JPH1097627A - Pattern matching method/device and movement control method/device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminated the needy of the preparation of a reference pattern in accordance with a distance, to reduce storage capacity and to speed up a processing by changing the focal distance of a video means so that the size of an object in the picture is matched with one reference pattern in accordance with a measured distance. SOLUTION: Various reference patterns showing postures against the respective angles of an unmanned dumper truck are previously prepared. Pattern matching for matching the respective reference patterns with the dumper truck in the video picture by a camera is executed. A matching degree between the truck in the picture and the various patterns is obtained. The reference pattern whose matching degree becomes maximum is selected. A driving control part mounted on a loader controls the relative movement of the loader against the dumper truck based on the relative posture angle of the dumper truck against the loader, which the selected reference pattern shows. Then, the loader approaches the dumper truck so as to execute loading work by giving a zoom command for changing the focal length to the camera.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern matching method and apparatus for determining the degree of coincidence of an object with a reference pattern, a method for controlling the relative movement of a moving object with respect to the object based on the result of the pattern matching, and Regarding the device.

[0002]

2. Description of the Related Art When loading a load from an unmanned wheel loader to an unmanned dump truck, an unmanned dump truck as an object is imaged by a camera mounted on the unmanned loader, and the unmanned dump truck viewed from the unmanned loader side is obtained from the imaged result. It is necessary to know the relative attitude of the dump truck.

In this case, various reference patterns (templates) indicating various postures of the unmanned dump truck are prepared, and pattern matching (template matching) for matching each reference pattern with a dump truck in a captured image is performed.
To determine the degree of coincidence (correlation degree) between the attitude of the dump truck in the image and the attitude indicated by each reference pattern, and determine the attitude indicated by the reference pattern with the highest degree of coincidence (highest degree of correlation). Is determined to be the posture of the dump truck.

Then, a relative attitude angle of the dump truck with respect to the loader is obtained in accordance with a result of the determination, and the relative movement of the loader with respect to the dump truck is controlled based on the relative angle, so that the loader is moved to the dump truck. The approach is taken and the loading work is performed automatically.

[0005]

However, since the loader on which the camera is mounted is constantly moving and the dump truck, which is the object, is also constantly moving, the distance between the camera and the dump truck to be imaged is small. It is constantly changing.

For this reason, the size of the dump truck shown in the captured image is constantly changing according to the above-mentioned changing distance.

For this reason, when performing pattern matching, it is necessary to prepare reference patterns of different sizes according to various distances. In addition, since these need to be prepared according to various postures, the storage capacity becomes enormous, the processing becomes complicated, and the processing takes time.

The present invention has been made in view of such a situation, and it is not necessary to prepare a reference pattern according to the distance, to reduce the storage capacity, to avoid complicated processing, and to speed up the processing. The task is to solve the problem.

[0009]

Therefore, in the main invention of the present invention, an object is imaged by an image pickup means, and an object in the image picked up by the image pickup means and a reference pattern of the object are identified. In a pattern matching method for determining a degree of coincidence of the object with the reference pattern by matching, a distance measurement step for measuring a distance between the imaging unit and the object, and a distance measured in the distance measurement step And a step of changing the focal length of the imaging means so that the size of the object in the image matches the size of one reference pattern.

That is, the focal length of the imaging means is changed according to the measured distance so that the size of the object in the image matches the size of one reference pattern. Regardless of the size, the size of the object in the image is set to a fixed size that matches the size of one reference pattern. Therefore, it is not necessary to prepare reference patterns of different sizes according to the distance, and it is sufficient to prepare only one reference pattern of a fixed size. Thus, the storage capacity can be reduced, and the processing can be performed at high speed without performing complicated processing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a pattern matching method and apparatus and a movement control method and apparatus according to the present invention will be described below with reference to the drawings.

In this embodiment, as shown in a top view of FIG. 4, an unmanned (wheel) loader 1
It is assumed that an operation of loading a cargo from 0 to the unmanned dump truck 20 is performed.

When performing such a loading operation, the unmanned dump truck 20 as an object is imaged by the camera 11 mounted on the unmanned loader 10 so that the unmanned loader 10 approaches the unmanned dump truck 20. It is necessary for the loader 10 to know the relative posture of the unmanned dump truck 20 from the unmanned loader 10 side, that is, the relative posture angle φ of the dump truck 20 with respect to the loader 10 from the imaging result. Note that the broken line in FIG. 4 indicates the field of view of the camera 11.

