DEVICE AND METHOD FOR CALIBRINGING A LASER SCANNER

Description

[0001] The present invention relates to a device for calibrating a laser scanner, in particular for calibrating a vehicle laser scanner, which comprises at least one reflection unit for reflecting a laser beam from the laser scanner. The invention also relates to a method for calibrating a laser scanner.

[0002] Vehicles, particularly autonomous vehicles such as self-driving mobile transport systems, are known to be equipped with one or more laser scanners. These mobile transport systems are used, for example, to transport objects within a technical facility. The technical facility is typically an industrial application, such as a production plant. A laser scanner emits a laser beam, detects a reflected laser beam, and calculates the distance to an object that reflects the laser beam. The laser scanner serves the autonomous vehicle, in particular, to detect obstacles within the technical facility.

[0003] The vehicle's laser scanner should be aligned so that the laser beams emitted by the scanner are as parallel as possible to the surface on which the vehicle is located. This ensures that the laser beams are not reflected by the surface, but rather by objects, especially obstacles, in the surrounding area. These objects can then be used for locating and navigating the vehicle. Aligning the laser scanner so that the laser beams are parallel to the surface, i.e., horizontal, is called laser scanner calibration.

[0004] From DE 10 2004 033 114 A1, a method for calibrating a distance image sensor is known. For this purpose, a device is used which has calibration objects with three calibration surfaces.

[0005] DE 101 16 278 A1 discloses a method for calibrating a distance sensor mounted on a vehicle. For this purpose, a device is used which has three reference objects.

[0006] From JP 2009 168472 A, a method for calibrating a laser scanner is known. This method uses a device that has a vertical surface whose right and left sides are parallel.

[0007] From EP 3 176 606 A2, a method for aligning a laser scanner is known. The alignment of the laser scanner can be changed about a pitch axis and a roll axis.

[0008] The invention is based on the objective of creating a device and a method for calibrating a laser scanner.

[0009] The problem is solved by a device for calibrating a laser scanner with the features specified in claim 1. Advantageous embodiments and further developments are the subject of the dependent claims. The problem is also solved by a method for calibrating a laser scanner with the features specified in claim 12. Advantageous embodiments and further developments are the subject of the dependent claims.

[0010] An inventive device for calibrating a laser scanner, in particular for calibrating a vehicle laser scanner, comprises at least one reflection unit for reflecting a laser beam from the laser scanner. The at least one reflection unit comprises a first shield, a second shield, and a screen, wherein the first shield is arranged in a beam direction between the second shield and the screen. The first shield has a first reflective surface extending at least approximately perpendicular to the beam direction, and the second shield has a second reflective surface extending at least approximately perpendicular to the beam direction, and the screen has a third reflective surface extending at least approximately perpendicular to the beam direction.The first shield is vertically offset from the second shield in such a way that a gap is formed between them, extending both vertically and laterally. The screen is designed and positioned such that a projection of the gap in the direction of the beam falls completely onto the third reflective surface of the screen.

[0011] The vertical direction extends perpendicular to the beam direction. The vertical direction also extends perpendicular to the transverse direction. The beam direction also extends perpendicular to the transverse direction. The directional terms vertical direction, transverse direction, and beam direction used here are each defined with respect to the reflecting unit. Any direction perpendicular to the vertical direction is also referred to as a horizontal direction. The transverse direction and the beam direction thus represent horizontal directions. The vertical direction also extends perpendicular to the surface on which the reflecting unit is placed. Aligning the laser scanner so that its laser beams are directed horizontally is called laser scanner calibration.

[0012] During calibration, the laser scanner is positioned at a defined vertical distance from a floor on which at least one reflector is also located. The first and second shields are aligned such that the slit is at the same defined vertical distance from the floor as a scan plane of the laser scanner. To calibrate the laser scanner, a laser beam is directed at the at least one reflector in the beam direction and moved transversely along the at least one reflector. For several positions of the laser beam in the transverse direction, the distance between the laser scanner and the reflective surface from which the laser beam is reflected is measured. When the laser beam strikes the slit, it is reflected by the third reflective surface of the shield.The laser beam of the laser scanner then travels in an angular range along at least one reflection unit in a horizontal direction.

[0013] The device according to the invention enables, in particular, the calibration of a vehicle's laser scanner, wherein the vehicle is, in particular, an autonomous vehicle, such as a self-driving mobile transport system. The autonomous vehicle is able to detect obstacles by means of the laser scanner. The device according to the invention requires relatively little space and allows for relatively high accuracy in the calibration of the laser scanner. The costs for the device according to the invention are relatively low.

