CN102401901A - Ranging system and ranging method - Google Patents

Abstract

The present invention provides a distance measurement system, comprising a light source, an image sensor and a control processing unit. The light source projects a light region to an object to be measured at a projection angle. The image sensor senses reflected light from the light region on the object to be measured. The control processing unit controls the light source to project the light region at the projection angle and determines a settable sampling range of the image sensor according to the projection angle and preset system parameters. The present invention also provides a distance measurement method.

Description

Ranging system and ranging method

technical field

The present invention relates to a ranging system, in particular to an optical ranging system and a ranging method with an adjustable image sensor and a settable sampling range.

Background technique

In recent years, 3D information technology is being rapidly developed and applied in different fields. In addition, 3-D range finding provides applications other than distance measurement, such as drop tests, observation of high-speed moving targets, and automatic control of robot vision. Since the existing 3-D rangefinding image sensor (3-D rangefinding image sensor) using the time-of-flight method cannot achieve fast 3D ranging, several methods combined with the light segment method (light -section method) of the three-dimensional ranging image sensor in order to improve the detection speed and detection accuracy.

However, in the existing three-dimensional ranging method using the light segment method, the image sensor will always output the sensing image data of the entire sensing array, and it is impossible to change the image sensor's settable data according to the actual detection conditions. The sampling range (window of interest, WOI) is limited, so it is difficult to further increase its operating efficiency.

In view of this, a ranging system with low power consumption and high frame rate is required in the detection system industry.

Contents of the invention

The object of the present invention is to provide a ranging system and a ranging method, which can adjust the settable sampling range (WOI) of the image sensor according to the projection angle of the light source, thereby reducing system power consumption and increasing frame rate.

Another object of the present invention is to provide a ranging system and a ranging method, which pre-stores the relative relationship between the projection angle of the light source and the settable sampling range of the image sensor, so as to automatically determine the image data to be processed according to the detection conditions , thereby reducing the amount of data processing.

To achieve the above object, the present invention proposes a distance measuring method for detecting objects to be detected within a preset depth range. The distance measuring method includes the following steps: providing a light source to project a light area to the object to be measured at a projection angle; providing a plurality of photosensitive units to sense the reflected light of the light area on the object to be measured; and according to the projection angle and The preset depth range determines the settable sampling range of the photosensitive unit.

The invention also proposes a ranging system for detecting objects to be measured within a preset depth range. The ranging system includes a light source, an image sensor and a control processing unit. The light source projects a light area to the object under test at a projection angle. The image sensor senses the reflected light of the light area on the object under test. The control processing unit controls the light source to project the light area at the projection angle and determines the settable sampling range of the image sensor according to the projection angle and preset system parameters.

The invention also proposes a ranging system, which is used to generate a stereoscopic image of the surface to be measured. The ranging system includes a light source, a plurality of photosensitive units and a control processing unit. The light source projects a light area to the surface to be measured. The photosensitive unit senses the reflected light of the surface to be measured. The control processing unit controls the light source to scan the surface to be measured with the light area and controls different parts of the photosensitive unit to output sensed image data according to different projection positions of the light area and preset system parameters.

According to another embodiment of the present invention, the distance measuring system further includes a light guide assembly for guiding the reflected light of the light area on the object to be measured to the image sensor.

In the ranging system and ranging method of the present invention, the preset system parameters include the spatial relationship of the light source, the image sensor and the light guide component and the preset detectable depth range; wherein the spatial relationship and the preset detectable The measuring depth range can be preset and stored in the control processing unit before the detection system leaves the factory.

Description of drawings

FIG. 1A is a perspective view of a ranging system according to an embodiment of the present invention;

FIG. 1B is an image frame sensed by the image sensor in FIG. 1A;

FIG. 2 is a schematic diagram of the operation of the ranging system according to the embodiment of the present invention;

FIG. 3 is another schematic diagram of the operation of the ranging system according to the embodiment of the present invention, wherein the projection angle of the light source is θ ₁ ;

FIG. 4 is another schematic diagram of the operation of the ranging system according to the embodiment of the present invention, wherein the projection angle of the light source is θ ₂ ;

FIG. 5 is a flow chart of a ranging method according to an embodiment of the present invention.

