JPH051920A - Moving distance detecting device for vehicle - Google Patents

Abstract

PURPOSE:To precisely detect the moving distance of a vehicle and facilitate the mounting on the vehicle. CONSTITUTION:The acceleration of a vehicle is detected by an acceleration sensor 4 provided on the vehicle, and the inclination of the vehicle within a vertical plane including the longitudinal direction of the vehicle is detected by an inclination sensor 5 provided on the vehicle. A horizontal acceleration component is determined from these detection outputs by a horizontal acceleration calculating part 6a. The determined horizontal acceleration component is doubly integrated in a time area by a horizontal moving distance calculating part 6b to determine the horizontal moving distance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle moving distance detecting apparatus, and more particularly to a vehicle moving distance detecting apparatus suitable for an on-vehicle navigator for detecting a vehicle position by dead reckoning.

[0002]

2. Description of the Related Art There is a vehicle-mounted navigator that guides a vehicle so that a driver can easily reach a desired destination. In this in-vehicle navigator, the position of the vehicle is detected, the map data around the vehicle position is read from the CD-ROM, the map image is drawn in the V-RAM, and the vehicle position mark is superimposed on a predetermined position on the map image. Draw and
The V-RAM image is output to the CRT display device while being converted into a video signal and displayed on the screen. As the current position changes due to the movement of the vehicle, the vehicle position mark is fixed at the center of the screen and the map is scrolled so that the map information around the vehicle position can always be seen at a glance.

In the vehicle-mounted navigator, there are a method of obtaining the vehicle position by satellite navigation such as GPS and a method of obtaining the vehicle position by detecting the azimuth and moving distance and by dead-reckoning navigation. The former can detect the absolute position, but it has the drawbacks of being expensive and not being able to detect the position where satellite radio waves are blocked, such as tunnels and buildings.Therefore, the latter is often used for dead reckoning vehicle position detection. Has been done.

The principle of dead reckoning will be described with reference to FIG. 6, in which the coordinates of the starting point are defined as points P ₀ (X ₀ , Y on the X, Y coordinate system.
₀ ), the vehicle direction at the departure point measured counterclockwise from the X coordinate axis is θ ₀ , and the vehicle directions are θ ₁ , θ ₂ , θ ₃ , ..., θ each time the vehicle moves a certain distance L _{0. When} changing to _i , X _i = X ₀ + L ₀ [cos {(θ ₀ + θ ₁ ) / 2} + cos {(θ ₁ + θ ₂ ) / 2} + cos {(θ ₂ + θ ₃ ) / 2} + ·· + cos {(θ _i-1 + θ _i ) / 2}] Y _i = Y ₀ + L ₀ [sin {(θ ₀ + θ ₁ ) / 2} + sin {(θ ₁ + θ ₂ ) / 2} + sin {( The current vehicle position P _i (X _i , Y _i ) is obtained as θ ₂ + θ ₃ ) / 2} + ... + sin {(θ _i-1 + θ _i ) / 2}].

To detect the moving distance in a conventional vehicle-mounted navigator, a rotation sensor utilizing a Hall element or the like is coupled to a wheel rotation drive system, and the rotation sensor detects, for example, one pulse per one rotation of the wheel. Every time the rotation is detected and the counter counts, for example, 3 pulses (= 3 rotations), a signal indicating that the vehicle has moved a fixed distance L ₀ is output to the vehicle position calculation unit. The vehicle position calculation unit inputs the vehicle direction from the direction sensor each time a signal indicating that the vehicle has moved L ₀ is input, and calculates the vehicle position by the above-described calculation formula. If the diameter of the wheel is 63 cm, L ₀ will be approximately 6 m.

[0006]

However, in the method of detecting the moving distance from the rotation of the wheel, for example, as shown in FIG. 7, an upward slope of _a length L _{a with} an inclination angle θ _a during the movement,
When slope with a descending slope of the length L _b at an inclination angle theta _b is present, while the moving distance of the overall slope is detected as L _a + L _b, the actual horizontal distance traveled L _a cos θ _a + L _b cos θ
_b only _{without, δL = L a (1-} cos θ a) + L b (1-cos θ b) only, the error occurs. This movement error cannot be removed even if the accuracy of the rotation sensor is improved, and it accumulates every time the vehicle travels on a slope, so it is displayed overlaid on the map screen by the in-vehicle navigator during long-distance travel. There has been a problem that the vehicle position of the vehicle greatly deviates from the actual position. Further, even if an in-vehicle navigator is to be retrofitted to a vehicle, it is difficult to attach a rotation sensor to a wheel rotation drive system, and an in-vehicle navigator cannot be installed unless it is an automobile manufacturer.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle movement distance detecting device capable of accurately detecting the movement distance of a vehicle and being easily mounted on the vehicle.

