Traffic road sign and road sign detection method

Abstract

The invention relates to a traffic road sign and a road sign detection method, and the traffic road sign comprises a body which is provided with at least one first reflection region; the first reflecting film comprises a base body and a plurality of reflecting protrusions, the base body covers the first reflecting area of the body, and all the reflecting protrusions are arranged on the surface of the side, opposite to the body, of the base body; wherein the first reflective film is made of a metal material. According to the traffic sign, the first reflecting film is made of the metal material, and the plurality of reflecting bulges are convexly arranged on the surface of one side, back on to the body, of the first reflecting film, so that the radar scattering sectional area and the anti-interference performance of the traffic sign are effectively improved, and the quantitative improvement of the target identification stability is realized; the radar sensing performance is improved with low cost, and meanwhile, the traditional visible light warning function is also ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of traffic safety, in particular to a traffic road sign and a road sign detection method. BACKGROUND

[0002] Traffic cone, also known as cone-shaped road sign, cone-shaped cylinder, red hat, and obelisk, is a kind of road traffic isolation warning facility, which is usually used for temporary road marking when engineering or accident occurs, and can also be used for separating or converging traffic, people flow and vehicle group to ensure the safety of engineering personnel and road users.

[0003] However, with the gradual popularization of intelligent driving, intelligent driving vehicles often automatically identify traffic cones through radar. However, due to the structural limitations of existing traffic cones, it is difficult to meet the identification requirements of vehicle-mounted radars, which limits the identification accuracy of vehicle-mounted radars, and further affects the driving experience and driving safety of drivers, hindering the further development of intelligent driving. SUMMARY

[0004] Therefore, it is necessary to provide a traffic road sign and a road sign detection method to solve the problem of low vehicle-mounted radar identification accuracy of traffic cones.

[0005] A traffic road sign, comprising:

[0006] a body having at least one first reflection area; and

[0007] a first reflection film comprising a base and a plurality of reflection protrusions, the base covering the first reflection area of the body, and all the reflection protrusions being arranged on a side surface of the base away from the body;

[0008] wherein the first reflection film is formed of a metal material.

[0009] In one embodiment, the material forming the first reflection film is aluminum.

[0010] In one embodiment, all the reflection protrusions are arranged in an array, and each reflection protrusion is conical.

[0011] In one embodiment, the side surface of the base where the reflection protrusions are arranged is a plane perpendicular to the thickness direction of the base.

[0012] In one embodiment, the base comprises a base layer and a plurality of protruding portions, the base layer covering the first reflection area of the body, and all the protruding portions being arranged on a side surface of the base layer away from the body.

[0013] In one of the embodiments, the body further has a second reflective region disposed adjacent to the first reflective region, and the traffic sign further comprises a second reflective film covering the second reflective region.

[0014] The second reflective film is formed of a non-metallic material.

[0015] In one of the embodiments, the second reflective film is formed of polycarbonate or polymethyl methacrylate; the color of the first reflective film is different from that of the second reflective film; and the first reflective region and the second reflective region are arranged alternately in the axial direction of the body.

[0016] In one of the embodiments, the radar scattering cross-section area of the traffic sign is 0.37 m²-0.71 m²; and / or

[0017] The retroreflective coefficient of the traffic sign is greater than 250 cd·lx -1 ·m -2 .

[0018] A road sign detection method based on vehicle-mounted radar, for detecting the traffic sign, comprising the following steps:

[0019] Performing radar detection on a detection target and receiving echo signals from the detection target; the echo signals include a radar scattering cross-section area;

[0020] When the size of the radar scattering cross-section area meets a preset condition, determining that the detection target is the traffic sign.

[0021] In one of the embodiments, the preset condition comprises:

[0022] When the incidence angle of the radar wave is within a first preset angle range, the radar scattering cross-section area is less than a first preset cross-section area;

[0023] When the incidence angle of the radar wave is greater than a second preset angle or less than a third preset angle, the radar scattering cross-section area is greater than a second preset cross-section area.

[0024] The traffic sign, since the first reflective film is formed of a metallic material and the side of the first reflective film facing away from the body is provided with a plurality of reflective protrusions, effectively improves the radar scattering cross-section area and anti-interference performance of the traffic sign, realizes quantitative improvement of target recognition stability, not only realizes a leap in radar perception performance at a small cost, but also guarantees the traditional visible light warning function. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this application. The embodiments of this application illustrate the embodiments of the present application and, together with the description, serve to explain the principles of the application.

