JPH03128409A - Three-dimensional shape sensor - Google Patents

Abstract

PURPOSE:To measure the three-dimensional shape of a measurement surface in real time without requiring any mechanical movement by composing the sensor of a projection device, an image pickup device, and an image processor. CONSTITUTION:The projection device 1 includes a laser light source 11 which emits luminous flux, an astigmatism optical system 12 which converts the luminous flux into luminous flux with astigmatism, and a luminous flux splitting means 13 which splits the luminous flux into plural components, and projects plural light spots on the measurement surface. The image pickup device 4 picks up an image of a light spot which is projected from the projection device 1 and reflected by the measurement surface 3. The image processor 5 operates the whole shape of the measurement surface 3 from the distances to respective spots which are calculated from the light spots picked up by the image pickup device 4. Then the luminous flux splitting means 13 splits the luminous flux to irradiate the measurement surface 3 with the light spots, so the distances to the respective light spots on the measurement surface can be measured at the same time and the three-dimensional shape of the measurement surface 3 can be detected without being scanned.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a three-dimensional shape sensor that detects the three-dimensional shape of a measurement surface using astigmatism.

[Prior Art] In order for robots to perform autonomous work, there is an urgent need to develop a three-dimensional shape sensor that can three-dimensionally perceive the working environment in P2.

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

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

The astigmatism optical system 92 includes a convex lens 92a and a cylindrical lens 92b, and converts the light beam imaged by the astigmatism optical system 92 into a light beam with 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 in a transverse section.

That is, when a light spot is imaged by the astigmatism optical system 92, the image of the light spot changes into a vertically long ellipse, a perfect circle, and a horizontally long ellipse depending on the position, like the measurement surfaces 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.

[Problem 9M to be solved by the invention] When trying to detect the three-dimensional shape of a measurement surface using the conventional shape sensor described above, it is necessary to scan the measurement surface with a light beam, and therefore In addition to requiring a highly accurate mechanism, there was a problem in that it took time to measure.

In addition, when using a shape sensor for a robot, depending on the task, there may be a so-called occlusion problem that blocks the optical path during the operation, and in other tasks, there is no occlusion problem, but the measurement range and accuracy may be affected. There are various aspects such as increasing the number of applications, and a wide range of application flexibility is desired.

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 can be used over a wide range of applications.

(Means for Solving tlB) In order to solve the above problems, the three-dimensional shape sensor according to the present invention includes a light source that emits a luminous flux, an astigmatism optical system that converts the luminous flux into a luminous flux with astigmatism, and a luminous flux that a light projection device that projects a plurality of light spots onto a measurement surface, including a light beam splitting means that splits the beam into a plurality of light beams, an imaging device that images the light spots projected from the light projection device and reflected on the measurement surface; and an image processing device that calculates the shape of the entire measurement surface based on the distance from each of the light spots imaged by the imaging device to each of the light spots calculated.

In this case, an optical path splitter may be provided on the optical path from the light projection device to the measurement surface, so that the light beams reflected on the same optical path are made to enter the imaging device.

Further, the light projection device and the imaging device may be arranged so that their optical axes are different from each other, and the image processing device may be configured to calculate the distance to each light spot based on a triangulation method.

[Function] According to the above configuration, the light beam splitting means divides the light beam and irradiates the measurement surface with a large number of light spots, so that the distance to each light spot on the measurement surface can be measured simultaneously, and the distance to each light spot on the measurement surface can be measured simultaneously. Three-dimensional shapes can be detected without scanning or the like.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below 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 sensor of the same embodiment.

The light projection device 1 includes all laser beams, an astigmatism optical system 12.
It includes a 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 the light beam oscillated from the laser light source 11 into a light beam with astigmatism, and includes a convex lens 12a.

It is composed of a cylindrical lens 12b.