[0014] According to the invention, the vertical extent of the third reflective surface of the screen is greater than the vertical extent of the slit, and the transverse extent of the third reflective surface of the screen is greater than the transverse extent of the slit. Thus, even laser beams that strike the slit at a slight angle to the beam direction still fall onto the third reflective surface of the screen.

[0015] According to a preferred embodiment of the invention, the device comprises a first reflection unit and a second reflection unit, which are aligned such that the beam direction of the first reflection unit extends at least approximately perpendicular to the beam direction of the second reflection unit. This at least approximately perpendicular offset of the two reflection units relative to each other makes it possible to calibrate the laser scanner for different emission angles of the laser scanner's laser beams and with respect to two horizontal, mutually orthogonal axes. When the laser beam strikes the slits of both reflection units, it is reflected by the third reflective surfaces of the screens of both reflection units. The laser scanner's laser beam then propagates in a horizontal direction at an angle greater than 90°.

[0016] Preferably, the first and second reflection units are aligned such that the beam direction of the first reflection unit extends at least approximately parallel to the transverse direction of the second reflection unit. This at least approximately perpendicular offset of the two reflection units relative to each other makes it possible to calibrate the laser scanner for different beam angles of the laser scanner's laser beams and relative to two horizontal, mutually orthogonal axes.

[0017] Preferably, the first and second reflection units are aligned such that the vertical direction of the first reflection unit is parallel to the vertical direction of the second reflection unit. This arrangement of the two reflection units relative to each other makes it possible to calibrate the laser scanner for different emission angles of the laser beams and with respect to two horizontal, mutually orthogonal axes.

[0018] Advantageously, the first and second reflection units are aligned such that the slits of the first and second reflection units are vertically aligned. If the two reflection units are placed on a common surface, their slits are equidistant from the surface, and the laser beams from the laser scanner strike both slits of both reflection units.

[0019] According to an advantageous embodiment of the invention, the at least one reflection unit has at least one spacer arranged such that the first shield and the screen are offset from each other by a first distance in the beam direction. This allows for more precise calibration of the laser scanner. Furthermore, the at least one spacer can be used for mechanically securing the screen.

[0020] According to an advantageous embodiment of the invention, the at least one reflection unit has at least one base which extends predominantly in the vertical direction and which is arranged such that the first shield and the second shield are offset from each other by a second distance in the beam direction. This allows the calibration of the laser scanner to be carried out with increased precision. Furthermore, the at least one base serves for the mechanical fastening of the shields.

[0021] According to an advantageous embodiment of the invention, the at least one reflection unit has at least one aperture, which is arranged transversely next to the second shield and / or next to the first shield. The at least one aperture has at least two reflective surfaces, which are arranged at an angle to one another. Laser beams from the laser scanner, which strike laterally in the transverse direction next to the first shield or next to the second shield, can also be reflected by the aperture. The mutually inclined reflective surfaces are at varying distances from the laser scanner and simplify the location of the at least one reflection unit for the laser beam.

[0022] According to an advantageous embodiment of the invention, the first reflective surface of the first shield and / or the second reflective surface of the second shield comprises a first reflective area and a second reflective area, wherein the reflective areas have different reflective properties, in particular different colors and / or different surface materials. It has been shown that different reflective properties of the reflective areas allow for the simulation of different distances to the laser scanner. The reflective areas with the different reflective properties thus simulate varying distances to the laser scanner and simplify the location of the reflective surface.

[0023] According to an advantageous embodiment of the invention, the first reflective surface of the first shield and / or the first reflective area of ​​the second reflective surface of the second shield are covered with black foam.

[0024] According to an advantageous embodiment of the invention, at least the edges of the first shield and / or the edges of the second shield adjacent to the gap of the reflection unit are covered with black foam.

[0025] According to a method according to the invention for calibrating a laser scanner, in particular for calibrating a vehicle laser scanner, using a device according to the invention, a laser beam of the laser scanner is directed at least approximately in the beam direction onto the at least one reflection unit, and the laser beam is moved in the transverse direction along the at least one reflection unit. For several positions of the laser beam in the transverse direction, the distance of the laser scanner to the reflection surface from which the laser beam is reflected is measured.