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the accompanying drawings needed to be used in the embodiments description will be briefly introduced. Obviously, the accompanying drawings in the following description only constitute some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0027] Figure 1 The structural schematic diagram of the traffic sign of an embodiment of the present application.

[0028] Figure 2 The sectional schematic diagram of the first reflecting film of the traffic sign of an embodiment of the present application.

[0029] Figure 3 The sectional schematic diagram of the first reflecting film of the traffic sign of another embodiment of the present application.

[0030] Figure 4 The sectional schematic diagram of the first reflecting film of the traffic sign of still another embodiment of the present application.

[0031] Figure 5 The flow schematic diagram of the traffic sign detection method of an embodiment of the present application.

[0032] Explanation of reference signs:

[0033] 100, traffic sign; 120, body; 140, first reflecting film; 141, base; 1412, base layer; 1414, protruding part; 143, reflecting protrusion; 160, second reflecting film; 180, base. DETAILED DESCRIPTION

[0034] In order to make the above purpose, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with the accompanying drawings. In the following description, a lot of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0035] In the description of the application, it should be understood that, if there are these terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application.

[0036] In addition, if there are these terms "first", "second", these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the application, if the term "multiple" appears, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0037] In this application, unless otherwise explicitly specified and limited, if there are terms such as "mounting", "connecting", "connecting", "fixing" and the like, these terms should be broadly understood. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0038] In this application, unless otherwise explicitly specified and limited, if there are similar descriptions such as "first feature on or under second feature", the meaning can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" of the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" of the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0039] It is to be noted that when an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or there can be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there can be an intervening element. The terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar terms as used herein only mean for the purpose of illustration and are not meant to be limiting.

[0040] The existing traffic cone reflective film generally includes two types, one is a glass bead type structure, and the other is a micro-prism type structure. Among them, the glass bead type reflective film body is formed by a transparent resin material, the glass beads with a high refractive index of 1.9-2.2 are uniformly embedded in the transparent resin, and an aluminum-plated reflection layer is formed at the bottom of the transparent resin, thereby forming a lens-reflection system, and the light is reflected back by the aluminum-plated reflection layer after being refracted by the glass beads. The micro-prism type reflective film body is formed by polycarbonate or polymethyl methacrylate, and a triangular pyramid microstructure is pressed on the surface of the reflective film body, and light is returned by total internal reflection.

[0041] However, as described in the background, the existing traffic cone has weak electromagnetic wave reflection ability and low radar scattering cross section due to the defects of structure and material, and therefore cannot meet the identification requirements of the vehicle-mounted radar in the intelligent driving vehicle, thereby limiting the further improvement of identification accuracy.

[0042] Referring to Figures 1 to 3 The embodiment of the present application provides a traffic road sign 100 for playing a traffic indication role.

[0043] The traffic road sign 100 includes a body 120 and a first reflective film 140, the body 120 has at least one first reflection area, and the first reflective film 140 includes a base 141 and a plurality of reflective protrusions 143, the base 141 covers the first reflection area of the body 120, and all the reflective protrusions 143 are arranged on the side surface of the base 141 away from the body 120. Among them, the first reflective film 140 is formed by a metal material.

[0044] The traffic road sign 100 described above, since the first reflective film 140 is formed by a metal material, and the side of the first reflective film 140 away from the body 120 is provided with a plurality of reflective protrusions 143, the radar scattering cross section and the anti-interference performance of the traffic road sign 100 are effectively improved, the quantitative improvement of target identification stability is realized, not only the radar perception performance is greatly improved at a small cost, but also the traditional visible light warning function is ensured.

[0045] In some embodiments, the body 120 is substantially hollow conical, and the outer diameter of the body 120 gradually increases from one end to the other end in the axial direction of the body 120. It can be understood that the shape of the body 120 is not limited thereto, for example, in other embodiments, the body 120 is hollow pyramid.

[0046] Further, the traffic sign 100 further comprises a base 180 connected to the end of the body 120 with a larger outer diameter, and the outer diameter of the base 180 is larger than that of the body 120, so that the traffic sign 100 can be stably placed on the ground. Specifically, in some embodiments, the cross section of the base 180 is polygonal. It can be understood that the shape of the base 180 is not limited thereto, and can be set as needed to meet different requirements.

