KR101401395B1 - Photosensor for measuring surface and measuring method of 3D depth and surface using thereof - Google Patents

Abstract

 The present invention relates to a method and apparatus for measuring a distance between an object and a measuring instrument by analyzing a ratio of the amount of light returned by reflecting each measuring light to a measuring object by irradiating a plurality of measuring lights within the sensing area, And a method for removing specificity, which is a region that can not be measured due to its characteristics. An object surface distance sensor according to an embodiment of the present invention includes a plurality of illumination units 100 for irradiating measurement light of different characteristics to a sensing region; An imaging device (200) for acquiring an image of a sensing area; A memory unit 300 for image processing images and images obtained by the image pickup device and storing the resultant images; An exposure control unit 410 for adjusting the light emission time for irradiating the measurement light of the illumination unit and the image pickup time of the image pickup device and the disturbance due to the external light emission from the plurality of images returned by the measurement light of the illumination unit An image processing unit 420 for separating only the effect of the specific illumination unit and extracting an individual image, and comparing the light amount of each pixel of each individual image, converting the light amount into a corresponding position of the measurement object, And a 3D shape restoring unit 430 for analyzing and extracting the surface distance of the object to be measured.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical sensor for measuring surface angle and a method for sensing surface angle and shape information using the same,

The present invention relates to an optical sensor for measuring a distance and a sensing method using the same. More particularly, the present invention relates to an optical sensor for measuring a distance by irradiating a plurality of measurement lights within a sensing area, A sensor for deriving a distance to the measurement point by using the ratio of the amount of light to the measurement point of the object corresponding to each pixel of the images by comparing the images of the object detected by the different illuminations, And a method for extracting a surface shape of an object to be measured by analyzing a distance to a plurality of measurement points to remove a specific phenomenon caused by an area in which irradiation light amounts by the different illumination are equally distributed .

Generally, as a method for measuring an object or an obstacle at a short distance, a sensor for measuring the presence or absence of an object or an obstacle in the sensing area by irradiating measurement light to the sensing area and measuring reflected light is widely used in the industrial field.

In recent years, by obtaining the measurement light image using the image pickup device, the ratio of the amount of light measured by using different illumination lights is calculated so that the distance from each pixel to the measurement object is determined not only by the presence of the object in the measurement area A technique has been developed to calculate the surface shape of the object.

However, according to the related art, even when two different lights are irradiated to a target object at the time of measuring the distance by the phase ratio, there is a case where there is no change in the image due to the measured light amount because the same light amount is distributed. In this case, when the distance is measured using the same measurement value, the ratio is set to '1'. In this case, there is an area that can not be measured. This is defined as the specificity in the distance measurement by the phase ratio. For example, as shown in FIG. 1, when the measurement light is irradiated from the surface of the object, diffracted light amounts are coincident with each other, so that the specificity of the distance measurement occurs as shown in the figure. This is defined as the specificity curve 10 .

The specificity curve 10 generally has a characteristic of moving away from the measurement camera depending on the distance. If this characteristic is reversed, it is possible to appropriately adjust the position of the irradiation light so that the specificity curve is generated outside the effective viewing angle of the camera. To do this, two different lights must be installed on either the left or the right side of the camera, which makes it impossible to measure the distance due to lack of light.

In order to compensate for this, different illuminations must be installed on both sides of the camera. This problem can be solved by using four LEDs 30 illumination as shown in FIG. That is, the distance to the object in the left hemisphere can be measured by the illumination of the two LEDs 30 on the left side of the camera 40, and the distance to the object in the right hemisphere is measured with the illumination of the two LEDs 30 on the right side can do.

U.S. Patent No. 6,219,461 U.S. Patent No. 4,873,651

Generally, a three-dimensional distance measuring sensor has been developed and used as a method for measuring an object or an obstacle at a close distance, which measures the presence or absence of an object or an obstacle in the sensing area by irradiating the sensing area with measurement light and measuring the reflected light with a camera . In this case, in order to reduce the error of the three-dimensional distance measurement due to diffuse reflection and total reflection due to the material and shape of the object, two or more lights are used to measure the reflection image according to each illumination with the camera, , It is possible to obtain a single function between the distance to the object and the constant ratio. That is, when each pixel of the camera is represented by x and y coordinates, the variable D representing the distance between the camera and the object can be expressed as follows.

