JPH05180635A - Shape measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain a shape measuring apparatus based on the principle of a slit-light projecting method, which can measure the shape continuously in high accuracy at a high speed even under the natural light conditions such as outdoors up to long distances. CONSTITUTION:Modulated slit light 103 is deflected at a constant angular velocity so as to scan an object scene 105. A slit image 107 of an object 106 obtained at this time is focused on an image sensing surface 109 of a non-scanning type image sensing element 200, which is constituted by arranging a plurality of one-dimensional optical-position detecting elements 201 in the direction of the short side. A slit-position information signal 110 of the slit image 107 on the image sensing surface 109 outputted from the non-scanning type image sensing element 201 in real time is amplified in band. Then, the signal is detected and demodulated, or the signal is detected in synchronization with a modulating signal 102 of the slit light. Thus, the position information data on the image sensing surface 109 of the slit light are obtained in real time. The space coordinate values of many representative points on the surface of the object 106 within the object scene 105 are obtained in real time based on the data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
A non-contact shape measurement that can continuously and rapidly obtain the spatial coordinates (three-dimensional coordinates) values of a large number of representative points on the surface of an object (hereinafter referred to as a target scene) in a target scene. The present invention relates to a device, and more particularly to a shape measuring device using a slit light projection method. This type of device is also called a range finder because it can obtain distance information about the target scene.

A non-contact shape measuring device using an image obtained by an image pickup device is used in not only engineering and industrial fields such as computer graphics, CAD / CAM, computer vision or robot vision, but also physical education, medicine and clothing. Its applications are expected in many fields, such as measurement and analysis of living bodies and natural objects in fields such as science.

[0003]

2. Description of the Related Art As a non-contact shape measuring method using images, a moire topography method, a stereo vision method, a slit light projection method and the like have been conventionally proposed. However, the moire topography method can obtain only relative distance information from the reference surface, requires time in the post-processing process, and is difficult to speed up measurement. Further, since the stereo vision method handles grayscale signal data over the entire imaging surface, it requires a huge storage capacity and a high-speed data processing device, and also requires a complicated processing process such as corresponding point detection. Therefore, it is still difficult to realize a high-speed and simple practical device.

On the other hand, in the slit light projection method, the target scene 105 is illuminated with the slit light 601 as shown in FIG. 6, and the slit image 107 of the target object 106 corresponding to this slit light 601 is captured on the image pickup surface of the image pickup device 108. Capture on 109. Then, the spatial coordinate value of a point p on the target object 106 corresponding to a certain point p on the slit image 107 is a plane S formed by the slit light 601 and a straight line connecting the point p and the lens center O of the camera. The coordinates of the intersection are obtained by the so-called triangulation principle. Therefore, the target object 1 corresponding to each point on the slit image 107 from one image
Since the spatial coordinate value of the point group on the 06 surface is obtained, three-dimensional information of the entire target scene 105 can be obtained by repeating the horizontal movement of the slit light 601 and image input. Thus, with the slit light projection method, three-dimensional information can be acquired without complicated post-processing steps such as corresponding point detection, and the amount of processed information is not so large, so there is a possibility of practical application at this stage. Considered to be the highest. In fact, recently, some shape measuring devices based on this method have been put into practical use.

However, in the ordinary slit light projection method, since a scanning type camera such as CCD is generally used as an image pickup device, a scanning time for one frame (about 1/30 sec.) Is input to one image. ) Is required. For this reason,
Step-by-step projection direction (deflection angle) of slit light
The scanning of the entire imaging surface must be repeated each time, controlling in steps. Therefore, for example, assuming that the target scene is divided by 128 slit lights, that is, assuming that the spatial resolution is 128, 128 images need to be input, which alone requires 4 seconds or more. Become. Target scene (object) that changes from moment to moment
In order to keep up with
High speed of about 30 seconds or more will be required. Therefore, various attempts to speed up the slit light projection method have been studied.

