JP3360505B2 - Three-dimensional measuring method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional measuring method and a three-dimensional measuring apparatus for irradiating an object with slit light or spot light to measure the shape of the object in a non-contact manner.

[0002]

2. Description of the Related Art A non-contact type three-dimensional measuring device called a range finder can perform higher-speed measurement than a contact type. Therefore, data input to a CG system or CAD system, body measurement, robot It is used for visual recognition.

[0003] As a measurement method suitable for a range finder, a slit light projection method (also called a light cutting method) is known. This method is a method of obtaining a three-dimensional image (distance image) by optically scanning an object, and is a kind of an active measurement method of irradiating specific detection light and photographing the object. The three-dimensional image is a set of pixels indicating the three-dimensional positions of a plurality of parts on the object. In the slit light projection method, a slit light having a linear cross section is used as detection light.

FIG. 15 is a diagram showing an outline of the slit light projection method, and FIG. 16 is a diagram for explaining the principle of measurement by the slit light projection method. The object Q to be measured is irradiated with slit light U having a narrow cross section and the reflected light is incident on, for example, an imaging surface S2 of a two-dimensional image sensor [FIG.
(A)]. If the irradiated portion of the object Q is flat, the captured image (slit image) becomes a straight line (FIG. 15B). If the irradiated portion has irregularities, the straight line may be bent or stepped (FIG. 15C). That is, the magnitude of the distance between the measurement device and the object Q reflects on the incident position of the reflected light on the imaging surface S2 (FIG. 15D). By deflecting the slit light U in the width direction, a three-dimensional position can be sampled by scanning the object surface in a range visible from the light receiving side. The number of sampling points depends on the number of pixels of the image sensor.

In FIG. 16, the light projecting system and the light receiving system are arranged such that the base line AO connecting the starting point A of the light projecting and the principal point O of the lens of the light receiving system is perpendicular to the light receiving axis. The light receiving axis is perpendicular to the imaging surface S2. Note that the principal point of the lens is defined as an image distance S by a so-called image distance (image distance) b when an image of a subject at a finite distance is formed on the imaging surface S2.
It is a point on the light receiving axis away from 2. The image distance b is the sum of the focal length f of the light receiving system and the lens extension for focus adjustment.

The principal point O is defined as the origin of a three-dimensional rectangular coordinate system.
The light receiving axis is the Z axis, the base line AO is the Y axis, and the length direction of the slit light is the X axis. When the slit light U reaches a point P (X, Y,
Assuming that the angle between the light projecting axis and the light projecting reference plane (light projecting surface parallel to the light receiving axis) when irradiating Z) is θa and the light receiving angle is θp,
The coordinate Z of the point P is represented by the equation (1).

Base line length L = L1 + L2 = Ztan θa + Ztan θp∴Z = L / (tan θa + tan θp) (1) The light receiving angle θp is a straight line connecting the point P and the principal point O.
This is an angle formed with a plane including the light receiving axis (light receiving axis plane).

Since the imaging magnification β = b / Z, if the distance in the X direction between the center of the imaging surface S2 and the light receiving pixel is xp and the distance in the Y direction is yp (see FIG. 16A), the point P Are represented by equations (2) and (3).

X = xp / β (2) Y = yp / β (3) The angle θa is uniquely determined by the angular velocity of the deflection of the slit light U. The light receiving angle θp can be calculated from the relationship tan θp = b / yp. In other words, the position (xp,
By measuring yp), the three-dimensional position of the point P can be obtained based on the angle θa at that time.

When a zoom lens group is provided in the light receiving system as shown in FIG. 16C, the principal point O is the rear principal point H '.
Assuming that the distance between the rear principal point H ′ and the front principal point H is M, the point P
Is represented by equation (1B).

L = L1 + L2 = Ztanθa + (Z−M) tanθp∴Z = (L + Mtanθp) / (tanθa + tanθp) (1B) In the measurement by the slit light projection method based on the above principle, the imaging surface S2 is, for example, like a CCD sensor. In the case of using an imaging unit having a finite number of pixels, the measurement resolution depends on the pixel pitch of the imaging unit. However, the resolution can be increased by setting the slit light U such that the width of the slit light U on the imaging surface S2 in the Y direction (scanning direction) is equivalent to a plurality of pixels.

