and a temperature T _{0 at which} the offset value of the turning angular velocity sensor is most stable, which is obtained by performing a temperature test in advance. Is set as the target temperature T of the turning angular velocity sensor, and the target temperature T set by the target temperature setting means is compared with the temperature t ₂ of the turning angular velocity sensor detected by the sensor temperature detecting means. , The temperature t of the turning angular velocity sensor is calculated based on the comparison result.
_In order to keep ₂ at the target temperature T, the temperature control means for controlling the temperature of the turning angular velocity sensor is included.

[0016]

In the azimuth detecting device according to claim 1, when the traveling discriminating means discriminates the traveling start of the vehicle, the holding temperature setting means detects the temperature of the turning angular velocity sensor at the beginning of traveling detected by the sensor temperature detecting means. t ₂ is set as the temperature T ₁ to be maintained during this traveling. Then, when the vehicle is traveling, the second temperature control means compares the holding temperature T ₁ set by the moving temperature setting means with the temperature t ₂ of the turning angular velocity sensor detected by the sensor temperature detection means. Based on the comparison result, the temperature of the turning angular velocity sensor is controlled so as to keep the temperature t ₂ of the turning angular velocity sensor at the holding temperature T ₁ .

On the other hand, when the vehicle is stopped, the first temperature control means sets the target temperature T set by the target temperature setting means.
And the temperature t ₂ of the turning angular velocity sensor detected by the sensor temperature detecting means are compared, and based on the comparison result, the temperature control of the turning angular velocity sensor is performed so as to keep the temperature t ₂ of the turning angular velocity sensor at the target temperature T. To do.

As described above, the control for maintaining the temperature of the turning angular velocity sensor at the target temperature T is performed only while the vehicle is stopped so that even if the offset value of the turning angular velocity sensor fluctuates, it can be accurately detected. In addition, since the temperature of the turning angular velocity sensor at the beginning of running is maintained, fluctuations in the offset value of the turning angular velocity sensor due to temperature changes can be suppressed during running. In other words, the recognized offset value of the turning angular velocity sensor while the vehicle is stopped can be used as it is as the offset value of the turning angular velocity sensor during traveling. Therefore, a turning angle error that occurs during traveling is reduced, and more accurate azimuth estimation can be performed.

According to the second aspect of the invention, the temperature T at which the variation of the offset value of the turning angular velocity sensor is most stable.
_{Since 0} is set as the target temperature T of the temperature of the turning angular velocity sensor, the temperature control is performed aiming at this temperature T ₀ while the vehicle is stopped. Therefore, it is possible to suppress the fluctuation of the offset value of the turning angular velocity sensor due to the change of the temperature and reduce the turning angle error due to the drift of the offset value. Therefore, the direction can be accurately estimated.

According to the third aspect of the invention, since the temperature obtained by adding a certain temperature to the outside air temperature t ₁ detected by the outside air temperature detecting means is set as the target temperature T, the control is performed while the vehicle is stopped. Since the temperature difference between the air temperature t ₁ and the target temperature T can be reduced, the time to reach the target temperature T can be shortened regardless of the season, and a stable turning angular velocity sensor offset value can be obtained in a short time.

According to the fourth aspect of the present invention, the temperature T _{0 at} which the offset value of the turning angular velocity sensor is most stable, which is obtained in advance by the temperature test, is the target temperature T of the turning angular velocity sensor.
In order to maintain the temperature t ₂ of the turning angular velocity sensor at this target temperature T, the temperature of the turning angular velocity sensor is controlled.

The change of the offset value due to the drift is not just proportional to the temperature, but is sensitive to the temperature change and stable, and there are individual differences of the turning angular velocity sensor. Therefore, in order to reduce the drift, a temperature that is stable with respect to a temperature change is set, and this temperature is set as a target temperature T to perform temperature control for stabilization.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for setting a target temperature and controlling the temperature will be described in detail below with reference to FIGS. This embodiment relates to the implementation of the invention as defined in claim 4. FIG. 1 is a block diagram showing the configuration of the azimuth detecting apparatus.

As shown in FIG. 1, the azimuth detecting device includes a vehicle speed sensor 1 for detecting the traveling distance of the vehicle by detecting the rotational speeds of the left and right wheels of the vehicle, a geomagnetic sensor 2 for detecting the absolute azimuth of the vehicle, and the vehicle. A gyro 3 that detects the turning angular velocity of the gyro 3, a heater 4 that is disposed inside the gyro 3 to heat the gyro 3, a temperature sensor 5 that is disposed inside the gyro 3 to detect the internal temperature of the gyro 3, and a road. Road map memory 6 storing map data and buffer memory 7
And a locator 8 for calculating the estimated azimuth of the vehicle based on the output data detected by the geomagnetic sensor 2 and the gyro 3 and for obtaining the current position of the vehicle together with the data of the vehicle speed sensor 1, The offset memory 9 and the read vehicle current position are displayed on the display 10 so as to be superimposed on the map, and various switches (including a touch switch on the screen) and a navigation controller 12 serving as an interface are configured.