[0006]

The point of increasing the speed of the slit light projection method is to obtain the projection slit light and the positional information of the slit image by the slit light, especially the latter, as fast as possible. For this reason, the applicants arranged a plurality of non-scanning image pickup elements that do not require scanning of the image pickup surface to obtain the position information of the slit image, that is, a plurality of -dimensional optical position detection elements arranged in the short side direction. Newly devised an imaging device (Patent application Sho 62-20
3862), as an example, a prototype shape measuring device using a PSD array was actually prototyped, and this device can perform not only high-speed measurement at a video rate or higher as desired, but also continuous measurement with an accuracy of about ± 0.3%. Confirmed to
^{(1). (2)} . ((1) K. Araki, M. Sato, T. Nod.
a, Y. Chiba and M.C. Shimizu:
"High Speed and Continuo
us Rangefinding System. ",
The IEICE Transaction on I
nforma-tion and System, Vo
l. E74, No. 10, pp. 3400-3406
(1991). (2) Kazuo Araki, Yu Shimizu, Takayuki Noda, Yuji Chiba, Yukifumi Tsuda, Kazutoshi Iketani, Kunio Sannomiya, Mutsuko Gomi: "High speed, continuous 3"
Dimensional Measurement System ", Proceedings of the 22nd Conference on Image Engineering Conference, Vol.22, pp.243-246 (199)
1))

[0007]

However, as long as continuous light is used as the slit light source, the current measurement distance is within about 1 m, and it is not suitable for applications in fields requiring fast distance measurement such as navigation systems. There are challenges. In addition, under natural light conditions, measurement accuracy is slightly insufficient due to low-frequency fluctuations of natural light and sudden disturbance light.

Under such a circumstance, the present invention has several m to 1
Provided is a shape measuring device capable of performing long-distance measurement of about 0 m, and also capable of performing high-speed and continuous measurement with high accuracy even under natural light conditions.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is related to the previously filed patent application Sho 62-2.
The following measures are taken for the shape measuring device of 03862 (Fig. 1).

First, the emission intensity of the slit light source 101 is controlled by the modulation signal 102 to have a sine wave shape or a pulse wave shape. The slit light controlled in this way is hereinafter referred to as modulated slit light 103. This modulated slit light 10
A slit light scanning mechanism 10 using a rotating mirror 3
The target scene 105 is deflected at a constant angular velocity ω by
The upper part is scanned, and the slit image 107 of the target object 106 obtained at this time is formed on the imaging surface 109 of the imaging device 108. This imaging surface 109 is disclosed in Japanese Patent Application No. Sho 62-203862.
The non-scanning image pickup device 200 (FIG. 2) described in the above. The non-scanning type image pickup device 200 is configured by arranging a plurality of one-dimensional light position detecting devices 201 in the short side direction thereof, and each one-dimensional light position detecting device (hereinafter sometimes referred to as each channel). The signal processing circuit 202 is connected to each of them, and outputs the position information signal 110 of the slit image 107 formed on each one-dimensional optical position detecting element 201 in real time.

On the other hand, when the modulated slit light 103 reaches a predetermined reference position, the reference position signal 111 is output, and the digitized elapsed time 11 is used as a starting point.
2 is output. As described above, the modulated slit light 103
Since the deflection angular velocity ω is controlled to be constant, this elapsed time 112 gives the projection direction of the modulated slit light 103. Therefore, the position information signal 110 and the elapsed time 112 of the slit image 107 output from the image pickup surface 109, that is, the non-scanning image pickup device 200, are processed by the signal processing / calculation unit 113.
Then, the spatial coordinates (three-dimensional coordinates) of points on the target object 106 are appropriately processed based on the above-described principle of the slit light projection method.
The value 114 is obtained.

In the signal processor / arithmetic unit 113, the position information signal 110 of the input slit image 107 is taken into consideration in consideration of the frequency of the modulation signal 102 of the modulated slit light 103, and the band amplifier 301 (FIG. 3). ), And the path I: after the detection and demodulation by the detection and demodulation circuit 302, A is set to an appropriate sampling time based on the elapsed time 112.
After A / D conversion by the / D converter 303, or path II: modulated slit light 1 without detection / demodulation
A / D conversion in synchronization with the 03 modulation signal 102,
The position information data 304 is obtained by digitizing the position information signal 110 on the basis of the elapsed time 112. At this time, the digitized order, that is, the sampling time of the A / D conversion is given to the projection direction of the modulated slit light 103, and the data at that time gives the position information of the corresponding slit image 107 on the imaging surface. The arithmetic circuit 305 performs processing based on the principle of the slit light projection method to obtain a spatial coordinate (three-dimensional coordinate) value 114 of a point on the target object 106.

After the position information signal 110 is band-amplified,
A method of A / D conversion in synchronization with the modulation signal 102 of the modulated slit light 103 without detection / demodulation (hereinafter,
In the case of the synchronous detection method), a plurality of light sources 101 (hereinafter referred to as light sources 1, 2, 3, ..., Light source n) are used, and these are as shown in FIG. Control is performed in a predetermined order, for example, in the order of the light sources 1, 2, 3, ..., N so that no two light sources are simultaneously emitting, and this is repeated as one sequence.

