CN212181013U

CN212181013U - Lidar protection device for a motor vehicle and motor vehicle comprising such a device

Info

Publication number: CN212181013U
Application number: CN202020093833.8U
Authority: CN
Inventors: 尤奈斯·卡达哈
Original assignee: Plastic Omnium SE
Current assignee: Plastic Omnium SE
Priority date: 2019-06-21
Filing date: 2020-01-16
Publication date: 2020-12-18
Anticipated expiration: 2030-01-16
Also published as: FR3097495B1; FR3097495A1; CN112114297A

Abstract

The utility model relates to a motor vehicle lidar (2) protection equipment (1A, 1B) and contain the motor vehicle of this equipment, wherein this protection equipment includes wall (11) that is used for being passed by the wave that lidar (2) transmitted, and its is remarkable in that, this wall (11) include that at least one deck can restrict the wave of lidar (2) is in reflection's antireflection covering (14, 15) on wall (11).

Description

Lidar protection device for a motor vehicle and motor vehicle comprising such a device

Technical Field

The present invention relates to the field of motor vehicles equipped with lidar and, more particularly, to the field of devices for shielding and protecting such lidar (also known as "radomes" or "lidar hoods"). In the following of this description the term "radome" is used as a synonym for "protection device".

Background

Laser telemetry, LiDAR (acronym for Light Detection and Ranging in English) or LaDAR (acronym for Laser Detection and Ranging in English) or Laser Radar is a remote measurement technique based on the analysis of the characteristics of the beam returning to the beam transmitter. In the following, the term "LiDAR" (is used to denote a LiDAR type device.

Unlike radars using radio waves or sonar using sound waves, lidar uses light (visible, infrared, or ultraviolet spectra). This light almost always comes from a laser and is therefore coherent. As an unavoidable active remote detection instrument, laser radar is applied to a very large number of fields, such as topographic survey, earth science, archaeology, air traffic control, automatic guidance of ground or space vehicles, or road safety or national defense. In particular, motor vehicles capable of running in an autonomous mode or in an ACC (adaptive Cruise Control) mode may be equipped with a lidar. Such lidar is used in particular for adjusting the vehicle speed in dependence on obstacles and/or traffic conditions on the road. The lidar detects the speed and distance of objects in front of the vehicle carrying the lidar to maintain a safe distance, particularly between vehicles.

Depending on their function, lidar is mounted on the front or rear face of the vehicle, most often behind the bumper. To the knowledge of the inventors, no solution currently exists that is able to protect such a lidar while ensuring its optimal performance, in particular a good transmission of the waves of the lidar.

In the prior art, such lidar, and in particular its laser transmitter/receiver, is either completely unprotected, i.e. exposed to the external environment, or covered by a plastic shield or radome. In the first case, there is a risk of exposure of the lidar to external aggressions (rain, ice, frost, sludge, insects, leaves, etc.) and not compliance with vehicle aesthetic standards. In the second case, plastic shields that have not undergone special treatment attenuate the transmission of the lidar waves to a greater or lesser extent, depending on the characteristics of the plastic material forming the shield. The attenuation of the transmission of the wave of the lidar is particularly related to the reflection of the wave of the lidar at the interface of two different media (air/plastic, plastic/air) and the absorption of the wave of the lidar by the plastic material of the shield.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is especially to remedy above-mentioned defect through providing a laser radar cover that can protect laser radar and ensure the good transmission of laser radar's ripples simultaneously. In other words, such a radome allows the passage of the laser radar waves with as little attenuation as possible, so as not to interfere with the operation of the laser radar itself.

To this end, the subject of the invention is a motor vehicle lidar protection device comprising a wall intended to be crossed by a wave emitted by a lidar, characterized in that the wall comprises at least one antireflection covering capable of limiting the reflection of the wave of the lidar on the wall.

"being able to limit reflections of the wave of the lidar" means being able to limit reflections of the wave of the lidar to at most 4% of the incident wave of the lidar. In the following of the present description, the term "anti-reflection" is used to describe such capability.