Where K is the diffuse reflection and total reflection property of the object and the surface material and angle, I is the irradiated light, and R is the distance between the object and the camera. When two different irradiation lights are used to remove the diffuse reflection and total reflection characteristics depending on the characteristic of the object from the measured reflected light at this time, the following Equation 2 and Equation 3 are applied to each irradiation light, ] Are obtained.

The ratio of the measurement light for two different irradiation lights can be obtained by using [Equation 2] and [Equation 3] as follows. In other words,

As can be seen from the above equation, the ratio of the distance to the object with respect to each pixel of the camera is a function of the ratio of the irradiated light amount, and it is possible to exclude the influence of diffuse reflection and total reflection due to the surface material or shape of the object.

However, when two different irradiation lights are used as the measurement light, a region where two light amounts coincide with each other is generated when a common measurement region is set. In this region, the distance from the object is measured This region is defined as a specific region. 2, the position of the first illumination L1 is represented by a1, b1, c1 and the position of the second illumination L2 is represented by a2, b2, c2 (X, y, z) of the measurement light at x, y and z is represented by x, y, z, and the coordinates of an arbitrary point on the three- x, y, z)) as follows.

The ratio of the measurement light D1 to the measurement light D2 is as follows.

Referring to FIG. 2, an arbitrary point in space is defined as x, y, and z in order to obtain a position on the space where the ratio of the measurement light D1 and the measurement light D2 is 1, and distances from the point to the two measurement lights are equal If you leave,

If we summarize the gastroparesis, we can obtain the following flat expression. In other words,

In other words, when measuring the three-dimensional distance using the constant ratio using measurement light having two identical characteristics, there exists a plane showing the specificity by the above equation. In such a specific plane, since the constant ratio is always 1, The distance measurement can not be used. In addition, due to the limitation of the size of the specific plane, it is always located inside the field of view of the camera.

However, by using the measurement light having two different characteristics, it is possible to prevent the specific surface from being included in the lens clock by modifying the shape of the specific plane. To this end, the ratio of the measurement light D1 and the measurement light D2, The above equation (7) can be modified as follows.

That is, the measurement light characteristic on the left side of the equation shows the spherical surface and the measurement light characteristic on the right side shows the characteristic of the deformed spherical surface, that is, the shape of the elliptic spherical surface.

In summary,

In other words, a spherical surface exhibiting specificity is present by the above equation when three-dimensional distance measurement using an aspect ratio is performed using light quantities representing two different characteristics. In order to prevent such a spherical surface from being included in a lens clock of a camera, And the relative position of the camera can be adjusted to obtain an image in which the specificity is removed. As shown in FIG. 1, when a measurement light having different characteristics is installed on the left and right sides of the camera, a three-dimensional sensor can be constructed and manufactured such that the specific spherical surface formed by Equation (10) deviates from the lens clock.

According to an embodiment of the present invention, there is provided an optical sensor for measuring a three-dimensional distance, including a plurality of illumination units 100 mounted at different positions or angles to irradiate measurement light of different characteristics to a sensing region, ; An imaging device (200) for acquiring an image of a sensing area; A memory unit 300 for storing an image obtained by the imaging device and a resultant image to which various image processing is applied; An exposure control unit 410 for adjusting the light emission time for irradiating the measurement light of the illumination unit and the image pickup time of the image pickup device, the disturbance caused by the external light emitter is removed from the plurality of images returned by the measurement light of the illumination unit, An image processing unit 420 for separating only the effect of the illuminating unit and extracting an individual light metering image, and an image processing unit 420 for comparing the light amount of each pixel of each individual metering image, converting the light amount of the respective light metering images into three- And a three-dimensional shape reconstruction unit 430 for compositing the images to reproduce a single three-dimensional image.

The illuminating unit 100 may use any or all of various types of lighting devices such as an incandescent lamp, a fluorescent lamp, a halogen lamp, an LED, and a laser illuminator capable of emitting light having various wavelengths.

The image pickup device 200 can be configured as any type of image pickup device sensitive to various wavelengths of light such as CCD, CMOS, and the like.

