Optical distance measurement method and device

Abstract

The present invention discloses an optical distance measuring device, comprising a light transmitter for transmitting light to a target object; a light receiver for receiving reflected light after transmitting light to the target object, the light receiver comprising a lens and an array image sensor, the array image sensor comprising a photosensitive area, the photosensitive area being divided into one or more photosensitive sub-areas, the one or more photosensitive sub-areas being used to collect one or more light spots of the reflected light, the light receiver being further used to generate a response signal, the response signal comprising position information of the one or more reflected light spots; a processor for receiving the response signal generated by the light receiver, and calculating the distance from the target object to the optical distance measuring device using a triangulation method according to the position information of the reflected light spots. The present invention effectively reduces the cost, improves the sampling density, and at the same time improves the tolerance to installation errors.

Description

Technical Field

[0001] The present invention belongs to the field of space positioning, and in particular, relates to an optical distance measurement method and device. Background Art

[0002] With the miniaturization of components and the reduction of costs, spatial positioning and ranging technology has become increasingly popular in the general consumer market. The most typical application scenario is the autonomous navigation field of mobile terminals such as small household robots and drones. In spatial ranging technology, optical ranging has advantages over other ranging methods such as ultrasonic ranging and radio frequency circuit ranging, such as high accuracy, fast response, and relatively strong anti-interference, so it is widely adopted. The most common optical positioning measurement device basically includes an optical transmitting device and an optical receiving device. The ranging methods include pulse time difference method, phase difference method, and triangulation method. Among these methods, the phase difference method has high accuracy and long measurement distance, but the measurement frequency is low and the response is slow, which is not suitable for high-speed mobile measurement; the pulse time difference method has a high measurement frequency and fast response, but it has high hardware requirements. The triangulation method is a more compromised method. Its measurement distance and accuracy are moderate, the response is fast, and the hardware cost is relatively low. Therefore, most consumer-grade optical ranging devices, such as the laser radar used in sweeping robots, widely use the triangulation method.

[0003] At present, most consumer-grade optical distance measuring devices (such as sweeping robots) have high requirements for acquisition response speed. Therefore, in order to ensure a high frame rate during measurement (for example, more than 1800 frames / second), in the prior art, optical devices for triangulation generally use a linear image sensor with a special structure, which costs 6-10 times that of ordinary area array image sensors. The high price makes it difficult to popularize. In addition, compared with area array image sensors, each pixel of a linear image sensor may be square or rectangular (such as: 32um*4um), and the number of pixels in its rows and columns shows obvious linear characteristics, for example (number of pixels per row: 2048, number of rows: 4 rows). It is precisely because the number of photosensitive pixel rows of linear image sensors is very small, resulting in a very narrow photosensitive area of ​​the sensor, so the light emitter needs to be strictly aligned with the horizontal position of the center of the linear sensor pixel to ensure that the reflected light can be received by the sensor. Therefore, there are high requirements for the installation error of the laser pitch angle, which is not conducive to production. In addition, the existing optical distance measuring device can only measure a single light point, and the sampling density is not high enough. Summary of the invention

[0004] The present invention provides a method and device for optical ranging, which adopts a cheap area array image sensor and can dynamically divide multiple photosensitive areas to collect multiple light points at one time, thereby solving the problems of high cost, high installation requirements and low sampling density caused by the use of linear image sensors to achieve optical ranging in the prior art, effectively reducing costs, improving sampling density, and improving tolerance to installation errors.

[0005] In order to achieve the above object, the present invention provides an optical distance measuring device, which includes:

[0006] A light emitter, used for emitting light to a target object;

[0007] A light receiver, used to receive reflected light after emitting light to the target object, the light receiver includes a lens and an area array image sensor, the area array image sensor includes a photosensitive area, the photosensitive area is divided into one or more photosensitive sub-areas, the one or more photosensitive sub-areas are used to collect one or more light spots of the reflected light, the light receiver is also used to generate a response signal, the response signal includes position information of the one or more reflected light spots;

[0008] The processor is used to receive the response signal generated by the optical receiver and calculate the distance from the target object to the optical distance measuring device by using triangulation according to the position information of the reflected light point.

[0009] In one embodiment of the present invention, the photosensitive area is divided into one or more photosensitive sub-areas, specifically:

[0010] The photosensitive area is divided into one or more strip-shaped photosensitive sub-areas, and the number of rows of the photosensitive sub-areas is M, where M is a positive integer greater than or equal to 1; the area array image sensor is also used to: after collecting the one or more reflected light spots in the one or more photosensitive sub-areas, obtain the column position information of the one or more reflected light spots.

[0011] In one embodiment of the present invention, the one or more photosensitive sub-areas are used to collect the one or more light spots of the reflected light, specifically:

[0012] When the light emitter emits multiple beams of point light, the multiple photosensitive sub-areas are used to collect multiple reflected light points, and the multiple reflected light points are distributed in the multiple photosensitive sub-areas in a cross-like or matrix-like shape.

[0013] In one embodiment of the present invention, the area array image sensor is used to obtain the column position information of the one or more reflected light points, specifically:

[0014] The area array image sensor acquires column coordinate information of the center of gravity position of the one or more reflected light spots.

[0015] In one embodiment of the present invention, the area array image sensor is further used to: calculate the average grayscale values ​​of several pixels in each column in the photosensitive sub-area, and the calculated result is the result of compressing M rows of pixel information into one or several rows of pixel information.

[0016] In one embodiment of the present invention, the area array image sensor includes the multiple photosensitive sub-areas, and the area array image sensor sets one or more of the multiple photosensitive sub-areas as effective photosensitive areas. After the effective photosensitive area collects the reflected light spot, the area array image sensor generates and outputs a response signal. The rest are set as invalid photosensitive areas. After the invalid photosensitive area collects the reflected light spot, the area array image sensor does not output a response signal.

[0017] In one embodiment of the present invention, the area array image sensor is also used for:

[0018] The height position of the photosensitive area is dynamically adjusted so that the center of gravity of one or more reflected light points falls within the photosensitive area.

