JP2004045321A - Position measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position measuring system which can obtain highly-accurate, stable three-dimensional position information. <P>SOLUTION: The system comprises: a light-emitting marker 1; plural moving picture cameras 2 receiving the light of this light-emitting marker; a light-reception/emission controlling/calculating means 3 erforming the light-reception/emission control of the light-emitting marker and the plural moving picture cameras and calculating the local position coordinate and light-emission area information of the light-emitting marker in a camera image frame of each of the moving picture cameras; a marker light-emitting area using calculating means 57 calculating a three-dimensional position of the light-emitting marker in a light-emitting area using system based on the information from this light-reception/emission controlling/calculating means; a stereoscopically calculating means 58 calculating a three-dimensional position of the light-emitting marker in a stereoscopic system based on the information from this light-reception/emission controlling/calculating means; and a position coordinate calculation selecting means 56 selecting the stereoscopically calculating means when the light-emitting marker is detected by two or more moving picture cameras, and the stereoscopically calculating means when it is detected by one moving picture camera. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light-emitting marker (light-emitting unit) such as a light-emitting diode (LED) and a position measurement system that recognizes a three-dimensional position of an object to which the light-emitting marker is attached.
[0002]
[Prior art]
FIG. 4 schematically shows a configuration of a first conventional position measurement system of this type disclosed in, for example, JP-A-09-243325. In FIG. 4, 1 is an LED light emitting marker as an example of a light emitting unit, 2 is a CCD camera as an example of a moving image camera, 3 is a light receiving / emitting control calculator, 4a is a computer, and 5a is obtained by the CCD camera 2. A three-dimensional position calculating unit 51 shown as a functional block of a computer for calculating a three-dimensional position from the distance and the coordinate position of the light emitting marker 1 is a marker light emitting area utilization calculating unit included in the three-dimensional position calculating unit 5a.
[0003]
FIG. 5 is a diagram for explaining a method of estimating the distance between the CCD camera 2 and the LED light emitting marker 1 with one CCD camera 2. 5A shows a case where the distance between the CCD camera 2 and the LED light emitting marker 1 is short, and FIG. 5B shows a case where the distance between the CCD camera 2 and the LED light emitting marker 1 is long. The light emitting area of the LED light emitting marker 1 decreases in inverse proportion to the square of the distance from the CCD camera 2. Therefore, if the ratio between the light emitting area and the distance at a certain reference point is obtained, the distance between the CCD camera 2 and the LED light emitting marker 1 can be calculated from the light emitting area of the LED light emitting marker 1. Thereby, the distance between the CCD camera 2 and the LED light emitting marker 1 can be calculated by one CCD camera 2.
[0004]
FIG. 6 schematically shows the configuration of a second conventional position measurement system disclosed in "Three-dimensional image measurement", by Iguchi and Sato, Shokodo, 1990. 6, the same or corresponding parts as those in FIG. 4 are denoted by the same reference numerals. 4b is a computer, 5b is a three-dimensional position calculator shown as a functional block of a computer for calculating a three-dimensional position from the distance and coordinate position of the light emitting marker 1 obtained by the CCD camera 2, and 53 is a three-dimensional position calculator 5b Is a stereo vision calculation unit included in. Here, two or more CCD cameras 2 are used.
[0005]
FIG. 7 shows the principle of stereo vision. By calculating the distance between the CCD camera 2 and the LED light emitting marker 1 from the positions of the two CCD cameras 2 and the direction of the LED light emitting marker 1 detected by the CCD camera 2, the three-dimensional position coordinates of the LED light emitting marker 1 are calculated. can do. When stereo vision is used, the distance between the CCD camera 2 and the LED light emitting marker 1 can be determined with high accuracy, so that three-dimensional position coordinates can be calculated with high accuracy.
[0006]
[Problems to be solved by the invention]
In the above-described conventional first device, the detection of the marker light emission area is not highly accurate, and thus the three-dimensional position measurement accuracy is not good. Further, since the moving image camera has a fixed field of view, measurement cannot be performed if the camera cannot detect the moving image. Therefore, there has been an issue of improving the accuracy of the three-dimensional position measurement, widening the area, and measures for hiding (measures when the visual field is obstructed by something).
