JPH08334377A - Traveling distance detecting device - Google Patents

Abstract

PURPOSE: To provide a traveling distance detecting device which can detect the traveling distance of a traveling object with high accuracy from the unit of distance displayed on an odometer. CONSTITUTION: In a picture processing section 8, an arithmetic section 9 converts the output signal of an image pickup element into signals which can be processed by a collating section 11. The collating section 11 discriminates each numeric pattern shown by the signals by comparing the numeric patterns with numeric patterns from '0' to '9' stored in advance in a memory 10. The accuracy of a traveling distance signal is improved by dividing the interval between a currently displayed numeral and the next displayed numeral into (n) equal parts and collating the numeric pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling distance detecting device for autonomous navigation of a car navigation system using both satellite radio navigation and autonomous navigation.

[0002]

2. Description of the Related Art In recent years, a navigation system for displaying the current position of a vehicle together with a road map around the vehicle on a display device such as a CRT is mounted on the vehicle in order to assist the vehicle traveling on an unfamiliar land. Has been used.

Generally, a navigation system uses both satellite radio navigation and autonomous navigation. What is satellite radio navigation?
It receives radio waves from satellites to detect the current position of the vehicle, and this method is usually used. Among them, GPS (Gl
obal Positioning System). This is a method of receiving the time signals emitted from multiple artificial satellites, calculating the arrival time difference of the radio waves from each satellite, calculating the reception position together with the satellite orbit information, and measuring the vehicle position. .

However, since the frequency of the radio wave used in this method is high and the straightness is strong, it may be impossible to measure due to being blocked by buildings, mountains, tunnels, etc., or a measurement error may occur due to the influence of reflection. is there. In such cases, switch to autonomous navigation. This method estimates the vehicle position from the detection of the moving direction by a direction sensor or the like and the detection of the moving distance by an odometer (rangefinder) or the like. When using autonomous navigation, the lowest digit of the odometer display distance is OC.
There is a device that detects a traveling distance by reading with an R (Optical Character Reader) (Japanese Patent Laid-Open No. 6-213668).
(See the official gazette). This mileage detection device calculates the mileage of the vehicle by the calculation unit based on the change of the display distance of the odometer for each unit time, and the mileage data obtained as a result is in a predetermined format, for example, digital pulse data. Is output as.

The display distance of the odometer is the total distance traveled by the vehicle, all represented by numbers, the lowest digit being 1
A unit of 00 m is common. The light and shade of this number is received by the camera unit, photoelectrically converted, and output as an electric signal to the character recognition unit. The character recognition unit recognizes each of the display distances based on the input electric signal.

Then, an electric signal corresponding to the recognized number is output to the arithmetic unit every unit time. The calculation unit temporarily stores the electric signal output from the character recognition unit for each unit time. That is, a number representing the display distance is stored. Then, based on the change in the display distance for each unit time, the distance data of the vehicle traveling in the unit time is calculated, and the number of pulses corresponding to the calculated traveling data is output to the locator.

[0007]

SUMMARY OF THE INVENTION This mileage detecting device has the lowest digit (generally 1) of the odometer display distance.
00m unit) is read by OCR and the display distance is at least 10
Since it changes in units of 0 m, the change per unit time is 100 m
There has been a problem that the distance data is not updated unless the vehicle travels above. Even if the display distance is cut out, a huge storage capacity is required to continuously grasp the change per unit time.

An object of the present invention is to provide a traveling distance detecting device capable of detecting a traveling distance with higher accuracy than a display distance unit of a distance meter.

[0009]

SUMMARY OF THE INVENTION The present invention is a mileage detection device having a range finder for displaying a mileage and an image pickup device for reading a number displayed on the range finder, the range finder being displayed on the range finder. Storage means for storing n display patterns when the display moves to the next number at equal intervals with respect to the least significant digit, and the stored display pattern and the display pattern read by the imaging device. A matching unit that matches the stored display pattern and the read display pattern, and detects the traveling distance with n times the accuracy displayed on the rangefinder. To do.

Further, according to the present invention, when the least significant digit displayed on the rangefinder is moved to the next digit at equal intervals, the dead zone of the image pickup device between the n numbers is displayed. A matching unit that matches the stored display pattern with the display pattern read by the imaging device; and detects the match between the stored display pattern and the read display pattern by the matching unit. Then
It may be characterized in that the traveling distance is detected with n times the accuracy displayed on the rangefinder.

