JPH04315914A - Vehicle running distance calculating device - Google Patents

Abstract

PURPOSE:To calculate the accurate running distance constantly regardless of the working variation of parts such as tires, by increasing or decreasing a distance correcting coefficient to renew it corresponding to the distance difference between the crossed junction and the calculated present position. CONSTITUTION:Depending on the generating phase number in one rotation of a driving shaft 1, a unit running distance D at every one phase generation is calculated by a specific numerical formula, and the distance D is written in a ROM 8 or a RAM 9 beforehand. A CPU 7 finds a running distance RL by multiplying a numerical value C made by adding 1 to every pulse generation from a distance sensor 3, the unit running distance D which has been read, and the distance correcting coefficient R respectively, and the present location is recognized from this distance RL and the running bearings obtained by a bearings sensor 1. And when a vehicle is decided to run curving a junction, the distance between the present position by the present position recognition and the joint detected this time, that is, a retracting distance L is found. When L>0 as the result of the discrimination, a specific value is added to the coefficient R, and when L<0, it is subtracted. And every time when the relations L>0, or L<0 are discriminated, the stored value of the RAM 9 is renewed.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD This field relates to a vehicle mileage calculation device.

0002

[Background technology] Map data including road data obtained by digitizing each point on a road on a map is stored in a storage medium such as a CD-ROM, and the current location of the vehicle is recognized and An in-vehicle navigation system that reads a group of map data from a storage medium for a certain range of areas, including the area, and displays it on a display as a map of the area around the vehicle's current location, and automatically displays the own vehicle's position indicating the vehicle's current location on the map. The system is disclosed in, for example, Japanese Unexamined Patent Publication No. 63-12096 and is already known. Such an on-vehicle navigation device is configured to use a distance sensor to determine the traveling distance of the vehicle, and a direction sensor to determine the traveling direction of the vehicle, and to estimate the current location of the vehicle on a map from the traveling distance and the traveling direction.

[0003] By the way, the travel distance of a vehicle, which is required as data in a navigation device, is determined by the JIS standard as the vehicle's drive shaft travels 1 km at 637 rotations. is detected using. In other words, the distance sensor uses a pulse generator that generates pulses in synchronization with the rotation of the vehicle's drive shaft, and the distance traveled is calculated by obtaining the number of rotations of the drive shaft from the number of pulses generated by the pulse generator. has been done.

[0004] However, errors occur in the calculated mileage due to the type of vehicle tires, tire wear, tire air pressure, tire slip, and the like. Therefore, in order to compensate for this error, it has been conventional practice to multiply the calculated travel distance by a distance correction coefficient to correct it, as disclosed in, for example, Japanese Patent Laid-Open No. 140018/1983. However, if the once-set distance correction coefficient is always used as shown in this publication, the travel distance cannot always be determined accurately.

[0005]

OBJECTS OF THE INVENTION An object of the present invention is to provide a mileage calculation device that can always calculate an accurate mileage regardless of changes over time in parts such as tires of a vehicle.

[0006]

[Structure of the Invention] The vehicle mileage calculation device of the present invention detects the number of rotations of the drive shaft, calculates the vehicle mileage based on the detected number of rotations, and corrects and calculates the mileage using a distance correction coefficient. A driving distance calculation device that calculates an actual driving distance based on a detection means for detecting that the vehicle has turned around an intersection, and an actual driving distance calculated at the time when the detection means detects that the vehicle has turned around an intersection. The present invention includes a calculating means for calculating the current location of the vehicle, a means for detecting a distance difference between a curved intersection and the calculated current location of the vehicle, and an increasing/subtracting means for increasing/decreasing the distance correction coefficient according to the distance difference. It is characterized by

[0007]