FIG. 17 is a diagram for explaining the principle of a conventional measuring method. Assuming that the reflectance of the irradiated portion on the object is uniform, the received light intensity has a normal distribution extending in the Y direction. If the effective intensity range of the normal distribution is for a plurality of pixels, the maximum intensity position (referred to as the center of gravity) can be measured in units equal to or less than the pixel pitch by performing an interpolation operation on the amount of received light of each pixel g. The interpolation calculation is to fit a normal distribution to the light receiving amount of each pixel. The coordinates Z, X, and Y are obtained based on the center of gravity obtained by the calculation. According to this method, the actual resolution is about 1/8 to 1/10 pixel.

In order to make the width of the slit light U on the imaging surface S2 a plurality of pixels, the width (length in the scanning direction) of the slit light U may be increased at the stage of light projection. However, in this case, the width of the slit light U in the Y direction is also widened on the object Q. Therefore, when the irradiated portion (point P) is, for example, a boundary between object colors, the distribution of the received light intensity is not a normal distribution, and the measurement error is reduced. growing.

Conventionally, the light projecting conditions are set so that the slit width on the object Q is as small as possible, and the width of the slit light U is expanded by a filter or the like in the light receiving system to be incident on the image pickup surface S2. Kaihei 7-174536).

[0015]

However, the slit light U
There is an optical limit to narrowing the width of the. The farther from the projection start point A, the wider the irradiation range (slit width) on the object Q. Therefore, conventionally, there has been a problem that the measurement distance (distance between the measurement device and the object Q) at which measurement with a predetermined accuracy is possible is irrespective of the distribution of the reflectance of the object Q.

According to the present invention, even when the reflectivity of an object is non-uniform, high-resolution and high-precision measurement can be performed similarly to the case where the reflectivity is uniform, and three-dimensional measurement with a large degree of freedom in setting a measurement distance. It is intended to realize the device.

The method according to the first aspect of the present invention uses light projecting means for irradiating a detection light to optically scan an object, and imaging means for receiving the detection light reflected by the object.
A dimension measurement method, wherein the specific light receiving area is incident on a specific light receiving area in an imaging surface of the imaging unit while changing an irradiation direction of the detection light to the object.
The amount of the detection light incident to periodically sampled multiple times by the imaging means, the maximum value of the sampled values of the amount of the specific light receiving region, wherein before and after the sampling of the sampling obtained the maximum value Specific recipient
This is a method of obtaining an irradiation timing at which the light amount in the specific light receiving region is maximized by interpolation based on a sampling value of the light amount in the light region . In the method according to the second aspect of the present invention, a position of a portion corresponding to the light receiving region on the object is determined based on a relationship between an irradiation direction of the detection light at the irradiation timing and an incident direction of the detection light on the light receiving region. Ask.

According to a third aspect of the present invention, there is provided a three-dimensional measuring apparatus comprising: a light projecting means for irradiating a detection light to optically scan an object; and an imaging surface comprising a plurality of light receiving areas. Imaging means for receiving the reflected detection light, and scanning means for changing the irradiation direction of the detection light on the object,
Imaging control means for the detection light to drive the imaging means so as to output a plurality of times periodically the light intensity of each light receiving area of the light receiving been <br/> the detection light while incident on the respective light receiving regions And a storage unit for storing, for each of the light receiving regions, a maximum value of the light amount periodically output by the imaging unit, and a light amount output before and after the output timing of the maximum value, and storage in the storage unit. Irradiation timing calculating means for obtaining an irradiation timing at which the light quantity of each of the light receiving areas is maximum based on the light quantity obtained. In the three-dimensional measurement apparatus according to the fourth aspect of the present invention, the position of a part corresponding to each of the light receiving regions on the object is determined by the irradiation direction of the detection light at the irradiation timing and the incident direction of the detection light to the light receiving region. And position calculation means for obtaining based on the relationship.

[0019]

FIG. 1 is a configuration diagram of a measurement system 1 according to the present invention. The measurement system 1 includes a three-dimensional camera (range finder) 2 that performs three-dimensional measurement by a slit light projection method, and a host 3 that processes output data of the three-dimensional camera 2.

The three-dimensional camera 2 displays color information of the object Q together with measurement data (slit image data) for specifying the three-dimensional positions of a plurality of sampling points on the object Q.
Outputs a dimensional image and data necessary for calibration. The host 3 is in charge of calculating the coordinates of the sampling points using the triangulation method.

The host 3 includes a CPU 3a, a display 3
b, a keyboard 3c, a mouse 3d, and the like. Software for processing measurement data is incorporated in the CPU 3a. Between the host 3 and the three-dimensional camera 2, both online and offline data transfer by the portable recording medium 4 is possible. As the recording medium 4,
There are a magneto-optical disk (MO), a mini disk (MD), and a memory card.