Also, the width of the space between the numbers is
It may be characterized by being smaller than the width of the numbers.

[0012]

In the present invention, the number indicating the distance traveled by the rangefinder is captured in the image pickup device, and the electric signal corresponding to the distance traveled is extracted by image processing. The display distance of the rangefinder is, for example, because numbers are printed on a rotating cylindrical piece,
The display distance moves continuously in the window. The moved display pattern for each number is stored in advance and collated with the fetched display distance, and when they match, an electric signal corresponding to the display distance is output. For the pattern for each number, if you prepare a display pattern that moves up to the next number that moves continuously by dividing it into n equal parts, a detailed distance signal that is one-nth of the distance displayed by the rangefinder will be obtained. Can be detected.

The same result can be obtained by storing a moving display pattern of the dead band of the image pickup device between the numbers and collating the display of the range finder. Here, the dead zone of the image pickup device is a blank portion that the image pickup device does not recognize as a number. At this time, even if the width of the dead zone to be detected is smaller than the width of the numeral, there is no problem in the detection. This is because the length and position of the dead zone in the moving direction are important in matching, and the width has little influence on detection.

[0014]

Embodiments of the present invention will be described with reference to the drawings. FIG.
FIG. 1 is a block diagram of a navigation system using a mileage detection device according to the present invention. This navigation system normally reads map data from the CD-ROM 3, processes the signal obtained from the GPS receiver 2 with the navigation engine 3, superimposes the vehicle position on the map, and displays it on the liquid crystal display 4. However, when the GPS receiver 2 is in a poor reception state and the vehicle position cannot be measured, the traveling direction of the vehicle is detected by the vibration gyro 5 as the autonomous navigation, and the traveling distance is obtained by solid-state imaging of the display distance of the odometer 6 on the meter panel. The image is captured by the device 7, and the image processing unit 8 performs image processing to perform character recognition. Then, it is output to the navigation engine 3 as a mileage signal, and an image is displayed on the liquid crystal display 4 by being superimposed on the map data.

Next, the display distance of the odometer 6 is changed to the image pickup device 7
A detailed description will be given of a mechanism for capturing an image as an image and converting it into a mileage signal. As described above, the solid-state image sensor 7 mounted on the odometer 6 captures the lower one digit of the display distance, and the captured pattern is sent from the solid-state image sensor 7 to the image processing unit 8 to extract the cross feature. Based on the law, recognition is performed by comparing patterns.

FIG. 2 shows a block diagram of the image processing section. In the image processing unit 8, the output signal from the image pickup device 7 is converted into a signal that can be processed by the matching unit 11 in the calculation unit 9. Each numerical pattern indicated by this signal is compared with the numerical patterns 0 to 9 stored in the memory 10 in advance by the collation unit 11 to be discriminated. Bottom 1 of odometer 6
The digit display is printed from 0 to 9 at equal intervals on the circumference of a rotating cylindrical piece. The numbers are not always located in the center of the display window. In particular, since the vehicle moves in proportion to the traveling speed during traveling, the minimum unit of display distance is generally detected only every 100 m in a single pattern comparison. So in the last digit of the odometer,
Prepare the pattern moved in the display window for each number.
For example, instead of recognizing only the number 3, the numbers 3 and 4 that move continuously, that is, the numbers 3 and 4
It recognizes the state where a part of is in the display window. Then, the interval between the currently displayed number and the next number is divided into n equal parts so that the traveling distance signal can be detected in more detail.

FIG. 3 shows how one of the numbers 0 to 9 moves within the display window of the odometer and the pattern changes. When the last digit of the odometer represents 100 m, in the embodiment, a scene in which the number changes from 3 to 4 is divided into 5 equal parts, and 5 types of patterns of 20 m per pattern are prepared. Bottom 1
FIG. 3A in which the digit pattern is stored in the memory in advance.
The image processing unit 8 detects the distance signal of the display 300 m at the time when If the displayed numbers match those in Fig. 3 (b),
The image processing unit 8 increases by ⅕ of the display distance unit 320
The distance signal of m is detected. Hereinafter, (c) to (k) of FIG.
The patterns up to are stored and 340 to 500 m are detected. In this way, a unit pulse is output each time the pattern matches the pattern stored in the memory. In this way each number 0 to 9
By preparing a similar pattern up to, it is possible to continuously detect the traveling distance in more detail than the display distance. Basically, the characters to be recognized are limited to the numbers from 0 to 9, and it is not necessary to recognize one character from a large number of characters like character recognition. Is.