[0019] In one embodiment of the present invention, the light transmitter includes a laser source and a beam splitter, and the beam splitter is used to split the point laser emitted by the laser source into one or more beams of point laser.

[0020] In one embodiment of the present invention, the beam splitter is a diffraction grating or an optical prism.

[0021] An embodiment of the present invention also provides an area array image sensor, which includes a photosensitive area, which is divided into one or more photosensitive sub-areas, and the one or more photosensitive sub-areas are used to collect one or more reflected light spots and obtain position information of the one or more reflected light spots. The area array image sensor is also used to generate a response signal and send the response signal to an optical ranging device, wherein the response signal includes the position information of the one or more reflected light spots.

[0022] In one embodiment of the present invention, the photosensitive area is divided into one or more photosensitive sub-areas, specifically: the photosensitive area is divided into one or more strip-shaped photosensitive sub-areas, the number of rows of the photosensitive sub-areas is M, where M is a positive integer greater than or equal to 1; then the photosensitive sub-area obtains the position information of the one or more reflected light points, specifically: after collecting the one or more reflected light points in the one or more photosensitive sub-areas, the column position information of the one or more reflected light points is obtained.

[0023] In one embodiment of the present invention, the one or more photosensitive areas are used to collect the one or more reflected light spots, including: the multiple photosensitive areas are used to collect multiple reflected light spots, and the multiple reflected light spots are distributed in a cross-like or matrix-like manner in the multiple photosensitive areas.

[0024] In one embodiment of the present invention, the area array image sensor is further used to: calculate the average grayscale values ​​of several pixels in each column in the photosensitive sub-area, and the calculated result is the result of compressing M rows of pixel information into one or several rows of pixel information.

[0025] In one embodiment of the present invention, the area array image sensor includes multiple photosensitive sub-areas, and the area array image sensor sets one or more of the multiple photosensitive sub-areas as effective photosensitive areas, and the effective photosensitive areas generate and output response signals after collecting the reflected light points, and the rest are set as invalid photosensitive areas, and the invalid photosensitive areas do not output response signals after collecting the reflected light points.

[0026] In one embodiment of the present invention, the area array image sensor is also used for:

[0027] The height position of the photosensitive area is dynamically adjusted so that the center of gravity of one or more reflected light points falls within the photosensitive area.

[0028] In one embodiment of the present invention, the area array image sensor is a complementary metal oxide semiconductor (CMOS) image sensor or a charge coupled device (CCD) image sensor.

[0029] The embodiment of the present invention further provides an optical distance measurement method, which is specifically:

[0030] The light emitter emits light to the target object;

[0031] The area array image sensor receives reflected light after the emitted light reaches the target object and generates a response signal, wherein the response signal includes position information of the one or more reflected light points, wherein the area array image sensor comprises a photosensitive area, and the area array image sensor divides the photosensitive area into one or more photosensitive sub-areas, so that the area array image sensor collects one or more light points of the emitted light through the one or more photosensitive sub-areas;

[0032] The processor calculates the distance of the target object according to the position information of the one or more reflected light points.

[0033] In one embodiment of the present invention, after collecting one or more reflected light spots, the method further includes: acquiring column position information of the one or more reflected light spots.

[0034] In one embodiment of the present invention, collecting the one or more light spots of reflected light includes:

[0035] When the optical distance measuring device emits multiple beams of point light, the multiple photosensitive sub-areas collect multiple reflected light points, and the multiple reflected light points are distributed in the multiple photosensitive sub-areas in a cross-like or matrix-like shape.

[0036] In one embodiment of the present invention, the method further includes: calculating the average grayscale values ​​of a plurality of pixels in each column in the photosensitive sub-area, and the calculated result is the result of compressing M rows of pixel information into one or several rows of pixel information.

[0037] The method of the embodiment of the present invention has the following advantages:

[0038] In the embodiment of the present invention, since a cheap area array image sensor is used to collect one or more reflected light spots, not only can the effect that can only be achieved by a traditional linear image sensor be achieved, but also the photosensitive area can be dynamically set and adjusted, thereby reducing the installation requirements, achieving high-speed, multi-area, and high-density measurement, effectively reducing the difficulty and cost of production, improving the competitive advantage of the product, and bringing commercial success. In addition, since the traditional area array image sensor is a two-dimensional data image sensor, its data processing volume is large, and the measurement frame rate cannot meet the requirements of high-speed ranging (at least 1800 frames / second), it is difficult to achieve consumer-grade high-speed optical ranging. The embodiment of the present invention creatively collects one or more reflected light spots at a time by selecting one or more photosensitive sub-areas, and averages multiple rows of pixels, which not only effectively reduces the data processing volume of the processor, but also increases the measurement density, thereby improving the measurement accuracy, ensuring the frame rate of high-speed measurement, and overcoming the technical prejudice that the area array image sensor is not suitable for high-speed optical ranging. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1a is a structural diagram of the optical distance measuring device in Example 1 of the present invention;

[0040] Figure 1b is a structural diagram of another optical distance measuring device in embodiment 1 of the present invention;

[0041] Figure 2a is a schematic diagram of photosensitive area division in Embodiment 1 of the present invention;

[0042] Figure 2b is a schematic diagram showing that the center of the light emitter and the center line of the photosensitive area are not aligned in Embodiment 1 of the present invention;

[0043] Figure 2c is a schematic diagram of a special case in which the number of reflected light points is 1 and the number of photosensitive sub-regions is 1 in Embodiment 1 of the present invention;

[0044] Figure 2d is a schematic diagram of a cross-shaped distribution of reflected light spots in Example 1 of the present invention;

[0045] Figure 2e is a schematic diagram of a matrix-like distribution of reflected light spots in Example 1 of the present invention;

[0046] Figure 3 is a schematic diagram of a single-column pixel merging algorithm in Embodiment 1 of the present invention;

[0047] Figure 4 is a schematic diagram of the structure of the area array image sensor in Embodiment 2 of the present invention;

[0048] Figure 5 This is a flow chart of the optical distance measurement method in Example 3 of the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0050] Example 1

[0051] To achieve the above objectives, Figure 1a As shown, the present invention provides an optical distance measurement device 11, and the device 11 includes the following components:

[0052] A light emitter 101, used to emit light to a target object;

[0053] Alternatively, if Figure 1b As shown, the light emitter 101 emits point light (such as laser) to the target object. The light emitter 101 includes a laser source 1011 and a beam splitter 1012. The laser source 1011 is used to generate and emit a laser source. The beam splitter 1012 is placed at the emission port of the laser source 1011 and is used to split the point laser emitted by the laser source 1011 into one or more beams of point lasers through the beam splitter 1012 and emit them to the target object, and generate one or more corresponding beams of point reflected lasers. By dividing a laser point into multiple laser points, it is possible to ensure that the optical distance measuring device collects multiple reflected light points at the same time, thereby improving the collection density.