[0007]
In addition, in the second conventional apparatus, since stereoscopic vision requires image information of light-emitting markers detected by two or more moving image cameras, three-dimensional position coordinates are required unless the range and conditions are visible from both cameras. Is not found. Therefore, there has been a problem of widening the three-dimensional position measurement and measures for hiding.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a position measurement system capable of obtaining highly accurate and stable three-dimensional position information.
[0009]
[Means for Solving the Problems]
In view of the above object, the present invention performs a light-emitting marker to be a position measurement object, a plurality of moving image cameras that receive light from the light-emitting marker, and light-receiving / emitting control of the light-emitting marker and the plurality of moving image cameras. Light-receiving / light-emitting control calculating means for calculating local position coordinates and light-emitting area information of the light-emitting marker in a camera image frame of each moving image camera, and a light-emitting marker based on a light-emitting area utilization method based on information obtained from the light-receiving / lighting control calculating means Marker light emitting area utilization calculating means for performing three-dimensional position calculation, stereoscopic calculating means for performing three-dimensional position calculation of a light-emitting marker by a stereoscopic method based on information obtained from the light receiving / receiving control calculating means, The stereo vision calculating means when detected by two or more moving image cameras, and when detected by one moving image camera. In the position measuring system, characterized in that it and a position coordinate calculating selecting means for selecting the stereo calculation unit.
[0010]
Further, the number of the luminescent markers is plural, and the number and the position of the luminescent markers are calculated based on the information of the luminescent markers obtained from the light receiving / emitting control calculating means. And a memory for storing at least the previous number of positions and the number of the light emitting markers, and performs position measurement for each of the valid light emitting markers. It is characterized by the following.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
FIG. 1 schematically shows a configuration of a position measuring system according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an LED light emitting marker as an example of a light emitting unit; 2, a CCD camera as an example of a moving image camera; 3, a light receiving / emitting control calculator; 4 c, a computer; This is a three-dimensional position calculator shown as a functional block of a computer that calculates a three-dimensional position from the distance and coordinate position of the light-emitting marker 1.
[0012]
In the three-dimensional position calculation unit 5c, 55 is a data validity determination unit, 56 is a position coordinate calculation method selection unit, 57 is a marker light emission area use calculation unit that performs three-dimensional position coordinate calculation of the light emission area use method described above, and 58 is a marker light emission area use calculation unit. This is a stereo vision calculation unit that performs the above-described stereo three-dimensional position coordinate calculation. Reference numeral 6 denotes a memory for storing the number of markers in a frame image described later, the position in the image of each marker, and the light emission area. The light emission / reception control calculation device 3 controls light emission / emission of the LED light emission marker 1 and the CCD camera 2, and calculates local position coordinates and light emission area information of the light emission marker in a camera image frame of each CCD camera.
[0013]
In the present invention, as shown in FIG. 1, two CCD cameras 2 are provided, and a function of switching a distance calculation method from the CCD camera 2 to the LED light emitting marker 1 according to an image detection condition of the LED light emitting marker 1 is provided by a position coordinate calculation method selecting unit. 56 is provided in the computer 4c.
[0014]
In operation, the LED light emitting marker 1 is mounted on the position measurement target. The two CCD cameras 2 are arranged so as to well cover the range in which the measurement target moves. For example, if the LED light emitting marker 1 exists at the overlapping portion of the camera visual fields of the two CCD cameras 2, the position coordinates can be calculated by the two CCD cameras 2 in a stereoscopic view.
[0015]
At the time of measurement, the LED light emission marker 1 is turned on by the light reception / emission control calculation device 3, and the camera image frame of each CCD camera 2 is taken into the light reception / emission control calculation device 3. From the captured image frame, the local position coordinates and light emitting area information of the LED light emitting marker 1 are calculated for each CCD camera 2 and transferred to the computer 4c.
[0016]
If both the two CCD cameras 2 can detect the LED light emitting marker 1, the stereo vision calculation unit 58 calculates the three-dimensional position coordinates of the LED light emitting marker 1 by stereo vision (hereinafter, stereo vision system). When the LED light emitting marker 1 can be detected by only one of the CCD cameras 2, the marker light emitting area use calculating unit 57 uses the light emitting area information of the LED light emitting marker 1 to determine the distance from the CCD camera 2 to the LED light emitting marker 1. By the calculation, the three-dimensional position coordinates of the LED light emitting marker 1 are calculated (hereinafter, a light emitting area use method). These switching operations are performed by the position coordinate calculation method selection unit 56.