In this case, various postures of the unmanned dump truck 20 (a posture corresponding to a posture angle φ = 0 °, a posture angle φ = 5 °)
, Posture corresponding to posture angle φ = 10 ° ...)
Are prepared in advance.

Each of these reference patterns and the camera 1
The pattern matching (template matching) for matching the dump truck 20 in the captured image according to No. 1 is performed, and the degree of coincidence (correlation degree) between the in-image dump truck 20 and each reference pattern is obtained, and the degree of coincidence becomes the largest. The reference pattern having the highest correlation degree is selected.

The relative movement of the dump truck 20 with respect to the dump truck 20 based on the relative posture angle φ of the dump truck 20 indicated by the selected reference pattern (for example, the posture angle φ = 10 °). The loader 10 is controlled by a drive control unit mounted on the loader to cause the loader 10 to approach the dump truck 20 to automatically perform a loading operation.

Here, the loader 1 on which the camera 11 is mounted
0 always moves on the outdoor work site, and the dump truck 20 as the object always moves on the outdoor work site.
The distance to 0 is constantly changing.

For this reason, the size of the dump truck 20 shown in the captured image is constantly changing according to the above-mentioned changing distance.

Therefore, when performing pattern matching as it is, it is necessary to prepare reference patterns of different sizes according to various distances.

FIG. 2 shows a case where the size of the dump truck 20 in the image is set to a fixed size that is adapted to the size of one reference pattern, regardless of the size of the distance, and each reference pattern having a different size is set. FIG. 4 is a block diagram showing a configuration of an apparatus for performing pattern matching only with a reference pattern of one size without preparing a pattern according to a distance.

As shown in FIG. 2, in the apparatus of the present embodiment, a camera 11 as an image pickup means for picking up an image of a dump truck 20 as an object, and an imaged image obtained based on an image pickup signal S of the camera 11 are provided. And the loader 10 (camera 1) for performing the above-described pattern matching.
1) GPS (global positioning sensor) 15, which is a position detector for detecting a coordinate position (x2, y2) on a two-dimensional plane, a radio receiver 14, a detection output of the GPS 15, and A control unit 13 that outputs a zoom command T to the camera 11 based on the received output and controls the magnitude of the focal length f of the lens of the camera 11 is mounted on the loader 10 and is similar to the GPS 15 described above. And a GPS 22 for detecting the position (x1, y1) of the dump truck 20 and receiving the detection output of the GPS 22 to the receiver 14 for the position data (x
1, a wireless transmitter 21 for wirelessly transmitting y1) is mounted on the dump truck 20.

Here, the zoom command T will be described.

FIG. 3 shows a geometrical optical system for explaining the relationship between the distance to the object and the zoom. The “object” corresponds to the actual dump truck 20, and the “image” is on the image taken by the camera 11. Corresponding to the dump truck 20.

For simplicity, assuming that the camera 11 has a single lens, the lens imaging equation can be expressed as follows: a is the distance from the lens to the object, and b is the distance from the lens to the image. The distance, f, is defined as 1 / a + 1 / b = 1 / f (1), where f is the focal length of the lens.

At this time, the image magnification M expressed by the ratio of the size of the object to the image is represented by Ha, the size of the object,
When Hb is the size of the image, M = Hb / Ha = b / a (2) By substituting equation (1) into equation (2), Hb = {Ha / (af)} * f (3) is obtained. Therefore, in order to keep the image size Hb constant, the zoom command T may be given to the camera 11 so as to change the focal length f of the lens according to the distance a from the lens to the object.

That is, assuming that the focal length when the distance between the camera 11 (loader 10) and the dump truck 20 changes from L by ΔL is f ′, from the equation (3), f / (L−f) = f '/ (L + ΔL-f') is obtained, so that f 'is obtained as follows.

F ′ = ｛(L + ΔL) / L｝ * f
(4) Therefore, as shown in the above equation (4), by giving a zoom command T to the camera 11 to change the sequential focal length f ′ according to the sequential distance L ′ = L + ΔL,
The size Hb of the image is always constant.