[0054] Optionally, the beam splitter 1012 is a diffraction grating (Diffraction Optical Elements, DOE) or an optical prism, or may be other beam splitting devices, which is not limited in the embodiment of the present invention.

[0055] The optical receiver 102 is used to receive the reflected light after the optical transmitter 101 transmits the light to the target object. The optical receiver 102 includes a lens 1021 and an area array image sensor 1022. The area array image sensor 1022 includes a photosensitive area, such as Figure 2a As shown, the photosensitive area is divided into one or more photosensitive sub-areas (photosensitive sub-area 1, photosensitive sub-area 2 ... photosensitive sub-area N), and the one or more photosensitive sub-areas are used to collect one or more light spots of the reflected light; the light receiver is also used to generate a response signal, and the response signal includes the position information of the one or more reflected light spots;

[0056] Compared with linear image sensors, each pixel of the former is a square, with the same width and height (for example, 3um*3um), and the number of pixels and rows in each row can be 4:3 or 16:9 (for example, 1280 pixels per row, 720 rows), while each pixel of the latter may be a square or a rectangle (for example, 32um*4um), and the number of pixels in rows and columns shows obvious linear characteristics, for example, 2048 pixels per row, 4 rows. The optical ranging devices used in service robots (such as sweeping robots) currently used in the consumer market all use expensive linear image sensors without exception, and no cheap area array image sensors are used. Because the area array image sensor itself can image a large area, its design function and manufacturing process do not have the characteristics of linear sensors: small window, small data, high frame rate and high sensitivity at low exposure time. Therefore, the purpose of the birth or the original intention of the area array image sensor is not to do linear scanning, that is, the area array image sensor is not used as a linear sensor. In summary, the many characteristics of the area array image sensor determine that it is not designed for high-speed linear scanning. If most of the imaging area of ​​the area array image sensor is discarded and only a small strip is used, and the frame rate is output at a high speed, this will cause two problems: first, it greatly wastes the resources of the area array image sensor; second, to output the frame rate at a high speed, many parameters must be adjusted for the underlying settings of the area array image sensor to ensure that it can achieve the purpose of high-sensitivity output at high speed (more than 1800 frames / second) and extremely short exposure time (tens of microseconds). At present, most of the area array image sensors on the market cannot do this. Therefore, for ordinary technicians in this field, consumer-grade high-speed and high-sensitivity optical ranging devices generally use linear image sensors instead of area array image sensors. However, in the embodiments of the present invention, a cheap area array image sensor is creatively proposed to replace the linear image sensor, and one or more photosensitive areas in the area array image sensor are used to collect one or more reflected light points. The data processing speed is fast, and the sampling accuracy and density are greatly improved, and the high-speed ranging effect that can only be achieved by a linear image sensor is also achieved. The following effects are brought about:

[0057] 1. Greatly reduced product costs, improved product competitiveness, and brought commercial success. Since the cost of linear image sensors is several times that of area array image sensors, the solution of using area array image sensors instead of linear image sensors will greatly reduce the cost of optical ranging devices, which is conducive to the popularization of products in the consumer market and brings commercial success.

[0058] 2. Overcoming technical prejudice. In summary, the current high-speed optical ranging devices in the consumer market all use linear image sensors and abandon area array image sensors. Obviously, due to the characteristics of large-area acquisition and large data processing volume of area array image sensors, ordinary technicians in this field believe that the use of area array image sensors is simply not feasible in the field of high-speed optical ranging. The solution provided by the embodiment of the present invention creatively uses area array image sensors instead of linear sensors and achieves the same technical effect, which overcomes the technical prejudice that area array image sensors cannot be used in the field of high-speed optical ranging.

[0059] Alternatively, if Figure 2a As shown, the photosensitive area can be divided into one or more strip-shaped photosensitive sub-areas, and the number of rows of all or part of the photosensitive sub-areas can be set to M rows, where M is a positive integer greater than or equal to 1. The starting row, ending row, starting column and ending column of each photosensitive sub-area can be configured in advance, and the height and position of each photosensitive sub-area can be dynamically adjusted, and it is only necessary to modify the corresponding starting row position, row height and column height in the register of the area array image sensor. For example, when the light emitter emits light to the target object and the area array image sensor starts exposure, the area array image sensor first globally scans each pixel on the photosensitive surface. After detecting the area where the reflected light point is located, the area array image sensor can dynamically set the photosensitive area on the photosensitive surface (the photosensitive area is the area containing all the reflected light points, and the size of the photosensitive area can be dynamically set, and its area is less than or equal to the area of ​​the photosensitive surface), and set the corresponding starting row position and row height, column height, and at the same time divide the photosensitive area into multiple photosensitive sub-areas. After that, it is only necessary to scan the pixels of the photosensitive area row by row to quickly obtain the position information of the reflected light point. The advantage of this is that if the center of gravity of the reflected light spot does not fall into the photosensitive area (such as the photosensitive area) due to installation errors during the production of the optical distance measuring device, Figure 2b As shown), the starting row position of the photosensitive area can be dynamically adjusted so that the reflected light spot still falls in the photosensitive area, thereby reducing the requirements for the production process.