In case after installing on the vehicle, set up the basis in laser radar the utility model discloses a protection equipment makes this laser radar invisible from the outside, and the vehicle consequently has better pleasing to the eye outward appearance. Moreover, the device protects the lidar from external aggressions (rain, ice, frost, sludge, insects, leaves, etc.), so that the lidar has a longer service life. Furthermore, due to the presence of the covering on the wall of the protection device, the reflection of the wave of the lidar at the wall is limited to a level less than or equal to 4% of the incident wave, which enables an improved transmission of the wave of the lidar through the wall of the device. As an example, in the case where both faces of the wall (the internal face and the external face) are covered with a covering capable of limiting the reflection of the wave of the lidar to 0.5%, the transmission of the wave of the lidar rises to 98% assuming that the loss associated with the absorption of the wave of the lidar by the wall itself is 1%. It is noted that the losses associated with absorption are typically very small (< 1% of the incident wave) for the material chosen for the fabrication of the walls. The increase in the transmissivity of the waves of the lidar through the protective wall can improve the performance of the lidar behind the wall by ensuring better transmission and reception of the waves.

The protection device may additionally comprise one or more of the following features taken alone or in combination:

the wall is made of two different plastic materials, one over-moulded over the other and of a material that is transparent to the lidar waves, at least in the position of use of the device. By "material transparent to light" is meant a material through which an incident stream of electromagnetic radiation having a wavelength of 10nm to 0.1mm passes that transmits more than 90% of the radiation stream passing through it. Walls made of such plastic materials are inexpensive and easy to manufacture (for example by injection moulding), and satisfactory transmission of the laser radar waves is already achieved even without an anti-reflection covering. Better transmission, e.g. above 94.5% or above 98%, can be achieved after applying an anti-reflection coating on one or both faces of the plastic wall.

The thickness of the wall is 2 to 3 mm. On the one hand, the wall should not have an excessively small thickness in order to ensure satisfactory rigidity and mechanical strength. On the other hand, it should not have an excessive thickness, especially in order not to absorb an excessive amount of the laser radar incident wave and not to raise the manufacturing cost. The inventors have observed that the thickness in the above interval provides a good compromise.

The thickness of the cap layer is less than or equal to 200 nm. This can be particularly advantageous for transparency to the waves of the lidar and to limit the cost and time of applying the covering, since a smaller amount of covering is used to achieve this smaller thickness.

The refractive index of the walls is higher than 1.43 and less than 1.56. This allows to obtain an optimal transmission of the wave of the lidar in the wall.

The wall comprises an outer face and an inner face facing the lidar in the device use position, the roughness of both faces of the wall being less than or equal to 0.02 microns. It is noted that the surface onto which the waves of the lidar are directed, if it has an excessive roughness, may lead in particular to an increased reflection of the waves of the lidar, which may affect the performance of the lidar. The inventors have determined that a roughness value of 0.02 microns is the preferred maximum value.

The wall is made of two different plastic materials, one over-moulded over the other and of a material that is transparent to the lidar waves, at least in the position of use of the device. This solution is advantageous, in particular because it is possible to ensure an aesthetic continuity with the adjacent skin of the vehicle on which the protection device according to the invention is installed.

The wavelength of the laser radar waves is 800 to 1600nm, preferably 850nm, 905nm, 1050nm or 1550 nm.

The covering being an anti-reflection varnish having a refractive index less than that of the wall or less than 1.57, e.g.

And (3) varnish.

The subject matter of the present invention is also a motor vehicle comprising at least one lidar protection device as described above.

Drawings

The invention will be better understood on reading the following description, provided by way of example only, with reference to the accompanying drawings, in which:

fig. 1 shows, as a non-limiting example, a lidar protection device in place on the front face of a vehicle.

Fig. 2 is a side view of a lidar protection apparatus according to a first embodiment of the present invention.

Fig. 3 is a side view of a lidar protection apparatus according to a second embodiment of the present invention.

Detailed Description

The present invention is described below with reference to fig. 1 to 3.