[0017]
By switching the three-dimensional position measurement method as described above, it is possible to perform three-dimensional position measurement with high accuracy, wide range, and strong in hiding.
[0018]
In the above description, an example of one LED light emitting marker 1 is shown, but a plurality of LED light emitting markers 1 may be used as long as the marker ID is identified. For example, if the LED light emitting markers 1 are sequentially turned on in synchronization with the image frame of the CCD camera 2, the marker ID can be easily identified. There is also a method of identifying a marker ID by matching with the nearest marker of the immediately preceding image frame.
[0019]
Although the number of the CCD cameras 2 is two, any number may be used as long as the number is two or more, and the stereoscopic calculation is performed by using any two CCD cameras 2 capable of detecting the LED light emitting marker 1 and performing the stereoscopic calculation. If the average of the position information is obtained, higher accuracy can be achieved.
[0020]
Further, the local position coordinates and the light emitting area information of the LED light emitting marker 1 were calculated from the image frame captured by the light receiving / emitting control computer 3, but the light receiving / emitting control calculating device 3 is provided in the computer 4c as the light receiving / emitting control calculating unit 30. , All calculations may be performed in a computer.
[0021]
When it is desired to widen the measurement range, the range in which the camera visual fields of the CCD cameras 2 overlap may be narrowed, and the use range of the single camera visual field may be expanded. When it is desired to emphasize the high accuracy, the range in which the camera visual fields of the CCD cameras 2 overlap may be widened.
[0022]
FIG. 2 shows a processing flowchart of the three-data validity judging unit 55, and FIG. 3 shows a processing flowchart of the position coordinate calculation method selecting unit 56, the marker light emission area use calculating unit 57, and the stereo vision calculating unit 58. In FIG. 2, the position coordinates and the area value in the image of each LED light emitting marker 1 for each CCD camera 2 are calculated, and it is determined whether the data is valid. In FIG. 7, three-dimensional position coordinates are calculated based on this information.
[0023]
The operation will be described with reference to the flowchart of FIG. First, frame image information is captured by the first CCD camera 2 (step S1). Next, in this frame image information, the number of LED light emitting markers 1 is detected (step S2). For example, for each horizontal scanning line, a portion where the luminance exceeds a set threshold is cut out as a marker existing portion (line segment), and at least the marker existing portion is located at the same position in the horizontal direction on a continuous horizontal scanning line. If so, the number of markers can be detected by determining that they are the same marker.
[0024]
Then, the positions of the detected LED light emitting markers 1 in the horizontal and vertical directions in the image and the light emitting area are obtained (step S3). In the horizontal direction, the position of the marker in the screen is determined by the clock counter from the horizontal synchronization signal, and in the vertical direction, by the number of horizontal scanning lines. The light emitting area is obtained by length integration of the marker existing portion (line segment) on each horizontal scanning line.
[0025]
Next, it is determined whether the detected marker data is valid. When detecting a light emitting marker as a camera image, the light emitting information of each marker cannot be correctly detected in the following three cases. First, (1) when two or more marker emissions overlap, this is called fusion. Next, (2) when the marker deviates from the viewing angle of the camera lens, and (3) when it is within the viewing angle of the camera lens but is hidden behind another object, these are called disappearances. Here, the validity of the marker data is determined by identifying these cases and the case where all the markers are visible.
[0026]
Specifically, first, the number of light emitting markers detected in the current frame is compared with that in the previous frame (step S4). For this reason, for example, a memory 6 is required to store the number of markers in the frame image, the position in the image of each marker, and the light emission area. As a result of the comparison, if the numbers are the same, all the marker data are valid as they are. If the numbers are different, it is determined whether two or more markers have approached in the previous frame (step S5). If they have approached each other, it is determined that the markers have merged, and all of the approaching marker data is invalidated (step S6). If not approaching, it is determined that the marker has disappeared, and the lost marker data is invalidated (step S7). The above processing is performed for each CCD camera 2.
[0027]
Subsequently, the operation will be described according to the flowchart of FIG. In the above processing, the effective marker data of each CCD camera 2 was obtained. Here, the three-dimensional position coordinate calculation method is switched according to the number of cameras for which each LED light emitting marker 1 has been effectively detected. If two or more cameras are validly detected, the stereoscopic method is used (steps S8 and S9). If one camera is validly detected, the light emitting area is used (steps S10 and S11). If not detected, the data of the previous frame is held (step S12), thereby calculating three-dimensional position coordinates.
[0028]
As described above, by switching the three-dimensional position coordinate calculation method between the stereoscopic viewing method and the light emitting area using method for each marker, highly accurate and stable three-dimensional position information can be obtained.
[0029]
【The invention's effect】
As described above, according to the present invention, a light emitting marker to be a position measurement object, a plurality of moving image cameras that receive light from the light emitting marker, and light emitting / receiving control of the light emitting marker and the plurality of moving image cameras are performed. Light-receiving / light-emitting control calculating means for calculating local position coordinates and light-emitting area information of the light-emitting marker in a camera image frame of each moving image camera, and a three-dimensional light-emitting area utilizing method based on information obtained from the light-receiving / lighting control calculating means. Marker light emitting area use calculating means for calculating a position, stereoscopic calculating means for calculating a three-dimensional position by a stereoscopic method based on information obtained from the light receiving / emitting control calculating means, and a moving image having two or more light emitting markers The stereo vision calculation means when detected by a camera, and the stereo vision calculation means when detected by one video camera And a position coordinate calculation selecting means for selecting, so that the light-emitting marker is normally detected only from one moving image camera by stereo vision using a plurality of moving image camera information. If this is not possible, the distance from the moving image camera to the light emitting marker is calculated based on the light emitting area information of the light emitting marker, so that highly accurate and stable three-dimensional position information can be obtained.
[0030]
Further, the number of the luminescent markers is plural, and the number and the position of the luminescent markers are calculated based on the information of the luminescent markers obtained from the light receiving / emitting control calculating means. And a memory for storing at least the previous number of positions and the number of the light emitting markers, and performs position measurement for each of the valid light emitting markers. As a result, reliability is improved.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a configuration of a position measurement system according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating the operation of the system of FIG. 1;
FIG. 3 is a flowchart for explaining the operation of the system of FIG. 1;
FIG. 4 is a diagram schematically showing a configuration of a conventional position measurement system.
FIG. 5 is a diagram for explaining the operation of the system in FIG. 4;
FIG. 6 is a diagram schematically showing the configuration of another conventional position measurement system.
FIG. 7 is a diagram for explaining the operation of the system in FIG. 6;
[Explanation of symbols]
Reference Signs List 1 LED light emitting marker, 2 CCD camera, 3 light receiving / emitting control calculating device, 4c computer, 5c 3D position calculating unit, 55 data validity determining unit, 56 position coordinate calculating method selecting unit, 57 marker light emitting area use calculating unit, 58 Stereo vision calculation unit, 6 memories.

Claims (2)

A light-emitting marker to be measured,
A plurality of moving image cameras for receiving light from the light emitting marker,
Light-receiving / light-emitting control calculating means for controlling light-emitting and light-emitting of the plurality of moving image cameras and calculating local position coordinates and light-emitting area information of the light-emitting markers in a camera image frame of each moving image camera;
A marker light emitting area use calculating means for calculating a three-dimensional position of a light emitting marker by a light emitting area using method based on information obtained from the light receiving / emitting control calculating means;
Stereo vision calculation means for calculating a three-dimensional position of a light emitting marker by a stereo vision method based on information obtained from the light reception / emission control calculation means,
When the light emitting marker is detected by two or more video cameras, the stereo vision calculation means, and when detected by one video camera, position coordinate calculation selection means for selecting the stereo vision calculation means,
A position measuring system comprising: A plurality of said luminescent markers,
The number and position of the light-emitting markers are calculated based on the information on the light-emitting markers obtained from the light-receiving / light-emission control calculation means, and the disappearance of the light-emitting markers and the fusion of the plurality of light-emitting markers are detected as compared with the previous time to invalidate the corresponding information. Means for determining data validity,
A memory for storing at least the last number and position of the light emitting markers,
The position measurement system according to claim 1, further comprising: performing position measurement on each of the effective light-emitting markers.

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