[0060] For the convenience of understanding by ordinary technicians in this field, each strip-shaped photosensitive sub-area can be understood as a photosensitive area of ​​a linear image sensor, and multiple strip-shaped photosensitive sub-areas can be understood as the longitudinal "superposition" of multiple linear image sensor photosensitive area arrays. When the number of photosensitive sub-areas is 1, and the number of collected reflected light points is also 1, the imaging effect is as follows: Figure 2cAs shown, in this case, for the sake of convenience, it can be understood that this case is a special case of using an area array image sensor to "simulate" a linear image sensor. However, those skilled in the art should understand that the description here is only used to facilitate technicians to more easily understand the technical solution provided by the embodiment of the present invention. In actual products, the area array image sensor is divided into one or more strip-shaped photosensitive sub-areas, which require complex configuration, verification and subsequent data processing, rather than simply "simulating" or "superimposing" the photosensitive area of ​​the linear image sensor.

[0061] Optionally, when the light emitter 101 emits multiple beams of point light through the beam splitter 1012, the multiple photosensitive sub-areas are used to collect multiple reflected light points, and the multiple reflected light points are distributed in a cross-like or matrix-like manner in the multiple photosensitive sub-areas. It should be noted that the cross-like distribution means that the imaging of the reflected light points is equal to or close to the cross-like distribution. For the imaging of the reflected light points, it is possible that the position of each light point has a deviation, so that it does not present an absolute cross-like distribution, but may present an imaging that is close to the cross-like distribution. Similarly, the matrix-like distribution means that the imaging is equal to or close to the matrix. Figure 2d This is a schematic diagram of the cross-shaped distribution of reflected light spots in the photosensitive area. Figure 2d As shown, in the photosensitive area, there are a total of P rows of reflected light spots (as shown in the schematic diagram, P=7), of which the middle row has Q spots (as shown in the schematic diagram, Q=4), and each of the remaining rows has 1 spot, where P and Q are both positive integers. Figure 2e This is a schematic diagram of the matrix-like distribution of reflected light spots in the photosensitive area. Figure 2e As shown, the difference between the matrix shape and the cross shape is that the matrix shape has a total of P rows, and each row has Q points.

[0062] Optionally, the position information of the reflected light spot includes row position information and column position information. The area array image sensor 1022 is also used to: after collecting the one or more reflected light spots in the one or more photosensitive sub-areas, obtain the column position information of the one or more reflected light spots. Optionally, obtaining the column position information of the one or more reflected light spots is specifically: the area array image sensor obtains the column coordinate information of the centroid position of the one or more reflected light spots. It should be noted that the centroid position is the position after the brightness weighted average of the valid coordinates in the area, and the centroid position is different from the center position, and the center position is the geometric center of the minimum bounding box of the area. For example, if the reflected light spot occupies 5 pixels in a photosensitive sub-area, the centroid position of the reflected light spot is the position after the brightness weighted average of the coordinates of the 5 pixels. The reason why the column coordinate information of the centroid position needs to be obtained is that according to the triangulation method, when the relative angle and spacing between the light emitter 101 and the area array image sensor 1022 are known, the distance of the target object from the optical distance measuring device can be calculated according to the column coordinate information. According to the triangulation method, only the column coordinate information needs to be known for measurement without obtaining the row coordinate information. Therefore, the photosensitive area can be mainly arranged in the column direction, and only one row or a very narrow number of rows can be used in the row direction.

[0063] Optionally, the area array image sensor 1022 is also used to perform a single-column pixel merging algorithm (Binning algorithm). The Binning algorithm can realize fast data reading of the area array image sensor by compressing the M rows of pixel information divided on the sensor into one or more rows. Specifically, the grayscale values ​​of several pixels in each column of the photosensitive sub-area are averaged, and the calculated result is the result of compressing the M rows of pixel information into one or more rows of pixel information. When the vertical field of view remains unchanged, the amount of data is reduced to a few times the original amount, and the signal-to-noise ratio of the output image is greatly improved. Figure 3 As shown in FIG. 1 , after M rows of data are collected, the amount of compressed data is only a fraction of the original data after the Binning algorithm is used.

[0064] Optionally, the area array image sensor 1022 may include multiple photosensitive sub-areas, and the area array image sensor sets one or more of the multiple photosensitive sub-areas as effective photosensitive areas. After the effective photosensitive areas collect the reflected light spots, the area array image sensor 1022 generates and outputs response signals. The rest are set as invalid photosensitive areas. After the invalid photosensitive areas collect the reflected light spots, the area array image sensor 1022 does not output response signals, thereby achieving the purpose of reducing the amount of image data processing per frame and obtaining a high frame rate.

[0065] The processor 103 is used to receive the response signal generated by the optical receiver 102, and calculate the distance from the target object to the optical distance measuring device 11 by using triangulation according to the position information of the reflected light point.

[0066] Optionally, the processor 103 may include a main control module and a data processing module. The main control module is used to turn on / off the light transmitter 101 to transmit light to the target object, and is also responsible for turning on / off the light receiver to receive reflected light. In an embodiment of the present invention, the main control module can simultaneously or sequentially turn on the photosensitive sub-areas for exposure, so that the area array image sensor 1022 can obtain one or more reflected light points at one time. The data processing module is used to receive the response signal generated by the light receiver 102 and use triangulation to measure the distance.

[0067] Triangulation is a commonly used measurement method in the field of optical distance measurement. The method is as follows: by calculating the centroid position of the area and the known relative angle and spacing between the laser emitting device and the image sensor, the distance of the target from the image sensor can be inferred. The basic measurement formula of triangulation is z = b*f / x; where b represents the spacing between the laser emitting device and the image sensor, f is the focal length of the lens used by the image sensor, x is the centroid position of the column coordinates of the reflected light projected on the image sensor, and z is the measured distance. From the formula, it can be seen that the measured distance is only related to the position of the centroid in the column direction and has nothing to do with the number of rows. Therefore, the photosensitive array can be mainly arranged in the column direction, and only one row or a very narrow number of rows can be used in the row direction; in addition, the measurement error formula is e = 1 / (b*f / (n*z)+1), where n represents the error of centroid extraction. It can be seen that the measurement error e is inversely proportional to b and f, and proportional to n and z. Therefore, when b, f and n are constant, it is necessary to select a relatively telephoto lens to reduce the error at different distances.