[0026] When the laser beam hits the first shield, it is reflected by the first reflective surface of the first shield. When the laser beam hits the second shield, it is reflected by the second reflective surface of the second shield. When the laser beam hits the slit, it is reflected by the third reflective surface of the screen. When the laser beam hits a foot of the reflection unit, it is reflected by the foot of the reflection unit.

[0027] During calibration, the laser scanner is positioned vertically at a defined distance from a surface on which at least one reflector is also located. The first and second shields are aligned such that the slit, and in particular its center, is at the same defined vertical distance from the surface. During calibration, the laser scanner is also positioned at a defined distance in the beam direction from the reflector.

[0028] The distance of the laser scanner in the beam direction to the reflecting unit is significantly greater than the transverse extent of the reflecting unit. Therefore, the distance of the laser scanner to a central area of ​​a reflecting surface is only slightly less than the distance of the laser scanner to an edge region of said reflecting surface. Thus, the distance of the laser scanner in the beam direction to a reflecting surface of the reflecting unit can be considered approximately constant. If the distance of the laser scanner in the beam direction to the reflecting unit is of a similar order of magnitude to the transverse extent of the reflecting unit, then the aforementioned approximation is not sufficiently accurate. In this case, it is advisable to convert the polar coordinates provided by the laser scanner—namely, beam angle and distance—into Cartesian coordinates—namely, position in the transverse direction and distance in the beam direction.

[0029] The distance between the laser scanner and the second reflective surface is less than the distance between the laser scanner and the foot. The distance between the laser scanner and the foot is less than the distance between the laser scanner and the first reflective surface. The distance between the laser scanner and the first reflective surface is less than the distance between the laser scanner and the third reflective surface. The respective distances between the laser scanner and each reflective surface are known.

[0030] The laser scanner's orientation is determined from the measured distances to each reflective surface. If the laser beam is reflected by the first reflective surface of the first shield, the laser scanner is tilted vertically upwards, away from the ground. If the laser beam is reflected by the second reflective surface of the second shield, the laser scanner is tilted vertically downwards, towards the ground. If the laser beam is reflected by the third reflective surface of the shield, the laser beam travels in a horizontal direction, and the laser scanner is horizontally oriented.

[0031] The method according to the invention particularly allows for the calibration of a vehicle's laser scanner, wherein the vehicle is in particular an autonomous vehicle, such as a self-driving mobile transport system. The autonomous vehicle is particularly able to detect obstacles by means of the laser scanner. The method according to the invention enables a relatively high accuracy in the calibration of the laser scanner and requires a relatively short amount of time.

[0032] According to a preferred embodiment of the invention, the device comprises a first reflection unit and a second reflection unit, which are oriented such that the beam direction of the first reflection unit extends at least approximately perpendicular to the beam direction of the second reflection unit. The laser beam of the laser scanner is directed at the first reflection unit at least approximately in the beam direction of the first reflection unit, and the laser beam is moved along the first reflection unit in the transverse direction. For several positions of the laser beam in the transverse direction, the distance of the laser scanner to the reflective surface of the first reflection unit from which the laser beam is reflected is measured.The laser beam of the laser scanner is also directed at the second reflection unit at least approximately in the beam direction of the second reflection unit, and the laser beam is moved along the second reflection unit in the transverse direction. For several positions of the laser beam in the transverse direction, the distance of the laser scanner to the reflective surface of the second reflection unit from which the laser beam is reflected is measured.

[0033] This approximately perpendicular offset of the two reflection units allows the laser scanner to be calibrated for different beam angles. When the laser beam strikes the slits of both reflection units, it is reflected by the third reflective surfaces of the screens of both units. The laser scanner's beam then travels horizontally at an angle of over 90°.

[0034] According to an advantageous embodiment of the invention, the determined orientation of the laser scanner is displayed optically and / or acoustically. Thus, it is displayed optically and / or acoustically whether the laser scanner is tilted vertically upwards, i.e., away from the ground, or whether the laser scanner is tilted vertically downwards, i.e., towards the ground, or whether the laser scanner is horizontally oriented.

[0035] The invention is not limited to the combination of features stated in the claims. For a person skilled in the art, further meaningful combinations of claims and / or individual claim features and / or features of the description and / or the figures will become apparent, in particular from the problem statement and / or the problem arising from a comparison with the prior art.