[0047] The material forming the body 120 is polyvinyl chloride (PVC) or thermoplastic polyurethane (TPU). Specifically, in an embodiment, the material forming the body 120 is polyvinyl chloride, which has the advantages of low cost, good flexibility, durability, and moderate weight. In another embodiment, the material forming the body 120 is thermoplastic polyurethane, which has good wear resistance, tear resistance and elasticity. It can be understood that the material forming the body 120 is not limited thereto, and can be set as needed to meet different requirements.

[0048] In some embodiments, the body 120 has two first reflection zones, which are arranged at intervals in the axial direction of the body 120, and each first reflection zone circumferentially surrounds the body 120. It can be understood that the number and width of the first reflection zones are not limited, and can be set as needed to meet different requirements.

[0049] The first reflection film 140 circumferentially surrounds the first reflection zone of the body 120. Specifically, in an embodiment, the metal material forming the first reflection film 140 is aluminum. Aluminum not only produces strong specular reflection of millimeter waves emitted by radar, but also has good visible light recognition due to its silver-white color.

[0050] Further, all the reflection protrusions 143 on the side of the first reflection film 140 facing away from the body 120 are arranged in an array or irregularly and randomly, and each reflection protrusion 143 is conical in shape, forming a "moth eye" structure. In some embodiments, the height H of the reflection protrusion 143 is 50-500 nm, the maximum diameter R of the reflection protrusion 143 is 0-500 nm, and the interval distance L between adjacent two reflection protrusions 143 is 50-500 nm.

[0051] It can be understood that the size, arrangement, arrangement density, and shape of each reflective protrusion 143 can be set as needed to achieve different reflection effects. In some embodiments, the reflective protrusion 143 is in the shape of a circular truncated cone, a circular cone, a prism, or a spherical cap.

[0052] In some embodiments, the reflective protrusion 143 is formed by etching a metal substrate, and in particular, the metal substrate can be etched by an inductively coupled plasma (ICP) etching method or a reactive ion etching (RIE) method. It can be understood that the formation method of the reflective protrusion 143 is not limited and can be set as needed to meet different requirements.

[0053] In some embodiments, as shown in Figure 2 , Figure 3 The side surface of the base 141 of the first reflective film 140 on which the reflective protrusions 143 are arranged is a plane perpendicular to the thickness direction of the base 141, so that all the reflective protrusions 143 are arranged on the same horizontal plane.

[0054] In other embodiments, as shown in Figure 4 The base 141 of the first reflective film 140 includes a base layer 1412 and a plurality of protruding portions 1414. The base layer 1412 covers the first reflective region of the body 120, and the side surface of the base layer 1412 away from the body 120 is a plane perpendicular to the thickness direction of the base 141, and all the protruding portions 1414 are arranged on the side surface of the base layer 1412 away from the body 120.

[0055] In this way, part of the reflective protrusions 143 are arranged on the side surface of the base layer 1412 away from the body 120 and are arranged in a staggered manner with the protruding portions 1414, and part of the reflective protrusions 143 are arranged on the side surface of the protruding portions 1414 away from the body 120. The arrangement of the protruding portions 1414 can achieve an anti-glare effect to reduce glare interference.

[0056] It can be understood that the arrangement of the protruding portions 1414 is not limited, and in some embodiments, the protruding portions 1414 are arranged in an array, and in other embodiments, the protruding portions 1414 can also be arranged irregularly. The shape of each protruding portion 1414 can be in the shape of a circular truncated cone, a circular cone, a prism, or a spherical cap, so as to achieve different anti-glare effects.

[0057] In some embodiments, the body 120 further has a second reflective region adjacent to the first reflective region, the first reflective region circumferentially surrounds the body 120, and the first reflective region and the second reflective region are alternately arranged along the axial direction of the body 120. Specifically, in an embodiment, the body 120 has two first reflective regions and two second reflective regions, and the two first reflective regions and the two second reflective regions are alternately arranged along the axial direction of the body 120.

[0058] The traffic marker 100 further includes a second reflective film 160 formed of a non-metallic material, and the second reflective film 160 covers the second reflective region. Since the second reflective film 160 is formed of a non-metallic material, the production cost of the traffic marker 100 is reduced while the reflection effect can be achieved.

