WO2018176321A1

WO2018176321A1 - Light surface imaging laser radar based on line light source and area-array camera and detection method

Info

Publication number: WO2018176321A1
Application number: PCT/CN2017/078784
Authority: WO
Inventors: 何赛灵; 林宏澤; 蔡夫鸿
Original assignee: 苏州优函信息科技有限公司
Priority date: 2017-03-27
Filing date: 2017-03-30
Publication date: 2018-10-04
Also published as: CN108663687B; CN108663687A

Abstract

A light surface imaging laser radar based on a line light source (1) and an area-array camera (4), and a detection method. The radar comprises a line light source (1), a lens (3), an area-array camera (4), and a calculation and analysis unit (5), wherein the plane illuminated by the line source (1), the plane of the lens (3) and the plane of the area-array camera (4) intersect on one line; when the line source (1) illuminates an obstacle on the plane, the light is reflected by the obstacle; the reflected light is imaged at a corresponding position of the area-array camera (4) through the lens (3); the shape of the image is a contour of the obstacle illuminated by the line source (1); and the position of a corresponding object is calculated according to the position of the image. This is equivalent to multi-point simultaneous parallel detection, so that an obstacle and an aerosol molecule, etc. appearing on an object surface can be imaged, and position and contour information about all illuminated objects is instantly calculated, and can be applied to various environments such as ranging and spatial detection.

Description

Smooth surface imaging laser radar based on line light source and area array camera and detection method

Technical field

The invention belongs to the field of radar detection, and particularly relates to a light surface imaging laser radar and a detection method based on an area array camera and a line light source.

Background technique

Lidar is an advanced measuring method. It has fast measuring speed, high data precision and good real-time performance. It can obtain obstacle information within a certain angle on the same plane by rotating scanning. The space is scanned to realize three-dimensional space reconstruction.

Conventional lidars use time-of-flight or phase methods to obtain distance information for obstacles in a single directional angle. The time-of-flight method measures the time difference between the transmission and reception of the laser pulse, and multiplies the speed of light to obtain the distance information. The phase method modulates the laser output, and compares the phase difference between the emitted light and the received light to convert the distance information. In order to obtain the distance information of obstacles at more angles, the method of rotating the motor is generally used; in order to increase the scanning rate, the laser is generally added, that is, multi-threaded and multi-channel simultaneous scanning, such as the internationally leading 64-line simultaneous scanning, domestically There are also companies that do 32-channel simultaneous scanning. However, the multi-line rotary scanning method has high requirements on system stability, motor angular stability, laser performance, etc., resulting in high cost of the entire system.

Aiming at the above problems of traditional laser radar, a smooth imaging laser radar and detection method based on area array camera and line source is proposed. When the subject surface, the lens surface and the imaging surface When the faces are intersected by a straight line and at an angle, the image plane can obtain a comprehensive and clear image of the object surface. Each point of the object surface can correspond to the image plane one by one, so that the position of the object can be estimated by the position of the image. When a line source is used to illuminate the object surface, if there is no obstacle on the object surface, no signal is generated on the image surface. When an obstacle appears on the object surface, a signal appears at the corresponding position on the image surface, and then the obstacle position and contour are obtained according to the correspondence between the object surface and the image surface.

Summary of the invention

1. Purpose of the invention.

The invention aims to solve the problems of complex structure of flight time and scanning type laser radar, high stability requirement, low scanning rate and high cost, and proposes an area array camera, line source light surface imaging laser radar and detection method. .

2. The technical solution adopted by the present invention.

The invention provides a smooth surface imaging laser radar based on a line source and an area array camera, comprising a line source, a lens, an area array camera, a calculation and analysis unit, a plane illuminated by a line source, a lens surface, and an area camera plane. The plane intersects a line; when the line source illuminates an obstacle on the plane, the light is reflected by the obstacle, and the reflected light is imaged by the lens at the corresponding position of the area array camera, and the shape of the image is the outline of the obstacle illuminated by the line source. The position of the corresponding object is calculated from the position of the image.

