A method for processing the expansion of high-reflective objects detected by laser radar at close range

Abstract

The present invention discloses a processing method for detecting expansion of a close-range high-reflective object by a laser radar, comprising: establishing a preset distance D set and preset reflectivity R set ; The laser radar emits light to detect the target object, obtains the reflectivity r of the target object and the distance d between the target object and the laser radar; if the distance d is less than the preset distance D set , then the target object is judged to be a close-range object; if the reflectivity r is greater than the preset reflectivity R set , then the target object is judged to be a high-reflective object; the direction of the object identified as a close-range high-reflective object is obtained, and the optical power emitted by the laser radar in this direction is lowered; or, the detection data of the object identified as a close-range high-reflective object is obtained, and the real data of the close-range high-reflective object is output after adjusting the detection data through an algorithm. The present invention can improve the problem of expansion of close-range high-reflective objects, thereby improving the accuracy of laser radar detection data and providing better support for vehicle automatic driving.

Description

Technical Field

[0001] The present invention relates to the field of laser radar technology, and in particular to a method for processing expansion of a close-range high-reflective object detected by a laser radar. Background Art

[0002] At present, autonomous driving technology has become a research hotspot, and LiDAR is an indispensable detection device in autonomous driving technology. On-board LiDAR not only needs to be able to detect at long distances to reserve more reaction time for the driver, but also needs to have better accuracy in close-range detection. However, these two demands are often contradictory in technical processing.

[0003] In order to increase the maximum detection distance of LiDAR, higher power lasers, larger gain settings, and more sensitive devices are usually selected. This will cause the LiDAR to easily experience object expansion when detecting close-range highly reflective objects (that is, the detected object size is larger than the actual size of the object).

[0004] The reasons for the high-reflection expansion may be caused by the following factors: (1) The point projected by the laser on the object is actually a surface diffused according to the divergence angle and the initial size of the light spot; (2) Due to the high precision and difficulty of optical collimation, the light spot is usually diffused relative to the ideal light spot size, resulting in a larger light spot relative to the theoretical size; (3) When the laser encounters a high-reflection object, the returned light energy is strong, and very weak light is also easy to be detected by the detector. The above reasons will cause the light spot projected to the edge of the object to be detected by the detector and output as a real object, causing the detected object to expand relative to its actual size (such as Figure 1 shown). Summary of the invention

[0005] The technical problem to be solved by the present invention is: in order to solve the technical problem that data expansion is easy to occur when laser radar detects close-range high-reflective objects. The present invention provides a processing method for the expansion of close-range high-reflective objects detected by laser radar, which can improve the expansion phenomenon of close-range high-reflective objects, thereby improving the accuracy of radar detection.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a processing method for detecting the expansion of a close-range high-reflective object by a laser radar, characterized in that it includes the following steps:

[0007] Step S1: Using the laser radar location as the reference point, establish a preset distance D set and preset reflectivity R set ;

[0008] Step S2: the laser radar emits light to detect the target object, and obtains the reflectivity r of the target object and the distance d between the target object and the laser radar;

[0009] Step S3: If the distance d is less than the preset distance D set , then the target object is judged to be a close-range object; if the reflectivity r is greater than the preset reflectivity R set , then the target object is judged to be a highly reflective object;

[0010] Step S4: obtaining the position of the object identified as a close-range highly reflective object, and lowering the optical power emitted by the laser radar at the position; or,

[0011] The detection data of the object identified as a close-range highly reflective object is obtained, and the real data of the close-range highly reflective object is output after the detection data is adjusted by an algorithm.

[0012] Further, in step S4, the position of the object identified as a close-range highly reflective object is obtained, and the optical power emitted by the laser radar at the position is lowered, which specifically includes:

[0013] According to the real-time data of the close-range highly reflective object, the horizontal angle and vertical angle of the close-range highly reflective object are obtained; and the laser radar adjusts the light output power of the laser inside the laser radar at this angle according to the horizontal angle and the vertical angle.

[0014] Furthermore, when the laser radar is provided with multiple lasers inside and the multiple lasers cover the same direction, if the laser radar identifies that there is a close-range highly reflective object in that direction, the laser radar turns off some of the lasers in that direction to reduce the light output power.

[0015] Furthermore, as the laser radar moves, it makes real-time judgments on the distance d and reflectivity r of the target object. When a highly reflective object is found at a close distance, the light output power of the laser in the corresponding direction is adjusted in real time.

[0016] Furthermore, if the laser radar does not detect a close-range highly reflective object or a no-return point at the same position at the next moment, the light output power of the laser corresponding to the position is automatically adjusted to the maximum.

