JP2673196B2 - 3D shape sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a three-dimensional shape sensor for detecting a three-dimensional shape of a measurement surface by utilizing astigmatism.

[Conventional technology]

In order for a robot to work autonomously, it is an urgent task to develop a three-dimensional shape sensor that recognizes the work environment three-dimensionally.

FIG. 8 is a diagram showing an example of an optical system of a shape sensor utilizing astigmatism.

The laser light source 91 is for oscillating a coherent light beam, and the light beam is guided to the astigmatism optical system 92.

The astigmatism optical system 92 includes a convex range 92a and a cylindrical lens 92b, and converts the light flux imaged by the astigmatism optical system 92 into a light flux having astigmatism. Astigmatism is an aberration that occurs when the focal length of a lens has different values in a longitudinal section including the optical axis and a lateral section.

That is, when a light spot is imaged by the astigmatism optical system 92, the image of the light spot changes to a vertically long ellipse, a perfect circle, or a horizontally long ellipse depending on the position, as in the measurement planes A, B, and C.

By measuring the shape of this light spot, the distance from the shape sensor to the measurement surface can be detected.

[Problems to be solved by the invention]

Using the above-mentioned conventional shape sensor, in order to detect the three-dimensional shape of the measurement surface, it is necessary to scan the measurement surface with a light beam, which requires a mechanism with high accuracy. There was a problem that it took time to measure.

In addition, when using the shape sensor of the robot, depending on the work, there is a problem of so-called blockage that blocks the optical path during the work, and in the case of other work, there is no problem of blockage, but the measurement range and accuracy are improved. There are various modes such as wanting to raise it, and it is desired to have a wide degree of freedom of application.

An object of the present invention is to provide a three-dimensional shape sensor that can measure the three-dimensional shape of a measurement surface in real time without requiring mechanical movement and has a wide range of use.

[Means for solving the problem]

In order to solve the above-mentioned problems, the invention of claim 1 includes a light source that emits a light beam, an astigmatism optical system that converts the light beam into a light beam having astigmatism, a light beam splitting unit that splits the light beam into a plurality, and a measurement surface. A light projecting device that projects a plurality of light spots on the image capturing device, an image capturing device that captures the light spot projected from the light projecting device and reflected on the measurement surface, and the light spots captured by the image capturing device. In a three-dimensional shape sensor including an image processing device that calculates the shape of the entire measurement surface based on the distance to each light spot, the light projecting device and the imaging device are arranged so that their optical axes are different, The image processing device is characterized in that the distance to each light spot is calculated based on the triangulation method.

[Action]

According to the above configuration, the luminous flux splitting unit divides the luminous flux and irradiates a large number of light spots on the measurement surface, so that the distance to each light spot on the measurement surface can be measured at the same time, and the three-dimensional shape of the measurement surface Can be detected without scanning.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings and the like.

FIG. 1 is a block diagram showing an embodiment of a three-dimensional shape sensor according to the present invention, and FIG. 2 is a perspective view showing a light projecting device of the same embodiment sensor.

The light projecting device 1 includes a laser light source 11, an astigmatism optical system 12, and a light beam splitting means 13.

The laser light source 11 oscillates a coherent light beam, and here, a He-Ne laser is used.
The astigmatism optical system 12 is an optical system that converts a light beam oscillated from the laser light source 11 into a light beam having astigmatism, and includes a convex lens 12a and a cylindrical lens 12b.

The light beam splitting means 13 is for two-dimensionally diffracting the light beam emitted from the astigmatism optical system 12 and projecting a large number of light spots regularly arranged in a matrix on the measurement surface 3. Here, a fiber grating is used.

The fiber grating is a diffraction grating in which hundreds of optical fibers each having a diameter of several μm are arranged in a sheet shape. Here, in order to generate two-dimensional diffracted light, two fiber gratings The structure is such that they are stacked orthogonally and are supported by being sandwiched by cover glass plates from both sides.

The light flux emitted from the light projecting device 1 is reflected by the mirror 21 and the half mirror 22 of the optical path splitter 2 and projected on the measurement surface 3.

The luminous flux projected on the measurement surface 3 is, as shown in FIG.
Depending on the positions of the measurement surfaces 3A to 3C, the shape of the light spot changes from a vertically long ellipse, a perfect circle, and a horizontally long ellipse.