[0059] Specifically, in an embodiment, the non-metallic material forming the second reflective film 160 is polycarbonate or polymethyl methacrylate, and a triangular pyramid microstructure is formed on the side surface of the second reflective film 160 away from the body 120, so that light is returned away by total internal reflection, achieving a good reflection effect. It can be understood that the material and microstructure of the second reflective film 160 are not limited to this, and can be set as needed to meet different requirements.

[0060] In some embodiments, the color of the first reflective film 140 is different from the color of the second reflective film 160, so as to achieve a more obvious warning effect. Specifically, in an embodiment, the color of the first reflective film 140 is silver white, and the color of the second reflective film 160 is orange red or red. It can be understood that the colors of the first reflective film 140 and the second reflective film 160 are not limited to this, and can be set as needed to meet different appearance needs.

[0061] Since the first reflective film 140 is made of a metal material such as aluminum, the radar cross section (RCS) of the traffic marker 100 can be between -20 dBsm and -10 dBsm, which is higher than the radar cross section of the traffic cone in the prior art, so it can fall into the most effective detection interval of the vehicle-mounted radar (77GHz). It will not be easily covered by environmental noise due to being too low (<-20 dBsm), resulting in a missed detection rate greater than 15%, nor will it trigger false alarms due to being too high (> -10 dBsm). The optimized radar cross section parameter can stabilize the radar received signal strength at -65 to -75 dBm (signal-to-noise ratio is improved by 8 dB -12 dB), and the detection distance is extended from the existing 50 m to 80 m-100 m.

[0062] The relationship between the signal-to-noise ratio SNR and the target radar cross section σ satisfies:

[0063]

[0064] In the formula, P t is the transmit power, which refers to the peak power of the signal radiated by the antenna when the radar is transmitting; G t is the transmit antenna gain, which refers to the ability of the transmit antenna to concentrate energy in a certain direction, and is the amplification multiple compared with an ideal omnidirectional antenna; G r is the receive antenna gain, which refers to the ability of the receive antenna to collect echo signals in a certain direction; λ is the wavelength, which refers to the wavelength of the electromagnetic wave transmitted by the radar; and σ is the radar cross section of the target, which is a parameter for measuring the ability of the target to reflect radar waves.

[0065] In the denominator of the above formula, (4π) 3 is a constant term, which describes the energy diffusion loss of the radar wave when propagating in free space; R 4 is the fourth power of the distance, which describes the phenomenon that the signal strength decays sharply with the distance; k is the Boltzmann constant, which is a power spectral density constant of thermal noise; B is the frequency range of the signal processed by the receiver; F is the noise figure of the received signal, which represents the noise figure of the received signal; and L is the system loss, which refers to the sum of all other power losses in the radar system that are not reflected in the numerator.

[0066] As can be seen from the above formula, since the radar cross section σ of the first reflective film 140 in the present application is high, the signal-to-noise ratio SNR is correspondingly improved, which means that the signal strength is enhanced relative to the noise, thereby improving the detection reliability of the radar.

[0067] Further, the relationship between the detection probability Pd and the signal-to-noise ratio SNR satisfies:

[0068]

[0069] In the above formula, P d is the detection probability, which represents the probability that the system correctly judges “there is a target” when the target actually exists, and is a positive indicator for measuring the detection performance of the radar; SNR linear is the linear signal-to-noise ratio, which represents the ratio of the signal power to the noise power; P fa is the false alarm probability, which refers to the probability that the system incorrectly judges “there is a target” when there is no target. represents a function for calculating the correct probability of detecting a signal with a certain amplitude in a noise background; -2ln(P fa ) is a normalized detection threshold, which is a threshold value uniquely determined by the false alarm probability P fa .

[0070] As can be seen from the above formula, since the signal-to-noise ratio SNR of the first reflective film 140 in the present application is improved, the detection probability Pd Significantly, for the correct judgment traffic sign 100 has a higher success rate.

[0071] Since the first reflective film 140 is provided with a "moth eye" structure of reflective protrusions 143, when the radar wave is irradiated onto the first reflective film 140, it will not be directly bounced back like a mirror surface, but will be trapped in the "moth eye" structure to produce multiple reflections, diffractions and resonances, and the reflection effect will also be different with different incidence angles of the radar wave. Therefore, on the one hand, during the driving of the vehicle, as the vehicle-mounted radar moves, the radar scattering cross-section value of the traffic sign 100 obtained by the radar can change regularly between -20 dBsm and -10 dBsm, so compared to the radar scattering cross-section of other interference objects which changes irregularly or remains unchanged, the traffic sign 100 has a higher recognition rate.

