JPH04115118A - Locator - Google Patents

Abstract

PURPOSE:To make it possible to detect a more accurate position by dividing a period when a vehicle stops into appropriate sections, obtaining an offset value for every section, and performing correction by the newest offset value. CONSTITUTION:In a locator 1, the number of output pulses from a wheel-speed sensor 41 is counted with a counter, and the number of rotation of the wheel is obtained. The outputted counted data are multiplied by the specified constant which indicates a distance per count in a multiplier. Thus, the running distance output data per unit time are computed. Meanwhile, the relative change in vehicle bearing is obtained from a gyroscope 43, and the bearing output data of the vehicle are computed. The locater 1 obtains the output data of the gyroscope 43 when the vehicle stops. The bearing output data of the vehicle are corrected by using the offset value obtained by averaging the output data of the gyroscope 43 for every constant period when the vehicle stops.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention uses azimuth data etc. obtained by a turning angular velocity sensor (for example, a fiber optic gyro, a mechanical gyro, a vibration gyro, a gas rate gyro) to detect a vehicle. position,
The present invention relates to a locator device that specifies a direction.

<Prior art> Conventionally, as a locator device that detects the position and direction of a vehicle traveling at any point on a road transportation network, a direction sensor that detects the direction of the vehicle, a speed sensor that detects the traveling speed, and a It is known that the vehicle is equipped with two sensors, and the information detected by these sensors is integrated to determine the current position and direction of the vehicle.

In the past, most of the azimuth sensors used sensors that detected the difference in rotational speed between the widths of both vehicles, but a new technology using a turning angular velocity sensor has been developed.

When determining the bearing using a locator device using a turning angular velocity sensor, the current bearing θ of the vehicle is calculated based on the angular velocity data Δθ using the formula % formula %. θO is the direction determined at the previous sampling point.

Based on this azimuth data θ and the vehicle travel distance data, which is separately submerged, the east-west direction component ΔX (=Δ
) x cos θ) and the north-south direction component Δy (−Δ, i'
X5inθ) and the previous vehicle position data (PX',
Py'), the current vehicle position data (Px, Py) can be obtained.

Note that in reality, the output of the turning angular velocity sensor is a digital value, which is A/D converted by an A/D converter.
The turning angle is determined by feeding the signal to a computer and reading out the digital value.

Furthermore, some systems use a geomagnetic azimuth sensor to determine the absolute azimuth, and compare it with azimuth data obtained from the output of the turning angular velocity sensor to obtain more reliable azimuth data.

Incidentally, in turning angular velocity sensors, even when the sensor output should be O during straight travel, there is a tendency for some output (offset) to occur due to the influence of temperature and humidity. This offset output has the property of accumulating when the addition or integration processing as shown in the above equation 0 is repeated, so that a direction deviated from the actual running direction will be detected.

Therefore, it is necessary to perform offset correction of the output of the angular velocity sensor, but in order to perform this offset correction, offset data is obtained during the period when the mileage sensor or stoppage was indicated, and by taking the average of that period, the A method of offset-correcting the output of a turning angular velocity sensor is known.

According to this method, the offset of the angular velocity output can be corrected based on data while the vehicle is stopped, so the accuracy of the azimuth data during subsequent travel is guaranteed.

<Problem to be Solved by the Invention> In the above technology, the problem is how to process data while the vehicle is stopped. That is, what is most commonly considered is to take the average of the data during stoppage and use it as the offset value.

However, if the vehicle is stopped for a long time, the offset value itself may drift due to environmental changes such as a rise in temperature around the device even while the vehicle is stopped. For this reason, it is expected that taking an average over a long period of time will actually worsen the accuracy.

The present invention was made in view of the above problem, and it is possible to obtain an accurate offset value when the output data of a turning angular velocity sensor is taken in and the current orientation of a moving object is calculated from that value and the past detected orientation. It is an object of the present invention to provide a locator device that can detect a more accurate position by correcting the azimuth data.

Means for Solving the Problems> The locator device of the present invention for achieving the above objects has the following features:
As shown in FIG. 1, a turning angular velocity sensor 11, a stop determining means 12 for determining whether the moving object has stopped, and a stop determining means 1
2) Offset calculation means 14 for calculating the offset of the turning angular velocity sensor output based on the turning angular velocity sensor output data every time a certain period of time elapses from the time when the moving body indicates a stop;
, a storage means 18 for storing the latest offset value calculated by the offset calculation means 14, and a turning angular velocity sensor 1.
1, or azimuth data θ obtained by accumulating the angular velocity data of the moving object, using the latest offset value stored in the storage means 18. It is something that

According to the above configuration, the period during which the vehicle is stopped can be appropriately divided, the offset value can be determined for each section, and the offset can be corrected using the latest offset value. Even if there is a difference, it will be less affected by the fluctuation.

