JPH04303213A - Position detector for vehicle - Google Patents

Abstract

PURPOSE:To obtain a position detector for vehicle which controls the position of a vehicle with a high precision and has no restrictions on setting of a route and easily changes the route. CONSTITUTION:This device consists of a marker discharging means 10 which discharges markers 20 from the front end of the vehicle onto the road surface at intervals of a preliminarily determined time in the going direction of the vehicle, a marker position detecting means 30 which detects the positions of these discharged markers 20, a control means 40 which calculates the position of the vehicle by marker position data from the marker position detecting means 30 and controls the going direction of the vehicle based on the calculation result, and a marker recovering means 50 which recovers markers 20 whose positions are already detected to the rear part of the vehicle.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle position detection device, and more particularly to a vehicle position detection device suitable for detecting the position of an automatic guided vehicle.

0002

BACKGROUND OF THE INVENTION In recent years, automatic guided vehicles have been used to transport parts and products in factories as part of their rationalization efforts. Automated guided vehicles travel to their destinations by following predetermined routes for safety.

[0003] Methods for recognizing the self-position of the automatic guided vehicle at this time include methods using internal sensors such as dead reckoning and inertial navigation using a gyro or the like.

[0004] Furthermore, as shown in Fig. 11, there is a system that recognizes its own position by triangulation using a corner cube, or as shown in Fig. 10, a route is marked on the floor in advance and this marking line is detected. Many devices are also in use that use external sensors to move while moving.

[0005]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional example, when an internal sensor is used, the error is large and accumulates over a long period of time, so the vehicle deviates from the predetermined route, resulting in an emergency. The disadvantage was that it was dangerous.

Further, when an external sensor is used, there are problems in that it takes time and effort to install corner cubes and create markings, and it is also very difficult to change the route.

[0007]

OBJECTS OF THE INVENTION An object of the present invention is to improve the inconveniences of the conventional example, and to make it possible to control the position of a vehicle with particularly high precision, to have no restrictions on route setting, and to easily change routes. The object of the present invention is to provide a vehicle position detection device.

[0008]

[Means for Solving the Problems] Accordingly, the present invention provides a marker emitting means that ejects a marker from the front end of the vehicle onto the road surface at predetermined time intervals in the direction in which the vehicle is traveling, and a marker position detecting means for detecting the position of the marker position detecting means; a control means for calculating the position of the vehicle based on the marker position data from the marker position detecting means and controlling the traveling direction of the vehicle based on the result of the calculation; The vehicle is configured to include a marker collecting means for collecting the collected markers at the rear of the vehicle. This aims to achieve the above-mentioned purpose.

[0009]

[Operation] ■ The marker is released onto the road surface from the marker release means. ■The marker position is detected by the marker position detection means. (2) Absolute coordinates of the vehicle position are calculated by the control means based on the marker position data from the marker position detection means. ■
The direction of travel of the vehicle is corrected based on instructions from the control means. ■The marker whose position has been detected is recovered into the vehicle by the marker recovery means. ■~■ are repeated continuously.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 10.

As shown in FIG. 1, a marker emitting means 10 is provided at the front of the vehicle for ejecting a marker 20 from the front end of the vehicle onto the road surface at predetermined time intervals in the direction of travel of the vehicle. 2. As shown in FIG. 3, a marker position detection means 30 detects the position of the marker 20 when the vehicle crosses the released marker 20, and the position of the vehicle is determined based on the marker position data from the marker position detection means 30. It is comprised of a control means 40 that performs calculations and controls the traveling direction of the vehicle based on the calculation results, and a marker collection means 50 that retrieves the marker 20 whose position has been detected at the rear of the vehicle.

As shown in FIG. 3, the marker position detecting means 30 is installed approximately at the lower center of the vehicle with the direction of detection oriented toward the road surface. In this example, FIG.
As shown in FIG.
A camera is used. However, it is not limited to this.

The lower part of FIG. 7 shows an example of an image taken by the CCD camera 30. The marker emission time interval by the marker emission means 10 is determined so that one or more markers 20 are always present in one screen. This image is subjected to image recognition processing such as edge extraction to detect the amount of movement of the vehicle and changes in the direction of the vehicle at each fixed sampling interval. The amount of movement and direction change for all markers 20 within the screen are calculated and averaged. Furthermore, if there is a marker 20 that goes outside the screen, that marker 20 is ignored. In such a case, if the navigation is combined with the navigation using the internal sensor of the vehicle, the route will not be deviated even when the marker 20 is not present on the screen.

Furthermore, as shown in FIG. 5, the marker 20 has a convex portion formed on one side for convenience during collection. Further, it has a disk shape and is color-coded into fan shapes so that image recognition by the CCD camera 30 can be easily performed. However, it is not limited to this.