[0008]

According to the present invention, there is provided a horizontal acceleration detecting means for detecting a horizontal acceleration of a vehicle, and a horizontal acceleration detected by the horizontal acceleration detecting means is double integrated in a time domain. This is achieved by providing a calculation means for obtaining the horizontal movement distance by

[0009]

According to the present invention, the horizontal acceleration of the vehicle is detected, and the detected horizontal acceleration is double integrated in the time domain to obtain the horizontal movement distance. As a result, even if the vehicle travels on a road having a difference in altitude such as a slope, the horizontal movement distance can be accurately detected, and the vehicle can be easily mounted.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an essential part of an in-vehicle navigator according to an embodiment of the present invention.

In the figure, 1 is a C storing map data.
D-ROM, 2 is an operation panel, which is provided with left, right, up, and down cursor keys, a departure point setting key, a map search key, an enlargement / reduction key, a start key, and the like. Reference numeral 3 denotes an azimuth sensor which is installed at a predetermined location of the vehicle and detects an azimuth in the traveling direction of the vehicle. Reference numeral 4 denotes an acceleration sensor which is installed at a predetermined location of the vehicle and detects an acceleration applied to the vehicle while the vehicle is running. A servo type acceleration sensor is used. Reference numeral 5 denotes a tilt angle sensor which is installed at a predetermined position of the vehicle and detects a tilt angle of the vehicle in a vertical plane including the front-back direction of the vehicle.

Reference numeral 6 is an output of an orientation sensor, an output of an acceleration sensor,
Reference numeral 6a denotes a vehicle position detection unit having a microcomputer configuration for detecting a vehicle position by performing a predetermined calculation based on the output of the inclination angle sensor. Of these, 6a indicates the horizontal acceleration of the vehicle from the outputs of the acceleration sensor 4 and the inclination angle sensor 5. It is a horizontal acceleration calculation unit for calculation. The horizontal acceleration calculator 6a inputs the acceleration signal output from the acceleration sensor 4 and the inclination angle signal output from the inclination angle sensor 5, and as shown in FIG. 2, the acceleration a (t) indicated by the acceleration signal. And the tilt angle θ indicated by the tilt angle signal
_The horizontal acceleration a _H (t) is obtained by calculating a _H (t) = a (t) × cos θ _V (t) from _V (t).

Reference numeral 6b denotes a horizontal movement distance calculation unit which double-integrates the horizontal acceleration calculated by the horizontal acceleration calculation unit 6a to calculate a horizontal movement distance (horizontal movement distance along a running locus). The horizontal vehicle speed is obtained by integrating a _H (t) once in the time domain, and the horizontal moving distance is obtained by further integrating this horizontal vehicle speed once in the time domain. In addition,
The integration constant = initial speed appearing in the equation of the horizontal vehicle speed when the horizontal acceleration a _H (t) is integrated once in the time domain can be set to zero if the calculation is started from the stopped state of the vehicle. Similarly, the integration constant appearing in the equation when the horizontal vehicle speed is integrated once in the time domain = the initial moving distance can be set to zero.

Reference numeral 6c inputs a heading signal from the heading sensor 3 every time the horizontal moving distance calculated by the horizontal moving distance calculating section 6b increases by a constant distance L ₀ , calculates the vehicle position by dead reckoning, and outputs the vehicle position data. It is a vehicle position calculation unit that outputs to a navigation controller described later. When outputting the vehicle position data, the vehicle position calculation unit 6c also outputs the data of the vehicle direction detected by the direction sensor 3 to the navigation controller.

A CRT display device 7 inputs a video signal and displays a map image and a vehicle position mark on the screen. Reference numeral 8 denotes a navigation controller, which inputs the vehicle position data and the vehicle direction data from the vehicle position detector 6, reads the map data around the vehicle position from the CD-ROM 1, and displays the map together with the vehicle position mark on the screen of the CRT display device 7. To display.

Reference numeral 8a is a buffer memory for temporarily storing the map data read from the CD-ROM 1, and 8b is a cursor position calculation unit, which is a cursor key of the operation panel 2, a map search key, a key for enlarging / reducing a map, etc. When the selection operation or cursor operation is performed, the longitude and latitude corresponding to the center of the map on the screen are calculated and output as the cursor position. 8
Reference numeral c is a map drawing control unit which, from the CD-ROM 1 to a buffer memory 8 stores desired map data selected by a key such as a map search and enlargement / reduction key on the operation panel 2 before starting traveling.
As the map position is read out to a and a map image is drawn in the V-RAM described later, or the cursor position input from the cursor position calculation unit 8b changes in accordance with the cursor operation,
If necessary, new map data is read from the CD-ROM 1 to the buffer memory 8a, the map image of the V-RAM is rewritten so that the cursor position is always at the center, and a cursor mark is drawn at the center of the V-RAM. Further, the map drawing control unit 8c, when traveling (after pressing the start key), changes new map data as necessary as the vehicle position data output from the vehicle position detection unit 6 changes.
While reading from the D-ROM 1 to the buffer memory 8a, the map image in the V-RAM is rewritten so that the vehicle position is at the center. Further, the map drawing control unit 8c draws a vehicle position mark in the center of the V-RAM so as to face a predetermined direction based on the vehicle direction data during traveling.