<Example> Embodiments will be described in detail below with reference to the accompanying drawings showing examples.

FIG. 2 is a block diagram showing an embodiment of the locator device of the present invention.

The locator device includes: - a wheel speed sensor 41 that detects the rotational speed of both left and right wheels (this sensor is used as a distance sensor) - a geomagnetic sensor 42 - a gyro 43 (a light that reads the turning angular velocity as a phase change of interference light) Selected from fiber gyros, vibrating gyros that detect turning angular velocity using cantilever vibration technology of piezoelectric elements, mechanical gyros, etc.

Used as a turning angular velocity sensor. ), - Calculates the estimated heading of the vehicle based on the output data detected by the road map memory 2 that stores the road map data, - the gyro 43 and the geomagnetic sensor 42, and calculates the estimated heading of the vehicle along with the data of the wheel speed sensor 41. A locator 1 that determines the current position and stores it in the memory 3, - A memory 20 attached to the locator 1, -
It displays the read current vehicle position on a map on a display 7, and also includes a navigation controller 5 that interfaces with a keyboard 8.

For example, the locator 1 obtains the rotational speed of the wheel by counting the number of output pulse signals from the wheel speed sensor 41, and uses a multiplier to calculate the number of rotations of the wheel by counting the number of output pulse signals from the wheel speed sensor 41. By multiplying by a predetermined constant indicating the distance per count, the mileage output data per unit time is calculated, and the gyro 4
3, the relative change in the vehicle direction is determined and the vehicle direction output data is calculated. Furthermore, the locator 1 corrects the azimuth output data of the vehicle using an offset value obtained by obtaining the output data of the gyro 43 while the vehicle is stopped and averaging this for each fixed period while the vehicle is stopped. It also has functions.

The buffer memory 20 stores the gyro 43 while the vehicle is stopped.
This is used to store offset data.

The road map memory 2 stores road map data covering a predetermined range in advance, and includes a semiconductor memory,
Cassette tape, CD-ROM.

IC memory, DAT, etc. can be used.

The display 7 uses a CRT, liquid crystal display, or the like to display a road map, the position and direction of the vehicle while the vehicle is traveling.

The navigation controller 5 is composed of a graphic processing processor, an image processing memory, etc., and performs map searching, scale switching, scrolling, etc. on the display 7.

A procedure for detecting vehicle direction using the device configured as described above will be explained. The locator device displays the vehicle's direction and position on the display 7 together with a map based on the output data of each sensor loaded into the locator 1.
3 output data, etc. are taken in, and the direction and position of the vehicle are updated. FIG. 3 shows a vehicle direction correction flow that is processed by interruption during this direction and position updating procedure. Note that this interrupt is performed every time one piece of output data from the gyro 43 is taken in.

First, in step (2), it is determined from the pulse output of the wheel speed sensor 41 whether the vehicle is stopped.

If the mobile body is stopped, in step (2), the mobile body waits for the elapse of a certain period of time Ta immediately after the mobile body stops. The output data of the gyro 43 obtained before this time Ta has elapsed will not be used. This is because immediately before the vehicle comes to a complete stop, the output of the wheel speed sensor 41 may be 0 even though the vehicle is moving a little.

After the elapse of time Ta, the output data Δθ of the gyro 43 is
Store in the FIFO memory built into locator 1 (step ■). This memory is structured so that when the data stored in the memory becomes full, the data stored first overflows. The capacity of the memory is selected so that (sampling time of the gyro 43) x (number of memories) = (certain time Tb immediately before the mobile body starts). This time Tb is
This corresponds to the period of time immediately before the vehicle starts, when the vehicle is considered to be moving slowly even though the output of the wheel speed sensor 41 is 0.

In step ■, wait until the FIFO memory overflows. When an overflow occurs, the overflow value is accumulated in the buffer memory 20 as the value S (step ■).
. That is, S - Σ Δ θ At the same time, a counter C indicating the number of data acquisition times is increased by 1 (step ■).

As described above, the data of the gyro 43 after the time Ta has elapsed since the vehicle stopped can be accumulated in S.

Therefore, the integrated value S is a value obtained by integrating the offset value of the gyro 43 over time when the vehicle is completely stopped.
In other words, it represents the orientation error. It should be noted that the FIFO mesori has data equivalent to the time TlH remaining, or this data is not used. Immediately before the pulse output from the wheel speed sensor 41 appears, the vehicle is considered to be moving slowly, so if the heading is corrected using the data remaining in the FIFO memory, not only the offset but also the
This is because there is a risk that actual driving data may be erroneously subtracted.