[0017] Further, obtain the preset distance D set and preset reflectivity R set The optical power curves at different distances and different reflectivities at a detection rate of 90% are obtained, and the optical power curves are input into the laser radar. The laser radar can adjust the output light power of the laser in real time according to the optical power curves.

[0018] Further, in step S4, the detection data of the object identified as a close-range highly reflective object is obtained, and the real data of the close-range highly reflective object is output after the detection data is adjusted by an algorithm, which specifically includes:

[0019] The laser radar reads the detection data of the close-range high-reflective object and compares any data point X in the detection data with the data point Y adjacent to the data point X. n Compare and calculate the difference between data point A and all data points Y n The distance difference and reflectivity difference between n Refers to n data points near X, n>1;

[0020] According to the distance difference and the reflectivity difference, it is identified whether the data point X is a non-expanded point. If so, the expanded point is deleted; if not, the data point X is retained.

[0021] Furthermore, if the data point X and the data point Y on its left and right n The distance difference between them is within the fluctuation range of the laser radar's own accuracy data, and the data point X and the data point Y on its left are n The reflectivity difference between the two exceeds the allowable range, and the data point Y n If the reflectivity difference between them is within the allowable range, the data point X is determined to be an edge point and is retained.

[0022] Furthermore, if the data point X and the data point Y on its left and right n The distance difference between them is within the fluctuation range of the laser radar's own accuracy data, and the data point X and the data point Y on its left and right sides are n If the reflectivity differences between them are all beyond the allowable range, the data point X is determined to be an expansion point and is deleted.

[0023] Furthermore, the method further includes: the laser radar reads the detection data of the close-range high-reflective object, and compares any data point X in the detection data with a data point Y adjacent to the data point X. n Compare and calculate the data point X and all data points Y n The echo pulse width between

[0024] According to the echo pulse width value, it is identified whether the data point X is not an expansion point. If so, the expansion point is deleted; if not, the data point X is retained.

[0025] The beneficial effect of the present invention is that the processing method of the present invention for detecting expansion of a high-reflective object at a close distance by a laser radar can improve the problem of expansion of a high-reflective object at a close distance by adjusting the optical power or data processing method, thereby improving the accuracy of the laser radar detection data and providing better support for vehicle automatic driving. In this way, the demand for long-distance detection by the laser radar can be met without reducing the accuracy of detecting close-range objects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0027] Figure 1 It is a schematic diagram of the expansion of a highly reflective object.

[0028] Figure 2 It is a flow chart of a processing method for detecting expansion of a close-range highly reflective object by a laser radar of the present invention.

[0029] Figure 3 It is a flow chart of adjusting the laser radar light output power of the present invention.

[0030] Figure 4 It is a schematic diagram of the horizontal angle and the vertical angle of the present invention.

[0031] Figure 5 It is a flow chart of the detection data processing of the present invention.

[0032] Figure 6 It is a schematic diagram of the laser radar echo pulse width of the present invention. DETAILED DESCRIPTION

[0033] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] like Figure 2As shown, the processing method of the laser radar of the present invention for detecting expansion of a close-range high-reflective object comprises the following steps:

[0037] Step S1: Using the laser radar location as the reference point, establish a preset distance D set and preset reflectivity R set .

[0038] Step S2: The laser radar emits light to detect the target object, and obtains the reflectivity r of the target object and the distance d between the target object and the laser radar.

[0039] Step S3: If the distance d is less than the preset distance D set , then the target object is judged to be a close-range object; if the reflectivity r is greater than the preset reflectivity R set , then the target object is judged to be a high-reflective object.

[0040] Step S4: Obtain the direction of the object identified as a close-range high-reflective object, and lower the optical power emitted by the laser radar in this direction; or, obtain the detection data of the object identified as a close-range high-reflective object, adjust the detection data through an algorithm, and then output the real data of the close-range high-reflective object.

[0041] That is to say, the present invention uses laser radar to measure the distance and reflectivity of the target object in real time, and identifies whether there is a close-range high-reflective object within the detection range of the laser radar. If so, the detection accuracy of the close-range high-reflective object is improved by adjusting the optical power or algorithm processing, thereby improving the problem of high-reflective expansion.

[0042] The present invention improves the high anti-expansion problem mainly through two methods: physical adjustment and algorithm adjustment. In practical applications, any one of the methods can be selected, of course, not limited to this, and the high anti-expansion problem can also be improved by optimizing the laser radar bias adjustment, system gain mechanism adjustment, etc.