[0072] On the other hand, the scattering signal azimuth angle of the first reflective film 140 is narrowed from ±15° to ±8°, thereby producing a more stable and pure echo waveform, and further reducing the measurement error from ±1.2m to ±0.5m at a close distance (<30m) and from ±3.5m to ±1.8m at a long distance (>80m).

[0073] In the scenario where the traffic signs 100 are densely placed (for example, the distance between two adjacent traffic signs 100 is 2-3m), the existing traffic cones have an 18% target merging misjudgment rate (identifying multiple traffic cones as a single obstacle) due to the homogenization of the reflected signals. However, due to the "moth eye" structure of the first reflective film 140 provided with reflective protrusions 143, the time-domain waveform can exhibit a 1.2μs periodic oscillation to form a unique echo fingerprint, so the vehicle-mounted radar can accurately distinguish each traffic sign 100 by identifying the characteristic waveform rather than simply the signal strength and position, thereby reducing the misjudgment rate in the densely placed scenario to below 3%.

[0074] Moreover, through the provision of the first reflective film 140, the reflection power of the traffic sign 100 of the present application is significantly suppressed to a safe interval of -32 to -28 dBm, compared to the reflection power of the existing traffic cone which is -15 dBm to -10 dBm, and the low reflection characteristic of the second reflective film 160, so that the overall probability of the radar receiving channel being saturated due to the too strong echo at a close distance (<5m) is effectively reduced from 23% to even completely reduced to 0%, ensuring the measurement stability at an extremely close distance.

[0075] Moreover, the first reflective film 140 can effectively diffuse the scattered energy to a wide-angle range of ±120°, which greatly reduces the intensity of the ground reflection clutter directly returned to the radar, reduces the intensity of the target signal from -30dB to -52dB, and thus reduces the false alarm rate of the radar in complex environments such as rainy days by 60%, and has good anti-interference performance.

[0076] Moreover, the retroreflective coefficient of the traffic marker 100 is greater than 250 cd lx -1 ·m -2 , preferably 295 cd lx -1 ·m -2 Therefore, the visible distance loss in the daytime is less than 5%, and the requirement for the retroreflective coefficient is still met.

[0077] In addition, the salt spray test life of the first reflective film 140 can reach 1000 hours, which is longer than the salt spray test life of 500 hours of the conventional reflective film, and is more suitable for long-term outdoor use.

[0078] In summary, the traffic marker 100 of the present application can improve the recognition accuracy of the vehicle-mounted radar to 94%, and reduce the missed detection rate by 82%, especially in complex scenes such as curves and tunnel entrances. Moreover, only by replacing part of the material (the coverage area of the first reflective film 140 can only account for 30% of the area of the outer surface of the body 120), the radar perception performance can be greatly improved at a minimum cost, while the visible light warning function of the conventional traffic cone is retained, which is conducive to the further popularization and application of intelligent driving technology.

[0079] As shown in Figure 5 , the present application also provides a road marker detection method based on a vehicle-mounted radar, which is used for detecting the traffic marker 100.

[0080] In some embodiments, the road marker detection method specifically includes the following steps:

[0081] S110: Radar detection is performed on the detection target, and a return signal from the detection target is received; the return signal includes a radar scattering cross-sectional area.

[0082] In some embodiments, when a vehicle travels forward at a certain speed, a vehicle-mounted radar installed on the vehicle can emit radar waves to perform radar detection on the surrounding detection target. In a specific embodiment, the working frequency band of the vehicle-mounted radar is 77GHz, and the frame rate (refresh rate) is 20Hz. It can be understood that the working parameters of the vehicle-mounted radar are not limited to this, and can be set as needed to meet different detection requirements.

[0083] When the radar wave encounters a detection target, part of the energy is reflected back to form a return signal which is received by the vehicle-mounted radar. In some embodiments, the return signal includes a radar cross section (RCS).

[0084] S120: When the size of the radar cross section meets a preset condition, the detection target is determined to be a traffic landmark.

[0085] In some embodiments, the preset condition includes: when the incident angle of the radar wave is within a first preset angle range, the radar cross section is less than a first preset cross section. When the incident angle of the radar wave is greater than a second preset angle or less than a third preset angle, the radar cross section is greater than a second preset cross section. When the size of the radar cross section meets the above preset conditions at the same time, the detection target is determined to be a traffic landmark 100.

