JPH04370706A - Visual sensor - Google Patents

Abstract

PURPOSE:To enlarge the displacement of markers on an image sensing surface for a minute displacement of an object by widening a space wherein the markers are disposed, in a visual sensor detecting the three-dimensional position and attitude of the object. CONSTITUTION:A visual input device 4 senses images of markers 2A and 2B and a computer 5 calculates the three-dimensional position and attitude of an object 1 from the positions of the markers 2A and 2B on an image sensing surface. Herein a target is set on the object 1, and the markers 2A and 2B in the target are disposed on the circumferences of the base and the top of a cone 7 assumed in the visual field 6 of the visual input device 4.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual sensor for detecting the three-dimensional position and orientation of an object, which is used when automatically manipulating or approaching an object.

0002

[Prior Art] Figure 3 shows, for example, the 2nd Space Artificial Intelligence/Robot/Automation Symposium (January 1986).
January 17) Lecture collection P. 51~P. 54 is a configuration diagram showing a conventional visual sensor shown in FIG.

In the figure, 1 is an object, 2 is a marker placed on or near the object 1, 3 is a support for supporting the marker 2 placed away from the object 1, and 4 is the marker 2. A visual input device such as a CCD camera that captures images, 5
is the object 1 based on the image output by the visual input device 4.
This is a computer (calculation device) that calculates the position and orientation of the object. Note that 6 indicates the field of view of the visual input device 4. Further, the target includes a marker 2 and a supporter 3.

Next, the operation will be explained. First, a target is attached to the object 1. The visual input device 4 then images the marker 2. The three-dimensionally arranged markers are projected and transformed into an image by the visual input device 4. Visual input device 4 outputs the image to computer 5.

[0005] The calculator 5 calculates the three-dimensional position of each marker 2 using the relative positional relationship (distance, angle, etc.) of each marker 2. Then, the position and orientation of the object 1 are determined using these positions.

[0006]

[Problems to be Solved by the Invention] Since the conventional visual sensor is configured as described above, it converts the marker position on the imaging surface into the position and orientation of the object 1, so it is possible to determine the minute position of the object. Alternatively, it is desirable that a large change occur in the marker position on the imaging surface in response to a change in posture. For this purpose, it is desirable that the markers 2 are arranged as widely as possible spatially. However, in the conventional visual sensor, the marker 2 is placed at the apex and bottom of the cone, so there is a problem in that the marker 2 is not placed in a wide area that makes full use of the field of view 6 of the visual input device 4.

[0007] Furthermore, when the distance to the object 1 is used for measurement over a wide range, it is desirable to increase the distance between markers as the distance increases. One method for this purpose is to provide multiple sets of multiple markers 2 close to each other and switch the set used depending on the distance. However, in the conventional arrangement, the marker 2 is located in the center, There was a problem in that it was not possible to arrange them efficiently, and as a result, the arrangement area became large.

[0008] This invention was made in order to solve the above-mentioned problems, and it is possible to widen the space in which markers are set. The purpose is to obtain a visual sensor that can be placed on a narrow surface when arranging a set of markers.

[0009]

[Means for Solving the Problems] A visual sensor according to the present invention includes two or more markers placed on the bottom surface of one or more truncated cones virtually assumed on an object, and The target includes two or more markers placed on the top surface.

0010

[Operation] In the target according to the present invention, the marker is arranged on a truncated cone, and the conical field of view of the visual input device is effectively utilized. Further, it is possible to set a plurality of sets consisting of a plurality of markers arranged in the same circular shape.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 2A is a marker placed on the circumference of the bottom surface of the truncated cone 7, 2B is a marker placed on the circumference of the top surface of the truncated cone 7, and 7 is a hypothetical truncated cone. Other parts are designated by the same reference numerals and are the same as or correspond to those shown in FIG. 3. Further, the target includes markers 2A, 2B and a supporter 3.

Next, the operation will be explained. The visual input device 4 inputs the target markers 2A, 2 as in the conventional case.
B is imaged, and the computer 5 marks the marker 2 on the imaged image.
The position and orientation of the object 1 are calculated from A and 2B.

[0013] Here, the target is configured as follows. A truncated cone 7 is assumed to be located at an appropriate position on the object 1, the bottom surface of which is in contact with the object 1, and whose entirety is within the field of view 6 of the visual input device 4. Two markers 2A are placed on the circumference of the bottom surface of the truncated cone 7. Further, two markers 2B are arranged on the circumference of the upper surface of the truncated cone 7, and the markers 2B are supported by the supporter 3.

[0014] As described above, by disposing the markers 2A and 2B on the circumferences of the bottom and top surfaces of the truncated cone 7, the markers 2A and 2B are disposed over a spatially wide range. Therefore, the displacement of the markers 2A and 2B on the imaging plane caused by the displacement of the object 1 becomes large.

FIG. 2 is a block diagram showing a visual sensor according to another embodiment of the present invention. In the figure, 8 is a second truncated cone assumed inside the truncated cone 7, 2C is a marker placed on the bottom circumference of the second truncated cone 8, and 2D is the upper surface of the second truncated cone 8. These are markers placed on the circumference.

In this case, the markers 2A to 2D can be switched and used depending on the distance from the visual input device 4 to the object 1. That is, when the distance is large, a set consisting of markers 2A and 2B can be used, and when the distance is small, a set consisting of markers 2C and 2D can be used. Furthermore, the number of markers may be increased assuming other truncated cones.

[0017] In each of the above embodiments, two
Although a case has been described in which 100 markers are arranged, more markers may be provided in order to reduce errors caused by placement errors of each marker and distortion of the lens of the visual input device 4.

Further, in the above embodiment, the case where the bottom surfaces of the truncated cones 7 and 8 are perfect circles has been described, but since the cross section of the field of view 6 of the visual input device 4 is generally rectangular, the bottom surfaces of the truncated cones 7 and 8 are elliptical. You can also assume a stand.

[0019]

As described above, according to the present invention, a visual sensor can be used as a target having two or more markers on each of the bottom and top surfaces of one or more truncated cones assumed on an object. This configuration allows markers to be placed over a wide spatial range, making it possible to accurately detect the position and orientation of the target.Furthermore, when the distance to the target is wide, multiple sets of markers can be placed over a wide range. This has the effect of being able to detect the position and orientation of an object with high accuracy even when the distance is wide.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a visual sensor according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a visual sensor according to another embodiment of the present invention.

FIG. 3 is a configuration diagram showing a conventional visual sensor.

[Explanation of symbols]

1 Object 2A~2D Marker (target) 3 Support device (target) 4 Visual input device 5. Calculator (calculating device)

Claims (1)

[Claims] 1. Two or more markers placed on the bottom surface of one or more truncated cones virtually imagined on an object, and two or more markers placed on the top surface of each of the truncated cones. A visual sensor comprising a target including a target, a visual input device that images each of the markers, and a calculation device that calculates the position and orientation of the object based on the markers on the image output by the visual input device.