[0043] For example Figure 3 and Figure 4 As shown, in step S4, the direction of the object identified as a close-range high-reflective object is obtained, and the light power emitted by the laser radar at this direction is lowered, specifically including: obtaining the horizontal angle and vertical angle of the close-range high-reflective object according to the real-time data of the close-range high-reflective object; the laser radar adjusts the light output power of the laser inside the laser radar at this angle (including the horizontal angle and the vertical angle) according to the horizontal angle and the vertical angle.

[0044] It should be noted that LiDAR is a radar system that emits laser beams to detect the position, speed and other characteristic quantities of a target. The working principle of LiDAR is to emit a detection signal (laser beam) to the target, and then compare the received signal reflected from the target (target echo) with the transmitted signal. After processing, relevant information about the target can be obtained (such as target distance, direction, height, speed, attitude, and even shape parameters). LiDAR is generally composed of a laser, an optical receiving device, a scanning system, and an information processing system. The laser converts electrical pulses into light pulses and emits them. The optical receiving device then converts the light pulses reflected from the target into electrical pulses and sends them to the information processing system.

[0045] The main reason for the expansion of high-reflectivity objects at close range is that the return light energy is too strong. Therefore, the expansion phenomenon can be improved by reducing the laser's transmitted light power to the high-reflectivity object. According to the real-time detection data of the laser radar, the distance d and reflectivity r of the target object can be obtained. The distance d and the preset distance Dset The comparison can identify whether it is a close-range object. If so, it is determined whether the reflectivity r of the target object exceeds the preset reflectivity R. set If so, the laser radar identifies the direction of the target object and obtains the horizontal angle α and vertical angle β of the target object relative to the laser radar. The laser radar adjusts the light power of the laser at these two angles according to the horizontal angle α and the vertical angle β, so that the light power emitted to the target object is reduced.

[0046] When multiple lasers are provided inside the laser radar, and the multiple lasers cover the same direction, if the laser radar identifies that there is a close-range high-reflective object in the direction, the laser radar turns off some of the lasers in the direction to reduce the light output power. In other words, there can be multiple lasers inside the laser radar. When the emission angles of multiple lasers all correspond to the same direction area, the laser radar can reduce the light output power by turning off some lasers. As the laser radar moves, the laser radar makes real-time judgments on the distance d and reflectivity r of the target object. When a close-range high-reflective object is found, the light output power of the laser in the corresponding direction is adjusted in real time. The present invention adaptively adjusts the light output power of the direction where the close-range high-reflective object is located, so that the detection distance of the laser radar itself is not affected, and the phenomenon of high-reflective expansion can be improved, thereby improving the detection accuracy of the laser radar for close-range objects. It should be noted that the laser radar is detecting in real time. If a high-reflective object is detected at a close distance at the current moment and the laser emission power is reduced, if the laser radar does not detect a high-reflective object at a close distance or a no-return point at the same position at the next moment, the laser output power corresponding to the position will be automatically adjusted to the maximum. In this way, the laser emission power can be adjusted according to the real-time situation to ensure that the laser radar maintains detection accuracy during movement.

[0047] For example, you can also obtain the set and preset reflectivity R set The optical power curves at different distances and different reflectivities at 90% detection rate are obtained, and the optical power curves are input into the laser radar. The laser radar can adjust the output light power of the laser in real time according to the optical power curve. The detection rate refers to the probability that the laser radar detects the target object. The optical power curve can be used as a basis for the laser radar to adjust the optical power. For example, if the laser radar identifies the target object at a distance d' and its reflectivity is r', the corresponding optical power P can be found on the optical power curve according to the distance d' and the reflectivity r', and the laser radar adjusts the output light power of the laser to the optical power P. In this way, the working efficiency of the laser radar can be improved. The present invention can reduce the emission power of the laser radar by adjusting the output light power or the number of laser working under different circumstances, which can not only improve the phenomenon of high anti-expansion, but also facilitate the heat dissipation of the laser radar itself and increase the service life of the laser radar.

[0048] For example Figure 5 and Figure 6 As shown, in step S4, the detection data identified as a close-range high-reflective object is obtained, and the real data of the close-range high-reflective object is output after the detection data is adjusted by an algorithm, specifically including: the laser radar reads the detection data of the close-range high-reflective object, and any data point X in the detection data and the data point Y adjacent to the data point X are output. n (Among them, Y n Refers to n data points near X, n>1) for comparison, and calculates the difference between data point A and all data points Y n The distance difference and reflectivity difference between them are used to identify whether the data point X is not an expansion point. If so, the expansion point is deleted; if not, the data point X is retained.