Explanation of main component symbols

1 ranging system 11 light source

12 image sensor 13 control processing unit

14 Light guide unit 9 Object to be tested

A The protruding part of the object to be measured B The plane area of the object to be measured

D ₁ Distance between protrusion and light source D ₂ Distance between plane area and light source

f Focal length of light guide unit θ, θ ₁ , θ ₂ Projection angle

111 ~ 114 rays S ₁₀ ~ S ₃₀ steps

L The distance between the center of the light source and the center of the light guide unit

X, X′, X ₁ , X ₂ , X ₁ , X ₂ , X ₁ ″, X ₂ ″ light reflection position

Detailed ways

In order to make the above and other objects, features, and advantages of the present invention more apparent, the following detailed description will be given in conjunction with the accompanying drawings. In addition, each reference numeral in the present invention only shows some components and components not directly related to the description of the present invention are omitted.

Please refer to FIG. 1A , which shows a perspective view of a ranging system according to an embodiment of the present invention. The distance measuring system 1 is used to measure the three-dimensional distance of the object 9 to be measured within a preset depth range and form a stereo image of the surface 90 to be measured of the distance measuring system 1 on the object 9 to be measured. For ease of description, the surface to be measured 90 here includes, for example, a protruding portion A and a plane area B; it must be noted that the shapes of the object to be measured 9 and the surface to be measured 90 are not intended to limit the distance measuring system 1 of the present invention what can be measured.

The ranging system 1 includes a light source 11 , an image sensor 12 and a control processing unit 13 . The light source 11 can be, for example, a radiation source, which preferably projects a light section to the surface 90 to be measured. In one embodiment, the light source 11 can be a line radiation light source, and the light area projected by it can be, for example, a line segment with an appropriate width, wherein the length of the line segment determines the range of energy measurement; the width of the line segment is determined by the light source 11 There is no specific limitation determined by the characteristics; the length direction of the line segment can be vertical or horizontal. In another embodiment, the light source 11 can also be a point radiation source, and project the light area to the surface 90 to be measured in a scanning manner, for example, from top to bottom or bottom to top in FIG. 1A A line segment is scanned on the surface 90 .

The image sensor 12 is preferably a CMOS image sensor or a three-dimensional ranging image sensor, which is used to sense the reflected light reflected by the light source 11 from the surface to be measured 90; the image sensor 12 preferably includes a plurality of photosensitive units (not shown) A line sensing array or sensing matrix of a CMOS chip is formed; each photosensitive unit outputs an electrical signal representing sensing image data according to the light energy it senses.

The control processing unit 13 is coupled to the light source 11 and the image sensor 12, and is used to control the light source 11 to project a light area to different positions of the surface to be measured 90 at different angles and scan the surface to be measured 90 with the light area. all or part of it. For example, when the light source 11 projects a line segment as shown in FIG. 1A , the control processing unit 13 controls the light source 11 to scan all or a part of the surface to be measured 90 from left to right or from right to left. In another embodiment, when the light source 11 is a point light source, the control processing unit 13 controls the light source 11 to scan a line segment from top to bottom or bottom to top, and then scan from left to right or right to left. Sequentially scan other line segments to cover all or a part of the surface to be measured 90 ; wherein, the scanning mode of the light source 11 and the scannable angle range can be preset and stored in the control processing unit 13 . In addition, the ranging system 1 may further include a light guide unit 14 for guiding the reflected light from the surface to be measured 90 to the image sensor 12 , and the light guide unit 14 may be, for example, a lens.

Please refer to FIG. 1A and FIG. 1B at the same time. FIG. 1B shows the image frame sensed by the image sensor 12 of FIG. The image frame, and the right figure is the image frame sensed by the image sensor 12 according to the light area projected by the light source 11 at time t2. The control processing unit 13 can determine the depth of each point relative to a light area according to the reflected light pattern in an image frame, that is, determine the relative distance between each point of the light area and the light source 11 . When the control processing unit 13 controls the light source 11 to scan the surface to be measured 90 with the light area, a stereoscopic image of the surface to be measured 90 can be generated according to the depth of each point.

According to FIG. 1A and FIG. 1B, with respect to each projection angle of the light source 11, only a part of the sensing array of the image sensor 12 senses the reflected light of the light source 11; therefore, the control processing unit in the present invention 13 also controls the image sensor 12 to output an electrical signal with a preset sampling range (WOI) according to the projection angle of the light source 11 combined with system preset parameters and performs post-processing. For example, when the image sensor 12 includes a plurality of photosensitive units, the control processing unit 13 controls a part (such as the photosensitive unit that senses the reflected light of the light source 11) to output an electrical signal while other parts (such as the photosensitive unit that does not sense the light source 11 The photosensitive unit of the reflected light) does not output an electrical signal. Thus, not only can the overall power consumption of the ranging system 1 be reduced, but also the frame rate can be increased because the image sensor 12 only needs to output the electrical signals sensed by a part of the sensing array. In one implementation state, the configurable sampling range (WOI) can be selected to be slightly larger than the area where the reflected light of the light source 11 can actually be sensed, and must be at least roughly equal to the area where the reflected light of the light source 11 can actually be sensed.