FIG. 2 is a diagram showing the appearance of the three-dimensional camera 2. A light emitting window 20a and a light receiving window 2 are provided on the front of the housing 20.
0b is provided. The light projecting window 20a is located above the light receiving window 20b. Slit light (band-like laser beam with a predetermined width w) U emitted from the internal optical unit OU
Goes to the object (subject) to be measured through the light emitting window 20a. The radiation angle φ in the length direction M1 of the slit light U is fixed. A part of the slit light U reflected on the surface of the object enters the optical unit OU through the light receiving window 20b. Note that the optical unit OU includes a two-axis adjustment mechanism for optimizing the relative relationship between the light projecting axis and the light receiving axis.

On the upper surface of the housing 20, zooming buttons 25a and 25b, a manual focusing button 26
a, 26b and a shutter button 27 are provided. As shown in FIG. 2B, on the back of the housing 20,
A liquid crystal display 21, a cursor button 22, a select button 23, a cancel button 24, analog output terminals 31 and 32, a digital output terminal 33, and a detachable opening 30a for the recording medium 4 are provided.

The liquid crystal display 21 (LCD) is used as an operation screen display means and an electronic finder.
The photographer can set the photographing mode by using the buttons 21 to 24 on the back. The analog output terminal 31 outputs measurement data, and the analog output terminal 31 outputs a two-dimensional image signal in, for example, the NTSC format. The digital output terminal 33 is, for example, a SCSI terminal.

FIG. 3 is a block diagram showing a functional configuration of the three-dimensional camera 2. In the figure, solid arrows indicate the flow of electric signals, and broken arrows indicate the flow of light. 3D camera 2
Has two optical systems 40 and 50 on the light projecting side and the light receiving side that constitute the optical unit OU described above. Optical system 40
, The wavelength 6 emitted by the semiconductor laser (LD) 41
The 70 nm laser beam becomes slit light U by passing through the light projecting lens system 42 and is deflected by the galvanomirror (scanning means) 43. Semiconductor laser 4
The driver 44, the driving system 45 of the light projecting lens system 42, and the driving system 46 of the galvanomirror 43 are controlled by a system controller 61.

In the optical system 50, a zoom unit 51
The light condensed by the beam splitter 52 is split by the beam splitter 52. The light in the oscillation wavelength band of the semiconductor laser 41 is
The light enters the sensor 53 for measurement. Light in the visible band enters the monitor color sensor 54. The sensor 53 and the color sensor 54 are both CCD area sensors. The zoom unit 51 is of an in-focus type, and a part of the incident light is used for auto focusing (AF). The AF function is realized by an AF sensor 57, a lens controller 58, and a focusing drive system 59. The zooming drive system 60 is provided for electric zooming.

The image information obtained by the sensor 53 is transmitted to the driver 5.
5 and is transferred to the output processing circuit 62 in synchronization with the clock from the fifth clock. Measurement data corresponding to each pixel of the sensor 53 is generated by the output processing circuit 62 and stored in the memories 63 and 64. Thereafter, when the operator instructs data output, the measurement data is transmitted to the SCSI controller 66 or N
The data is output online in a predetermined format by the TSC conversion circuit 65 or stored in the recording medium 4. An analog output terminal 31 or a digital output terminal 33 is used for online output of measurement data. Image information from the color sensor 54 is transferred to the color processing circuit 67 in synchronization with a clock from the driver 56. The color-processed imaging information is output online via the NTSC conversion circuit 70 and the analog output terminal 32, or quantized by the digital image generation unit 68 and stored in the color image memory 69. Thereafter, the color image data is transferred from the color image memory 69 to the SCSI controller 66, output online from the digital output terminal 33, or stored in the recording medium 4 in association with the measurement data. In addition,
The color image is an image having the same angle of view as the distance image obtained by the sensor 53, and is used as reference information during application processing on the host 3 side. The processing using color information includes, for example, processing of generating a three-dimensional shape model by combining a plurality of sets of measurement data having different camera viewpoints, and processing of thinning out unnecessary vertices of the three-dimensional shape model. The system controller 61 gives an instruction to the character generator 71 to display appropriate characters and symbols on the screen of the LCD 21.