Details of the marker collecting means 50 will be explained with reference to FIG. The marker 20 is gathered at the center of the vehicle by the guide B, and the convex portion of the marker 20 is inserted into the elevator A. When a microswitch (not shown) installed at the rear end of the elevator A is turned on by the marker 20, the elevator A is raised by motor drive using the slide D. When the elevator A rises, the protrusion of the marker 20 is caught by the hook E of the belt conveyor C, and as the belt conveyor C moves, the marker 20 is recovered inside the vehicle.

Next, the operation of this embodiment will be explained. (2) When the vehicle starts moving, the marker 20 is released from the marker release means 10 onto the road surface in front of the vehicle. ■The vehicle moves so as to straddle the released marker 20. (2) When the marker 20 enters the screen of the CCD camera 30, image data is sent to the control means 40 at regular sampling intervals. ■The control means 40 uses image processing to mark the marker 2.
The position of zero is determined, and then the amount of movement of the vehicle and the change in direction of the vehicle are determined. (2) If the direction of travel of the vehicle deviates from the planned direction, a correction signal is sent from the control means 40 to the controller of the vehicle to correct the position of the vehicle. (2) When the marker 20 reaches the rear position of the vehicle, it is collected by the marker collecting means 50. While the vehicle is moving, the above operations (1) to (2) are performed continuously.

Depending on the angle of view of the lens of the CCD camera 30, the height of the vehicle may increase as shown in FIG. 8, but this does not affect the above operation. Furthermore, it is also possible to collect the marker 20 by shifting it from the center of the vehicle.

Next, a method for positioning a vehicle in absolute coordinates from image data will be explained.

The position and direction of the marker 20 are (x, y, θ)
Then, the position of the marker 20 at a certain time t is (xt,
yt, θt). The sampling period of Δt time must be shorter than the time it takes the marker 20 to pass through the screen of the CCD camera. The movement of the vehicle can be seen from the two states shown in FIG.

If the position and direction of the vehicle are expressed as absolute coordinates (X, Y, Θ), unlike the coordinate system within a CCD camera, then at time t they become (Xt, Yt, Θt). Here, as can be seen from FIG. 10, the position of the marker 20 is expressed by the following equation.

[0021]

[Math 1]

[0022] Then, the direction becomes θt+Θt.

Further, at time t+Δt, the following equation is obtained.

[0024]

[Math 2]

The above two coordinates and directions are equal in absolute coordinates.

θt+Θt=θt+Δt+Θt+Δt
(3)

[0027] Transforming equation (3),

Θt+Δt=θt+Θt−θt+Δt
(4)

In other words, Θt is Θ
Since it is determined by equation (4) from 0, Θt and Θ
t+Δt can be known. Using these relationships,

[0030]

[Math 3]

According to equation (5), Xt and Yt can also be determined from X0 and Y0. In this way, the absolute coordinates of the vehicle are determined.

Note that these calculations are performed by the control means 40.

[0033]

As described above, according to the present invention, there is provided a marker emitting means for emitting a marker from the front end of a vehicle onto the road surface, a marker position detecting means for detecting the position of the ejected marker, and a marker position detecting means for detecting the position of the ejected marker. Since the structure is comprised of a control means that calculates the position of the vehicle based on data from the means and controls the traveling direction of the vehicle based on the calculation results, and a marker collection means that retrieves the markers, The position of the vehicle can be controlled without the need for this information. Therefore, it is possible to provide an unprecedented and superior vehicle position detection device that can accurately control the position of the vehicle, has no restrictions on route setting, and can easily change the route.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of a vehicle showing an embodiment of the present invention.

FIG. 2 is a schematic diagram of FIG. 1 viewed from above.

FIG. 3 is a sectional view taken along the vehicle center line in the front-rear direction.

FIG. 4 is a schematic diagram of FIG. 1 viewed from below.

FIG. 5 is an example of a marker shape.

FIG. 6 is an explanatory diagram of marker collection means.

FIG. 7 is an explanatory diagram of a marker position detection method.

FIG. 8 is an explanatory diagram of the installation position of marker position detection means.

FIG. 9 is an example of image data at time t and time t+Δt.

FIG. 10 is a relationship diagram between relative coordinates and absolute coordinates.

FIG. 11 is a schematic diagram of a conventional example using a corner cube.

FIG. 12 is a schematic diagram of a conventional example using marking lines.

[Explanation of symbols]

10 Marker release means 20 Marker 30 Marker position detection means 40 Control means 50 Marker collection means

Claims (1)

[Claims] Claims: 1. A position detection device for a vehicle moving to a destination along a predetermined route, wherein a marker is emitted from the front end of the vehicle onto a road surface at predetermined time intervals in the direction of travel of the vehicle. a marker emitting means for detecting the position of the ejected marker; a marker position detecting means for detecting the position of the ejected marker; and a marker position detecting means for calculating the position of the vehicle based on the marker position data from the marker position detecting means. 1. A vehicle position detection device comprising: a control means for controlling the marker; and a marker collection means for collecting the marker after position detection at the rear of the vehicle.