It can be understood that the relative relationship between the projection angle of the light source 11 and the settable sampling range of the image sensor 12 can be obtained in advance using trigonometric functions according to the spatial correlation among the components of the ranging system 1, and stored in the In the control processing unit 13.

In other embodiments, when the light source 11 projects a horizontal light area to the surface 90 to be measured, relative to different projection angles, the length direction of the settable sampling range is along the sensing array of the image sensor 12 in the horizontal direction.

Next, the manner in which the control processing unit 13 determines the settable sampling range of the image sensor 12 according to the projection angle of the light source 11 and preset system parameters will be described.

Please refer to FIG. 2 , which shows a schematic diagram of the operation of the ranging system according to the embodiment of the present invention. In FIG. 2 , it is assumed that the distance between the protrusion A and the light source 11 is D ₁ and the distance between the plane area B and the light source 11 is D ₂ ; wherein the range between D ₁ and D ₂ represents, for example, the range of the distance measuring system 1 The detection depth range can be preset before the distance measuring system 1 leaves the factory or can be set by the user according to the depth of the object 9 to be measured. Meanwhile, it is assumed that the lateral distance between the center of the light source 11 and the center of the light guide unit 14 is L and the light guide unit 14 has a focal length f. When the projection direction of the light source 11 is parallel to the normal of the surface to be measured 90, the light 111 projected by the light source 11 onto the protrusion A will be reflected to the position _X1 on the sensing array of the image sensor 12 and the light source The light 112 projected on the planar area B by 11 will be reflected to the position _X2 on the sensing array of the image sensor 12 . When there is an angle θ between the projection direction of the light source 11 and the normal line of the surface to be measured 90, the light 113 projected by the light source 11 to the protrusion A will be reflected to the position X on the sensing array of the image sensor 12 and The light 114 projected by the light source 11 onto the plane area B will be reflected to the position X′ on the sensing array of the image sensor 12 .

When the light source 11 is projected along the normal direction of the surface to be measured 90 (i.e. θ=0), the following relationship can be obtained according to the trigonometric function relationship:

D ₁ /L=f/X ₁ formula (1)

D ₂ /L=f/X ₂ formula (2)

When there is an angle (that is, θ≠0) between the light source 11 and the normal direction of the surface to be measured 90, the following relationship can be further obtained according to the trigonometric function relationship:

D ₁ ＝(f×L)/(X+f×tanθ) Formula (3)

D ₂ ＝(f×L)/(X′+f×tanθ) Formula (4)

Wherein, X represents the position on the sensing array of the image sensor 12 reflected from the protrusion A when the projection angle θ≠0 of the light source 11; X′ represents the reflection from the plane area B when the projection angle θ≠0 of the light source 11 to a position on the sensing array of the image sensor 12 . According to formula (3) and formula (4), since f, L, D ₁ and D ₂ are the spatial relationship between components in the system and can be obtained in advance, when the control processing unit 13 controls the light source 11 to project at an angle of θ When the light area is known, the area on the sensing array of the image sensor 12 that can sense the reflected light of the light source 11 is known, so the control processing unit 13 can determine the settable sampling range of the image sensor 12 accordingly. In other words, the system preset parameters include the spatial relationship of the light source 11 , the image sensor 12 and the light guide component 14 and the preset depth range (D ₁ -D ₂ ).

For example, as shown in FIG. 3 , when the control processing unit 13 controls the light source 11 to project the light area to the surface-to-be-measured 90 at an angle θ ₁ , the reflected light is reflected from the protruding portion A to the position X ₁ ′ on the image sensor 12 And reflected from the plane area B to the position X ₂ ′ on the image sensor 12; the settable sampling range can be set as the area from X ₁ ′ to X ₂ ′, or can be slightly larger than the area from X ₁ ′ to X ₂ ′ area.

For example, as shown in FIG. 4 , when the control processing unit 13 controls the light source 11 to project the light area on the object 90 to be measured at an angle θ ₂ , the reflected light is reflected from the protruding portion A to the X ₁ ″ on the image sensor 12. The position is reflected from the plane area B to the position of X ₂ "on the sensing array of the image sensor 12; the settable sampling range can be set as the area from X ₁ " to X ₂ ", or can be slightly larger than X ₁ " to X ₂ ″ area.