[Operation of the Invention] In the vehicle mileage calculation device of the present invention, each time it is detected that the vehicle has turned at an intersection, the distance difference between the intersection at which the vehicle turned and the current location of the vehicle calculated at that intersection becomes small. (preferably 0), the distance correction coefficient is updated. Therefore, by calculating the vehicle mileage based on the number of rotations of the drive shaft and correcting it using the updated distance correction coefficient, accurate mileage can always be obtained regardless of changes in vehicle tires and other parts over time. be able to.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of an on-vehicle navigation system to which a mileage calculation system according to the present invention is applied. In this navigation device, a direction sensor 1 detects the running direction of the vehicle, an angular velocity sensor 2 detects the angular velocity of the vehicle, and a distance sensor 3 detects the distance traveled by the vehicle. Pos
tioning system) The device 4 is for detecting the absolute position of the vehicle from latitude and longitude information, etc., and the detection output of each of these sensors (devices) is supplied to the system controller 5. As the direction sensor 1, for example, a geomagnetic sensor is used that detects the running direction of the vehicle using geomagnetism (earth's magnetic field). Further, the distance sensor 3 includes a pulse generator that generates a pulse every time a drive shaft (not shown) of the vehicle rotates by a predetermined angle. This pulse generator is a known one that generates pulses by magnetically or optically detecting the rotational angular position of the drive shaft.

The system controller 5 has an interface 6 which receives the detection outputs of the sensors (devices) 1 to 4 and performs processing such as A/D (analog/digital) conversion.
Performs various image data processing and interface
A CPU (Central Processing Circuit) that calculates the vehicle's travel distance, travel direction, current location coordinates (longitude, latitude), etc. based on the output data of each sensor (device) 1 to 4 sent sequentially from the bus 6. 7 and a ROM (read/write) in which various processing programs and other necessary information for the CPU 7 are written in advance.
RAM (random access memory) 8 is used to write and read information necessary for executing programs.

[0010] External storage media include a read-only non-volatile storage medium such as a CD-ROM, and a writable and readable non-volatile storage medium such as a D-ROM.
AT (digital audio tape) is used. Note that external storage media include CD-ROM and DA.
It is also possible to use a non-volatile storage medium such as an IC card. The CD-ROM stores in advance map data obtained by digitizing (numerizing) each point on a road on a map. This CD-ROM is a CD-ROM
The stored information is read by the M driver 10. The read output of the CD-ROM driver 10 is CD-ROM
It is decoded by M decoder 11 and sent to bus line L.

On the other hand, the DAT is used as a so-called backup memory, and information is recorded or read by the DAT deck 12. When the vehicle power is cut off, information such as the current location coordinates of the vehicle stored in the RAM 9 immediately before is supplied to the DAT deck 12 via the DAT encoder/decoder 13 as backup data. The information stored in the DAT is read out by the DAT deck 12 when the vehicle power is turned on. The read information is sent to the DAT encoder/
The signal is sent to the bus line L via the decoder 13 and stored in the RAM 9.

Turning on and off the vehicle power is detected by a detection circuit 14 that monitors the output level of a so-called accessory switch SW of the vehicle. The vehicle power supply from the battery (not shown) via the accessory switch SW is regulated.
The power is stabilized by a power source 15 and supplied as power to each part of the device. Due to the time constant of the circuit, the output voltage of the regulator 15 does not fall instantly when the accessory switch SW is turned off, and during this falling period, backup data is stored in the DAT as a backup memory. It turns out.

[0013] When the vehicle is running, the CPU 7 operates a timer.
The running direction of the vehicle is calculated based on the output data of the direction sensor 1 at a predetermined period by an interrupt, and the running direction of the vehicle is calculated based on the running distance and the running direction by an interrupt every time a certain distance is traveled based on the output data of the distance sensor 3. Find the current location coordinates and save map data of a certain area including the current location coordinates to a CD-RO
The collected data is temporarily stored in the RAM 9 as a buffer memory and displayed on the display device 16.
supply to.

The display device 16 includes a display 17 such as a CRT, a graphic memory 18 consisting of a V (Video) RAM, etc., and a map data sent from the system controller 5 into the graphic memory 18. ―
a graphic controller 19 that draws as a data center and outputs this image data;
The display controller 20 controls the display of a map on the display 17 based on the image data output from the controller 19. The input device 21 consists of a keyboard or the like, and issues various commands to the system controller 5 through key input by the user.