Denoted at 8d is a starting point setting section. Before the start of traveling, when the cursor at the center of the screen is aligned with the starting point by operating the operation panel 2 and the starting point setting key is pressed, the current point is set. The output of the cursor position calculation unit 8b is set as the departure point data and is output to the vehicle position detection unit 6 and the map drawing control unit 8c. 8e is a V-RAM, and the map drawing control unit 8
The map image drawn in c (including the cursor mark when the cursor is operated before the start of traveling and including the vehicle position mark during traveling) is stored. A video conversion unit 8f converts the image data output from the V-RAM 8e into a video signal and outputs the video signal to the CRT display device 7.

FIG. 3 is a flow chart showing the operation of the navigation controller 8, FIG. 4 is a flow chart showing the operation of the vehicle position detecting section 6, and FIG. 5 is an explanatory view for explaining the operation of the horizontal moving distance by the horizontal moving distance calculating section 6b. Yes, and will be described below with reference to these figures.

First, when a map search operation of the operation panel 2 and a selection operation of a map of a desired area at a desired scale by operating keys for enlarging / reducing, the map drawing control unit 8c causes the desired map from the CD-ROM 1. The data is read to the buffer memory 8a, a map image is drawn on the V-RAM 8e, the video conversion unit 8f converts the video signal to output to the CRT display device 7, and the map is displayed on the screen (step 101 in FIG. 3, 1
02). Next, when the cursor key is operated on the operation panel 2, the cursor position calculation unit 8b calculates the cursor position (coordinates of longitude and latitude) (steps 103 and 104), and the map drawing control unit 8c follows the change of the cursor position. , CD-R
While reading predetermined map data from the OM 1 to the buffer memory 8a, a map image is drawn on the V-RAM 8e such that the center is always at the cursor position, and a cursor mark is drawn at the center. As a result, the map on the screen moves in accordance with the cursor operation with the cursor mark displayed in the center of the screen (steps 105 and 106). When the cursor mark on the screen reaches the departure point, stop the cursor operation and press the departure point setting key on the operation panel 2,
The departure point setting unit 8d is the cursor position calculation unit 8b at that time.
The cursor position data output from is set and registered as the departure point data (steps 107 and 108).

When the setting and registration of the departure place are completed in this way, the data of the departure place are output to the vehicle position calculation unit 6c and the map drawing control unit 8c. Here, when the start key is pressed on the operation panel 2 to start traveling, the map drawing control unit 8c detects the departure point data set by the departure point setting unit 8d and the direction sensor 3 to detect the vehicle position detection unit 6c. On the basis of the vehicle direction data θ ₀ of the departure place output from the vehicle position calculation unit 6c (see step 202 in FIG. 4), a map image centering on the departure place is drawn in the V-RAM 8e, and
A vehicle position mark is drawn in the center so as to face the direction indicated by the vehicle direction (steps 109 and 110). As a result, the map and the vehicle position mark around the departure center (current position of the vehicle) are displayed on the screen.

On the other hand, in the vehicle position detector 6, the start key
When is pressed, the vehicle position calculation unit 6c
Vehicle direction θ related to the detection output of the direction sensor 3₀Data of
Output to the map drawing control unit 8c, and also the departure place setting unit 8d
Starting point data (X ₀, Y₀) In (X_,Y)
initialize. Furthermore, the horizontal movement distance calculation unit 6b determines that the velocity v
_H(T) = 0, and the moving distance L = 0 is initialized (see FIG. 4).
Steps 201, 202). And when you start running,
The direction of the vehicle is detected by the direction sensor 3 and
Acceleration a (t) corresponding to acceleration / deceleration is detected by the acceleration sensor 4.
The detected tilt angle θ of the vehicle_v(T) is inclined
The angle sensor 5 detects the angle. The horizontal acceleration calculator 6a
Acceleration signal at constant short time Δt (eg 0.5S) interval
Signal and tilt angle signal are input, and the acceleration signal indicates
Acceleration a (t) and inclination angle θ indicated by the inclination signal_VBased on (t)
Therefore, a (t) × cos θ_VCalculate (t) and add horizontally
Speed a_HCalculate (t) and output horizontal acceleration data
(Step 203).