[0068] for Figure 2d and Figure 2e The cross-shaped and matrix-shaped distance measurement, each of which is also applicable to triangulation, in addition, for each reflected light point, the connected domain segmentation method is generally used to obtain the area of ​​the point, so multiple points appearing in the same row can also be solved. The connected domain segmentation method is one of the commonly used algorithms for those skilled in the art, and the embodiments of the present invention will not be repeated here.

[0069] In the embodiment of the present invention, the planar array image sensor used in this scheme is low-cost. The laser beam is divided into multiple parts by a beam splitter, and imaging is performed in multiple photosensitive sub-areas of the sensor. The distance data of the measured object can be obtained at high speed, high density, and multiple areas. Moreover, since there are more rows of exposed pixels, the accuracy and redundancy of the calculation are improved. At the same time, the image is compressed using a single-column pixel merging algorithm, which improves the signal-to-noise ratio and saves calculation complexity. In addition, since the sub-areas of this scheme can be dynamically adjusted in position, a certain range of laser installation errors can be allowed. When the angle of the laser changes due to collisions and other problems, only the starting height of the sub-area needs to be dynamically adjusted, and there is no need to disassemble the measurement module and adjust the installation process.

[0070] Example 2

[0071] The embodiment of the present invention provides a planar array image sensor 41, such as Figure 4 As shown, the area array image sensor 41 includes a photosensitive area 401, which is divided into one or more photosensitive sub-areas, and the one or more photosensitive sub-areas are used to collect one or more light spots of reflected light and obtain position information of the one or more reflected light spots. The area array image sensor 41 is also used to generate a response signal, and send the response signal to the optical ranging device, so that the optical ranging device measures the distance from the target object to the optical ranging device by triangulation according to the response signal, wherein the response signal includes the position information of the one or more reflected light spots.

[0072] In the embodiment of the present invention, the area array image sensor may be a complementary metal oxide semiconductor (CMOS) image sensor or a charge coupled device (CCD) image sensor.

[0073] Compared with linear image sensors, each pixel of the former is a square, with the same width and height (for example, 3um*3um), and the number of pixels and rows in each row can be 4:3 or 16:9 (for example, 1280 pixels per row, 720 rows), while each pixel of the latter may be a square or a rectangle (for example, 32um*4um), and the number of pixels in rows and columns shows obvious linear characteristics, for example, 2048 pixels per row, 4 rows. The optical ranging devices used in service robots (such as sweeping robots) currently used in the consumer market all use expensive linear image sensors without exception, and no cheap area array image sensors are used. Because the area array image sensor itself can image a large area, its design function and manufacturing process do not have the characteristics of linear sensors: small window, small data, high frame rate and high sensitivity at low exposure time. Therefore, the purpose of the birth or the original intention of the area array image sensor is not to do linear scanning, that is, the area array image sensor is not used as a linear sensor. In summary, the many characteristics of the area array image sensor determine that it is not designed for high-speed linear scanning. If most of the imaging area of ​​the area array image sensor is discarded and only a small strip is used, and the frame rate is output at a high speed, this will cause two problems: first, it greatly wastes the resources of the area array image sensor; second, to output the frame rate at a high speed, many parameters must be adjusted for the underlying settings of the area array image sensor to ensure that it can achieve the purpose of high-sensitivity output at high speed (more than 1800 frames / second) and extremely short exposure time (tens of microseconds). At present, most of the area array image sensors on the market cannot do this. Therefore, for ordinary technicians in this field, consumer-grade high-speed and high-sensitivity optical ranging devices generally use linear image sensors instead of area array image sensors. However, in the embodiments of the present invention, a cheap area array image sensor is creatively proposed to replace the linear image sensor, and one or more photosensitive areas in the area array image sensor are used to collect one or more reflected light points. The data processing speed is fast, and the sampling accuracy and density are greatly improved, and the high-speed ranging effect that can only be achieved by a linear image sensor is also achieved. The following effects are brought about:

[0074] 1. Greatly reduced product costs, improved product competitiveness, and brought commercial success. Since the cost of linear image sensors is several times that of area array image sensors, the solution of using area array image sensors instead of linear image sensors will greatly reduce the cost of optical ranging devices, which is conducive to the popularization of products in the consumer market and brings commercial success.

[0075] 2. Overcoming technical prejudice. In summary, the current high-speed optical ranging devices in the consumer market all use linear image sensors and abandon area array image sensors. Obviously, due to the characteristics of large-area acquisition and large data processing volume of area array image sensors, ordinary technicians in this field believe that the use of area array image sensors is simply not feasible in the field of high-speed optical ranging. The solution provided by the embodiment of the present invention creatively uses area array image sensors instead of linear sensors and achieves the same technical effect, which overcomes the technical prejudice that area array image sensors cannot be used in the field of high-speed optical ranging.

[0076] Optionally, the photosensitive area 401 is divided into one or more photosensitive sub-areas, specifically: the photosensitive area is divided into one or more strip-shaped photosensitive sub-areas, the number of rows of the photosensitive sub-areas is M, where M is a positive integer greater than or equal to 1; the starting row, ending row, starting column and ending column of each photosensitive sub-area can be configured, and the height and position of each photosensitive sub-area are dynamically adjustable, and it is only necessary to modify the corresponding starting row, row height and column height in the register of the area array image sensor. For example, when the light emitter emits light to the target object and the area array image sensor starts to expose, the area array image sensor first globally scans each pixel on the photosensitive surface. After detecting the area where the reflected light point is located, the area array image sensor can dynamically set the photosensitive area on the photosensitive surface (the photosensitive area is the area that includes all the reflected light points, and the size of the photosensitive area can be dynamically set, and its area is less than or equal to the area of ​​the photosensitive surface), and set the corresponding starting row position and row height and column height. At the same time, the photosensitive area is divided into multiple photosensitive sub-areas. After that, it is only necessary to scan the pixels of the photosensitive area row by row to quickly obtain the position information of the reflected light point. The advantage of this is that if the center of gravity of the reflected light point does not fall into the photosensitive sub-area due to installation errors during the production of the optical ranging device (such as Figure 2b As shown), the starting row position of the photosensitive area can be dynamically adjusted so that the reflected light spot still falls in the photosensitive area, thereby reducing the requirements for the production process.