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

A fiber grating is a diffraction grating in which hundreds of optical fibers with a diameter of several tens of micrometers are arranged in a sheet form.Here, in order to generate two-dimensional diffracted light, two fiber gratings are aligned along the axis of the optical fiber. The structure used is that they are stacked so that they are perpendicular to each other and supported by sandwiching them between cover glass plates from both sides.

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

As shown in FIG. 2, the shape of the light spot of the light beam projected onto the measurement surface 3 changes from a vertically long ellipse to a perfect circle to a horizontally long ellipse depending on the position of the measurement surfaces 3A to 3C.

A portion of the light beam reflected by the measurement surface 3 passes through the half mirror 22 of the optical path splitter 2 and enters the imaging device 4 .

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

The optical filter 41 transmits only the wavelength of the laser beam,
The imaging lens 42 is a bandpass filter that cuts out disturbance light, and the imaging lens 42 is a lens that focuses an image on the detection surface of the imaging element 43. The image sensor 43 is a two-dimensional array of photodetecting elements with photoelectric conversion and charge storage functions, which can be read out sequentially. I am using something like this.

The image processing device 5 is a device for transmitting a signal for controlling the laser light source 11 and for processing an image signal from the imaging device 4, and includes a central processing device 51, a camera controller 52, and an image memory 53. , a display/recording device 54 , and a laser controller 55 .

The camera controller 52 is for converting the output of the imaging device 4 into an input signal of the image memory 53.

The image signal from the imaging device 4 is sent to the camera controller 52.
The image is temporarily stored in the image memory 53 via. Central processing unit 51 processes data on image memory 53. In other words, the central processing unit 51 recognizes the shape of each light spot, calculates the distance to each light spot from the shape, and finally calculates the distance of all the imaged light spots and the distances between the light spots. The three-dimensional shape of the measurement surface 3 is calculated and output from the relative positional relationship between the two. The output of the central processing unit 51 can be output to a display/recording device 54 such as a CRT, printer, or magnetic recording device, or can be directly connected to a robot controller or the like for use as control information for the robot.

The three-dimensional shape sensor of the first embodiment has a light beam splitting means 13
By dividing the light beam with astigmatism into a two-dimensional regular matrix, the three-dimensional image of the measurement surface 3 can be measured in one go without mechanical movement or optical scanning within the device. Shape can be detected.

In addition, using the optical path splitter 2, the light projecting device 1 and the imaging device 4
Since the optical path is shared, 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, parts that perform the same functions as those in the first embodiment described above are given the same reference numerals, and only unique parts will be explained.

This method utilizes a so-called triangulation method in which a light spot 7) from a light projector IA is projected onto the measurement surface 3 and detected by an imaging device 4A whose optical axis is placed apart by a base line length d. .

In the second section, a case will be described in which the three-dimensional position at point a on the measurement surface 3A is determined.

Now, the light emitted from point P of the projector IA is on the measurement surface 3A.
Assume that the light is reflected at point a above and incident on point Q of the imaging device 4A. In this case, the base PQ (=W line length d
) is known, so if the angles θ and 9 θ2 are found, the distance to point a can be calculated. The angle θ2 can be determined from the position Nu of the light spot SI on the imaging device 33 and the focal length f of the imaging lens 32 from the following equation.

θ, = tan−' (u/r) while the angle θ
1 can be determined by knowing the diffraction order of the optical band. However, the optical spot S+ imaged at the position U on the image sensor 33 shown in FIG.
The light bulb 7 30 may be reflected at point a of the measurement surface 3B.
It is not possible to distinguish from a single image whether the light was reflected at point b or not. For this reason, 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, by using the astigmatism optical system 12, it is possible to determine whether the light spot S0 is reflected at point b or not.
Whether the light spot S is reflected at eight points or not is determined from the shape of the spot on the image sensor 33,
As a result, the measurement distance could be expanded.