Then, with respect to the horizontal acceleration calculated by the horizontal acceleration calculating section 6a, the horizontal moving distance calculating section 6b sets the initial velocity at the starting point = 0 and the moving distance = 0, and the vehicle is calculated by double integration in the time domain. The horizontal movement distance L along the traveling locus is obtained, and the horizontal movement distance data is output. At this time, every time the horizontal acceleration a _H (t) is obtained by the horizontal acceleration calculator 6a, v _H (t) = a (t) × Δt + v _H (t) L = v _H (t) × Δt + L is calculated. Go and perform discrete integration (steps 206, 20)
7, FIG. 5 (1), (2)).

The vehicle position calculation unit 6c inputs the horizontal movement distance data calculated by the horizontal movement distance calculation unit 6b, and every time the horizontal movement distance L increases by a constant distance L ₀ , the direction sensor 3 outputs the vehicle direction at that time. Enter the signal and select the departure point (X ₀ , Y
_The vehicle position is detected by dead reckoning from ₀ ) as a starting point (see FIG. 6), and the vehicle position data and the vehicle direction data are output to the navigation controller 8. The navigation controller 8 stores the map data around the vehicle position in the buffer memory 8a from the CD-ROM 1 based on the vehicle position data and the vehicle direction data input from the vehicle position calculation unit 6c every time the vehicle travels a certain distance L ₀ after the start of traveling. While reading, a map image is drawn on the V-RAM 8e so that the center is the vehicle position, and a vehicle position mark is drawn on the center of the V-RAM 8e in the direction indicated by the vehicle direction data (steps 111 to 112 in FIG. 3). .. As a result, the map on the screen scrolls in the direction opposite to the traveling direction of the vehicle, the map around the vehicle position is always displayed, and the vehicle position is marked on the map.

Here, even if the vehicle travels on a slope having a difference in height as shown in FIG. 7, according to this embodiment, the horizontal acceleration of the vehicle is calculated and double-integrated in the time domain to calculate the moving distance. Therefore, the actual horizontal movement distance (L _a cos θ _a + L _b
It is possible to calculate cos θ _b ) accurately, and the vehicle position on the screen is also accurate. And the acceleration sensor 4
Since the inclination angle sensor 5 does not have a restriction on the mounting position to the vehicle like the conventional rotation sensor, it is easy to retrofit the vehicle-mounted navigator to the vehicle.

In the above embodiment, the acceleration applied to the vehicle and the inclination angle of the vehicle in the vertical plane including the longitudinal direction of the vehicle are detected, and the horizontal component of the acceleration is obtained from these acceleration and inclination angle. However, from the beginning, an acceleration sensor that can detect only the acceleration of the vehicle in the horizontal direction may be used from the beginning.

Further, the horizontal component of the acceleration applied to the vehicle is obtained, and the horizontal acceleration is double integrated in the time domain to obtain the horizontal movement distance along the running locus. In addition, in the front-back direction (travel direction)
And the left and right directions (directions orthogonal to the traveling direction) are detected using two acceleration sensors, the accelerations of the respective components are vector-synthesized, and then double integrated in the time domain to calculate the horizontal movement distance. You may do it.

[0027]

As described above, according to the present invention, the horizontal acceleration detecting means for detecting the acceleration in the horizontal direction of the vehicle and the horizontal acceleration detected by the horizontal acceleration detecting means are double integrated in the time domain to move horizontally. By providing a calculating means for obtaining the distance, detecting the horizontal acceleration of the vehicle, and double-integrating the detected horizontal acceleration in the time domain to obtain the horizontal movement distance, a slope-like Even if the vehicle travels on a road having a difference in altitude, the moving distance in the horizontal direction can be accurately detected, and the vehicle can be easily mounted.

[Brief description of drawings]

FIG. 1 is a block diagram of a main part of an in-vehicle navigator according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a method of calculating horizontal acceleration by the horizontal acceleration calculating unit in FIG.

FIG. 3 is a flowchart showing the operation of the navigation controller of FIG.

FIG. 4 is a flowchart showing the operation of the vehicle position detector of FIG.

5 is a diagram showing the operation of the horizontal movement distance calculation unit in FIG. 1. FIG.

FIG. 6 is an explanatory diagram showing the principle of general dead reckoning.

FIG. 7 is an explanatory diagram showing a defect of a conventional moving distance detecting method.

[Explanation of symbols]

 4 acceleration sensor 5 tilt angle sensor 6a horizontal acceleration calculation unit 6b horizontal movement distance calculation unit

Claims (1)

Claim: What is claimed is: 1. A horizontal acceleration detecting means for detecting an acceleration in the horizontal direction of a vehicle, and a horizontal moving distance by double integrating the horizontal acceleration detected by the horizontal acceleration detecting means in a time domain. A moving distance detecting apparatus for a vehicle, comprising: