JP2002092587A - Target measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measuring accuracy by realizing image analysis of high reliability and high accuracy. SOLUTION: The image of a target photographed by an image pickup camera 11 is subjected to smoothing and differential filter processing to form a work image. A part with the large change of brightness in the work image is extracted, and a brightest picture element is selected out of a picture element of the target image corresponding to the part with high brightness, and a plurality of picture elements around the picture element. With the average value of the picture element as a threshold value, binarization processing of the target image is performed to generate image data, and the position and attitude of a work object 13 is computed on the basis of the image data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manipulator which is mounted on a spacecraft, for example, for constructing various structures in outer space, and for exchanging work including installation work of work objects used for various space experiments. The present invention relates to a target measuring device suitable for use in a system or a docking system for rendezvous-docking space vehicles.

[0002]

2. Description of the Related Art In the field of space development, a space station in which humans can reside is constructed in space, and this space station is used as a space base to implement maintenance and inspection of other spacecraft, Plans are underway to conduct various space experiments. In such a space station construction concept, it is considered to use a manipulator system that executes a work manipulator by remotely operating a work manipulator on behalf of a human to carry out and assemble building materials.

By the way, in such a manipulator system, as shown in FIG. 7, an imaging camera 2 is mounted on a work manipulator main body 1, and a work target 3 as a work target is provided with a plurality of markers. A target measuring device is provided in which the target member 4 is attached and arranged corresponding to the grip 3a for gripping, and the position and orientation of the work target 3 are detected by the target measuring device to execute remote control of the manipulator body 1. The method is adopted.

That is, in this target measuring device, first, the imaging camera 2 of the manipulator main body 1 captures an image of the target member 4 provided on the work target 3, and the target image is obtained. This target image is subjected to a binarization process based on a threshold value determined by the user, for example, using a 128-level gradation at the center of all 256 gradation levels in an arithmetic processing unit (not shown), and a marker image is formed. The position and orientation of the work target 3 are extracted and analyzed by the image analysis, and the position and orientation of the work target 3 are obtained. Then, the manipulator body 1 is remotely driven and controlled based on the position and orientation information of the work target 3, and a desired work is performed by gripping the handle 3 a of the work target 3 with the grip portion 1 a. .

[0005] However, in the above-described target measurement device, the entire binarized image may be darkened in a state where the binarization process is performed on the target image captured by the imaging camera 2 according to the imaging environment or the like. Since the marker image may be difficult to identify, the reliability of the image analysis is poor,
There is a problem that the measurement accuracy is poor.

For this reason, when applied to a manipulator system or the like, there is a problem that the workload of an operator who remotely operates the manipulator body 1 is very large, and the operation work is very complicated.

[0007] Such a situation is not limited to the manipulator system, and is the same when, for example, the present invention is applied to a system in which rendezvous docking between space vehicles in space is performed remotely from a ground station or the like.

[0008]

As described above, the conventional target measuring apparatus has a problem that the reliability of image analysis is low and the measurement accuracy is low.

The present invention has been made in view of the above circumstances, and provides a target measuring apparatus capable of realizing highly reliable and accurate image analysis and improving measurement accuracy. Aim.

[0010]

According to the present invention, a target member provided on a target and provided with at least one marker different in brightness from the surroundings is provided on a moving body for tracking the target. An imaging unit for imaging the target member, and after performing a smoothing process on the target image captured by the imaging unit, perform a differential filter process to generate a work image, and a change in brightness of the work image is large. A location is extracted, and a pixel of the target image corresponding to the extracted location data and a brightest pixel selected from a plurality of pixels surrounding the pixel are selected. A target measuring device, comprising: Form was.

According to the above arrangement, a working image is obtained by subjecting the acquired target image to a smoothing process and a differential filter process, and a place where the change in brightness is large in the working image is extracted. By selecting the brightest pixel from the pixels of the target image corresponding to the large location of the target image and a plurality of pixels surrounding the pixel, and performing the binarization process of the target image using the average value of the pixels as a threshold value ,
An optimum threshold can be set for each target image, and stable and reliable image data is obtained. Therefore,
Image analysis can be performed based on highly reliable image data, and stable and highly accurate target position calculation can be performed.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a target measuring device according to an embodiment of the present invention. A manipulator main body 10 has an imaging camera 11 for monitoring work. An arithmetic processing unit 12 is connected to the imaging camera 11, and a target image captured by the imaging camera 11 is input to the arithmetic processing unit 12.

The arithmetic processing unit 12 smoothes the input target image (see FIG. 2) as will be described in detail later, performs a differential filtering process on the target image, and extracts a working image (image obtained by extracting an edge portion) (FIG. 3). ) Is extracted, and a place where the change in brightness of the work image is large is extracted. Thereafter, the arithmetic processing unit 12 selects the brightest pixel from among the pixels of the target image captured by the imaging camera 11 and the plurality of pixels surrounding the pixel corresponding to the extracted location data in the work image (FIG. 4), the target image is binarized using the average value of the brightest pixels as a threshold, and the binarized image data is generated (see FIG. 5). Is calculated.

In FIGS. 2 to 5, for convenience, the boundary between light and dark is shown by a broken line in each figure.

A target member 14 for measuring a target is attached to the work target 13 as a work target facing the manipulator body 10. This target member 1
4 has, for example, one surface formed in black, and on one surface, first to third markers 141, 142, and 143 are provided at predetermined intervals.

The first and third markers 141, 1
Reference numerals 42 and 143 are formed in a substantially circular shape having a bright color such as white. On the other hand, the first to third markers 14
The second marker 142 located at an intermediate portion between the first and the first 143 is
It is formed in a substantially columnar shape, and its tip is given a bright color such as white.

In the above configuration, the manipulator body 1
0, the manipulator body 10 is first driven and controlled, and its imaging camera 1 is controlled.
At 1, the target member 14 of the work target 13 is photographed,
The target image (see FIG. 2) is input to the arithmetic processing unit 12.

Here, as shown in FIG. 6, when the target image is input in step S1 as shown in FIG. 6, in step S2, the arithmetic processing unit 12 checks the input target image (see FIG. 2, the boundary between the marker image and the surrounding image). After performing a smoothing process on the (blurred image), a differential filter process is performed to generate a work image (see FIG. 3) in which a so-called image edge portion is extracted.

Subsequently, in step S3, a place where the brightness of the extracted work image has a large change in brightness is extracted, and a pixel of the target image shown in FIG. 2 corresponding to the extracted place data and a plurality of pixels around the pixel are extracted. Pixels, for example, a total of 9 pixels of 8 pixels are selected.

In step S4, the brightest pixels are respectively extracted from the selected 1 pixel + 8 pixels, that is, 9 pixels in total (see FIG. 4), the average value of the brightest pixels is calculated, and the average value is calculated. And calculate the average value, for example, 91
The target image is binarized using the gradation as a threshold to obtain bright and dark image data of the marker image and the surrounding image as shown in FIG. Subsequently, in step S5, the position and orientation of the target are calculated based on the obtained image data.

In such an operation for calculating the position and orientation, the image data is generated in real time by repeatedly executing the above-described steps S1 to S5 in a state where the imaging camera 11 has acquired the target image. The position and orientation of the object are calculated based on the data.

The manipulator body is driven and controlled via a drive control unit (not shown) based on the position and orientation information of the object 13 calculated by the arithmetic processing unit 12,
A desired work is executed by holding the work target 13 with the holding portion.

As described above, the target measuring device generates a work image by performing a smoothing process and a differential filter process on the target image photographed by the imaging camera 11, and a change in brightness in the work image is large. The location is extracted, and the brightest pixel is selected from the pixels of the target image corresponding to the location having the higher brightness and a plurality of pixels around the pixel, and the average value of the pixels is used as a threshold value to select the target image. Image data is generated by performing a binarization process, and the position and orientation of the work target 13 are calculated based on the image data.