In still another specific embodiment, the placement angle of the light source, the lens, and the area array camera conforms to an imaging formula: an image plane position is an angle between the lens surface and the object plane a, a lens center distance is a three-sided intersection distance L, and a lens focal length f It is decided that the angle b between the image plane and the object surface can be obtained by the following formula:

u=sin a·X _obj

h _o =cos a·X _obj -L

Where X _obj is the distance of the obstacle on the object surface from the intersection of the object surface, the lens surface and the image plane;

By adjusting the three parameters a, L, and f, the lidar ranging and space detection range can be adjusted.

In still further embodiments, the filter is further disposed between the lens and the object surface, in front of the lens.

In still another specific embodiment, the filter is a band pass filter.

In still another specific embodiment, the line source is a laser source or an LED source.

In still further embodiments, the line source is generated by a point source through a linear laser generating lens or by a plurality of laser beams forming a plane.

In still further embodiments, a lens common lens, an achromatic lens, or an auto zoom lens is used.

In still further embodiments, the area array camera used is a monochrome area array camera or an RGB three-color area array camera, a CCD area array camera or a CMOS area array camera. The area camera can also be replaced by a structure consisting of several line array cameras.

Light-emitting imaging laser detection based on line source and area array camera proposed by the invention The method is specifically:

Step 1. The planes of the line source, the lens surface, and the plane of the area camera are intersected in one line; the parameters a, f, and L are determined according to the specific detection target. The parameter b is obtained by the following formula:

u=sin a·X _obj

h _o =cos a·X _obj -L

Step 2: When an obstacle appears on the line illuminating plane, the light is reflected by the obstacle, and the reflected light is imaged by the lens at a corresponding position of the area array camera, and the shape of the image is a contour illuminated by the line source;

Step 3. The output signal of the area array camera is transmitted to the calculation analysis unit for data processing.

In a further preferred embodiment, four points a, b, c, and d are formed in a rectangular shape on the object surface, and the length of the rectangle is m and the width is n; according to the image formed by the four points a', b', c', d' in the position of the area camera, fine-tuning the three parameters a, L, f, so that the point of the object surface matches the point of the image surface; for the point on the object surface (X _obj , Y _obj , 0) The corresponding point (x, y, z) on the image surface conforms to the following formula:

x=-sin a·v+cos a(h ₁ +L)

z=cos a·v+sin a(h ₁ +L)

among them,

u=sin a·X _obj

h _o =cos a·X _obj -L

After the correction training, the calculation analysis unit matches the object plane position corresponding to the image point and outputs the data.

3. The technical effect produced by the present invention.

(1) The present invention adopts a linear light source for smooth surface imaging, and a structure in which three planes of a plane illuminated by a line source, a lens surface, and an area plane camera plane intersect with one line can realize rapid scanning, and the present invention is equivalent to multiple points simultaneously. Parallel detection, compared with the single-point scanning in the prior art, the efficiency is increased by more than 1000 times; not only the scanning speed is improved, but also the speed and accuracy of imaging are greatly improved.

(2) The present invention uses an imaging system for ranging and space detection instead of a motor scanning structure, which simplifies the system, improves system stability, and prolongs system life.

(3) The present invention has lower requirements on circuits and devices, and greatly reduces the cost.

(4) The invention can image the obstacles, aerosol molecules and the like appearing on the object surface, and instantaneously calculate the position and contour information of all the illuminated objects, and the system can be applied to various measurements. Distance and space exploration and other projects.

DRAWINGS

Figure 1 is a method of generating a line source. The upper left corner is a linear laser generating lens. The upper right corner is a schematic view of the laser along the xz plane when the linear laser is generated. The lower right corner is a schematic diagram of the direction along the xy plane when the laser generates a linear laser.

2 is a schematic diagram of a result of a glossy imaging lidar device based on an area array camera and a line source. The system consists of a line source 1, a filter 2, a lens 3, an area array camera 4, and a calculation and analysis unit 5. The line light source 1 illuminates the object surface, and the reflected light is filtered by the filter 2, received by the lens 3, and imaged on the area array camera 4. The lines L ₁ ... L _n parallel to the three-sided intersection on the object plane are imaged on the area array camera by L' ₁ ... L' _{n , respectively} . If there are no obstacles on the object surface, no signal is generated on the image surface. When an obstacle appears on the object surface, such as three obstacles appearing on the L _n line, a signal appears at the corresponding position on the image surface, indicating the obstacle position and contour.