Spatial coordinate value 11 obtained as described above
4 is immediately displayed on the display and / or stored in a large-capacity external storage device 115 such as a large-capacity memory unit, magnetic tape, magnetic disk, optical disk, etc., and subjected to digital processing by a computer or the like.

A dummy electrode 203 is provided between each channel of the non-scanning type image pickup device 200 used in the present invention and is grounded. Further, dummy resistance layers 204 are provided at both ends outside the effective light receiving surface of each channel.

[0016]

Basically, the method described in Japanese Patent Application No. Sho 62-203862 is used, and high-speed measurement and continuous measurement are possible.

Since the modulated slit light 103 is used to amplify the position information signal 110 outputted in real time from the non-scanning type image pickup device 200 in a band and selectively extract an effective signal component, noise resistance is improved. The performance is dramatically improved, and weak signal components buried in noise can be detected, which enables long-distance measurement. In addition, since it is possible to eliminate the effects of steady and low-frequency light fluctuations under natural light conditions and sudden disturbance light, it is possible to perform outdoor measurement.

Further, in the case of a system in which the position information signal 110 is band-amplified and then detected and demodulated, the necessary signal is the envelope wave of the amplitude-modulated position information signal 110, and therefore the slit is used to improve the accuracy. The frequency of the light modulation signal 102 must be high, but as a result, the demands on the frequency characteristics of the image pickup device and the signal processing circuit portion become strict, which is disadvantageous in terms of practical application. However, in the present invention, in the case of adopting the method of detecting in synchronization with the signal for modulating the light beam without detecting and demodulating, that is, in the case of adopting the above-mentioned synchronous detection method, it is necessary to modulate at a frequency corresponding to the spatial resolution. Since it is good, low frequency modulation is generally sufficient. For example, the spatial resolution is 128, that is, 128 slit light /
When measuring with a measurement speed of 32 scenes / second with a scene resolution, a modulation frequency of 128 × 32 = 4096 Hz is sufficient.

Further, the slit light projection method has a problem of so-called blind spot in that it is impossible to measure a portion which is shaded with respect to the projected light. In order to reduce this problem, the second, third, ... A so-called multiple light source system may be adopted in which the nth light source is provided and the measurement is repeated by projecting from different directions. However, in the case of the conventional multi-light source method, after the measurement of one scene is completed by the first light source, the measurement is repeated by sequentially switching to the second, third, ... Although the time lag between the scenes is large, the time lag between the scenes in the synchronization detection method of the present invention is only about one cycle of the slit light modulation signal 102 and can be substantially ignored. In other words, substantially the same result as when the measurement is performed while simultaneously emitting a plurality of light sources is obtained.

The method in which the dummy electrodes 203 are provided between the channels of the non-scanning type image pickup device 200 and grounded, the crosstalk between the channels is significantly reduced and the measurement accuracy is improved. Further, the dummy resistance layers 204 provided at both ends of each channel improve the detection accuracy in the vicinity of both ends of the non-scanning type image pickup device 200.

[0021]

FIG. 5 shows an embodiment of the measuring device according to the present invention. A semiconductor laser 501 is used as a light source of slit light, pulsed light is emitted by a pulse signal 502 having a constant cycle, and this modulated output beam is vertically expanded by a lens system 503 including a cylindrical lens,
The modulated slit light 103 is obtained. This modulated slit light 10
3 is deflected at a constant speed ω by a slit light scanning mechanism 104 composed of a galvanometer and a mirror attached thereto, and a target scene 105 is scanned. The slit image 107 of the target object 106 obtained at this time is formed on the image pickup surface 109 of the image pickup device 108, and this image pickup surface is constituted by, for example, a PSD array 504 of 128 rows and 1 column. The PSD array 504 outputs the position information signal 110 of the slit image 107 on the imaging surface 109 in real time. (Kazuo Araki, Yu Shimizu, Takayuki Noda, Yuji Chiba, Yukifumi Tsuda, Kazutoshi Ikeya, Kunio Sannomiya, Mutsuko Gomi: "High-speed and continuous 3D measurement system", 22nd Conference on Image Engineering Conference, Vol22, pp.243- 246
(1991))

On the other hand, as described above, the modulated slit light 10
Since No. 3 is deflected at a constant angular velocity ω, the projection direction of the modulated slit light 103 is associated with the elapsed time 112 from the time when the modulated slit light 103 passes a certain reference direction. Therefore, in the present embodiment, the slit light scanning mechanism 1
When the rotation angle of the 04 galvanometer reaches a predetermined angle (that is, when the rotation angle control signal voltage to the galvanometer reaches a predetermined constant value), the reference position signal 111 is output, and this is used as a trigger signal. The clock counter 505 is activated to output the digitized elapsed time 112. Since the signal processing / calculation unit 113 can be easily configured by using ordinary electronic components, the position information signal 110 and the elapsed time 112 are introduced to the signal processing / calculation unit 113 to perform the processing as described in detail in the section of means for solving the problem. Then, the spatial coordinate value 114 of the point on the target object 106 is output, sequentially displayed on the display, and stored in the memory 506.