A sensing method using a surface angle measuring optical sensor according to an embodiment of the present invention includes:

(a) a plurality of illumination units 100 for irradiating measurement light of different characteristics are sequentially driven to acquire an image under different light control conditions. First, in a state in which the first illumination unit is controlled to irradiate measurement light, (200) is exposed to obtain a first illumination light image (image with 1st light) in the sensing area, and then the imaging element (200) is exposed in the state of controlling to irradiate measurement light in the second illumination part Measuring a third illumination light image within the sensing area by exposing the imaging element (200) while obtaining a second illumination light metering image (image with 2nd light) and controlling the measurement light not to be irradiated .

(b) extracting difference images or ratio images by performing a comparison operation process on a plurality of nth illuminated light images obtained in step (a); (c) converting the light quantity difference or the light quantity ratio stored in each pixel of the difference image or the non-image into a distance to a measurement point of the object by substituting the characteristics of the object, the distance, And synthesizing a plurality of images from which the specificity is removed to reproduce a single three-dimensional image.

In the step (a), the method may further include the step of acquiring an ambient light image in the sensing area by exposing the imaging element in a state in which the illumination light is not irradiated to all the illumination parts.

In the step (b), in the comparative calculation processing of the acquired images, in order to more precisely cancel the effect of the external light, the external light image obtained in a state in which the measurement light of the illumination unit is not irradiated, And a step of extracting the image data.

The step (c) may further include the step of deriving the surface shape information by synthesizing the surface angles of the measurement points corresponding to each pixel as necessary.

The step (d) may further include the step of adjusting a fine offset in combining the plurality of images to reproduce a finer three-dimensional image.

The optical sensor and the sensing method using the same according to the present invention irradiate light having different illumination characteristics to a target object through a plurality of illumination units arranged at different positions / angles, and analyzing the difference of reflected and reflected images, It is possible to measure the distance to the object using the image in which the specificity is removed.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description, serve to further the understanding of the technical idea of the invention, And shall not be interpreted.
FIG. 1 is a view for explaining a technique of irradiating a plurality of measurement lights to a surface of a target object to remove angle and shape information of the object surface by eliminating the specificity due to the phase ratio.
Fig. 2 is a view for explaining the principle of generating the specificity due to the phase ratio.
3A and 3B are views for explaining a method of arranging light emitting elements for eliminating specificity.
4 is a view schematically showing a configuration of an infrared ray sensor according to an embodiment of the present invention.
5A and 5B are flowcharts for explaining a process of acquiring an infrared image using the infrared sensor of the present invention.
6 is a graph for explaining a method for optimizing the manner in which the infrared sensor operates in accordance with the flowchart shown in FIG.

Hereinafter, a surface angle measuring optical sensor according to preferred embodiments of the present invention and a sensing method using the same will be described in detail with reference to the accompanying drawings.

1 is a view schematically showing a configuration of a surface angle sensor according to an embodiment of the present invention. For ease of understanding, two illumination groups can be used to measure the distance from the target object in one direction, and the same measurement principle can be extended to two directions. That is, with respect to the measurement sensor, the surface angle at each measurement point of the object can be expressed by two degrees of freedom (a, b), and at least two different characteristics Two illumination units 100 having a minimum diopter angle (2DOF, a and b) are required. In order to measure both diopters (2DOF, a and b), four illumination units 100 having at least different characteristics are required as shown in FIG.

3, in order to construct a plurality of illumination units 100 for irradiating measurement light of different characteristics, a distance of 1 (distance) to the horizontal axis of the image pickup device 200, Two illumination groups are arranged so that the measurement light can be irradiated in a direction parallel to the photographing direction of the image pickup device 200. [ In this case, in addition to the method shown in FIG. 3, a plurality of illumination units 100 may be installed in various positions or directions, and modified to irradiate different measurement light in the sensing area. Any and all kinds of lighting devices that emit light in various frequency wavelength bands such as incandescent lamps, fluorescent lamps, halogen lamps, LEDs, laser lights, and the like can be used alone or in combination as the lighting devices constituting the lighting unit 100. In order to increase the light amount of each illumination unit 100, a plurality of light emitting devices may be used as a group.