[0036] The invention will now be explained in more detail with reference to the illustrations. The invention is not limited to the embodiments shown in the illustrations. The illustrations only depict the subject matter of the invention schematically. They show: Figure 1: a schematic representation of a device for calibrating a laser scanner, Figure 2: a top view of a reflection unit, Figure 3: a side view of a reflection unit, Figure 4: a front view of a reflection unit, Figure 5: a top view of a reflection unit according to a first modification, Figure 6: a perspective view of a reflection unit according to a second modification, Figure 7: a first diagram of measured distances, Figure 8: a second diagram of measured distances, and Figure 9: a third diagram of measured distances.

[0037] Figure 1Figure 1 shows a schematic representation of a device for calibrating a laser scanner 3 of a vehicle 2. The vehicle 2 is, in this case, an autonomous vehicle, specifically a self-driving mobile transport system. The vehicle 2 has an approximately rectangular footprint. A laser scanner 3 is arranged at each of two diagonally opposite corners of the vehicle 2. Each laser scanner 3 emits a laser beam L, detects a reflected laser beam L, and calculates a distance D to an object that reflects the laser beam L. Each laser beam L emitted by the laser scanner 3 is moved within an angular range of approximately 270°.

[0038] The laser scanners 3 are connected to a digital computer 4. During calibration of the laser scanners 3, data, in particular data about measured distances D to objects, are transferred from the laser scanners 3 to the digital computer 4. The digital computer 4 determines the orientation of the laser scanner 3 from the measured distances D and displays the determined orientation of the laser scanner 3 both visually and audibly.

[0039] The device comprises a first reflection unit 21 for reflecting a laser beam L from the laser scanner 3 and a second reflection unit 22 for reflecting a laser beam L from the laser scanner 3. The vehicle 2 and the reflection units 21, 22 are located on a level surface. The reflection units 21, 22 are objects that reflect laser beams L.

[0040] Each of the reflecting units 21, 22 has a front face that extends at least approximately perpendicular to a respective beam direction S. A respective transverse direction Y extends perpendicular to the respective beam direction S. A respective vertical direction Z extends perpendicular to the respective beam direction S and perpendicular to the respective transverse direction Y. The aforementioned directions vertical direction Z, transverse direction Y, and beam direction S are each defined with respect to the respective reflecting unit 21, 22. In this case, the vertical directions Z of the reflecting units 21, 22 extend parallel to each other and perpendicular to the ground on which the reflecting units 21, 22 and the vehicle 2 are standing.

[0041] Each of the reflection units 21, 22 is oriented such that a laser beam L emitted by the vehicle 2's laser scanner 3, which strikes the front of the respective reflection unit 21, 22 centrally in the respective transverse direction Y, travels at least approximately in the respective beam direction S. Thus, at a specific emission angle, the laser beam L strikes the front of the respective reflection unit 21, 22 at least approximately perpendicular to the surface.

[0042] The beam direction S of the first reflection unit 21 extends at least approximately perpendicular to the beam direction S of the second reflection unit 22. The beam direction S of the first reflection unit 21 extends at least approximately parallel to the transverse direction Y of the second reflection unit 22. A beam angle in which the laser beam L strikes the front of the first reflection unit 21 at least approximately perpendicular to the front is thus offset by at least approximately 90° from a beam angle in which the laser beam L strikes the front of the second reflection unit 22 at least approximately perpendicular to the front.

[0043] Figure 2 shows a top view of one of the in Figure 1The reflection units 21 and 22 shown are identical in design. Each reflection unit 21 and 22 comprises a first shield 7, a second shield 8, and a screen 5. The first shield 7 is positioned between the second shield 8 and the screen 5 in the direction of the beam S. The first shield 7 and the screen 5 are offset from each other by a first distance A1 in the direction of the beam S. The first shield 7 and the second shield 8 are offset from each other by a second distance A2 in the direction of the beam S.

[0044] The reflection unit 21, 22 has two feet 6, which extend predominantly in the vertical direction Z. The shields 7, 8 are attached to the two feet 6, with the feet 6 being arranged in the beam direction S between the first shield 7 and the second shield 8. The two feet 6 are offset from each other in the transverse direction Y. The extension of the two feet 6 in the beam direction corresponds approximately to the second distance A2.

[0045] Figure 3 Figure 1 shows a side view of a reflection unit 21, 22. The first shield 7 is arranged offset in the vertical direction Z relative to the second shield 8. The shields 7, 8 are attached to the sides of the feet 6 opposite each other in the beam direction S.

[0046] Figure 4Figure 1 shows a front view, i.e., a view of the front side, of a reflection unit 21, 22. The first shield 7 has a first reflective surface 31, which extends at least approximately perpendicular to the beam direction S. The second shield 8 has a second reflective surface 32, which also extends at least approximately perpendicular to the beam direction S. The screen 5 has a third reflective surface 33, which also extends at least approximately perpendicular to the beam direction S.