In this way, by inputting the pulses into the navigation engine shown in FIG. 1 and accumulating the pulses, the traveling distance can be calculated and used as a signal for autonomous navigation.

Another distance detecting method will be described below. In the horizontal direction of the display window of the odometer 6, there is a dead zone for a portion where a number is not printed at all with a certain width, that is, for the image sensor. For example, as shown in FIG. 4, there is a dead zone S between the numbers 3 and 4 with a blank. The dead zone S continuously moves from the bottom to the top in the display window frame as the vehicle travels. Since the dead zone S has ten numbers 0 to 9 printed on the outer circumference of the cylindrical frame, the dead zone S in the blank portion between each number is limited to ten. If the detection device simply outputs one unit pulse each time one dead zone passes through the display window, 100 m per unit pulse can be represented. However, as shown in FIG. 5, it is stored in advance which position the dead band is located in the vertical direction in the window frame, and a unit pulse is output every time the displayed dead band S matches any pattern. The mileage can be detected in more detail than the displayed numbers. Since the order of the patterns that move with the traveling of the vehicle is fixed, it is possible to detect an error by matching the patterns with the matching pattern in order.

In this embodiment, five patterns were prepared so that the minimum detection distance was 20 m. In this embodiment, the dead zone is detected with a half width. This is because the pattern is identified by the difference in the length and the position of the dead zone in the vertical direction, so that the distance detection does not interfere even if the detection width is short. Figure 5
As shown in (a) to (e), for example, when the numeral 3 is located in the center of the display window frame, the dead zones S appearing at the upper and lower ends of the numeral 3 are detected to be 300 m, and the dead zone between 3 and 4 is set. S
However, it is detected as 320, 340, 360, 380 m by detecting the pattern in the state of moving upward in the figure. The distance signal with higher accuracy than the number displayed in this way is detected.

By inputting and accumulating the above pulses into the navigation engine 3 shown in FIG. 1, the traveling distance can be calculated,
It can be used as a signal for autonomous navigation. According to this method, the characters displayed on the odometer 6 are individually recognized, and the number is 3
Alternatively, it is possible to detect the traveling distance in detail without discriminating that the number is 4, use an image pickup device with low reading accuracy, and further simplify the recognition system, and it is possible to reduce the cost. Moreover, since the detection range can be reduced by halving the width of the dead zone S to be detected, the inexpensive imaging device 7 can be used.

[0022]

As described above, according to the present invention, in the autonomous navigation of car navigation, the display pattern of each moving number of the range finder is compared and collated with the previously stored display pattern, and the display distance unit of the range finder is compared. Since a more accurate mileage signal can be taken out, a car navigation system with less error can be constructed.

According to another aspect of the present invention, since the display pattern of the movement of the dead zone between the numbers is stored and compared with the detected display pattern, it can be realized by a simpler recognition system and can be made cheaper. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a navigation system using a mileage detection device according to the present invention.

FIG. 2 is a block diagram of an image processing unit used in this navigation system.

3A to 3K are explanatory diagrams showing movement patterns of numbers displayed on an odometer.

FIG. 4 is an explanatory diagram of a dead zone generated between numbers.

5 (a) to 5 (e) are explanatory views showing a dead zone pattern.

[Explanation of symbols]

 8 image processing unit 10 memory 11 collating unit

Claims (3)

[Claims] 1. A mileage detecting device having a range finder for displaying a mileage and an image pickup device for reading a number displayed on the range finder, wherein the least significant digit displayed on the range finder is: A display unit that stores the n display patterns when the display moves to the next number at equal intervals, and a collation unit that collates the stored display pattern with the display pattern read by the imaging device; A mileage detecting device, characterized in that the matching means detects a match between the stored display pattern and the read display pattern and detects the mileage with n times the accuracy displayed on the rangefinder. 2. A mileage detecting device having a range finder for displaying a mileage and an image pickup device for reading a number displayed on the range finder, wherein the least significant digit displayed on the range finder is: When moving to the next number at equal intervals, storage means for storing a display pattern of the dead zone of the imaging device between n numbers and the number, and the stored display pattern and the display pattern read by the imaging device are collated. And a matching unit that detects the match between the stored display pattern and the read display pattern by the matching unit, and detects the traveling distance with n times the accuracy displayed on the rangefinder. Distance detection device. 3. The mileage detection device according to claim 2, wherein the width of the space between the numbers is smaller than the width of the numbers.