JPH0626865A - Vehicle orientation correction device - Google Patents

Abstract

(57) [Summary] [Structure] The difference between the turning angle of the vehicle obtained from the output of the GPS receiver 42 and the turning angle of the vehicle obtained from the output data of the gyro regardless of whether the vehicle is running or stopped. Based on, the offset is calculated even while the vehicle is running, and the gyro 4
Correct the output of 3. [Effect] Since the offset correction, especially the offset drift amount can be corrected even while the vehicle is traveling, a more accurate azimuth of the vehicle can be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle azimuth correcting device capable of correcting an offset of a gyro (for example, an optical fiber gyro, a mechanical gyro, a vibration gyro, a gas rate gyro).

[0002]

2. Description of the Related Art Conventionally, a gyro (hereinafter referred to as "gyro") and an output signal from the gyro are subjected to necessary processing as a device for detecting the direction of a vehicle traveling in an arbitrary portion of a road traffic network. It has been proposed to obtain the current heading data of the vehicle by using a heading change amount (angular velocity) Δθ that accompanies traveling of the vehicle and that includes a processing device.

The system adopted in this device is the angular velocity Δθ.
Based on the above, the present direction θ of the vehicle is calculated by θ = θo + Δθ. θo is the azimuth obtained at the time of the previous sampling. Based on this azimuth data θ and the 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 are calculated based on the previous vehicle position data. (Px
′, Py ′), the current vehicle position data (Px, Py) can be obtained. Therefore, the azimuth detecting device is used for detecting the position of the vehicle.

However, in the gyro, while the vehicle is traveling,
Regardless of the stop, there is a tendency that some output (offset) is generated under the influence of temperature and humidity. Since this offset output has a property of accumulating, a direction deviated from the actual traveling direction will be detected. Therefore, it is necessary to always obtain an accurate offset value and correct the detected angular velocity. Therefore, a method is considered in which the offset amount is subtracted from the data during the subsequent traveling by utilizing that only the offset amount appears in the output of the gyro when the vehicle is stopped at the signal. Various devices for correcting the offset by using the output of the gyro while stopped have been proposed (for example, Japanese Patent Publication No. 58-3).
9360 gazette).

[0005]

However, the gyro offset has the property of drifting due to changes in temperature and humidity regardless of whether the gyro is stopped or running. Therefore, the offset value measured while the vehicle is stopped changes due to the drift after starting, and as a result, an error occurs in the azimuth obtained despite the offset correction.

FIG. 8 is a graph showing how the output of the gyro drifts with time t, and the true offset value Ω deviates from the estimated offset value Ω ′ measured while the vehicle is stopped at time to. You can see how it goes. A value obtained by integrating the difference between Ω and Ω ′ with time becomes the estimated heading error S. If the time from the start of the vehicle to the next stop is short, the correction can be performed again while the drift is small, but if the time from the start of the vehicle to the next stop is long, there is no opportunity to correct the offset and the drift is large. Become. Therefore, the error due to the drift amount is accumulated.

It is an object of the present invention to provide a mileage sensor, a gyro, and a vehicle position detecting device for detecting the position of the vehicle based on the mileage data and the azimuth data of the vehicle obtained from the mileage sensor and the gyro. It is an object of the present invention to provide a vehicle azimuth correction device that can accurately correct an offset value of a gyro used for detection even while the vehicle is traveling.

[0008]

A vehicle heading correction apparatus of the present invention for achieving the above object obtains vehicle heading data supplied from a GPS receiver and an accumulating means for accumulating output data of a gyro. The azimuth data acquiring means, the first calculating means for obtaining the turning angle of the vehicle based on the azimuth data when the azimuth data acquiring means acquires the vehicle azimuth data twice. The difference between the turning angle of the vehicle obtained by these two calculating means and the second calculating means for obtaining the turning angle of the vehicle between the two acquisitions based on the integrated value of the output data of the gyro,
It has an offset calculation means for obtaining an offset value of the gyro output by dividing the time obtained by the two acquisitions, and an offset correction means for performing offset correction of the gyro output using the offset value obtained by the offset calculation means. Is.

