JPH04250313A - Travel distance calculating device for vehicle - Google Patents

Abstract

PURPOSE:To exactly calculate the travel distance for vehicles except for the vehicle the number of pulse generatons per one rotation of a drive shaft of which is preliminarily determined. CONSTITUTION:The travel distance calculating device receives and holds operating input numerical data indicating the number od pulses per one rotation of a drive shaft in answer to an iniyial setting command, calculates unit travel distance each time a pulse is generated based on the number of pulses per one rotation of the drive shaft, and exactly calculates the travel distance from the relationship between the counted value of pulses and the unit travel distance for each time a pulse is generated, even for vehicles except for the vehicles the number of pulse generations for one rotation of the drive shaft of which is preliminarily determined.

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. are doing.

However, there are cases where a pulse generator used as a distance sensor is used that is pre-installed on the vehicle, and in this case, the number of pulses generated per one revolution of the drive shaft may differ depending on the vehicle.
There is a problem in that it is not possible to accurately calculate the travel distance for vehicles other than those that generate a predetermined number of pulses.

[0005]

OBJECT OF THE INVENTION It is an object of the present invention to
It is an object of the present invention to provide a mileage calculating device capable of accurately calculating a mileage even in a vehicle other than a vehicle in which the number of pulses generated with respect to rotation is a predetermined number of pulses generated.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The vehicle mileage calculation device of the present invention counts the number of pulses generated in a vehicle equipped with a pulse generating means that generates a pulse every time a drive shaft rotates by a predetermined angle, and calculates a pulse count value. A device that calculates the traveling distance from the relationship with the unit traveling distance for each pulse generation, and includes a means for accepting numerical data in accordance with an initial setting command, and a means for accepting the received numerical data per rotation of the drive shaft. The present invention is characterized by having a holding means for holding the pulse number as the number of pulses, and a calculating means for calculating a unit traveling distance based on the numerical data held in the holding means.

[0007]

Effect of the Invention The vehicle mileage calculation device of the present invention accepts and holds operational input numerical data indicating the number of pulses per revolution of the drive shaft in accordance with an initial setting command, and Since the unit travel distance for each pulse generation is calculated based on the number of pulses per revolution, the number of pulses generated per revolution of the drive shaft should be set to an appropriate value even in vehicles other than the predetermined number of pulses generated. Can be done. Therefore, the travel distance can be accurately calculated from the relationship between the pulse count value and the unit travel distance for each pulse generation.

[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 in-vehicle 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, a distance sensor 3 detects the distance traveled by the vehicle, and the GPS ( Global
Positioning System) The device 4 is for detecting the absolute position of the vehicle from latitude and longitude information, etc., and the detection outputs of these sensors (devices) are 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, the processing procedure for calculating the travel distance executed by the CPU 7 will be explained with reference to the flowchart shown in FIG. This subroutine recognizes the current location of the vehicle based on the output data of the direction sensor 1 and the distance sensor 3, and extracts a group of map data of a certain area including the current location from the CD-ROM. During the execution of a main routine (not shown) that performs a process of reading out a map of the area around the current location of the vehicle and displaying it on the display 17, and displaying the own vehicle position indicating the current location of the vehicle on the map, or During the execution of the initial setting routine after installing the navigation device, the key input from the input device 21 is
When the menu for setting the number of pulses per revolution of the drive shaft is selected by input, this selection becomes an initial setting command that is called up and executed.

The CPU 7 first determines whether or not a numerical value indicating the number of pulses generated by the distance sensor 3 during one rotation of the drive shaft, ie, operation input data, has been input by key (step S1). When a numerical value is entered by the key, it is captured (step S2), and the captured numerical value is stored in the RAM 9 as a holding means as the number n of pulses generated during one revolution of the drive shaft (step S3). Further, the unit travel distance for each pulse generation is calculated and stored in the RAM 9 (step S4). J.I.
According to the S standard, a car's drive shaft is set to travel 1 km every 637 rotations, so from the number of pulses generated during one rotation of the drive shaft, n, 1
The unit traveling distance D for each pulse generation is D=1000/(n×637) [m]
...(1)
It can be calculated as follows.

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 in the main routine, etc., it reads the unit mileage D obtained from the above formula (1) from the RAM 9 and calculates RL=C×D [m]

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

In the above 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-described embodiment, the number of pulses generated is counted, but it is also possible to always obtain the traveling distance RL by adding the unit traveling distance D for each pulse every time a pulse is generated. good. Further, the present invention is not limited to being applied to the above-mentioned in-vehicle navigation device, but can also be applied to other devices, for example, simply displaying distance traveled.

[0020]

As described above, the vehicle mileage calculation device of the present invention accepts and holds numerical data indicating the number of pulses per revolution of the drive shaft in accordance with the initial setting command, and Since the unit traveling distance for each pulse generation is calculated based on the number of pulses per one revolution of the drive shaft, even if the number of pulses generated per one revolution of the drive shaft is not the predetermined number of pulses, it is possible to Since the number of pulses per rotation can be secured as data, the travel distance can be accurately calculated from the relationship between the pulse count and the unit travel distance for each pulse generated.

[Brief explanation of the drawing]

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.

[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 (2)

[Claims] Claim 1: In a vehicle equipped with a pulse generating means that generates a pulse every time a drive shaft rotates by a predetermined angle, the number of generated pulses is counted, and the counted value of the pulse and the unit traveling distance for each pulse generated are calculated. This is a device that calculates mileage based on the relationship between
holding means for holding the received numerical data as the number of pulses per rotation of the drive shaft; and calculating the unit traveling distance based on the numerical data held in the holding means. What is claimed is: 1. A vehicle mileage calculation device, comprising: calculation means for calculating a mileage of a vehicle. 2. The calculation means calculates and stores the unit travel distance from a relationship between the number of pulses per rotation of the drive shaft and a predetermined travel distance per unit rotation of the drive shaft. 2. The vehicle mileage calculating device according to claim 1, wherein the mileage is obtained by multiplying the pulse count value by the stored unit mileage.