FIG. 4 is a schematic diagram showing the configuration of the light projecting lens system 42. FIG. 4A is a front view, and FIG. 4B is a side view. The projection lens system 42 includes the collimator lens 4
21, a variator lens 422, and an expander lens 423. The laser beam emitted from the semiconductor laser 41 is subjected to an optical process for obtaining an appropriate slit light U in the following order. First, the beam is collimated by the collimator lens 421. Next, the beam diameter of the laser beam is adjusted by the variator lens 422. Finally, the beam is expanded in the slit length direction M1 by the expander lens 423.

The variator lens 422 is provided to allow the slit light U having a width of three or more pixels to enter the sensor 53 regardless of the photographing distance and the angle of view of photographing. The drive system 45 moves the variator lens 422 so as to keep the width w of the slit light U on the sensor 53 constant according to an instruction from the system controller 61. The variator lens 422 and the zoom unit 51 on the light receiving side are linked.

By increasing the slit length before deflection by the galvanomirror 43, distortion of the slit light U can be reduced as compared with the case where deflection is performed after deflection. By arranging the expander lens 423 at the last stage of the light projecting lens system 42, that is, by bringing it closer to the galvanometer mirror 43, the size of the galvanometer mirror 43 can be reduced.

FIG. 5 is a schematic diagram of a zoom unit 51 for receiving light. The zoom unit 51 includes a front image forming unit 51
5, a variator unit 514, a compensator unit 513, a focusing unit 512, a rear image forming unit 511, and a beam splitter 516 for guiding a part of incident light to the AF sensor 57.
It is composed of The front imaging unit 515 and the rear imaging unit 511 are fixed with respect to the optical axis.

The movement of the focusing unit 512 is performed by the focusing drive system 59, and the movement of the variator unit 514 is performed by the zooming drive system 60. Focusing drive system 5
Reference numeral 9 includes a focusing encoder 59A that indicates a moving distance (amount of extension) of the focusing unit 512. The zooming drive system 60 includes a variator unit 514.
The zooming encoder 60A indicates the moving distance (the zoom step value) of the moving image.

FIG. 6 is a schematic diagram of the beam splitter 52, FIG. 7 is a graph showing the light receiving wavelength of the sensor 53 for measurement, and FIG.
Is a graph showing the light receiving wavelength of the color sensor 54 for monitoring.

The beam splitter 52 includes a color separation film (a dichroic mirror) 521, two prisms 522 and 523 sandwiching the color separation film 521, and an emission surface 52 of the prism 522.
2b, an infrared cut filter 524 provided on the front side of the sensor 53, a visible cut filter 525 provided on the front side of the sensor 53,
Infrared cut filter 526 provided on exit surface 523b of prism 523, and low-pass filters 527 and 5
28.

Light UC incident from the zoom unit 51
Enter the color separation film 521 through the low-pass filter 527 and the prism 522. Light U0 in the oscillation band of the semiconductor laser 41 is reflected by the color separation film 521 and
After being reflected by the incident surface 522a, the light exits from the exit surface 522b toward the sensor 53. Of the light U0 emitted from the prism 522, the light transmitted through the infrared cut filter 524 and the visible cut filter 525 is received by the sensor 53. On the other hand, the light C0 transmitted through the color separation film 521
Are emitted from the emission surface 523b toward the color sensor 54 through the prism 523. Of the light C0 emitted from the prism 523, the light transmitted through the infrared cut filter 526 and the low-pass filter 528 is the color sensor 54.
Is received by the

In FIG. 7, as indicated by the broken line, the color separation film 521 reflects light in a relatively wide wavelength band including the wavelength of the slit light (λ: 670 nm). That is, the wavelength selectivity of the color separation film 521 is insufficient to selectively cause only the slit light to enter the sensor 53. However, since the beam splitter 52 is provided with the infrared cut filter 524 having the characteristics indicated by the dashed line and the visible cut filter 525 having the characteristics indicated by the solid line,
The light finally incident on the sensor 53 is light having a wavelength in a narrow range indicated by oblique lines in FIG. As a result, measurement with a small influence of ambient light, that is, a large optical SN ratio can be realized.

On the other hand, the color sensor 54 blocks the infrared band light transmitted through the color separation film 521 having the characteristic shown by the broken line by the infrared cut filter 528 having the characteristic shown by the solid line in FIG. Only visible light enters.
Thereby, the color reproducibility of the monitor image is improved.

Instead of using two filters, the infrared cut filter 524 and the visible cut filter 525, a single filter having a characteristic of blocking infrared and visible light may be used. Both the infrared cut filter 524 and the visible cut filter 525 may be provided on the prism 522 side.
May be provided on the side of. 6, the visible cut filter 525 may be provided on the prism 522 side, and the infrared cut filter 524 may be provided on the sensor 53 side.