Fig. 1 shows, as a non-limiting example, a protective device for protecting a lidar 2, also referred to as a radome 1 or lidar, in place on the front face of a vehicle 3. In this example, a laser radar 2 is arranged behind the radome 1 such that electromagnetic waves (light of the visible, infrared or ultraviolet spectrum) emitted or received by the laser radar 2 pass through the radome 1. Those skilled in the art will appreciate that lidar 2 may be mounted at other locations of the vehicle, such as the rear face, depending on its function.

Fig. 2 schematically shows a radome 1A for protecting a laser radar 2 according to a first embodiment of the invention in a side view. Radome 1A includes a wall 11 having an exterior face 13 and an interior face 12 facing lidar 2 in the use position of radome 1. The exterior face 13 is visible from the outside, thus forming part of the vehicle exterior element. The outer face 13 must be treated to make it aesthetically pleasing. As an example, the outer face 13 may be covered with a varnish that meets the specifications for exterior parts of motor vehicles. Moreover, radome 1A comprises, on its internal face 12, one or more layers of covering 14 able to limit the reflection of the waves of lidar 2. According to a variant, the radome 1A comprises such a covering on its external face 13.

Fig. 3 schematically shows a radome 1B for protecting a lidar 2 according to a second embodiment in a side view. Radome 1B differs from radome 1A in that it includes, on both of its major faces (i.e., outer face 13 and inner face 12), one or more layers of

coverings

15 and 14 capable of limiting reflection of the wave of lidar 2.

In both embodiments, the wall 11 is made of a plastic material that is transparent to light, in particular to the waves of a lidar, such as materials based on Polycarbonate (PC), polymethyl methacrylate (PMMA) and Cyclic Olefin Copolymer (COC). The use of plastic has several advantages, including: the transparent plastic wall is light in weight, easy to manufacture and low in cost; its transparency facilitates the transmission of the laser radar waves.

Advantageously, the wall 11 can be made of two different plastic materials, attached one to the other, for example by overmoulding. Of course, the material that faces the lidar at least in the position of use of the radome is transparent to the waves of the lidar. This solution allows greater flexibility, versatility, and complexity of the radome. In particular, thanks to the presence of the second plastic material, aesthetic continuity of the adjacent skin of the vehicle on which the radome is mounted can be ensured.

The wall 11 may have a shape that is adapted to its mounting position (e.g., the front or rear of the vehicle). Preferably, the shape of the wall 11 is such that it ensures an aesthetic continuity with the adjacent component.

Moreover, the thickness of the wall 11 may be 2 to 3mm, in order to achieve a compromise between mechanical performance, cost and absorption of the waves of the lidar. It is obvious that a person skilled in the art will be able to select a suitable value for the thickness according to the actual requirements.

Advantageously, the roughness of the two faces of the wall is less than or equal to 0.02 micron. It is noted that a small roughness also contributes in itself to limiting the reflection of the wave of the lidar. 0.02 microns is the preferred maximum value determined by the inventors.

In an advantageous example, the covering is an anti-reflection varnish with a refractive index less than that of the wall or less than 1.57, preferably less than 1.33, for example

Varnish, which is capable of limiting the reflection of the waves of visible light (wavelengths from 400nm to 800nm) to below 2%, but the fact shows that it is also effective in limiting the reflection of the waves of lidar (wavelengths generally from 800nm to 1600nm, preferably 850nm, 905nm, 1050nm or 1550 nm).

Typically, a varnish having a thickness of at most 200nm is applied on said one or more faces of the wall 11. This results in reasonable cost and satisfactory wave transmission of the lidar.

Preferably, the refractive index of the wall 11 is greater than 1.43 and less than 1.56. The wall 11 having such a refractive index allows good transparency thereof to the waves of the lidar. By means of the anti-reflection cover, a better transmission of the wave of the lidar is obtained.