[0009]

According to the present invention, azimuth data is obtained twice from the output of the GPS receiver regardless of whether the vehicle is running or stopped.
The turning angle of the vehicle during this period is obtained. Further, the output data of the gyro is integrated and the turning angle of the vehicle is obtained based on the integrated value. Based on the difference between these two angles, the output of the gyro can be corrected by obtaining the offset even while the vehicle is traveling.

In this way, offset correction, especially correction including offset drift, can be performed even while the vehicle is traveling, so a more accurate vehicle azimuth can be detected. The GPS (Global Positioning System) is a technology for positioning one's position by using radio waves from GPS satellites, and its principle is that a plurality of artificial satellites orbiting in a predetermined orbit are generated. The two-dimensional or three-dimensional position of the self is measured by measuring the propagation delay time of the radio wave. To find the heading of a vehicle with a GPS receiver,
The Doppler shift generated by receiving radio waves from GPS satellites while traveling may be measured.

[0011]

Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments. FIG. 1 is a block diagram showing an embodiment in which the vehicle azimuth correction apparatus of the present invention is applied to a vehicle position detection apparatus.
The vehicle position detection device includes a wheel speed sensor 41 (this sensor is used as a distance sensor) that detects the number of rotations of the left and right wheels, a GPS receiver 42, and a gyro 43 (turning angular velocity as a phase change of interference light). Optical fiber gyro to be read, vibration gyro that detects turning angular velocity using cantilever vibration technology of piezoelectric element, mechanical gyro, etc.), road map memory 2 that stores road map data, locator 1, a shift type buffer memory 21 attached to the locator 1, and a navigation controller 5 for displaying the detected current vehicle position on the map on the display 7 and for interfacing with the keyboard 8.

The locator 1 obtains the number of rotations of a wheel by counting the number of output pulse signals from the wheel speed sensor 41 with a counter, and the count output data output from the counter is multiplied by a multiplier. The traveling distance output data per unit time is calculated by multiplying by a predetermined constant indicating the distance per count, and
Calculate the relative change of the vehicle direction from the gyro 43, and
The azimuth output data of the vehicle is calculated from the absolute azimuth output data of the PS receiver 42, and the vehicle position is detected based on the traveling distance and the azimuth of the vehicle.

In addition, the locator 1 according to the present invention is a G
The turning angle of the vehicle is calculated based on the output data detected twice by the PS receiver 42, and the turning angle of the vehicle during this time is calculated based on the integrated value of the output data of the gyro 43. And the offset value of the gyro output is obtained by dividing by the time when the two acquisitions are performed, and the offset correction is performed.

The road map memory 2 stores road map data covering a predetermined range in advance, and a semiconductor memory, a cassette tape, a CD-ROM, an IC memory, a DAT or the like can be used. The display 7 uses a CRT, a liquid crystal display or the like to display a road map and a vehicle direction while the vehicle is traveling.

The navigation controller 5 is
Consists of a graphics processor, image processing memory, etc.,
Searching the map on the display 7, switching the scale,
Scroll and display the current direction of the vehicle. A vehicle azimuth correction procedure performed by the device having the above configuration will be described. While the vehicle is traveling, the azimuth and position of the vehicle are displayed together with the map on the display 7 based on the output data of each sensor fetched in the locator 1, and the GPS receiver 42 is also displayed at regular intervals during the display. The output data of is captured.