FIG. 9 is a principle diagram for calculating a three-dimensional position in the measurement system 1. In the figure, the components corresponding to those in FIGS. 15 and 16 are denoted by the same reference numerals for easy understanding.

The object Q is irradiated with a relatively wide slit light U corresponding to a plurality of pixels on the imaging surface S2 of the sensor 53. Specifically, the width of the slit light U is set to 5 pixels. The slit light U is generated on the imaging surface S2 by one every sampling cycle.
The object Q is scanned by being deflected from top to bottom in FIG. 9 so as to move by the pixel pitch pv.
One frame of photoelectric conversion information is output from the sensor 53 every sampling period.

Focusing on one pixel g on the imaging surface S2,
Effective light receiving data is obtained in five samplings out of N samplings performed during scanning. The timing at which the optical axis of the slit light U passes through the object surface ag in the range in which the target pixel g is glazed (the time barycenter Npeak: the time when the amount of received light of the target pixel g is maximum) is obtained by an interpolation operation on these five received light data. . In the example of FIG. 9B, the amount of received light is maximum between the n-th time and the (n−1) -th time immediately before the n-th time. The position (coordinate) of the object Q based on the relationship between the irradiation direction of the slit light at the obtained timing and the incident direction of the slit light on the target pixel
Is calculated. This enables measurement with a higher resolution than the resolution defined by the pixel pitch pv of the imaging surface.

The amount of light received by the target pixel g depends on the reflectance of the object Q. However, the relative ratio of the amount of received light in the five samplings is constant regardless of the absolute amount of received light. That is, the shading of the object color does not affect the measurement accuracy.

In the measurement system 1 of the present embodiment, the three-dimensional camera 2 outputs the received light data for five times for each pixel g of the sensor 53 to the host 3 as measurement data, and the host 3 outputs the object Q based on the measurement data. Calculate the coordinates. The output processing circuit 62 (see FIG. 3) of the three-dimensional camera 2 is responsible for generating measurement data corresponding to each pixel g.

FIG. 10 is a block diagram of the output processing circuit 62.
FIG. 11 is a diagram showing a reading range of the sensor 53. The output processing circuit 62 includes an AD conversion unit 620 that converts the photoelectric conversion signal of each pixel g output from the sensor 53 into 8-bit light reception data, four frame delay memories 621 to 624 connected in series, and five effective times. Five memory banks 625A to 625E for storing received light data, a memory bank 625F for storing a frame number (sampling number) FN at which the received light data is maximum, and a comparator 62
6, a generator 627 indicating the frame number FN,
And memory control means (not shown) for specifying addresses of the memory banks 625A to 625A. Each of the memory banks 625A to 625E has a capacity capable of storing the same number of received light data as the number of measurement sampling points (that is, the number of effective pixels of the sensor 53).

Four frame delay memories 621 to 6
24, the received light data of 5 frames for each pixel g is simultaneously stored in the memory bank 6.
25A to 25E. In addition,
The reading of one frame by the sensor 53 is performed by the imaging surface S2
Is performed on only a part of the effective light receiving area (band image) Ae of the imaging surface S2 as shown in FIG. The effective light receiving area Ae shifts by one pixel for each frame with the deflection of the slit light U. In the present embodiment, the number of pixels of the effective light receiving area Ae in the shift direction is fixed to 32. A method of reading out only a part of the captured image of the CCD area sensor is disclosed in Japanese Patent Application Laid-Open No. 7-174536.

The AD conversion section 620 has 32
The light receiving data D620 for the line is serially output in the arrangement order of the pixels g. Each frame delay memory 621-6
24 is an FI having a capacity of 31 (= 32-1) lines.
FO.

When the light reception data D620 of the target pixel g output from the AD converter 620 is delayed by two frames, the comparator 626 outputs the previous light reception data D620 of the target pixel g stored in the memory bank 625C. Is compared to the maximum value of Delayed light reception data D620 (output of frame delay memory 622)
Is larger than the past maximum value, the output of the AD converter 620 at that time and the frame delay memories 621 to 621
The output of 624 is stored in each of memory banks 625A to 625E, and the stored contents of memory banks 625A to 625E are rewritten. At the same time, a frame number FN corresponding to the received light data D620 stored in the memory bank 625C is stored in the memory bank 625F.