A part of the light flux reflected by the measurement surface 3 is the optical path splitter 2
The light passes through the half mirror 22 and enters the image pickup device 4.

The imaging device 4 is a device for converting an optical image, which is a light spot emitted from the light projecting device 1 and reflected on the measurement surface 6, into an electrical image signal, and includes an optical filter 41 and an imaging lens 42. And an image sensor 43 and the like.

The optical filter 41 transmits only the wavelength of the laser light,
The imaging lens 42 is a bandpass filter that cuts ambient light, and the imaging lens 42 is a lens for forming an image on the detection surface of the image sensor 43. The image sensor 43 is a two-dimensional array of photodetectors having the functions of photoelectric conversion and charge storage, which can be sequentially read out.Here, an array in which CCD elements are two-dimensionally arranged is used. I am using a shape.

The image processing device 5 is a device for sending a signal for controlling the laser light source 11 and for processing the image signal from the image pickup device 4, and includes a central processing unit 51, a camera controller 52, and an image memory 53. , A display / recording device 54,
It is composed of a laser controller 55.

The camera controller 52 is for converting the output of the imaging device 4 as an input signal of the image memory 53. The image signal from the imaging device 4 is temporarily stored in the image memory 53 via the camera controller 52. Central processing unit 51
Processes data on the image memory 53. That is, the central processing unit 51 recognizes the shape of each light spot, calculates the distance from that shape to each light spot, and finally, the distance of all the imaged light spots and those light spots. The three-dimensional shape of the measurement surface 3 is calculated and output from the relative positional relationship of. The output of the central processing unit 51 is
Display / recording device consisting of CRT, printer, magnetic recording device, etc.
It can be output to 54 or directly connected to a robot controller or the like for use as robot control information.

The three-dimensional shape sensor of the first embodiment has a light beam splitting means 13
Since the light beam having astigmatism is divided into a two-dimensional regular matrix by the three-dimensional method, the three-dimensional measurement of the measurement surface 3 can be performed at once without mechanical movement or optical scanning in the device. The shape can be detected.

Moreover, since the optical path splitter 2 is used to share the optical path of the light projecting device 1 and the image pickup device 4, the problem of blockage can be solved.

FIG. 3 is a diagram showing a second embodiment of the three-dimensional shape sensor according to the present invention.

In this embodiment, the parts having the same functions as those of the first embodiment described above are designated by the same reference numerals, and only the unique parts will be described.

This is a so-called triangulation method in which a light spot from the light projecting device 1A is projected on the measurement surface 3 and is detected by the image pickup device 4A whose optical axis is arranged a distance of the base line length d.

Here, a case where a three-dimensional position at the point a on the measurement surface 3A is obtained will be described.

Now, it is assumed that the light emitted from the point P of the light projecting device 1A is reflected at the point a on the measurement surface 3A and enters the point Q of the imaging device 4A.
In this case, since the base PQ (= baseline length d) of the triangle PQa is known, if the angles θ ₁ and θ ₂ are obtained, the distance to the point a can be calculated. The angle θ ₂ can be obtained from the following equation from the position u of the light spot S ₁ on the image pickup device 33 and the focal length f of the image pickup lens 32.

θ ₂ = tan ⁻¹ (u / f) On the other hand, the angle θ ₁ can be obtained by knowing the diffraction order of the light spot. However, the image sensor 33 shown in FIG.
Imaged light spot position u of the above, or not the light spot S ₁ is reflected by a point of measurement surface 3A, the or not the light spot S ₀ is reflected by the point b of the measurement surface 3B, the single It cannot be distinguished from the image. Therefore, if the range in which the object exists is limited to a specific range, the diffraction order can be determined, but conversely, the measurable range is limited.

Therefore, in this embodiment, the astigmatism optical system 12 is used to determine whether the light spot S ₀ is reflected at the point b or the light spot S ₁ is reflected at the point a. It was decided to start from the shape of the spot on the element 33, and as a result, the measurement distance could be expanded.

In the second embodiment, since the distance is basically obtained by the principle of triangulation method, the measurement accuracy is improved and the measurable distance can be expanded.

4 to 7 are diagrams schematically showing other examples of the light projecting device used in the embodiment of the three-dimensional shape sensor according to the present invention.

The light projecting device 6 shown in FIG.
The light is condensed by the lens 62 and guided to the astigmatism lens array 63. The astigmatism lens array 63 imparts astigmatism and splits the light flux. The astigmatism lens array 63 is an array of identical astigmatism lenses, and each astigmatism lens having a diameter of about several mm can be used.