FIGS. 2 and 3 show vehicle azimuth correction flows that are processed by interruption based on the output data of the GPS receiver 42 regardless of whether the vehicle is moving or stopped. Further, FIG. 4 shows an example of the time distribution of the traveling speed of the vehicle. First, when the output data of the GPS receiver 42 is acquired, it is determined in step S1 whether an end determination flag (described later) is on. Since it is not on at first, step S
The routine proceeds to step 2 to determine whether the current vehicle speed v obtained from the wheel speed sensor 41 exceeds the reference speed vc. Here, the reference speed is compared with the reference speed vc because when the speed of the vehicle is obtained from the output data of the GPS receiver 42, the smaller the speed of the vehicle is, the more the speed of the vehicle obtained includes the error r. VP is provided, and only when the current vehicle speed v exceeds the reference speed vc, GP
This is because the output data of the S receiver 42 is adopted. If the current vehicle speed v does not exceed the reference speed vc, the GPS azimuths θ1 and θ2 and the vehicle speeds v1 and v2 stored in the buffer memory 21 are cleared to 0 (step S10). The current vehicle speed v is the reference speed v
If it exceeds c, the process proceeds to step S3, and it is determined whether the output data of the GPS receiver 42 is valid. When the output data is not valid, for example, the vehicle is blocked by a building or a mountain so that a predetermined number of GPS satellites cannot be seen. If the output data is valid, the GPS azimuth θ2 stored in the buffer memory 21 is moved to θ1 and the vehicle speed v2 is moved to v1 (step S4). Then, the effective GPS azimuth θ is stored as θ2, and the vehicle speed v at that time is stored as v2 (see FIG. 5).

Then, in step S5, it is determined whether or not it is the first time acquisition of GPS data. If it is the first time, since there is no data in θ1 and v2, the process proceeds to step S11 and the gyro 43 is integrated. Clear the value. If it is not the first time, the current speed v in step S6
It is determined whether 2 is smaller than the previous speed v1.
If it is smaller, it can be confirmed that the vehicle has started decelerating (see the peak at time t1 in FIG. 4), so the end determination flag is turned on (step S7) and the previous speed v1
And the GPS azimuth θ1 are registered (step S8), the velocity v1 thus registered is set to vA, and the GPS azimuth θ1 is set to θA. Further, the integration of the output data of the gyro 43 is started (step S9).

Returning to the beginning, when the next step S1 comes, since the end determination flag is turned on, the process proceeds to step S21 of FIG. 3 and whether or not the data integration time of the gyro 43 exceeds a certain time Tc. Find out. If the data integration time is too short, the data will have a large error. Therefore, the correction is intended only when the time Tc is set and the data is integrated longer than this. It is also for avoiding complicated offset correction.

If the data integration time exceeds the fixed time Tc, the process proceeds to step S22, and it is determined whether or not the current vehicle speed v obtained from the wheel speed sensor 41 exceeds the reference speed vc, and YES. If so, step S23
Then, it is determined whether the output data of the GPS receiver 42 is valid, and if it is valid, the stored content of the buffer memory 21 is shifted (step S24) and it is checked whether it is the first time (step S25). If not, it is confirmed whether or not the vehicle has started decelerating (step S26), and when deceleration is started (see the peak at time t2 in FIG. 4),
It proceeds to step S27.

In step S27, the previous speed v1 and the GPS azimuth θ1 are registered, and the speed v1 thus registered is set to vB and the GPS azimuth θ1 is set to θB. Then, the offset estimation error ε of the gyro output is calculated based on the following equation. ε ² = η ² / T + {κΣφ (t)} ² / T ² + {r ² (v1)
+ R ² (v2)} / T ² where t1 is the time when vA and θA are registered in step S8, t2 is the time when vB and θB are registered in step S27, and T = t2-t1 η : Gyro noise (constant) κ: Gyro scale factor (constant) Σφ (t): Gyro output φ (t) integrated from t1 to t2 r (v): GPS heading error. As shown in FIG. 6, r (v) is obtained in advance as a function of vehicle speed (for example, r (v) = av ^-1 + b, a, b: constant) (at step S2, the current vehicle It is also determined whether the vehicle speed v exceeds the reference speed vc because the GPS heading error r (v) increases when the current vehicle speed v falls below the reference speed vc). The offset estimation error ε has the property of decreasing with time as can be inferred from the form of the equation.

In step S28, the drift amount Ω of the offset of the gyro output is obtained by the following equation, for example. Ω = Be + be × T Here, Be is an offset value when the offset is corrected last time, be is an offset fluctuation rate per unit time, and all are known values.