The gyro 3 is selected from an optical fiber gyro that reads the turning angular velocity as a phase change of the interference light, a vibration gyro that detects the turning angular velocity using the cantilever vibration technology of a piezo electric element, a mechanical gyro, and the like. . The heater 4 uses a heating element such as a nichrome wire, and the temperature sensor 5 uses a thermocouple or the like.

The road map memory 6 stores road map data covering a predetermined range in advance, and includes a semiconductor memory, a cassette tape, a CD-ROM, an IC memory,
DAT or the like can be used.

The locator 8 obtains the number of rotations of the wheel by counting the number of output pulse signals from the vehicle speed sensor 1, for example, and counts the count output data output from the counter by the multiplier for the distance per count. The traveling distance output data per unit time is calculated by multiplying it by a predetermined constant, and the relative change of the vehicle orientation is obtained from the gyro 3, and the vehicle orientation output is obtained from this and the absolute orientation output data of the geomagnetic sensor 2. The data is calculated.

The offset memory 9 preliminarily tests the temperature of the gyro 3 in a thermostatic chamber, and stores the offset value itself of the gyro 3 at that time in a table in relation to the temperature. By using this table, the offset value can be determined by searching the table at any time during traveling.

The locator 8 also includes an offset memory 9
The function of setting the temperature T _{0 at} which the offset of the gyro 3 is most stable stored as the target temperature T of the gyro 3, and the target temperature T and the internal temperature t of the gyro 3 detected by the temperature sensor 5. ₂ and the internal temperature t ₂ of the gyro 3 is set to the target temperature T based on the comparison result.
In order to keep on, the heater 4 has a function of controlling ON / OFF.

The display 10 uses a CRT, a liquid crystal display or the like to display a road map and a vehicle direction while the vehicle is traveling. Navigation controller 12
Is composed of a graphic processor, an image processing memory, etc., and is used to search the map on the display 10, switch the scale, scroll, display the current direction of the vehicle, and the like.

A vehicle azimuth detecting operation of the azimuth detecting apparatus will be described. While the vehicle is running, the position of the vehicle is displayed on the display 10 based on the output data of the vehicle speed sensor 1, the geomagnetic sensor 2 and the gyro 3 which are taken into the locator 8.
Although it is displayed together with the map above, the interrupt position is updated at regular intervals during the display.

That is, first, the locator 8 is the gyro 3
Output data Δθ ^G and output data of geomagnetic sensor 2 θ ^H
And are taken in and the offset of the output data Δθ ^G of the gyro 3 is obtained. Therefore, the internal temperature information of the gyro 3 of the temperature sensor 5 is read, and the offset value according to the temperature is read from the offset memory 9.

Then, the locator 8 corrects the output data Δθ ^G of the gyro 3 by subtracting it from the output data Δθ ^G of the gyro 3 using the read offset value. Using this corrected output data Δθ ^G , the current azimuth θ ^G is obtained, compared with the output data θ ^H of the geomagnetic sensor 2, and the data with higher reliability is selected.

To make this selection, for example, Japanese Patent Laid-Open No.
As disclosed in Japanese Unexamined Patent Publication No. 0-122311, a geomagnetic sensor is normally used, and when the variation of the geomagnetic sensor within a designated time is equal to or more than a set value and the variation of the gyro is less than or equal to the set value, data of the gyro Alternatively, the weighted average may be obtained by obtaining the respective variance values of the output data of the gyro and the output data of the geomagnetic sensor in the past, and multiplying the data with less variation by a heavier coefficient.

Then, the present position of the vehicle is calculated from the azimuth data obtained as described above and the traveling distance data obtained from the output of the vehicle speed sensor 1. At this time, the temperature T ₀ at which the variation of the offset of the gyro 3 is most stable
Is recognized and T ₀ is set as the target temperature T of the gyro 3 so that the offset value of the gyro 3 does not change so much. The stable operation of the gyro temperature will be described with reference to the flowchart shown in FIG.

After the processing routine is started, step S1
In, the internal temperature data t ₂ of the gyro 3 is fetched from the temperature sensor 5, and it is determined in step S2 whether the internal temperature data t ₂ of the gyro 3 exceeds the target temperature T. Here, if the internal temperature data t ₂ of the gyro 3 exceeds the target temperature T, the process proceeds to step S3, the heater 4 is turned off, and the process returns. On the other hand, if the internal temperature data t ₂ of the gyro 3 exceeds the target temperature T, the process proceeds to step S4, the heater 4 is turned on to heat the gyro 3, and the process returns.