Next, FIG. 2 shows a flowchart of the processing procedure for updating the distance correction coefficient R executed by the CPU 7.
The following subroutines are explained below. Note that this subroutine corrects each output data of the distance sensor 3 using the distance correction coefficient R, and recognizes the current location of the vehicle based on these corrected output data. A main routine that reads out a group of regional map data from a CD-ROM and displays it on the display 17 as a map of the area around the vehicle's current location, as well as displays the own vehicle position indicating the vehicle's current location on the map. (not shown) is a subroutine that is always executed as part of the main routine. It is assumed that the current location recognition operation continues.

[0016] Furthermore, when the navigation device detects that the vehicle has turned at an intersection, it uses current location recognition to detect an intersection near the current location from map data and sets this detected intersection as the current location on the map. It is assumed that so-called intersection pull-in is performed. The processing procedure for intersection pull-in is described in detail in Japanese Patent Laid-Open No. 11813/1983. This processing procedure digitizes each location on the road and the intersection location on the map and stores it as map data, and every time you drive a certain distance, the nearest neighbor on the road from your current location is determined based on the sensor output. The distance to the current location is determined based on map data, and when this distance is greater than a predetermined reference distance and it is detected that the vehicle has turned right or left, the nearest intersection from the current location is determined based on the map data. detect,
This detected intersection is recognized as the vehicle's current location.

In the subroutine, the CPU 7 first performs the following steps.
Determine whether the vehicle has turned at the intersection (step S1
). This determination method is, for example, the method disclosed in the above-mentioned publications, that is, the distance from the current location to the nearest position on the road line segment is determined from map data by current location recognition.
A method is used that detects that this distance is smaller than a predetermined reference distance and that the vehicle has turned right or left. Note that the method for determining whether a vehicle is turning right or turning left is also described in the publication.

[0018] When it is determined that the vehicle has turned at the intersection, the CP
U7 is the inter-intersection distance Lm between the currently detected intersection and the previously detected intersection by intersection retraction based on the map data.
Then, the distance between the current location based on current location recognition and the currently detected intersection, that is, the distance corrected by the intersection retraction (hereinafter referred to as retraction distance) ΔL is determined (step S2). It is determined whether the pull-in distance ΔL is greater than 0 (step S3), and if ΔL>0, as shown in FIG. 3, the intersection has not been reached on the map data, so the distance is corrected. Add a predetermined value to the coefficient R (step S4
). It is determined whether the pull-in distance ΔL is smaller than 0 (step S5), and if ΔL<0, the intersection has already been reached on the map data as shown in FIG. 4, so the distance is corrected. A predetermined value is subtracted from the coefficient R (step S6). Note that the initial value of the distance correction coefficient R is 1, which is stored in a predetermined area of the RAM 9 and updated every time step S5 or S6 is executed. In addition, in FIGS. 3 and 4, solid lines indicate roads, and broken lines indicate the trajectory of the vehicle based on current location recognition. For ease of understanding, each line is shown separately so as not to overlap.

On the other hand, if the number of pulses generated during one rotation of the drive shaft is n, then the JIS standard sets the car to travel 1 km every 637 rotations of the drive shaft, so the number of pulses generated per one pulse is set to n. The unit mileage D is D=1000/(n×637) [m]
...(1)
It can be calculated as follows. Unit mileage D is ROM
8 or RAM9. However, it is assumed that a value predetermined by the distance sensor 3 is used as the number n of pulses generated during one rotation of the drive shaft.

Each time a pulse is generated from the distance sensor 3, the CPU 7 performs pulse counting from a predetermined position, such as a starting point or an intersection, by interrupt processing. That is, if the pulse count value is C, then at the above predetermined position, C=
0, and the count value C is calculated every time a pulse from the distance sensor 3 is generated.
It adds 1 to and holds it. When the CPU 7 obtains the mileage RL as the actual mileage in the main routine, etc., it reads the distance correction coefficient R and the unit mileage D obtained from the above formula (1), and calculates RL=C×D×R [m ]

...(2) Calculate the travel distance RL from the following calculation formula.