Figure 3 is a side view of the system to illustrate the principle of system ranging. For the sake of simplicity, only the case of a line on the object surface is described. As can be seen from the figure, the image plane is imaged from near to far to the image area array camera. The angle b between the image plane and the object plane is determined by the angle a between the lens surface and the object plane, the distance L between the center of the lens and the focal length f of the lens. The three variables are determined based on the specific detection range of the lidar. The image of the other position of the object can be extended by the point of the connector and the midpoint of the lens, and the position of the image is found at the intersection with the image plane.

Figure 4 is a plan view of the system in the first embodiment. For example, four points a, b, c, and d arranged in a rectangle are respectively imaged onto a', b', c', d' of the area camera.

Fig. 5 is a view showing a relationship in which the distance between the pixel point on the area array camera and the object surface x-axis direction is satisfied along the x-axis in the first embodiment.

Figure 6 is a perspective view of the system in the second embodiment. Three aerosol molecules on the surface were observed on an area array camera.

detailed description

As shown in FIG. 1, the line light source 1 of the present invention may be a laser light source or an LED light source or the like. One method of generating a line source is by a point source that can be produced by a linear laser generating lens (also known as a Powell prism). The effect is to divergence a beam of collimated light in a dimension to create a smooth surface. The filter 2 used in the present invention is a band pass filter, and the transmittance of the line source is selected from the center wavelength, and the transmittance is not less than 10%; the OD (optical density) value is not less than 4; the parameters of the filter may but not Limited to the parameters listed in this document. The lens 3 used in the present invention is a general lens, an achromatic lens, an automatic zoom lens or the like. The area array camera 4 used in the present invention is a monochrome area array camera, an RGB three-color area array camera, or the like. The area array camera used in the present invention includes, but is not limited to, a CCD area array camera and a CMOS area array camera.

Example 1

2 is a schematic structural view of a glossy imaging laser radar apparatus based on an area array camera and a line light source according to the present invention, FIG. 3 is a side view, FIG. 4 is a plan view of Embodiment 1, and FIG. 5 is an embodiment 1 Axis, the relationship between the pixel point on the area array camera and the object surface x-axis direction is satisfied. Line light source 1 (405 nm diode laser, 300 mW, fan angle 150 °, divergence angle 1 mrad) emitted light illuminating the object surface. The light reflected by the three obstacles on the object surface passes through the filter 2, and is imaged by the lens 3 (focal length 60 mm) onto the array camera 4 (1088 × 2048 pixels, single pixel dot size 5.5 μm × 5.5 μm). The angle between the lens 3 and the line light source 1 is 90°. The angle between the lens 3 and the area camera 4 is 31°. The distance from the point to the object surface of the lens 3 is 10 cm. The system has a detection range of 200 meters and can be used as an unmanned vehicle. Car laser radar is used.

One of the ranging methods adopted by the present invention can be based on four points a, b, c, d of known positions on the image plane, and present a', b', c', d' on the area array camera. Four points can be used to calibrate the relationship between pixel points and object position. As seen from the top view of FIG. 4, along the x-axis, the distance between the pixel of the area array camera and the x-axis of the object surface satisfies the relationship of FIG. 5; the y-axis of the pixel point and the y-axis of the object surface satisfy the imaging relationship.

Example 2

By detecting the backscattering signals of atmospheric aerosols, lidar can monitor vehicle exhaust, smoke generated by waste incineration, industrial pollution emissions, and PM2.5 pollution. It is also possible to measure the wind speed of the entire area by monitoring the flow of the aerosol. Aerosol monitoring is also widely used in industries, agriculture, medicine and other fields. Figure 6 is a diagram of the application of the invention in space aerosol detection. The three aerosol molecules on the object surface reflect the illumination light, and after passing through the filter 2, the lens 3 (focal length 75 mm) is imaged onto the array camera 4 (1088×2048 pixels, single pixel point size 5.5 μm×5.5 μm). Form three highlights. The angle between the lens 3 and the line light source 1 is 90°. The angle between the lens 3 and the area camera 4 is 37°. The distance from the point to the object surface of the lens 3 is 10 cm. The system has a detection range of 20 meters and can be used as a position detection of aerosol molecules in the air.