The image sensing device 200 that acquires an image of the sensing area can use any type of sensing device capable of sensing a light intensity image by sensing light of various wavelength bands such as CCD and CMOS. At this time, an appropriate filter may be inserted to effectively extract the photometric image by the illumination unit 100.

The memory unit 300 stores an image obtained by the image pickup device and an image resulting from the image processing. For example, an image acquired directly through the image sensing device 200 in a state where the illumination of each illumination unit 100 is turned on or off, or image processing obtained by applying a difference operation or a non- You can save the resulting images.

The exposure control unit 410 of the controller 400 adjusts the light emission time and the duration of the plurality of illumination units 100 and controls the shooting time and the exposure time of the imaging device 200, And controls the exposure time of the image pickup device 200 in conjunction with the drive time so as to obtain a photometry image in the dim state of the different illumination units. More specifically, when the one-directional measurement illumination is used, the imaging device 200 is exposed in a state in which the first illumination group is irradiated with the measurement light, and the first illumination group image (image with 1st light, I1), and then acquires a second illumination group image (image with 2nd light) I2 in the sensing area by controlling the imaging device 200 to be controlled so as to irradiate measurement light at the second illumination unit. If two-way illumination is used, continue to acquire the nth light-metering image (image with nth light, In).

(Image with 1st light in 1st group, I1-1) obtained in a controlled state so as to irradiate only the first measurement light belonging to the first illumination group when acquiring the first illumination group photometry image I1, (Image with 2nd light in 1st group, I1-2) obtained by controlling only the second measurement light belonging to the first illumination group, and obtains the ratio of the two images to obtain the first illumination group photometric image I1 Can be formed.

At this time, the object existing in the sensing area is slightly differently measured in the photometric images due to the different lighting effects. In particular, since the plurality of illumination units 100 are located at different positions / angles, a difference in reflection angle occurs on the surface of the object, and the amount of light of the light- .

When calculating the image ratio using the two measurement lights belonging to the first illumination group, since the first illumination groups are all disposed on the left side of the camera lens, an accurate image of the object on the right side of the measured image can not be obtained. That is, the first illumination group photometry image I1 forms a lighting group for measuring the distance to the object on the left side of the camera, so that the image without the right half of the image is regarded as the I1 image.

When acquiring the second illumination group metering image I2, the image obtained with the image (with image 1st light in 2st group, I2-1) obtained in a controlled state to irradiate only the first measurement light belonging to the second illumination group is acquired, , The image obtained with the image (with image 2nd light in 2nd group, I2-2) obtained in a controlled state to irradiate only the second measurement light belonging to the second illumination group is obtained, Can be formed.

At this time, the object existing in the sensing area is slightly differently measured in the photometric images due to the different lighting effects. In particular, since the plurality of illumination units 100 are located at different positions / angles, a difference in reflection angle occurs on the surface of the object, and the amount of light of the light- .

When calculating the phase ratio using the two measurement lights belonging to the second illumination group, since the second illumination group is all installed on the right side of the camera lens, an accurate image of the object on the left side of the measured image can not be obtained. That is, the second illumination group metering image I2 forms a lighting group for measuring the distance to the object on the right side of the camera, so that the image without the left half of the image is regarded as the I2 image.

Finally, the image I1 obtained by the first illumination group and the image I2 obtained by the second illumination group can be combined to obtain a complete image ratio image for a given object. If n lighting groups are used, the lighting that can best be represented by each lighting group is named In, and if a phase ratio image by all the lighting groups is obtained, the phase ratio images are synthesized in the same way, Can be obtained.

5 is a flowchart illustrating a shape sensing method using an optical sensor for measuring a surface angle according to an embodiment of the present invention. Referring to FIG. 5, an image 30 of an external light source is acquired through the imaging element 300 (S500) while the illuminating unit 100 is controlled not to irradiate the measuring light.

Next, the light measuring time of the first illumination unit and the exposure time of the image sensing device 200 are adjusted through the controller to acquire the measurement light image, and the measurement time of the second illumination unit and the exposure time of the image sensing device are adjusted And acquires the optical image (S510 - S540).