Then, the offset estimation error ε is compared with the offset drift amount Ω, and if ε <Ω, offset correction is performed (step S29, see FIG. 7). That is, the offset correction amount δ is calculated based on the following equation. δ = {Σφ (t)-(θB-θA)} / T As described above, azimuth data θA and θB are obtained when the vehicle speed is maximum regardless of whether the vehicle is running or stopped. The turning angle (θB−θA) of the vehicle is calculated. Further, the output data of the gyro is integrated to obtain, and the turning angle Σφ (t) of the vehicle is obtained based on the integrated value.

The offset correction amount δ can be obtained based on the difference between these two angles, and the output of the gyro can be corrected. In this case, the azimuth data is adopted on condition that the vehicle speed v exceeds the reference speed vc and the vehicle speed v has a maximum value. Thereby, the azimuth data under the best condition can be adopted.

Further, the offset estimation error ε is predicted from the curve of FIG. 6 and compared with the offset drift amount Ω, and the correction is made only when the offset estimation error ε is less than the drift amount Ω. As a result, it is possible to avoid meaningless offset correction that causes an increase in error. Further, since the offset correction is performed only when the integrated time of the gyro output is longer than the reference time Tc, the complicated offset correction can be avoided.

The gyro output data thus offset-corrected is used together with the traveling distance data obtained from the output of the wheel speed sensor 41 to calculate the current position of the vehicle. At this time, a map matching method may be employed in which the estimated heading of the vehicle is corrected by comparing the degree of correlation with the road map data, the estimated heading of the vehicle is corrected, and the current heading of the vehicle is set on the road. (See Sho 63-148115).

Although the vehicle heading correction apparatus of the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the present invention. It is possible to apply.

[0027]

As described above, according to the present invention, the turning angle of the vehicle obtained from the output of the GPS receiver and the vehicle obtained from the output data of the gyro are obtained regardless of whether the vehicle is running or stopped. The offset of the gyro can be corrected based on the difference from the turning angle of the gyro even when the vehicle is traveling.

Therefore, even when the vehicle is running, the offset correction, particularly the offset drift amount correction can be performed, so that a more accurate vehicle azimuth can be detected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a hardware configuration of a position detection device incorporating a vehicle orientation correction device of the present invention.

FIG. 2 is a flowchart showing a direction correction procedure.

FIG. 3 is a flowchart showing a azimuth correction procedure (sequel to FIG. 2).

FIG. 4 is a running speed distribution map of the vehicle.

5 is a diagram showing a structure of a buffer memory 21. FIG.

FIG. 6 is a graph showing the relationship between GPS heading error and vehicle speed r (v).

FIG. 7 is a graph showing changes in offset estimation error ε and offset drift amount Ω.

FIG. 8 is a graph showing how the offset included in the output data of the gyro varies.

[Explanation of symbols]

 1 Locator 21 Buffer Memory 41 Wheel Speed Sensor 42 GPS Receiver 43 Gyro

Claims (1)

[Claims] 1. A gyro output, which is used for a vehicle distance detection device, a gyro, and a vehicle position detection device for detecting the position of a vehicle based on the vehicle mileage data and azimuth data obtained from the mileage sensor and the gyro. An integrating means for accumulating data, an azimuth data acquiring means for acquiring vehicle azimuth data supplied from a GPS receiver, and a vehicle azimuth data acquiring means for acquiring these two times when the vehicle azimuth data is acquired twice. First calculating means for obtaining a turning angle of the vehicle based on the azimuth data during the above-mentioned operation, and second calculating means for obtaining a turning angle of the vehicle during the two acquisitions based on an integrated value of output data of the gyro. The offset value of the gyro output is obtained by taking the difference between the turning angles of the vehicle obtained by these two calculation means and dividing by the time when the two acquisitions are made. Offset calculation means, a vehicle heading correction apparatus characterized by comprising an offset correction means for performing an offset correction of the gyro output with the offset value determined from the offset calculating means for determining.