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and combinations thereof may be made without departing from the spirit and scope of the invention. Simplifications should all be equivalent replacements and are included in the scope of the present invention.

Claims

A light surface imaging laser radar based on a line light source and an area array camera, comprising a lens (3), an area array camera (4), a calculation and analysis unit (5), characterized in that: a line source (1) smooth surface imaging is further included The planes illuminated by the line source, the lens surface, and the plane of the plane camera intersect in a line; when the line source illuminates the obstacle on the plane, the light is reflected by the obstacle, and the reflected light is imaged through the lens (3). The position of the area camera (4), the shape of the image is the outline of the obstacle illuminated by the line source, and the position of the corresponding object is calculated by the position of the image.
The light surface imaging laser radar based on a line light source and an area array camera according to claim 1, wherein the light source (1), the lens (3), and the area array camera (4) are arranged at an angle conforming to an imaging formula. The image plane position is determined by the angle between the lens surface and the object plane a, the lens center distance from the three sides of the intersection line L, and the focal length f of the lens. The angle b between the image plane and the object plane can be obtained by the following formula:

u=sin a·x obj

h o =cos a·x obj -L

Where X obj is the distance of the obstacle on the object surface from the intersection of the object surface, the lens surface and the image plane;

By adjusting the three parameters a, L, and f, the lidar ranging and space detection range can be adjusted.
The light source imaging based on the line source and the area array camera according to claim 1 The light radar is characterized in that it further comprises a filter (2) located between the lens (3) and the object surface, in front of the lens (3).
The light surface imaging laser radar based on a line source and an area array camera according to claim 3, wherein the filter (2) is a band pass filter.
The light source imaging laser radar based on a line light source and an area array camera according to claim 1, wherein the line light source (1) is a laser light source or an LED light source.
The light source imaging laser radar based on a line light source and an area array camera according to claim 5, wherein a pattern of said line source is generated by a point source through a linear laser generating lens; said line Another way to create a light source is to form a smooth surface with multiple lasers.
The light source imaging laser radar based on a line source and an area array camera according to claim 1, wherein the lens (3) used may be a normal lens, an achromatic lens or an auto zoom lens.
The light surface imaging laser radar based on a line light source and an area array camera according to claim 3, wherein the area array camera (4) used is a monochrome area array camera or an RGB three color area array camera, and a CCD surface. An array camera consisting of a matrix camera or a CMOS area camera or a number of line array cameras.
A light surface imaging laser detecting method based on line light source and area array camera, characterized in that:

Step 1, the plane illuminated by the line source, the lens surface, and the plane of the plane camera plane intersect one line; the parameters a, f, L are determined according to the specific detection target, and the parameter b is determined by the formula according to claim 2;

Step 2. When the line light source (1) illuminates an obstacle on the plane, the light is reflected by the obstacle, and the reflected light is imaged by the lens (3) at the corresponding position of the area array camera (4), and the shape of the image is an obstacle. The outline illuminated by the light source;

Step 3. The output signal of the area array camera (4) is sent to the calculation analysis unit (5) for data processing.
The method for detecting a laser based on a line source and an area array camera according to claim 9, wherein four points a, b, c, and d of a rectangle are selected on the object surface, and the length of the rectangle is m. The width is n; according to the four points formed by a', b', c', d' in the position of the area array camera, fine-tuning the three parameters a, L, f, so that the point of the object surface and the point of the image plane A match is reached; for a point on the object surface (X obj , Y obj , 0), the corresponding point (x, y, z) on the image plane conforms to the following formula:

x=-sin a·v+cos a(h 1 +L)

z=cos a·v+sin a(h 1 +L)

among them,

u=sin a·z 1

h o =cos a·z 1 -L

After the correction training, the calculation analysis unit matches the object plane position corresponding to the image point and outputs the data.