Although the focal length cannot be changed with one lens, a general camera is composed of several groups of lenses, so that the focal length can be changed as a lens system.

FIG. 1 is a flowchart for explaining the processing executed by the control unit 13.

First, position data (x1, y1) of the dump truck 20 is input from the receiver 14 (step 101), and position data (x2, y2) of the camera 11 (loader 10) is input from the GPS 15. (Step 102).

Next, based on these position data, the current distance L '(= L + .DELTA.L) between the camera 11 (loader 10) and the dump truck 20 is calculated as follows: L' =. SIGMA. ((X1-x2) 2+ (y1-y2) 2) ... (5) is calculated. It should be noted that () 2 means square (step 103).

The current distance L '(= L +
ΔL) is substituted into the above equation (4) to determine the focal length f ′, and a zoom command T for obtaining the focal length f ′ is output to the camera 11 (step 10).
4, 105).

As a result, regardless of the distance L ', the size (Hb) of the dump truck 20 in the image picked up by the camera 11 is set to a constant size suitable for the size of one reference pattern. You.

For this reason, it is not necessary to prepare reference patterns of different sizes according to the sequential distance L ', and it is sufficient to prepare only one reference pattern of a fixed size (Hb constant) (size). Is constant, but it is necessary to prepare a plurality of reference patterns corresponding to various postures). Thus, the storage capacity can be reduced, and the pattern matching processing can be performed at high speed without performing complicated processing.

In this embodiment, it is assumed that a loading operation is performed, but the present invention may be applied to a case where the distance between two vehicles is kept constant.

Further, in the present embodiment, two moving bodies are assumed, but the present invention can be applied if at least one of the moving bodies is changed and the relative distance between the two is changed.

In this embodiment, the distance is calculated based on the output of the position detector. However, a measuring device for directly measuring the distance may be used.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an embodiment of a method according to the present invention, and is a flowchart illustrating a procedure of processing performed by a control unit illustrated in FIG. 2;

FIG. 2 is a configuration block diagram of an embodiment of an apparatus according to the present invention.

FIG. 3 is a diagram illustrating a geometric optical system used for explaining a zoom command;

FIG. 4 is a top view of the unmanned loader and the unmanned dump truck applied to the embodiment.

[Explanation of symbols]

 Reference Signs List 11 camera 12 image processing unit 13 control unit 15 GPS 22 GPS

Claims (4)

[Claims] 1. An object is imaged by an image pickup means, and the degree of coincidence of the object with the reference pattern is determined by matching an object in the image picked up by the image pickup means with a reference pattern of the object. In the pattern matching method to be obtained, a distance measurement step for measuring a distance between the imaging unit and the object, and a size of the object in the image according to a distance measured in the distance measurement step is one criterion. A step of changing the focal length of the imaging means so as to match the size of the pattern. 2. An image pickup means is mounted on a moving body, an image of an object is picked up by the image pickup means, and the object in the picked-up image is matched with a reference pattern of the object by the image pickup means. In a movement control method of performing pattern matching for obtaining a degree of coincidence with a reference pattern and controlling relative movement of the moving body with respect to the target object according to a result of the pattern matching, a distance between the imaging unit and the target object And the focal length of the imaging means so that the size of the object in the image matches the size of one reference pattern according to the distance measured in the distance measurement process. A movement control method comprising a step of changing. 3. An object is imaged by an image pickup means, and the degree of coincidence of the object with the reference pattern is determined by matching an object in the image picked up by the image pickup means with a reference pattern of the object. In the pattern matching device to be obtained, a distance measuring unit that measures a distance between the imaging unit and the target, and a size of the target in the image according to a distance measured by the distance measuring unit is a reference. Means for changing the focal length of said imaging means so as to match the size of the pattern. 4. An image pickup means is mounted on a moving body, an image of an object is picked up by the image pickup means, and the object in the picked-up image is matched with a reference pattern of the object to obtain the object. In a movement control device that performs pattern matching for obtaining a degree of coincidence with a reference pattern and controls relative movement of the moving object with respect to the object according to a result of the pattern matching, a distance between the imaging unit and the object Distance measuring means for measuring the focal length of the imaging means so that the size of the object in the image matches the size of one reference pattern, according to the distance measured by the distance measuring means. A movement control device comprising means for changing.