[0047] The first shield 7 is arranged offset in the vertical direction Z from the second shield 8 such that a gap 9 is formed between the first shield 7 and the second shield 8, extending in the vertical direction Z and in the transverse direction Y. In the transverse direction Y, the gap 9 is bounded by the two feet 6. The first reflection unit 21 and the second reflection unit 22, which are in Figure 1The slits shown are aligned such that the slit 9 of the first reflection unit 21 and the slit 9 of the second reflection unit 22 are aligned with each other in the vertical direction Z.

[0048] The screen 5 is designed and arranged such that a projection of the slit 9 in the beam direction S falls completely onto the third reflective surface 33 of the screen 5. The extent of the third reflective surface 33 of the screen 5 in the vertical direction Z is greater than the extent of the slit 9 in the vertical direction Z, and the extent of the third reflective surface 33 of the screen 5 in the transverse direction Y is greater than the extent of the slit 9 in the transverse direction Y.

[0049] Figure 5Figure 1 shows a top view of a reflection unit 21, 22 according to a first modification. The reflection unit 21, 22 has two spacers 10, which are arranged such that the first shield 7 and the screen 5 are offset from each other in the beam direction S by the first distance A1. The two spacers 10 are each arranged in the beam direction S between one of the feet 6 and the screen 5.

[0050] The reflection unit 21, 22 also has two apertures 11, which are arranged in the transverse direction Y next to the second shield 8 and next to the first shield 7. The shields 7, 8 and the feet 6 are thus arranged in the transverse direction Y between the two apertures 11. The two apertures 11 each have two reflective surfaces, which are arranged at an angle to each other. Both reflective surfaces of the apertures 11 run parallel to the vertical direction Z. Both reflective surfaces of the apertures 11 run at an angle to the beam direction S and at an angle to the transverse direction Y.

[0051] Figure 6Figure 1 shows a perspective view of a reflection unit 21, 22 according to a second modification. In addition to the first shield 7, the second shield 8, and the two feet 6, the reflection unit 21, 22 also includes a screen 5, which is not shown here. Furthermore, the reflection unit 21, 22 includes a crossbar 16, which is attached to the feet 6 and extends in the transverse direction Y between the feet 6. The crossbar 16 serves to mechanically stabilize the reflection unit 21, 22.

[0052] The first reflective surface 31 of the first shield 7 has a uniform reflective area, which is a surface of black ESD foam. The second reflective surface 32 of the second shield 8 comprises a first reflective area 12, a second reflective area 13, a third reflective area 14, and a fourth reflective area 15.

[0053] The first reflection area 12 is a surface of black ESD foam. The second reflection area 13, the third reflection area 14, and the fourth reflection area 15 are each surfaces of an aluminum sheet. The first reflection area 12 therefore exhibits different reflection properties for laser beams L than the other reflection areas 13, 14, and 15 of the second shield 8.

[0054] The third reflection area 14 is located in the transverse direction Y at one edge of the second shield 8 in front of one foot 6. The fourth reflection area 15 is located in the transverse direction Y at the other edge of the second shield 8 in front of the other foot 6. The first reflection area 12 extends in the transverse direction Y between the feet 6. The second reflection area 13 is located midway between the feet 6 and extends in the transverse direction Y over part of the extent of the first reflection area 12.

[0055] To calibrate one of the in Figure 1 In the depicted laser scanner 3, a laser beam L of said laser scanner 3 is directed onto a surface in Figure 6 The reflection unit 21, 22 shown is directed. Of course, one of the elements in the Figures 2 to 5 The depicted reflection units 21, 22 are suitable for calibrating the laser scanner 3. The laser beam L is moved in the transverse direction Y along the reflection unit 21, 22. The laser beam L traverses a range of beam angles. Each position P of the laser beam L in the transverse direction Y corresponds to a specific beam angle of the laser beam L. For several positions P of the laser beam L in the transverse direction Y, a distance D of the laser scanner 3 to the reflection surface 31, 32, 33 from which the laser beam L is reflected is measured. The orientation of the laser scanner 3 is then determined from the measured distances D.