In this way, the internal temperature data t ₂ of the gyro 3 from the temperature sensor 5 is fetched, and this temperature data t
₂ is compared with the target temperature T which is the temperature T ₀ at which the offset variation of the gyro 3 is most stable, and the heater 4 is turned on / off to keep the internal temperature of the gyro 3 at the target temperature T.
Since the OFF control is performed, fluctuations in the offset value of the gyro 3 due to temperature can be suppressed and stabilized.
Therefore, the turning angle error due to the drift of the offset can be further reduced, and the bearing can be accurately estimated.

Next, an embodiment of the invention described in claims 1-3 will be described in detail with reference to FIG . FIG. 3 is a flowchart showing the stable operation of the gyro temperature of the azimuth detecting apparatus according to the present embodiment. In the present embodiment, as shown in FIG. 3 , after the target temperature T of the internal temperature of the gyro 3 is set, it is determined whether or not the vehicle is traveling based on the output signal of the vehicle speed sensor 1, and the traveling of the vehicle is determined. During this traveling, the internal temperature t of the gyro 3 at the beginning of traveling detected by the temperature sensor 5
₂ is set as the temperature T ₁ to be held, and when the vehicle is stopped, the target temperature T and the internal temperature t ₂ of the gyro 3 detected by the temperature sensor 5 are compared, and based on this comparison result, the gyro In order to maintain the internal temperature t ₂ of the heater 3 at the target temperature T, the heater 4 is ON / OFF controlled, and when the vehicle is running, the holding temperature T ₁ inside the running gyro 3
Internal temperature t _{2 of} the gyro 3 detected by the temperature sensor 5
And the heater 4 is turned on / off in order to keep the internal temperature t ₂ of the gyro 3 at the holding temperature T ₁ based on the comparison result.
It is an OFF control.

The above operation will be described in more detail with reference to FIG . 3. After the start of the processing routine, the internal temperature data t ₂ of the gyro 3 is fetched from the temperature sensor 5 in step S1, and the vehicle speed sensor is read in step S2. 1
It is determined whether or not the vehicle is traveling based on the output signal of. If it is determined that the vehicle is traveling, it is further determined in step S3 whether or not the vehicle has started to move. If the vehicle has started to move, in step S4, the gyro at the beginning of traveling detected by the temperature sensor 5 is detected. The internal temperature t _{2 of} 3 is set as the temperature T ₁ to be maintained during traveling, and step S5
Move to On the other hand, if it is determined in step S3 that the holding temperature T ₁ has already been set, the process directly proceeds to step S5.

Then, in step S5, the temperature sensor 5
It is determined whether or not the internal temperature t ₂ of the gyro 3 detected in step S4 exceeds the internal holding temperature T ₁ of the gyro 3 during traveling set in step S4. Here, if the internal temperature t ₂ of the gyro 3 exceeds the holding temperature T ₁ , the heater 4 is turned off in step S6, and the process returns. on the other hand,
If the internal temperature t ₂ of the gyro 3 exceeds the holding temperature T ₁ , the heater 4 is turned on in step S7 and the process returns.

If it is determined in step S2 that the vehicle is stopped, in step S8 the gyro 3
It is determined whether or not the internal temperature data t _{2 of} exceeds the target temperature T. Here, the internal temperature data t ₂ of the gyro 3
If the temperature exceeds the target temperature T, the process proceeds to step S9,
Turn off the heater 4 and return. On the other hand, gyro 3
If the internal temperature data t ₂ of the temperature exceeds the target temperature T, the process proceeds to step S10, the heater 4 is turned on and the gyro 3 is turned on.
Heat and return.

As described above, the control of the internal temperature of the gyro 3 by the heater 4 is performed only while the vehicle in which the offset value of the gyro 3 can be accurately detected is stopped, and during traveling, the inside of the gyro 3 at the beginning of traveling is controlled. Since the temperature is maintained, the offset value of the stopped gyro 3 recognized by the locator 8 that occurs until the internal temperature of the gyro 3 is raised to the target temperature T is the offset value of the running gyro 3. Can be adopted as. Therefore, a turning angle error is not newly generated during traveling, and more accurate azimuth estimation can be performed.

The present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made within the scope of the present invention.

[0044]

As is apparent from the above description, claim 1
According to the invention described above, the control of the temperature of the turning angular velocity sensor is performed only while the vehicle that can accurately detect the offset value of the turning angular velocity sensor is stopped, and during running, the temperature of the turning angular velocity sensor at the beginning of the running is adjusted. Since it is held, the offset value of the turning angular velocity sensor during traveling can be made constant. Therefore, it is possible to more accurately estimate the azimuth even while traveling.