In the second embodiment, the distance is basically determined based on the principle of triangulation, so that 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. 4 emits a light beam from a light source 61.
The light is condensed by a lens 62 and guided to an astigmatic lens array 63, which imparts astigmatism and splits the luminous flux. This astigmatism lens array 63 is an array of all identical astigmatism lenses, and each astigmatism lens may have a diameter of about several mm.

The lens array 64 shown in FIG. 5 combines the astigmatism optical system 12 and the diffraction means 13 (FIGS. 1 and 3) into one element by using a combination of minute lenses. . This lens array 64 is composed of lenses having a diameter of several tens of μm arranged in a grid pattern (FIG. 5(a)).
. By making laser light incident on this lens array 64, the laser light incident on each lens is once condensed, and a spherical wave is generated from that point. The spherical waves generated from each of these lenses interfere at a distance, and an effect equivalent to that of the diffraction means 13 can be obtained. In addition, the lens array 64 has astigmatism as a whole by varying the optical characteristics (lens thickness) of each lens depending on the position (Fig. 5(b), (C1)). It is.

The light projection device 7 shown in FIG. 6 emits a luminous flux from a light source 71.
It is divided by a screen 72 having a large number of pinholes 72a, and has astigmatism by an astigmatism optical system 73 consisting of a convex lens 13a and a cylindrical lens 73b.

The light projecting device 8 shown in FIG. 7 does not rely on optical diffraction, but instead reflects the light beam from the light source 81 sequentially between a mirror 82 and a half mirror 83.
After a large number of divided light beams are emitted from the side, they are made to have astigmatism using an astigmatism optical system (not shown).

In this example, there is no need 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 beam splitting means 13 may be placed in front of the astigmatism optical system 12, or may be placed between the convex lens 12a and the cylindrical lens 12b that constitute the astigmatism optical system 12.

〔Effect of the invention〕

As explained above in detail, according to claim (1), the beam splitting means projects the beam having astigmatism as a large number of light spots, so that mechanical movement within the device,
The three-dimensional shape of the measurement surface can be detected in one measurement without optical scanning.

Furthermore, according to claim (2), the optical path splitter is used to share the optical path of the projector and the imaging device, which solves the so-called blockage problem in which observation is obstructed by blocking the optical path. did it.

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

[Brief explanation of the drawing]

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 sensor of the same embodiment. 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 using astigmatism. 1, IA, IB... Light projection device 11... Coherent light source 12... Astigmatism optical system 12a... Convex lens 12b... Cylindrical lens 13... Light beam splitting means 2... Optical path splitting Container 21...Mirror 22...Half mirror
3...Measurement surface 4.4A...Imaging device 41...Optical filter 42...Imaging lens 43
...Image element 5...Image processing device 51...Central processing unit 52...Camera controller 53...Image memory 54...Display/recording device 55...Laser controller 6... Light projecting device 61...Light a 62...Lens 63...
- Astigmatism lens array 64...Lens array 7...Light projector 71...Light R72...Screen 73...Astigmatism optical system 8...Light projector 81...Light source 82...Mirror 83.
・Half mirror

Claims (3)

[Claims] (1) A light source that emits a luminous flux, an astigmatism optical system that converts the luminous flux into a luminous flux with astigmatism, and a light projection device that includes a luminous flux splitting means that divides the luminous flux into a plurality of parts and projects a plurality of light spots onto the measurement surface. , an imaging device that images a light spot projected from the light projection device and reflected on the measurement surface, and a distance to each light spot calculated from each of the light spots imaged by the imaging device, and the measurement surface A three-dimensional shape sensor consisting of an image processing device that calculates the overall shape. (2) According to claim (1), an optical path splitter is provided on the optical path from the light projection device to the measurement surface, so that the light beams reflected on the same optical path are made to enter the imaging device. 3D shape sensor. (3) The light projection device and the imaging device are arranged so that their optical axes are different from each other, and the image processing device is configured to calculate the distance to each light spot based on a triangulation method. The three-dimensional shape sensor according to claim (1).