The current location recognition operation is performed based on the travel distance RL calculated in this way and the travel direction obtained by the direction sensor 1. The subroutine described above may be executed by an interrupt process when it is detected that a turn has been made at an intersection. In this case, the subroutine is executed from step S2 in FIG. 2 by an interrupt, and the distance correction coefficient R is updated. Ru.

Furthermore, in the above-described embodiment, the distance sensor 3 was described as a mere pulse generator, but it may also be provided with a counter together with the pulse generator and output the counted value of the counter. In this case, the counter needs to be reset by a reset signal from the CPU 7. Further, such a counter may be provided in the interface 6 to perform counting.

Further, in the above embodiment, the number of pulses generated is counted, but the distance RL may always be obtained by adding D×R for each pulse generated. . Furthermore, the present invention is applicable to the above-mentioned in-vehicle navigation game.
The present invention is not limited to application to a driving distance device, but can also be applied to other devices, for example, simply displaying distance traveled.

Further, in the above-described embodiment, in step S3, it is determined whether or not the retracting distance ΔL is greater than 0, but it is determined whether or not the retracting distance ΔL is not 0 and is greater than an allowable value. It's fine. Also in step S5, the retraction distance ΔL
It is also possible to determine whether or not the value is smaller than a permissible value. Furthermore, when increasing or decreasing the distance correction coefficient R in steps S4 and S6, instead of always changing by a constant value, the increase or decrease value may be changed depending on the magnitude of the pull-in distance ΔL.

[0025]

[Effects of the Invention] As described above, the vehicle mileage calculation device of the present invention detects that the vehicle has turned at an intersection, and calculates the current location of the vehicle based on the actual mileage calculated at the time of detection. , the distance difference between the curved intersection and the calculated current location of the vehicle is detected, and the distance correction coefficient is increased or decreased and updated according to the distance difference. That is,
The distance correction coefficient is updated so that the distance difference between the curved intersection and the vehicle's current location calculated at the intersection becomes smaller. Therefore, by calculating the vehicle mileage based on the number of rotations of the drive shaft and correcting it using the updated distance correction coefficient, accurate mileage can always be obtained regardless of changes in vehicle tires and other parts over time. be able to.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a navigation device to which a mileage calculation device according to the present invention is applied.

FIG. 2 is a flow diagram showing the operating procedure of the mileage calculation device according to the present invention.

FIG. 3 is a diagram for explaining the operation of the mileage calculation device according to the present invention.

FIG. 4 is a diagram for explaining the operation of the mileage calculation device according to the present invention.

[Explanation of symbols of main parts]

1 Direction sensor 3 Distance sensor 5. System controller 10 CD-ROM driver 16 Display device 17 Display

Claims (3)

[Claims] Claim 1: A mileage calculation device that detects the number of rotations of a drive shaft, calculates the mileage of a vehicle based on the detected number of rotations, and corrects it using a distance correction coefficient to obtain the calculated actual mileage. a detection means for detecting that the vehicle has turned around the intersection; a calculation means for calculating the current location of the vehicle based on the actual travel distance at the time when the detection means detects that the vehicle has turned around the intersection; A vehicle mileage calculation device comprising: means for detecting a distance difference between an intersection and the calculated current location of the vehicle; and an increase/subtract means for increasing/decreasing the distance correction coefficient according to the distance difference. 2. The increase/subtract means increases the distance correction coefficient by a predetermined value if the distance difference is such that the calculated current location of the vehicle does not reach the curved intersection, and the increase/subtraction means increases the distance correction coefficient by a predetermined value. 2. The vehicle mileage calculation device according to claim 1, wherein if the distance difference is beyond an intersection, the distance correction coefficient is decreased by the predetermined value. 3. The vehicle mileage calculation device according to claim 1, wherein the calculation means calculates the current location of the vehicle using a travel direction of the vehicle in addition to the actual travel distance.