Due to the presence of such varnish on the inner face and/or on the outer face of the wall 11, the transmission of the wave of the lidar through the wall is enhanced, since the proportion of reflection at the surface covered by the varnish is significantly reduced, from 4% to 0.5% according to one non-limiting example. In this example, assuming a loss of 1% associated with the absorption of the wave of the lidar by the wall itself (in most cases this loss is less than 1%), if the varnish is applied only on one face of the wall 11, the wall allows 94.5% (-1-0.5% -4% -1%) of the incident wave transmission of the lidar, i.e. an increase of 3.5% with respect to the case where the wall 11 has no anti-reflection varnish on any of its faces (a transmittance of 91% (-1-4% -4% -1%)); if varnish is applied on both faces of the wall 11, the wall allows an incident wave transmission of the lidar of 98% (-1-0.5% -0.5% -1%), i.e. an increase of 7% with respect to the case of a wall 11 completely free of anti-reflection varnish (transmission 91% (-1-4% -4% -1%)).

In both embodiments, the one or more layers of the cover may be applied to the face by any suitable means known to those skilled in the art. For example, after the wall 11 itself has been manufactured (for example by injection moulding), the varnish is applied to one or both faces of the wall 11 by placing the wall 11 in a varnish bath or by spray spraying. Spraying can be achieved ultrasonically or by means of a "rotating bowl".

The utility model discloses still relate to a motor vehicle, this motor vehicle includes at least one above-mentioned radome. The radome is arranged in front of the lidar, which itself is mounted on the front or rear face of the vehicle or elsewhere. The radome is configured to at least partially shield the lidar from external intrusion, UV, etc. without thereby affecting its performance.

Claims

1. A lidar (2) protection device (1A, 1B) for a motor vehicle, comprising a wall (11) for being traversed by waves emitted by the lidar (2), characterized in that the wall (11) comprises at least one anti-reflection covering (14, 15) capable of limiting the reflection of the waves of the lidar (2) on the wall (11).

2. Lidar (2) protection device (1A, 1B) for a motor vehicle according to claim 1, wherein the wall (11) is made of a plastic material transparent to the waves of the lidar.

3. The lidar (2) protection device (1A, 1B) for a motor vehicle according to claim 2, wherein the plastic material is a Polycarbonate (PC), Polymethylmethacrylate (PMMA) or Cyclic Olefin Copolymer (COC) based material.

4. The lidar (2) protection device (1A, 1B) for a motor vehicle according to any of claims 1-3, wherein the thickness of the wall (11) is 2 to 3 mm.

5. The lidar (2) protection device (1A, 1B) for a motor vehicle according to any of claims 1-3, wherein the thickness of the cover layer is less than or equal to 200 nm.

6. The lidar (2) protection device (1A, 1B) for a motor vehicle according to any of claims 1-3, wherein the refractive index of the wall (11) is larger than 1.43 and smaller than 1.56.

7. Lidar (2) protection device (1A, 1B) for a motor vehicle according to any of claims 1-3, wherein the wall (11) comprises an outer face (13) and an inner face (12) facing the lidar (2) in a position of use of the protection device (1A, 1B), the roughness of both faces (12, 13) of the wall (11) being less than or equal to 0.02 micrometer.

8. Motor vehicle lidar (2) protection device (1A, 1B) according to any of claims 1-3, wherein the wall (11) is made of two different plastic materials, one material being overmoulded on the other material and the one material facing the lidar (2) being transparent to the lidar waves at least in the device use position.

9. The lidar (2) protection device (1A, 1B) for a motor vehicle according to any of claims 1-3, wherein the wavelength of the lidar is 800 to 1600 nm.

10. Lidar (2) protection device (1A, 1B) for a motor vehicle according to claim 9, wherein the wavelength of the lidar is 850nm, 905nm, 1050nm or 1550 nm.

11. The lidar (2) protection device (1A, 1B) for a motor vehicle according to any of claims 1-3, wherein the cover is an anti-reflective varnish having a refractive index smaller than the refractive index of the wall or smaller than 1.57.

12. Lidar (2) protection device (1A, 1B) for a motor vehicle according to claim 11, wherein the anti-reflective varnish is

And (3) varnish.

13. A motor vehicle (3) comprising at least one lidar (2) protection device (1A, 1B) according to any of the preceding claims.