That is, when the amount of light received by the target pixel g becomes the maximum in the n-th (n <N) frame, the data of the (n + 2) th frame is stored in the memory bank 625A, and is stored in the memory bank 625B. The data of the (n + 1) th frame is stored, and the data of the nth frame is stored in the memory bank 625C.
Data of the (n-1) th frame is stored in D, data of the (n-2) th frame is stored in the memory bank 625E, and n is stored in the memory bank 625F.

Next, the operation of the three-dimensional camera 2 and the host 3 will be described together with the measurement procedure. Hereinafter, the number of measurement sampling points is assumed to be 200 × 231. That is, the number of pixels in the slit length direction on the imaging surface S2 is 231 and the substantial number of frames N is 200.

The user (photographer) determines the camera position and orientation while watching the color monitor image displayed on the LCD 21, and sets the angle of view. At that time, a zooming operation is performed as needed. In the three-dimensional camera 2, the aperture adjustment of the color sensor 54 is not performed, and a color monitor image whose exposure is controlled by the electronic shutter function is displayed. This is because the incident light amount of the sensor 53 is increased as much as possible by opening the aperture.

FIG. 12 is a diagram showing the data flow in the three-dimensional camera 2, FIG. 13 is a diagram showing the data flow in the host 3, and FIG. 14 is a diagram showing the relationship between each point of the optical system and the object Q. .

The variator 51 of the zoom unit 51 is operated in accordance with the angle of view selection operation (zooming) by the user.
4 is performed. Also, manual or automatic focusing by moving the focusing unit 512 is performed.
In the course of focusing, the approximate inter-object distance d ₀ is measured.

In response to such lens driving of the light receiving system, the amount of movement of the variator lens 422 on the light projecting side is calculated by an arithmetic circuit (not shown), and the movement of the variator lens 422 is controlled based on the calculation result.

The system controller 61 is provided with a focusing encoder 59 via a lens controller 58.
The output of A (the feed amount Ed) and the output of the zooming encoder 60A (the zoom step value fp) are read. Inside the system controller 61, a distortion table T1, a principal point position table T2, and an image distance table T3
, And the photographing condition data corresponding to the feeding amount Ed and the zoom step value fp are output to the host 2. The photographing condition data here includes a distortion aberration parameter (lens distortion correction coefficient d1, d2), a front principal point position FH, and an image distance b. The front principal point position FH is represented by the distance between the front end point F of the zoom unit 51 and the front principal point H. Since the front end point F is fixed, the front principal point H can be specified by the front principal point position FH.

The system controller 61 calculates the output (laser intensity) of the semiconductor laser 41 and the deflection conditions (scan start angle, scan end angle, deflection angular velocity) of the slit light U. This calculation method will be described in detail. First, assuming that a planar object exists at an approximate distance d ₀ between the objectives, the projection angle is set so that the reflected light is received at the center of the sensor 53. The pulse lighting for calculating the laser intensity described below is performed at the set projection angle.

Next, the laser intensity is calculated. When calculating the laser intensity, a human body may be measured, so safety considerations are indispensable. First, the minimum strength LDm
The pulse is turned on at “in”, and the output of the sensor 53 is captured. Captured signal [Son (LDmin)] and appropriate level S
Calculate the ratio with typ and set a temporary laser intensity LD1.

LD1 = LDmin × Type / MAX
[Son (LDmin)] Subsequently, the pulse is turned on again with the laser intensity LD1 and the sensor 5
Capture the output of # 3. Captured signal [Son (LD
If 1)] is an appropriate level Type or a value close thereto, LD1 is determined as the laser intensity LDs. In other cases, a temporary laser intensity LD1 is set using the laser intensity LD1 and MAX [Son (LD1)], and the output of the sensor 53 is compared with the appropriate level Styp. Until the output of the sensor 53 becomes a value within the allowable range, the temporary setting of the laser intensity and the confirmation of suitability are repeated. Note that the output of the sensor 53 is captured for the entire imaging surface S2. this is,
This is because it is difficult to estimate the light receiving position of the slit light U with high accuracy in passive distance calculation by AF. The integration time of the CCD in the sensor 53 is one field time (for example, 1/60 second), which is longer than the integration time at the time of actual measurement. Therefore, by performing pulse lighting, a sensor output equivalent to that at the time of measurement is obtained.