The lens array 64 shown in FIG. 5 is one in which the astigmatic optical system 12 and the diffracting means 13 (FIGS. 1 and 3) are combined into one element by using a combination of minute lenses. . The lens array 64 is an array of lenses having a diameter of several tens of μm arranged in a grid pattern (FIG. 5 (a)). By entering the laser light into the lens array 64, the laser light entering each lens is once condensed and a spherical wave is generated from that point. The spherical waves generated from each of these lenses interfere with each other at a distance, and an effect equivalent to that of the diffracting means 13 can be obtained. Further, the lens array 64 is made to have astigmatism as a whole by making the optical characteristics (lens thickness) of each lens different depending on the position where they are arranged (FIGS. 5B and 5C). It is a thing.

The light projecting device 7 shown in FIG.
The screen 72 is divided by a screen 72 having a large number of pinholes 72a, and astigmatism is provided by an astigmatism optical system 73 composed of a convex lens 73a and a cylindrical lens 73b.

The light projecting device 8 shown in FIG. 7 does not rely on optical diffraction but sequentially reflects the light flux from the light source 81 between the mirror 82 and the half mirror 83 so that a large number of light beams are emitted from the half mirror 83 side. After the divided light flux is emitted, astigmatism is provided by an astigmatism optical system (not shown). In this example, it is not necessary to use a coherent light source as the light source 81.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the present invention.

The light beam splitting means 13 may be arranged in front of the astigmatism optical system 12 or may be arranged between the convex lens 12a and the cylindrical lens 12b which constitute the astigmatism optical system 12.

〔The invention's effect〕

As described in detail above, according to claim (1),
Since the luminous flux having the astigmatism is projected as a large number of light spots by the luminous flux splitting means, it is possible to perform three-dimensional measurement of the measurement surface with one measurement without mechanical movement or optical scanning in the device. It is possible to detect various shapes.

Further, according to claim (2), by using an optical path splitter,
Since the light path of the projector and the imaging device is shared,
We were able to solve the problem of so-called obstruction, which obstructs the observation due to black shielding.

Further, according to claim (3), since the distance is obtained by the principle of the triangulation method, the measurement accuracy is improved and the measurable distance can be expanded.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a three-dimensional shape sensor according to the present invention, and FIG. 2 is a perspective view showing a light projecting device of the same embodiment sensor. FIG. 3 is a diagram showing a second embodiment of the three-dimensional shape sensor according to the present invention. 4 to 7 are diagrams schematically showing other examples of the light projecting device used in the embodiment of the three-dimensional shape sensor according to the present invention. FIG. 8 is a diagram showing an example of an optical system of a shape sensor utilizing astigmatism. 1,1A, 1B …… Projector 11 …… Coherent light source 12 …… Astigmatism optical system 12a …… Convex lens 12b …… Cylindrical lens 13 …… Light splitting means 2 …… Optical path splitter 21 …… Mirror, 22 ...... Half mirror 3 …… Measuring surface 4,4A …… Imaging device 41 …… Optical filter, 42 …… Image forming lens 43 …… Imaging device 5 …… Image processing device 51 …… Central processing device 52 …… Camera controller 53 ... Image memory, 54 ... Display / recording device 55 ... Laser controller 6 ... Projector 61 ... Light source, 62 ... Lens 63 ... Astigmatism lens array 64 ... Lens array 7 ... Projection Optical device 71 …… Light source, 72 …… Screen 73 …… Astigmatism optical system 8 …… Projector 81 …… Light source, 82 …… Mirror 83 …… Half mirror

Claims (1)

(57) [Claims] 1. A light source for emitting a light beam, an astigmatism optical system for converting the light beam into a light beam having astigmatism, a light beam dividing means for dividing the light beam into a plurality of light beams, and a light projecting device for projecting a plurality of light spots on a measurement surface. A device, an imaging device for imaging a light spot projected from the light projecting device and reflected on the measurement surface, and the device based on a distance to each light spot calculated from each light spot imaged by the imaging device. In a three-dimensional shape sensor including an image processing device that calculates the shape of the entire measurement surface, the light projecting device and the imaging device are arranged so that their optical axes are different, and the image processing device uses the triangulation method based on the triangulation method. A three-dimensional shape sensor characterized by calculating the distance to each light spot.