[0023]

According to the present invention, the distance information of the target scene can be continuously acquired up to a long distance under a natural light condition as well as in a dark room condition. It can respond to changes and can capture the three-dimensional movement of the target object in a more natural state. Therefore, not only industrial fields such as CAD / CAM, computer vision, mobile robot vision, computer graphics, 3D animation, and 3D image transmission, but also engineering, physical education, medicine, fashion, etc. It can be applied in various fields such as measurement and analysis, and its ripple effect will be immeasurable.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a shape measuring apparatus according to the present invention.

FIG. 2 is a structural example of a non-scanning image sensor used in the present invention.

FIG. 3 is a configuration example of a signal processing / arithmetic unit in the present invention.

FIG. 4 is an example of light emission timing of a multi-light source type light source group according to the present invention.

FIG. 5 is a configuration diagram of a shape measuring apparatus according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram of a slit light projection method that provides the basic measurement principle of the present invention.

[Explanation of symbols]

Reference numeral 101 slit light source 102 modulation signal for slit light 103 modulated slit light, that is, modulated slit light 104 slit light scanning mechanism 105 target scene 106 target object 107 slit image of target object 108 imaging device 109 imaging surface 110 imaging surface 110 imaging of slit image 107 Position information signal on surface 109 111 Reference position signal 112 Elapsed time 113 Signal processing / arithmetic unit 114 Spatial coordinate value of point on target object 106 Large capacity external storage device 116 Overall control unit 200 Non-scanning image sensor 201 One-dimensional Optical position detection element 202 Signal processing circuit 203 Dummy electrode 204 Dummy resistance layer 301 Band amplifier 302 Detection / demodulation circuit 303 A / D converter 304 Digitized position information data 305 Operation circuit 501 Semiconductor laser 5 2 modulation pulse shape signal (= modulation signal 102) 503 lens unit 504 PSD array, such as a cylindrical lens (= the imaging surface 109) 505 clock counter 506 memory 601 slit light

Claims (4)

[Claims] 1. The emission intensity of a slit light source is controlled in a sinusoidal or pulsed manner by a modulation signal, the slit light thus controlled is deflected at a constant angular velocity, and the slit light is projected onto a target scene. , A slit-shaped optical image (slit image) of the target object obtained at this time is formed on a non-scanning image pickup device configured by arranging a plurality of one-dimensional optical position detection elements in the short side direction. The position information signal amplitude-modulated at the frequency of the modulation signal of the slit image output in real time by the scanning image sensor is band-amplified and then detected / demodulated, or the modulation is performed without detection / demodulation. The position information data of the slit image is acquired in synchronization with the use signal, while the projection direction data of the slit light deflected at a constant angular velocity is acquired in real time. A shape measuring apparatus capable of obtaining three-dimensional information of a target scene in real time from the light projection direction data and the position information data of the slit image. 2. A plurality of slit light sources according to claim 1 are used, and these slit light sources are controlled in a predetermined order so that no two emit light at the same time.
A method of projecting a target scene from different directions while repeating light emission as a sequence, and the method of claim 1.
The method of acquiring the position information data of the slit image in synchronization with the modulation signal of the slit light without band-amplifying the position information signal of the slit image output in real time, which is described in, without performing detection / demodulation. By being used together, a shape measuring device that alleviates the problem of so-called blind spot, which is one of the weak points of the light projection method, and significantly enhances the temporal synchronicity between measured scenes. 3. The large-capacity external storage device such as a large-capacity memory, a magnetic tape, a magnetic disk, or an optical disk stores the three-dimensional information of the target scene acquired in real time by the shape measuring apparatus according to claim 1 or 2. A shape measuring device capable of acquiring three-dimensional information of a target scene at high speed and continuously by storing it in real time. 4. A dummy electrode is provided between each channel of the non-scanning type image pickup device according to claim 1, and grounding the dummy electrode reduces crosstalk between the channels and an effective light receiving surface of each channel. An image sensor with improved optical position detection performance near both ends of the image sensor by providing dummy resistance layers on both outer ends.