[0077] For the convenience of understanding by ordinary technicians in this field, each strip-shaped photosensitive sub-area can be understood as a photosensitive area of ​​a linear image sensor, and multiple strip-shaped photosensitive sub-areas can be understood as the longitudinal "superposition" of multiple linear image sensor photosensitive area arrays. When the number of photosensitive sub-areas is 1, and the number of collected reflected light points is also 1, the imaging effect is as follows: Figure 2cAs shown, in this case, for the sake of convenience, it can be understood that this case is a special case of using an area array image sensor to "simulate" a linear image sensor. However, those skilled in the art should understand that the description here is only used to facilitate technicians to more easily understand the technical solution provided by the embodiment of the present invention. In actual products, the area array image sensor is divided into one or more strip-shaped photosensitive sub-areas, which require complex configuration, verification and subsequent data processing, rather than simply "simulating" or "superimposing" the photosensitive area of ​​the linear image sensor.

[0078] Optionally, obtaining the position information of the one or more reflected light points is specifically: after collecting the one or more reflected light points in the one or more photosensitive sub-areas, obtaining the column position information of the one or more reflected light points. Optionally, obtaining the column position information of the one or more reflected light points is specifically: the area array image sensor obtains the column coordinate information of the center of gravity position of the one or more reflected light points. It should be noted that the center of gravity position is the position after the brightness weighted average of the valid coordinates in the area, and the center of gravity position is different from the center position, and the center position is the geometric center of the minimum bounding box of the area. For example, if the reflected light point occupies 5 pixels in a photosensitive sub-area, the center of gravity position of the reflected light point is the position after the brightness weighted average of the coordinates of the 5 pixels. The reason why it is necessary to obtain the column coordinate information of the center of gravity position is that according to the triangulation method, when the relative angle and spacing between the light emitter and the area array image sensor 41 are known, the distance of the target object from the optical distance measuring device can be calculated according to the column coordinate information.

[0079] Optionally, one or more photosensitive areas are used to collect the one or more reflected light spots. Specifically, when the area array image sensor receives multiple beams of point light, the multiple photosensitive areas are used to collect multiple reflected light spots, and the multiple reflected light spots are distributed in a cross-like or matrix-like manner in the multiple photosensitive areas.

[0080] Optionally, the area array image sensor is also used to perform a single-column pixel merging algorithm, that is, the grayscale values ​​of several pixels in each column of the photosensitive sub-area are averaged, and the calculated result is the result of compressing M rows of pixel information into one or several rows of pixel information. This makes the data volume several times smaller than the original under the condition that the vertical field of view remains unchanged, and the signal-to-noise ratio of the output image is greatly improved. Figure 3 As shown, after M rows of data are collected, the compressed data amount is only a fraction of the original data amount after the single-column pixel merging algorithm.

[0081] Optionally, the area array image sensor 41 includes a plurality of photosensitive sub-areas, and the area array image sensor sets one or more of the plurality of photosensitive sub-areas as effective photosensitive areas, and the effective photosensitive areas generate and output response signals after collecting the reflected light points, and the rest are set as invalid photosensitive areas, and the invalid photosensitive areas do not output response signals after collecting the reflected light points, thereby achieving the purpose of reducing the amount of image data processing per frame and obtaining a high frame rate.

[0082] In the embodiment of the present invention, an inexpensive area array image sensor is used, which can dynamically divide multiple photosensitive areas to collect multiple light points at one time, thereby solving the problems of high cost, high installation requirements and low sampling density caused by the use of linear image sensors to achieve optical ranging in the prior art, effectively reducing costs, improving sampling density, and at the same time improving tolerance to installation errors.

[0083] Example 3

[0084] The embodiment of the present invention provides a method for optical distance measurement, such as Figure 5 As shown, the method includes:

[0085] S501. The light emitter emits light to the target object;

[0086] Optionally, the optical distance measuring device may include a beam splitter for splitting a beam of emitted light into one or more beams of emitted light and transmitting them to the target object, and generating one or more corresponding beams of point-shaped reflected laser light. By dividing a laser point into multiple laser points, it is possible to ensure that the optical distance measuring device collects multiple reflected light points at the same time, thereby improving the collection density.

[0087] S502. The optical distance measuring device receives reflected light after emitting light to the target object through an area array image sensor to generate a response signal, wherein the response signal includes position information of the one or more reflected light points, wherein the area array image sensor includes a photosensitive area, and the area array image sensor divides the photosensitive area into one or more photosensitive sub-areas (photosensitive sub-area 1, photosensitive sub-area 2, ... photosensitive sub-area N), so that the area array image sensor can collect one or more light points of the emitted light through the one or more photosensitive sub-areas;

[0088] Compared with linear image sensors, each pixel of the former is a square, with the same width and height (for example, 3um*3um), and the number of pixels and rows in each row can be 4:3 or 16:9 (for example, 1280 pixels per row, 720 rows), while each pixel of the latter may be a square or a rectangle (for example, 32um*4um), and the number of pixels in rows and columns shows obvious linear characteristics, for example, 2048 pixels per row, 4 rows. The optical ranging devices used in service robots (such as sweeping robots) currently used in the consumer market all use expensive linear image sensors without exception, and no cheap area array image sensors are used. Because the area array image sensor itself can image a large area, its design function and manufacturing process do not have the characteristics of linear sensors: small window, small data, high frame rate and high sensitivity at low exposure time. Therefore, the purpose of the birth or the original intention of the area array image sensor is not to do linear scanning, that is, the area array image sensor is not used as a linear sensor. In summary, the many characteristics of the area array image sensor determine that it is not designed for high-speed linear scanning. If most of the imaging area of ​​the area array image sensor is discarded and only a small strip is used, and the frame rate is output at a high speed, this will cause two problems: first, it greatly wastes the resources of the area array image sensor; second, to output the frame rate at a high speed, many parameters must be adjusted for the underlying settings of the area array image sensor to ensure that it can achieve the purpose of high-sensitivity output at high speed (more than 1800 frames / second) and extremely short exposure time (tens of microseconds). At present, most of the area array image sensors on the market cannot do this. Therefore, for ordinary technicians in this field, consumer-grade high-speed and high-sensitivity optical ranging devices generally use linear image sensors instead of area array image sensors. However, in the embodiments of the present invention, a cheap area array image sensor is creatively proposed to replace the linear image sensor, and one or more photosensitive areas in the area array image sensor are used to collect one or more reflected light points. The data processing speed is fast, and the sampling accuracy and density are greatly improved, and the high-speed ranging effect that can only be achieved by a linear image sensor is also achieved. The following effects are brought about:

[0089] 1. Greatly reduce product costs and improve product competitive advantages. Since the cost of linear image sensors is several times that of area array image sensors, the solution of using area array image sensors instead of linear image sensors will greatly reduce the cost of optical ranging devices, which is conducive to the popularization of products in the consumer market and brings commercial success.

[0090] 2. Overcoming technical prejudice. In summary, the current high-speed optical ranging devices in the consumer market all use linear image sensors and abandon area array image sensors. Obviously, due to the characteristics of large-area acquisition and large data processing volume of area array image sensors, ordinary technicians in this field believe that the use of area array image sensors is simply not feasible in the field of high-speed optical ranging. The solution provided by the embodiment of the present invention creatively uses area array image sensors instead of linear sensors and achieves the same technical effect, which overcomes the technical prejudice that area array image sensors cannot be used in the field of high-speed optical ranging.

[0091] Wherein, after collecting one or more reflected light spots, the area array image sensor may also obtain the column position information of the one or more reflected light spots. Optionally, obtaining the column position information of one or more reflected light spots is specifically: the area array image sensor obtains the column coordinate information of the center of gravity position of the one or more reflected light spots. It should be noted that the center of gravity position is the position after the effective coordinates in the region are weighted averaged by brightness, and the center of gravity position is different from the center position, and the center position is the geometric center of the minimum bounding box of the region. For example, if the reflected light spot occupies 5 pixels in a photosensitive sub-region, the center of gravity position of the reflected light spot is the position after the brightness weighted average of the coordinates of the 5 pixels. The reason why the column coordinate information of the center of gravity position needs to be obtained is that according to the triangulation method, when the relative angle and spacing between the light emitter and the area array image sensor are known, the distance of the target object from the optical distance measuring device can be calculated according to the column coordinate information. According to the triangulation method, only the column coordinate information needs to be known for measurement, and there is no need to obtain its row coordinate information. Therefore, the photosensitive sub-region can be mainly arranged in the column direction, and only one row or a very narrow number of rows can be used in the row direction.

[0092] The collecting of the one or more reflected light spots specifically comprises: when the optical ranging device emits multiple beams of point light, the multiple photosensitive areas collect multiple reflected light spots, and the multiple reflected light spots are distributed in a cross-like or matrix-like manner in the multiple photosensitive areas.

[0093] The method further includes: the optical distance measuring device calculates the average grayscale value of several pixels in each column of the photosensitive sub-area, and the calculated result is the result of compressing M rows of pixel information into one or several rows of pixel information. This makes the data volume several times smaller than the original under the condition that the vertical field of view remains unchanged, and greatly improves the signal-to-noise ratio of the output image. Figure 3 As shown, after M rows of data are collected, the compressed data amount is only a fraction of the original data amount after the single-column pixel merging algorithm.

[0094] S503. The processor calculates the distance of the target object according to the position information of the one or more reflected light points.

[0095] Triangulation is a commonly used measurement method in the field of optical distance measurement. The method is as follows: by calculating the centroid position of the area and the known relative angle and spacing between the laser emitting device and the image sensor, the distance of the target from the image sensor can be inferred. The basic measurement formula of triangulation is z = b*f / x; where b represents the spacing between the laser emitting device and the image sensor, f is the focal length of the lens used by the image sensor, x is the centroid position of the column coordinates of the reflected light projected on the image sensor, and z is the measured distance. From the formula, it can be seen that the measured distance is only related to the position of the centroid in the column direction and has nothing to do with the number of rows. Therefore, the photosensitive array can be mainly arranged in the column direction, and only one row or a very narrow number of rows can be used in the row direction; in addition, the measurement error formula is e = 1 / (b*f / (n*z)+1), where n represents the error of centroid extraction. It can be seen that the measurement error e is inversely proportional to b and f, and proportional to n and z. Therefore, when b, f and n are constant, it is necessary to select a relatively telephoto lens to reduce the error at different distances.

[0096] The method provided by the embodiment of the present invention uses a cheap area array image sensor to dynamically divide into one or more photosensitive sub-areas to collect one or more reflected light points at one time, thereby solving the problems of high cost, high installation requirements and low sampling density caused by the use of linear image sensors to achieve optical ranging in the existing optical ranging technology, effectively reducing costs, improving sampling density, and improving tolerance to installation errors.

[0097] It should be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0098] Those of ordinary skill in the art will appreciate that the modules and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0099] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0100] Each part of this specification is described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device and system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiment part.

[0101] Finally, it should be noted that the above is only a preferred embodiment of the technical solution of the present application and is not intended to limit the scope of protection of the present application. Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the scope of the present application. If these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, any modifications, equivalent substitutions, improvements, etc. made shall be included in the scope of protection of the present application.

Claims

1. An optical distance measuring device, characterized in that: The optical distance measuring device comprises: A light emitter, used for emitting light to a target object; A light receiver, used to receive reflected light after emitting light to the target object, the light receiver includes a lens and an area array image sensor, the area array image sensor includes a photosensitive area, the photosensitive area is divided into one or more photosensitive sub-areas, the one or more photosensitive sub-areas are used to collect one or more light spots of the reflected light, the light receiver is also used to generate a response signal, the response signal includes position information of the one or more reflected light spots; a processor, configured to receive the response signal generated by the optical receiver, and calculate the distance from the target object to the optical distance measuring device by using triangulation according to the position information of the reflected light spot; The area array image sensor is also used for: By modifying the corresponding starting row position, row height and column height in the register of the area array image sensor, the height and position of the photosensitive area are dynamically adjusted so that the center of gravity of the one or more reflected light points falls within the photosensitive area.