A measurement light image and an external light image stored in the memory 300 are read out and a comparison operation process is applied through the image processing unit 420 to obtain a measurement that is generated purely by the first illumination and the second illumination of the first illumination unit The optical images I1-1 and I1-2 are extracted and stored in the memory 300 again (S600). Here, as a comparison operation processing method, subtraction can be used, and various comparison operation processing methods such as exclusive or other can be used. In the same manner, the external light effect is removed from a photometric image of the second illumination unit, and the photometric images I2-1 and I2-2 generated by the influence of the first illumination and the second illumination are extracted and stored in the memory (S600).

Next, each pixel of I1-1 and I1-2 is compared to determine the surface angle of the object measured by the first illumination unit with respect to the light amount of the pixel (S610). Further, each pixel of I2-1 and I2-2 is compared to determine the surface angle of the object measured by the second illumination unit with respect to the light amount of the pixel (S620).

As an additional step, the surface angle of the photographed object is calculated by summing the surface angles at specific positions of the objects corresponding to the derived pixels (S700). And finally deriving the shape of the object from the surface angle of the derived object. At this time, operations such as Fourier transform or modified FFT can be applied in hardware (S710).

It is possible to continuously measure the object in the sensing area by repeating the above-mentioned eleventh step. In this case, referring to FIG. 6, the operation cycle of the optical sensor 100 for the angle measurement may be minimized by starting the first step of the next N + 1 rotation before completing the fourth rotation of the N rotation .

Through the above process, the optical sensor 200 for measuring the surface angle of the present invention irradiates the measurement light from the plurality of illumination units 100 to the detection area, calculates the light amount difference of each pixel of the obtained image, The surface angle at the measurement point corresponding to each pixel of the sensed object can be extracted.

It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Should be regarded as belonging to the following claims.

10: specificity curve,
20: 3D sensor,
30: LED,
40: camera,
50: the viewing angle of the camera,
100: illumination part,
200:
300: memory part,
400:
410: Exposure control unit,
420: image processing unit,
430: 3D shape reconstruction unit.

Claims (7)

1. An optical sensor for sensing an object surface angle by irradiating measurement light within a detection area,
A plurality of illumination units (100) mounted at different positions and angles to irradiate measurement light of different characteristics to the detection region;
An imaging device (200) for sensing an image of the sensing area in response to light incident from the sensing area;
A memory unit 300 for storing the image or a resultant image of the images; And a control unit 400,
The control unit (400)
An exposure control unit (410) for adjusting a light emission time for irradiating measurement light of the illumination unit and an image pickup time of the image pickup device;
An image processor (420) for removing disturbance caused by the external illuminant from a plurality of images reflected from the sensing area of the illumination unit, and extracting the individual light metering images captured by only the light amount of each illumination unit; And
Dimensional shape restoration that restores the surface shape of at least a part of the object surface based on a surface angle of each of the pixels converted by converting a light amount of each pixel of each of the individual light metering images into a surface angle of the object surface, (430). ≪ / RTI > The method according to claim 1,
Wherein the illumination unit (100) is a halogen lamp or an infrared LED. The method according to claim 1,
Wherein the imaging element (200) is a CCD or a CMOS. The method according to claim 1,
Wherein the plurality of illumination units (100) are arranged such that the light measuring directions of the illumination units are parallel to each other. The method according to claim 1,
Further comprising a filter for irradiating the image pickup device (200) with light of a specific wavelength range. A method for sensing surface angle and shape information using a surface angle measuring optical sensor according to claim 1, wherein the measuring angle is measured by irradiating a plurality of measuring lights having different characteristics to the sensing area,
(a) acquiring a plurality of photometry images by each of the plurality of illumination units (100), which is a configuration of the surface angle measuring optical sensor, through the imaging device (200);
(b) calculating a phase ratio by each of the plurality of illumination units (100) from the obtained photometry images;
(c) synthesizing the image ratios obtained from each of the plurality of illumination units (100) to obtain a phase ratio image that obtains a phase ratio image from which a point at which a phase ratio, which is a specificity at the time of distance measurement by the phase ratio, Acquiring step; And
(d) calculating a surface angle of the object in the sensing area based on the image of the aspect ratio obtained by the controller (400), which is a component of the surface angle measuring optical sensor A method for sensing surface angle and shape information using sensors. The method according to claim 6,
Wherein,
And calculating a shape of an object surface in the sensing area by connecting the calculated surface angle information of each pixel to the detected surface angle information.

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