Next, the distance d between the objects is determined by triangulation from the projection angle and the light receiving position of the slit light U when the laser intensity is determined. Finally, the determined objective distance d
The deflection condition is calculated based on. In calculating the deflection condition, the offset doff in the Z direction (see FIG. 16) between the rear principal point H ′ of the light receiving system, which is the distance measurement reference point of the object distance d, and the projection start point A is considered. Further, in order to secure the same measurable distance range d 'as that at the center in the scanning direction, an overscan of a predetermined amount (for example, for 8 pixels) is performed. Scan start angle th1, scan end angle th
2. The deflection angular velocity ω is expressed by the following equation.

Th1 = tan ⁻¹ [β × pv (np / 2 +
8) + L) / (d + doff)] × 180 / π th2 = tan ⁻¹ [−β × pv (np / 2 + 8) + L)
/ (D + doff)] × 180 / π ω = (th1−th2) / np β: imaging magnification (= d / effective focal length freal) pv: pixel pitch np: effective number of pixels in the Y direction of the imaging surface S2 L: base line Length Next, the main emission is performed under the conditions calculated in this manner, the object Q is scanned (slit projection), and the measurement data (slits) for five frames per pixel obtained by the output processing circuit 52 is obtained. Image data) D62 is sent to the host 2. At the same time, device information D10 indicating the deflection condition (deflection control data) and the specifications of the sensor 53 are also transmitted to the host 3.
Sent to Table 1 summarizes main data that the three-dimensional camera 2 sends to the host 3.

[0060]

[Table 1]

As shown in FIG. 13, in the host 3, the slit center of gravity calculation # 31, the distortion aberration correction calculation # 32, the camera line-of-sight equation calculation # 33, the slit plane equation calculation # 34, and the three-dimensional position calculation # 35 is performed, whereby the three-dimensional position (coordinates X, Y, Z) of the 200 × 231 sampling points is calculated. The sampling point is the intersection of the camera's line of sight (a straight line connecting the sampling point and the rear principal point H ') and the slit plane (the optical axis plane of the slit light U irradiating the sampling point).

The time center of gravity Npeak of the slit light U (FIG. 9)
) Is given by equation (3) using the received light data D (i) at each sampling. Npeak = n + Δn (3) Δn = [− 2 × D (n−2) −D (n−1) + D (n +
1) + 2 × D (n + 2)] / ΣD (i) (i = n−2, n−1, n, n + 1, n + 2) or Δn = [− 2 × [D [n−2] −minD (i)) ]-
[D (n-1) -minD (i)] + [D (n + 1)-
minD (i)] + 2 × [D (n + 2) -minD
(I)]] / ΣD (i) By subtracting the minimum data minD (i) from the five received light data to obtain a weighted average, the influence of ambient light can be reduced.

The camera line-of-sight equations are equations (4) and (5). (U-u0) = (xp) = (b / pu) × [X / (Z-FH)] (4) (v−v0) = (yp) = (b / pv) × [Y / (Z -FH)] (5) b: Image distance FH: Front principal point position pu: Horizontal pixel pitch on the imaging surface pv: Vertical pixel pitch on the imaging surface u: Horizontal pixel position on the imaging surface u0: Center pixel position in the horizontal direction on the imaging surface v: Pixel position in the vertical direction on the imaging surface v0: Center pixel position in the vertical direction on the imaging surface The slit plane equation is given by equation (6).

[0064]

(Equation 1)

The geometric aberration depends on the angle of view. Distortion occurs in the target substantially at the center pixel. Therefore, the amount of distortion is represented by a function of the distance from the center pixel. Here, the distance is approximated by a cubic function. The secondary correction coefficient is d1, and the tertiary correction coefficient is d2. The corrected pixel positions u ′ and v ′ are given by equations (7) and (8).

[0066] u '= u + d1 × t2 2 × (u-u0) / t2 + d2 × t2 3 × (u-u0) / t2 ... (7) v' = v + d1 × t2 2 × (v-v0) / t2 + d2 × t2 ³ × (v−v0) / t2 (8) t2 = (t1) ⁻² t1 = (u−u0) ² + (v−v0) ^{2 In the} above equations (4) and (5), u 'instead of u
And substituting v ′ for v, a three-dimensional position taking distortion into account can be obtained. For calibration, IEICE Technical Report, PRU91-113 [Geometric correction of images without camera positioning] Onodera and Kanaya, IEICE Transactions D-II vol. J74-D-II No.9 pp.1227-1235, '91 / 9
[High-precision calibration method of range finder based on three-dimensional model of optical system] Ueshiba, Yoshimi, Oshima, etc. have detailed disclosure.