2. The optical distance measuring device according to claim 1, characterized in that: The photosensitive area is divided into one or more photosensitive sub-areas, including: The photosensitive area is divided into one or more strip-shaped photosensitive sub-areas, and the number of rows of the photosensitive sub-areas is M, where M is a positive integer greater than or equal to 1; Then the area array image sensor is also used for: After the one or more photosensitive sub-areas collect the one or more reflected light spots, column position information of the one or more reflected light spots is acquired.

3. The optical distance measuring device according to claim 2, characterized in that: The one or more photosensitive sub-areas are used to collect the one or more light spots of the reflected light, including: When the light emitter emits multiple beams of point light, the multiple photosensitive sub-areas are used to collect multiple reflected light points, and the multiple reflected light points are distributed in the multiple photosensitive sub-areas in a cross-like or matrix-like shape.

4. The optical distance measuring device according to claim 2 or 3, characterized in that: The area array image sensor is used to obtain column position information of the one or more reflected light points, including: The area array image sensor acquires column coordinate information of the center of gravity position of the one or more reflected light points.

5. The optical distance measuring device according to claim 4, characterized in that: The area array image sensor is also used for: The grayscale values ​​of several pixels in each column of the photosensitive sub-area are averaged, and the calculated result is the result of compressing M rows of pixel information into one or several rows of pixel information.

6. The optical distance measuring device according to any one of claims 1 to 3, characterized in that: The area array image sensor includes the multiple photosensitive sub-areas, and the area array image sensor sets one or more of the multiple photosensitive sub-areas as effective photosensitive areas. After the effective photosensitive areas collect the reflected light spots, the area array image sensor generates and outputs response signals. The rest are set as invalid photosensitive areas. After the invalid photosensitive areas collect the reflected light spots, the area array image sensor does not output response signals.

7. The optical distance measuring device according to any one of claims 1 to 3, characterized in that: The optical transmitter comprises a laser source and a beam splitter, wherein the beam splitter is used to split the point laser emitted by the laser source into one or more beams of point laser light.

8. The optical distance measuring device according to claim 7, characterized in that: The beam splitter is a diffraction grating or an optical prism.

9. An area array image sensor, characterized in that: The area array image sensor includes a photosensitive area, the photosensitive area is divided into one or more photosensitive sub-areas, the one or more photosensitive sub-areas are used to collect one or more light points of reflected light and obtain position information of the one or more reflected light points, the area array image sensor is also used to generate a response signal, send the response signal to the processor, the response signal includes the position information of the one or more reflected light points; The area array image sensor is also used for: By modifying the corresponding starting row position, row height and column height in the register of the area array image sensor, the height and position of the photosensitive area are dynamically adjusted so that the center of gravity of the one or more reflected light points falls within the photosensitive area.

10. The area array image sensor according to claim 9, characterized in that: The photosensitive area is divided into one or more photosensitive sub-areas, including: The photosensitive area is divided into one or more strip-shaped photosensitive sub-areas, and the number of rows of the photosensitive sub-areas is M, where M is a positive integer greater than or equal to 1; Then the step of obtaining the position information of the one or more reflected light points includes: After the one or more photosensitive sub-areas collect the one or more reflected light spots, column position information of the one or more reflected light spots is acquired.

11. The area array image sensor according to claim 10, characterized in that: The one or more photosensitive sub-areas are used to collect the one or more light spots of the reflected light, including: The multiple photosensitive sub-areas are used to collect multiple reflected light points, and the multiple reflected light points are distributed in a cross-like or matrix-like manner in the multiple photosensitive sub-areas.

12. The area array image sensor according to any one of claims 9 to 11, characterized in that: The area array image sensor is also used for: The grayscale values ​​of several pixels in each column of the photosensitive sub-area are averaged, and the calculated result is the result of compressing M rows of pixel information into one or several rows of pixel information.

13. The area array image sensor according to claim 12, characterized in that: The area array image sensor includes the plurality of photosensitive sub-areas, and the area array image sensor sets one or more of the plurality of photosensitive sub-areas as effective photosensitive areas, and the effective photosensitive areas generate and output response signals after collecting the reflected light spots, and the rest are set as invalid photosensitive areas, and the invalid photosensitive areas do not output response signals after collecting the reflected light spots.

14. The area array image sensor according to claim 9, characterized in that: The area array image sensor is a complementary metal oxide semiconductor (CMOS) image sensor or a charge coupled device (CCD) image sensor.

15. A method for optical distance measurement, characterized in that: The optical distance measurement method comprises: The light emitter emits light to the target object; The area array image sensor receives reflected light after the emitted light reaches the target object and generates a response signal, wherein the response signal includes position information of the one or more reflected light points, wherein the area array image sensor comprises a photosensitive area, and the area array image sensor divides the photosensitive area into one or more photosensitive sub-areas, so that the area array image sensor collects one or more light points of the emitted light through the one or more photosensitive sub-areas; The processor calculates the distance of the target object according to the position information of the one or more reflected light points; The area array image sensor is also used for: By modifying the corresponding starting row position, row height and column height in the register of the area array image sensor, the height and position of the photosensitive area are dynamically adjusted so that the center of gravity of the one or more reflected light points falls within the photosensitive area.

16. The optical distance measurement method according to claim 15, characterized in that: After collecting one or more light spots of reflected light, the method further includes: The column position information of the one or more reflected light spots is obtained.

17. The optical distance measurement method according to claim 15, characterized in that: The collecting the one or more light points of reflected light comprises: When the optical distance measuring device emits multiple beams of point light, the multiple photosensitive sub-areas collect multiple reflected light points, and the multiple reflected light points are distributed in the multiple photosensitive sub-areas in a cross-like or matrix-like shape.

18. The optical distance measurement method according to any one of claims 15 to 17, characterized in that: The method further comprises: The grayscale values ​​of several pixels in each column of the photosensitive sub-area are averaged, and the calculated result is the result of compressing M rows of pixel information into one or several rows of pixel information.

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