According to FIG. 2 to FIG. 4 , according to the spatial relationship among the various components of the system, each projection angle of the light source 11 corresponds to a settable sampling range of the image sensor 12 . When the image sensor includes a line sensing array, the settable sampling range can be a section of photosensitive unit; when the image sensor includes a sensing matrix, the settable sampling range can be an area of a photosensitive unit. In addition, it can be understood that the dimensions and spatial relationships of the components shown in FIGS. 2 to 4 are only exemplary, and are not intended to limit the present invention.

Please refer to FIG. 2 to FIG. 5 at the same time. FIG. 5 shows a flow chart of the distance measuring method according to the embodiment of the present invention, including the following steps: providing a light source to project a light area to the object to be measured at a projection angle (step S ₁₀ ); providing A plurality of photosensitive units sense the reflected light of the light area on the object under test (step S ₂₀ ); determine the settable sampling range of the photosensitive unit according to the projection angle and the preset depth range (step S ₃₀ ); control the The light source projects the light area at different projection angles to scan the object under test (step S ₄₀ ); determines the different settable sampling ranges of the photosensitive unit according to different projection angles and the preset depth range (step S ₅₀ ); and then Processing sensing data with different settable sampling ranges (step S ₅₀ ); wherein, the post-processing, for example, determines the depth of each point relative to the light area according to the sensing data with settable sampling ranges or according to different settable Sensing data with a fixed sampling range is used to generate a stereoscopic image of the object under test. In addition, the ranging method of the present invention has been described in detail in FIG. 2 to FIG. 4 and related descriptions, so it will not be repeated here.

To sum up, because the image sensor always outputs the sensing data of the entire sensing array when the existing ranging system is in operation, it has low operating efficiency. The present invention also proposes a ranging system and a ranging method, which can pre-establish the relative relationship between the projection angle of the light source and the settable sampling range of the image sensor according to the spatial correlation of the system components and the detectable depth range. When the light source projects a light area to the object under test at different angles, the image sensor is controlled according to the relative relationship to only output sensing data with a settable sampling range, thereby reducing the overall energy consumption of the system and increasing the frame rate.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Any person skilled in the art of the present invention can make various variations and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the appended claims.

Claims (11)

1. a range measurement system is used to detect the determinand in the predetermined depth scope, and this range measurement system comprises:

Light source is used for throwing a light zone to this determinand with a crevice projection angle;

Imageing sensor is used for the regional reflected light of this light on this determinand of sensing; And

Controlled processing unit is used to control this light source with this light zone of this crevice projection angle projection, and confirms the sampling the set scope of this imageing sensor according to this crevice projection angle and predetermined system parameter.

2. range measurement system according to claim 1, wherein, this range measurement system also comprises leaded light component, is used to guide reflected light to the said imageing sensor in the said light zone on the said determinand.

3. range measurement system according to claim 2, wherein said predetermined system parameter comprise the spatial relationship and the said predetermined depth scope of said light source, said imageing sensor and said leaded light component.

4. range measurement system according to claim 1, wherein said imageing sensor also comprise line sensing array or sensing matrix.

5. distance-finding method according to claim 1, wherein said light zone is a line segment.

6. a range measurement system is used to produce to be measured stereo-picture, and this range measurement system comprises:

Light source is used to throw light zone to this to be measured;

A plurality of photosensitive units are used for this reflected light of to be measured of sensing; And

Controlled processing unit is used to control this light source with this to be measured of this light sector scanning, and exports the view data of institute's sensing based on the different piece that the different launching positions and the predetermined system parameter in this light zone are controlled said photosensitive unit.

7. range measurement system according to claim 6, wherein this range measurement system also comprises leaded light component, is used to guide reflected light to the said imageing sensor in the said light zone on the said determinand.

8. range measurement system according to claim 7, wherein said predetermined system parameter comprise the spatial relationship and the predetermined depth scope of said light source, said imageing sensor and said leaded light component.

9. range measurement system according to claim 6, wherein said light source are beta radiation light source or some radiating light source; Said leaded light component is lens.

10. range measurement system according to claim 6, wherein said photosensitive unit forms the image sensing array of CMOS chip.

11. range measurement system according to claim 6, wherein said controlled processing unit also produce said to be measured said stereo-picture according to the view data that the different piece of said photosensitive unit is exported.

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