In the above embodiment, the host 3 performs the calculation for calculating the three-dimensional position based on the measurement data D62. However, the three-dimensional camera 2 may be provided with a calculation function for calculating the three-dimensional position. . It is also possible to calculate the three-dimensional position by a look-up table method. Optical system 5 on the receiving side
At 0, the imaging magnification may be changed by an interchangeable lens instead of the zoom unit 51.

[0068]

According to the onset light according to the present invention, is capable of high precision measurement with high resolution similarly to the reflectance of the object is uniform even when a heterogeneous, degree of freedom in setting the measurement distance It is possible to provide a three-dimensional measurement device having a large value.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a measurement system according to the present invention.

FIG. 2 is a diagram illustrating an appearance of a three-dimensional camera.

FIG. 3 is a block diagram illustrating a functional configuration of a three-dimensional camera.

FIG. 4 is a schematic diagram illustrating a configuration of a light projecting lens system.

FIG. 5 is a schematic diagram of a zoom unit for receiving light.

FIG. 6 is a schematic diagram of a beam splitter.

FIG. 7 is a graph showing a light receiving wavelength of a sensor for measurement.

FIG. 8 is a graph showing a light receiving wavelength of a monitor color sensor.

FIG. 9 is a principle diagram of calculation of a three-dimensional position in the measurement system.

FIG. 10 is a block diagram of an output processing circuit.

FIG. 11 is a diagram showing a reading range of a sensor.

FIG. 12 is a diagram showing a data flow in the three-dimensional camera.

FIG. 13 is a diagram showing a data flow in the host.

FIG. 14 is a diagram illustrating a relationship between each point of the optical system and an object.

FIG. 15 is a diagram showing an outline of a slit light projection method.

FIG. 16 is a diagram for explaining the principle of measurement by the slit light projection method.

FIG. 17 is a diagram for explaining the principle of a conventional measurement method.

[Explanation of symbols]

 Reference Signs List 1 measurement system (three-dimensional measurement device) 3 host (computing means) 40 optical system (light emitting means) 43 galvanometer mirror (scanning means) 53 sensor (imaging means) 61 system controller (imaging control means) 62 output processing circuit (storage) Means) g Pixel (light receiving area) Npeak Time barycenter (irradiation timing) S2 Imaging surface U Slit light (detection light) Q Object

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-80510 (JP, A) JP-A-7-174536 (JP, A) JP-A-6-34366 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G01B 11/00 G01B 11/24 G06T 7/00

Claims (4)

(57) [Claims] 1. A three-dimensional measuring method using light projecting means for irradiating a detection light to optically scan an object, and imaging means for receiving the detection light reflected by the object, while changing the irradiation direction of the detecting light relative to the object, incident on the specific light receiving area in the imaging plane of the image pickup means
While the imaging means periodically samples the light amount of the detection light incident on the specific light receiving region a plurality of times by the imaging unit, and calculates the maximum value of the sampling value of the light amount of the specific light receiving region and the maximum value. based on the sampling <br/> ring value of the amount of the specific light receiving region before and after the sampling of the resulting sampling, the specific light receiving territory by interpolation
A three-dimensional measurement method , wherein an irradiation timing at which the light amount in a region becomes maximum is obtained. 2. The method according to claim 1, wherein a position of a part corresponding to the light receiving area on the object is determined based on a relationship between an irradiation direction of the detection light at the irradiation timing and an incident direction of the detection light on the light receiving area. Item 3. The three-dimensional measurement method according to Item 1. 3. An illuminating means for irradiating a detection light to optically scan an object, and an imaging means having an imaging surface comprising a plurality of light receiving areas and receiving the detection light reflected by the object. Scanning means for changing the irradiation direction of the detection light on the object, and the amount of the detection light received in each of the light receiving areas while the detection light is incident on each of the light receiving areas. Imaging control means for driving the imaging means so as to periodically output a plurality of times; and for each of the light receiving regions, a maximum value of the light amount periodically output by the imaging means, and an output timing of the maximum value. Storage means for storing the amount of light output before and after, and irradiation timing calculating means for obtaining an irradiation timing at which the amount of light in each of the light receiving regions is maximum based on the amount of light stored in the storage means. 3 characterized by
Dimension measurement device. 4. A position for obtaining a position of a portion corresponding to each of said light receiving regions on said object based on a relationship between an irradiation direction of said detection light at said irradiation timing and an incident direction of said detection light to said light receiving region. The three-dimensional measurement device according to claim 3, further comprising a calculation unit.