According to the second aspect of the invention, the temperature T at which the variation of the offset value of the turning angular velocity sensor is most stable.
_{Since 0} is set as the target temperature T of the temperature of the turning angular velocity sensor and the temperature can be controlled so that the temperature of the turning angular velocity sensor reaches the target temperature T, in addition to the effect of the invention according to claim 1, a change in temperature can be achieved. It is possible to suppress the variation in the offset value of the turning angular velocity sensor that is caused and reduce the turning angle error due to the drift of the offset value. Therefore, the direction can be accurately estimated.

According to the third aspect of the present invention, the temperature obtained by adding a constant value to the outside air temperature t ₁ detected by the outside air temperature detecting means is set as the target temperature T. Therefore, the outside air temperature t ₁ and the target temperature T
In addition to the effect of the invention of claim 1, the time to reach the target temperature T can be shortened regardless of the season, and a stable offset value of the turning angular velocity sensor can be obtained in a short time. Obtainable.

According to the fourth aspect of the invention, the temperature T at which the variation of the offset value of the turning angular velocity sensor is most stable.
_{Since 0} is set as the target temperature T of the temperature of the turning angular velocity sensor and the temperature can be controlled so that the temperature of the turning angular velocity sensor reaches the target temperature T, fluctuations in the offset value of the turning angular velocity sensor due to temperature changes are suppressed. It is possible to reduce the turning angle error due to the drift of the offset value.
Therefore, the direction can be accurately estimated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an azimuth detecting device.

FIG. 2 is a flowchart showing a stable operation of a gyro temperature.

FIG. 3 shows a stable operation of the gyro temperature of the azimuth detecting device .
It is a flowchart.

[Explanation of symbols]

 1 Vehicle speed sensor 3 Gyro 4 Heater 5 Temperature sensor 8 Locator 9 Offset memory 13 Outside air temperature sensor

Claims (4)

(57) [Claims] 1. A vehicle having a function of correcting an offset of a turning angular velocity sensor when the vehicle is stopped, taking in azimuth data obtained from the output of the turning angular velocity sensor, and estimating the current position of the vehicle from the value and past estimated azimuth data. In an azimuth detecting device for obtaining an azimuth, a sensor temperature detecting means for detecting a temperature t ₂ of a turning angular velocity sensor, a target temperature setting means for setting a target temperature T of the turning angular velocity sensor, and a running for judging whether or not a vehicle is running When the determining means and the traveling determining means determine that the vehicle has started traveling, the temperature t ₂ of the turning angular velocity sensor at the start of traveling detected by the sensor temperature detecting means during this traveling is set as the holding temperature T _1. The temperature setting means, the target temperature T set by the target temperature setting means and the temperature of the turning angular velocity sensor detected by the sensor temperature detecting means when the vehicle is stopped. comparing the t _2, based on the comparison result,
In order to keep the temperature t ₂ of the turning angular velocity sensor at the target temperature T,
First temperature control means for controlling the temperature of the turning angular velocity sensor,
Also, when the vehicle is traveling, the holding temperature T ₁ set by the holding temperature setting means is compared with the temperature t ₂ of the turning angular velocity sensor detected by the sensor temperature detecting means, and based on the comparison result,
To keep the temperature t ₂ of the turning angular velocity sensor to the holding temperature T _1, azimuth detecting device characterized by comprising a second temperature control means for temperature control of the turning angular velocity sensor. 2. The azimuth detecting apparatus according to claim 1, wherein the target temperature setting means sets a target temperature T ₀ which is a temperature T ₀ which is the most stable offset value of the turning angular velocity sensor. Direction detection device. 3. The azimuth detecting device according to claim 1, further comprising an outside air temperature detecting means for detecting an outside air temperature, wherein the target temperature setting means has an outside air temperature t detected by the outside air temperature detecting means. _The value obtained by raising a certain constant temperature to ₁ is the target temperature T
An azimuth detecting device characterized by the following. 4. A azimuth detecting device which takes in azimuth data obtained from an output of an offset-corrected turning angular velocity sensor and obtains a current estimated azimuth of a vehicle from the value and past estimated azimuth, wherein a temperature t of the turning angular velocity sensor Sensor temperature detecting means for detecting ₂ ; target temperature setting means for setting as a target temperature T of the turning angular velocity sensor a temperature T _{0 at} which the offset value of the turning angular velocity sensor is most stable, which is obtained by performing a temperature test in advance; The target temperature T set by the target temperature setting means and the temperature t _{2 of} the turning angular velocity sensor detected by the sensor temperature detecting means
And a temperature control means for controlling the temperature of the turning angular velocity sensor so as to keep the temperature t ₂ of the turning angular velocity sensor at the target temperature T based on the comparison result. [0001]