[0086] In a specific embodiment, the vehicle travels forward at a speed of 60 km / h, so the vehicle-mounted radar on the vehicle also moves forward at a speed of 60 km / h. As the vehicle moves, the incident angle θ of the radar wave reaching the detection target also changes constantly. In a specific embodiment, the incident angle θ changes from +60° to -60°. In this process, the vehicle-mounted radar can capture multiple angle points at a preset frequency to construct an RCS-θ curve, thereby obtaining the change trend of the radar cross section following the change of the incident angle.

[0087] In an embodiment, the first preset angle range is +10° to -10°, and the first preset cross section is -15 dBsm. The second preset angle is +30°, the third preset angle is -30°, and the second preset cross section is -10 dBsm. It can be understood that the specific values of the first preset angle range, the first preset cross section, the second preset angle, and the third preset angle are not limited to this, and can be set as needed to meet different needs.

[0088] When the incident angle of the radar wave is +10° to -10°, if the radar cross section of the detection target is less than -15 dBsm (even reaching -20 dBsm), and when the incident angle of the radar wave is greater than +30° or less than -30°, the radar cross section of the detection target is equal to or greater than -9 dBsm, indicating that the detection target is a traffic landmark 100.

[0089] In this way, compared with the radar cross section of the cone barrel in the prior art being a constant value, or other interfering objects (such as plastic bags) being irregularly changing values, the radar cross section of the traffic landmark 100 in the present application changes according to a certain rule (specifically, a U-shaped change) as the vehicle travels, so it can be converted into a recognition feature to improve the recognition accuracy of the traffic landmark 100, and will not be confused with other interfering objects.

[0090] Each technical feature of the above-described embodiments can be combined with any other technical feature, and for the sake of brevity, not all possible combinations are described, but it is understood that the scope of the present disclosure encompasses all such possible combinations.

[0091] The above-described embodiments are merely illustrative of several embodiments of the present application, and the description is relatively specific and detailed, but should not be understood as limiting the scope of the patent application. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.

Claims

1. A traffic sign, characterized in that, include: The body has at least one first reflective zone; as well as The first reflective film includes a substrate and a plurality of reflective protrusions. The substrate covers the first reflective area of ​​the body, and all the reflective protrusions are disposed on the side surface of the substrate facing away from the body. The first reflective film is formed of a metallic material.

2. The traffic sign according to claim 1, characterized in that, The material forming the first reflective film is aluminum.

3. The traffic sign according to claim 1, characterized in that, All the reflective protrusions are arranged in an array, and each of the reflective protrusions is conical.

4. The traffic sign according to claim 1, characterized in that, The surface of the substrate on which the reflective protrusion is located is a plane perpendicular to the thickness direction of the substrate.

5. The traffic sign according to claim 1, characterized in that, The substrate includes a base layer and a plurality of protrusions. The base layer covers the first reflective area of ​​the body, and all the protrusions protrude from the surface of the base layer away from the body.

6. The traffic sign according to claim 1, characterized in that, The body also has a second reflective area disposed adjacent to the first reflective area, and the traffic sign further includes a second reflective film, which covers the second reflective area; The second reflective film is formed of a non-metallic material.

7. The traffic sign according to claim 6, characterized in that, The second reflective film is formed of polycarbonate or polymethyl methacrylate; the color of the first reflective film is different from that of the second reflective film; the first reflective area and the second reflective area are arranged alternately in the axial direction of the body.

8. The traffic sign according to any one of claims 1 to 7, characterized in that, The radar cross-section of the traffic sign is 0.37 m²-0.71 m²; and / or The retroreflectivity of the traffic sign is greater than 250 cd·lx. -1 ·m -2 .

9. A road sign detection method based on vehicle-mounted radar, used to detect traffic road signs as described in any one of claims 1 to 8, characterized in that, Includes the following steps: The target is detected by radar, and the echo signal from the target is received; the echo signal includes the radar cross section. When the size of the radar cross-section meets the preset conditions, the detected target is determined to be the traffic sign.

10. The road sign detection method according to claim 9, characterized in that, The preset conditions include: When the incident angle of the radar wave is within the first preset angle range, the radar scattering cross-section is smaller than the first preset cross-section. When the incident angle of the radar wave is greater than the second preset angle or less than the third preset angle, the radar scattering cross-section is greater than the second preset cross-section.

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