[0049] That is, the laser radar identifies the detection data of the close-range high-reflective object as the data that needs to be adjusted. The detection data contains multiple data points. First, a data point X is randomly selected in the detection data, and then all data points Y adjacent to the data point X are filtered out. n , compare data point X and data point Y n Compare one by one and calculate the data point X and each data point Y n The distance difference Δd n and reflectivity difference Δr n , according to the distance difference Δd n and reflectivity difference Δr n Identify whether data point X is not an expansion point. If so, delete the expansion point; if not, retain data point X.

[0050] The range of neighboring data points can be obtained in advance through training. For example, data points within the radius L of data point X are considered to be neighboring points.

[0051] Specifically, if data point X and data point Y on its left and right n The distance difference between them is within the fluctuation range of the laser radar's own accuracy data, and the data point X and the data point Y on its left are n The reflectivity difference between the two exceeds the allowable range, and the data point Y n If the reflectivity difference between the two is within the allowable range, the data point X is determined to be an edge point and retained. It should be noted that this determination method is for data points located on the left side of the center line of the target object. If it is a data point on the right side of the center line, then the data point X and the data point Y on its right side are retained. n The reflectivity difference between the two exceeds the allowable range, and the data point Y n If the reflectivity difference between them is within the allowable range, the data point X is determined to be an edge point and is retained.

[0052] If data point X and its left and right data points Y n The distance difference between them is within the fluctuation range of the laser radar's own accuracy data, and the data point X and the data point Y on its left and right sides are n If the reflectivity difference between them exceeds the allowable range, the data point X is determined to be an expansion point and deleted. After deleting the expansion point, the second echo is identified at the position of the data point as the real data output to prevent holes from appearing in the radar field of view and affecting the field of view judgment.

[0053] The method further includes: the laser radar reads the detection data of the close-range high-reflective object, and compares any data point X in the detection data with a data point Y adjacent to the data point X. n Compare and calculate the data point X and all data points Y n The echo pulse width value between . According to the echo pulse width value, it is identified whether the data point X is not an expansion point. If so, the expansion point is deleted; if not, the data point X is retained. As shown in the figure, data points B and C are adjacent points of data point A. The echo pulse width value of data point B is smaller than the echo pulse width value of data point A, and the echo pulse width value of data point C is basically the same as the echo pulse width value of data point A. Then it can be determined that data point B is an expansion point and can be deleted.

[0054] Of course, in practical applications, the distance difference Δd can also be calculated n , reflectivity difference Δr n The extreme value and standard deviation of the echo pulse width are used as the basis for judgment.

[0055] In summary, the processing method of the present invention for detecting expansion of a high-reflective object at a close distance by a laser radar can improve the problem of expansion of a high-reflective object at a close distance by adjusting the optical power or data processing method, thereby improving the accuracy of the laser radar detection data and providing better support for vehicle automatic driving. In this way, the laser radar's demand for long-distance detection can be met without reducing the accuracy of detecting close-range objects.

[0056] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for processing expansion of a close-range high-reflective object detected by a laser radar, characterized in that: The following steps are involved: Step S1: Using the laser radar location as the reference point, establish a preset distance D set and preset reflectivity R set ; Step S2: the laser radar emits light to detect the target object, and obtains the reflectivity r of the target object and the distance d between the target object and the laser radar; Step S3: If the distance d is less than the preset distance D set , then the target object is judged to be a close-range object; if the reflectivity r is greater than the preset reflectivity R set , then the target object is judged to be a highly reflective object; Step S4: Acquire detection data of the object identified as a close-range high-reflective object, and adjust the detection data through an algorithm to output the real data of the close-range high-reflective object; Step S4 specifically includes: The laser radar reads the detection data of the close-range high-reflective object and compares any data point X in the detection data with the data point Y adjacent to the data point X. n Compare and calculate the data point X and all data points Y n The distance difference and reflectivity difference between n Refers to n data points near X, n>1; Identify whether the data point X is an expansion point according to the distance difference and the reflectivity difference. If so, delete the expansion point; if not, retain the data point X; If data point X and its left and right data points Y n The distance difference between them is within the fluctuation range of the laser radar's own accuracy data, and the data point X and the data point Y on its left are n The reflectivity difference between the two exceeds the allowable range, and the data point Y n If the reflectivity difference between them is within the allowable range, the data point X is determined to be an edge point and is retained; If data point X and its left and right data points Y n The distance difference between them is within the fluctuation range of the laser radar's own accuracy data, and the data point X and the data point Y on its left and right sides are n If the reflectivity differences between them are all beyond the allowable range, the data point X is determined to be an expansion point and is deleted.

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