According to this, an optimum threshold value can be set for each target image, and stable and highly reliable image data is obtained, so that image analysis can be performed based on highly reliable image data. Therefore, the position and orientation of the work target 13 can be determined with high reliability and stability.

In the above embodiment, the first to third
The description has been given of the case where the target member 14 having the markers 141, 142, and 143 is attached to the work object 13 to measure the position and orientation of the work object 13. However, the present invention is not limited to this. It is also applicable to a configuration in which only the position of the work target 13 is measured by mounting the work target 13 on a target member provided with one mark, and substantially the same effect is expected.

In the above embodiment, the manipulator body 10 constructed in outer space is used as a control object.
The description has been given of the case where the present invention is applied to a system that is remotely controlled from the ground. However, the present invention is not limited to this. For example, in space, a space vehicle such as an artificial satellite is remotely controlled to cause so-called rendezvous docking between space vehicles. It is also applicable in a system.

Further, in the above-described embodiment, the case where the present invention is applied to a system for remotely operating between outer space and the ground has been described. However, the present invention is not limited to this. The present invention can be applied to a system that is remotely operated, and substantially the same effect can be expected.

Therefore, the present invention is not limited to the above-described embodiment, and various other modifications can be made in the implementation stage without departing from the scope of the invention. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements.

For example, even if some components are deleted from all the components shown in the embodiment, the problem described in the section of the problem to be solved by the invention can be solved, and the effects described in the effects of the invention can be solved. Is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention.

[0031]

As described in detail above, according to the present invention, it is possible to provide a target measuring apparatus which can realize highly reliable and accurate image analysis and can improve the measuring accuracy. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a target measurement device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a part of a target image.

FIG. 3 is an enlarged view of a part of a work image.

FIG. 4 is a diagram showing an image in which the brightest pixels are extracted.

FIG. 5 is a diagram showing image data subjected to a binarization process.

FIG. 6 is a flowchart shown to explain an image processing operation of the arithmetic processing unit in FIG. 1;

FIG. 7 is a diagram shown to explain a problem of a conventional target measuring device.

[Explanation of symbols]

 10 ... manipulator body. 11 An imaging camera. 12 ... arithmetic processing unit. 13 ... Work target. 14 Target member. 141... First marker. 142... Second marker. 143... Third marker.

Claims (4)

[Claims] 1. A target member provided on a target and provided with at least one marker having a different brightness from the surroundings; and an imaging means provided on a moving body that tracks the target and imaging the target member. After performing a smoothing process on the target image captured by the imaging unit, a differential filter process is performed to generate a work image, and a place where the change in brightness of the work image is large is extracted. A pixel of the target image corresponding to the location data and a brightest pixel are selected from a plurality of pixels around the pixel, and the target image is binarized using an average value of the brightest pixels as a threshold,
A target measuring device comprising: an arithmetic processing unit that calculates at least a position of the target based on the image data subjected to the binarization processing. 2. The method according to claim 1, wherein the arithmetic processing unit selects a darkest pixel from the pixels of the target image and a plurality of pixels around the pixel, and sets an average value of the darkest pixels as a threshold. Item 2. The target measuring device according to Item 1. 3. A method according to claim 2, wherein a plurality of markers are arranged on the target member at predetermined intervals, and the arithmetic processing means calculates the position and orientation of the target based on the binarized image data. The target measuring device according to claim 1 or 2, wherein: 4. A pixel of the target image corresponding to the location data of the working image generated by the arithmetic processing means, and a total of nine pixels around the pixel, each of which is selected from the nine pixels. Is selected, and the target image is binarized using the average value of the brightest pixels as a threshold value, and at least the position of the target is calculated based on the binarized image data. 4. The target measuring device according to claim 1, wherein