Furthermore, in step (2), it is determined whether the counter C has reached 01 or not. C1 corresponds to the time set to invalidate the previous offset value, because if the vehicle is stopped for a long time, the offset value itself may drift due to environmental changes such as a rise in temperature around the device even while the vehicle is stopped. is the number of sampling times. That is, the average of the offsets is performed only for the data corresponding to 01 pieces.

Letting to be the time corresponding to the number of sampling times C1, to is determined by the balance between the degree to which noise contained in the output data of the gyro 43 is reduced by averaging and the amount of drift of the output data of the gyro 43.

Suppose that the output data of the gyro 43 has a standard deviation of σo (deg/s), and the acquisition of that data is f (
Hz), the noise component of the obtained average value M is σ0/V−r1−, and decreases in proportion to the time t to the 11/2 power.

On the other hand, assuming that the drift increases in proportion to time, it is expressed by the following equation (m is a proportionality coefficient).

t Therefore, since the accuracy of the data will not increase after the time when the two cross, no matter how many averages are taken, it is sufficient to set the time when the two cross as t□.

It is expressed as

If the counter C has reached cl in step ■, calculate the average value M-S/C1 of 01 offset outputs (step ■), and store the average value M in the buffer 7 memory 20 (step [phase]) . If previous data remains in the buffer memory 20, the previous data is erased and the average value M is newly stored. Then, set C to 0 and set a flag to 1 to indicate that the average value M has been memorized (step ■).
.

Next, assume that it is determined from the pulse output of the wheel speed sensor 41 that the vehicle has started moving.

When the start of the vehicle is detected, the process proceeds from step ① to step @, and flag n is checked. If n is l, step ■
The average value M stored in the buffer memory 20 is read out. Then, using this data, Gyro 4
Offset correction is performed by subtracting from the output data of step 3 (step ■).

Step ① is a counter C indicating the number of times the data is stored.
Set it to O and clear the FIFO memory, S. In step [Yes], the flag is returned to O to indicate that offset correction has been completed.

If n-0 in step @, it means that the vehicle has completed offset correction, and returns to return.

As described above, when the vehicle starts for the first time after stopping, the offset can be calculated based on the output data of the gyro 43 while the vehicle is stopped, and the offset can be corrected. In this case, in step ①, we averaged the data divided by data number CI, replaced the old average value with the new average value, and corrected the offset using this new average value.
Even if the vehicle is stopped for a long time, the negative effects of drift in the offset value itself can be prevented as much as possible.

Furthermore, data from the geomagnetic sensor 41 may be used in combination, the current position of the vehicle is calculated from the obtained azimuth data and the travel distance data obtained from the output of the wheel speed sensor 41, and at this time, road map data and A map matching method may be adopted in which the estimated direction of the vehicle is corrected by comparing and evaluating the degree of correlation with road map data, and the current direction of the vehicle is set on the road (see Japanese Patent Laid-Open No. 148115/1983) ) etc. are conventional techniques, so their explanation will be omitted.

Although the locator device of the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. Various design changes can be made without departing from the gist of the invention.

<Effects of the Invention> As described above, according to the locator device of the present invention, a period is divided every time a certain period of time elapses from the time when the stop judgment means indicates that the moving body has stopped, and an offset is set for each divided period. Since the value can be determined and the offset can be corrected using the latest offset value, even if there is a fluctuation in the offset during a long period of time when the vehicle is stopped, the influence of the fluctuation is reduced.

By doing this, you will always get the correct offset value and
By correcting the orientation data, it becomes possible to detect a more accurate position.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing the configuration of the locator device of the present invention, FIG. 2 is a block diagram showing the hardware configuration of the locator device, and FIG. 3 is a flowchart showing the offset correction procedure. 1... Locator, 11... Turning angular velocity sensor, 12
...Stop judgment means, 14...Offset calculation means,
16... Orientation correction means, 18... Storage means, 20...
Buffer memory, 41...Wheel speed sensor, 42...
Gyro Figure 1 1 day patent applicant Sumitomo Electric Industries Co., Ltd. Agent

Claims (1)

[Claims] 1. Take in the azimuth data obtained from the output of the turning angular velocity sensor, determine the current estimated azimuth of the moving object from that value and the past estimated azimuth, and calculate the current estimated azimuth of the moving object along with the vehicle's travel distance data. A locator device that determines the position of a vehicle includes a turning angular velocity sensor, a stop determining means for determining whether a moving object has stopped, and a turning angular velocity sensor output data that is collected every time a certain period of time elapses from the time when the stop determining means indicates that the moving object has stopped. an offset calculation means for calculating an offset of the turning angular velocity sensor output based on the turning angular velocity sensor; a storage means for storing the latest offset value calculated by the offset calculating means; A locator device comprising azimuth correction means for correcting cumulatively determined azimuth data θ using the latest offset value stored in the storage means.