[0056] In the transverse direction Y at the center of the reflection unit 21, 22, the laser beam L travels at least approximately in the beam direction S and strikes the reflection unit 21, 22 at least approximately perpendicularly. If the distance of the laser scanner 3 in beam direction S to the reflection unit 21, 22 is significantly greater than the extent of the reflection unit 21, 22 in the transverse direction Y, then the emission angle of the laser beam L is approximately proportional to the position P of the laser beam L in the transverse direction Y. If this approximation is not sufficiently accurate, then the polar coordinates supplied by the laser scanner 3, namely emission angle and distance D, must be converted into Cartesian coordinates, namely position P in the transverse direction Y and distance D in the beam direction S.

[0057] Figure 7The first diagram shows measured distances D as a function of the position P of the laser beam L in the transverse direction Y. The position P of the laser beam L is divided into five sections B1, B2, B3, B4, B5.

[0058] In the first section B1, the laser beam L passes laterally past one foot 6 onto the screen 5 and is reflected by the third reflective surface 33. In the second section B2, the laser beam L strikes one foot 6 and is reflected by it. In the third section B3, the laser beam L passes through the slit 19 onto the screen 5 and is reflected by the third reflective surface 33. In the fourth section B4, the laser beam L strikes the other foot 6 and is reflected by it. In the fifth section B5, the laser beam L passes laterally past the other foot 6 onto the screen 5 and is reflected by the third reflective surface 33.

[0059] A predefined target field F in the first diagram describes the distance D of the laser scanner 3 to the screen 5 with predefined tolerances. Within the third section B3, the measured distance D lies within the aforementioned target field F. The laser beam L therefore travels in a horizontal direction, and the laser scanner 3 is horizontally oriented.

[0060] Figure 8 A second diagram shows measured distances D as a function of the position P of the laser beam L in the transverse direction Y. The position P of the laser beam L is divided into five sections B1, B2, B3, B4, B5.

[0061] In the first section B1, the laser beam L passes laterally past one foot 6 onto the screen 5 and is reflected by the third reflective surface 33. In the second section B2, the laser beam L strikes the third reflective area 14 of the second shield 8 and is reflected by it. In the third section B3, the laser beam L strikes alternately the first reflective area 12 and the second reflective area 13 of the second shield 8 and is reflected by each. In the fourth section B4, the laser beam L strikes the fourth reflective area 15 of the second shield 8 and is reflected by it. In the fifth section B5, the laser beam L passes laterally past the other foot 6 onto the screen 5 and is reflected by the third reflective surface 33.

[0062] A predefined target area F in the second diagram describes the distance D of the laser scanner 3 to the screen 5 with predefined tolerances. Within the third section B3, the measured distance D lies outside the aforementioned target area F. The measured distance D in the third section B3 changes abruptly due to the different reflection properties of the first reflection area 12 and the second reflection area 13. The laser beam L therefore travels downwards in the vertical direction Z, and the laser scanner 3 is tilted downwards in the vertical direction Z, i.e., towards the ground.

[0063] Figure 9 A third diagram shows measured distances D as a function of the position P of the laser beam L in the transverse direction Y. The position P of the laser beam L is divided into five sections B1, B2, B3, B4, B5.

[0064] In the first section B1, the laser beam L passes laterally past one foot 6 onto the screen 5 and is reflected by the third reflective surface 33. In the second section B2, the laser beam L strikes one foot 6 and is reflected by it. In the third section B3, the laser beam L strikes the first shield 7 and is reflected by the first reflective surface 31. In the fourth section B4, the laser beam L strikes the other foot 6 and is reflected by it. In the fifth section B5, the laser beam L passes laterally past the other foot 6 onto the screen 5 and is reflected by the third reflective surface 33.

[0065] A predefined target area F in the third diagram describes the distance D of the laser scanner 3 to the screen 5 with predefined tolerances. Within the third section B3, the measured distance D lies outside the aforementioned target area F. The measured distance D in the third section B3 is approximately constant. Therefore, the laser beam L travels upwards in the vertical direction Z, and the laser scanner 3 is tilted upwards in the vertical direction Z, i.e., away from the ground. Reference symbol list

[0066] 2 Vehicle 3 Laser scanner 4 Digital computer 5 Screen 6 Foot 7 First sign 8 Second sign 9 Gap 10 Spacer 11 Aperture 12 First reflection area 13 Second reflection area 14 Third reflection area 15 Fourth reflection area 16 Crossbar 21 First reflection unit 22 Second reflection unit 31 First reflection surface 32 Second reflection surface 33 Third reflection surface A1 First distance A2 Second distance B1 First section B2 Second section B3 Third section B4 Fourth section B5 Fifth section D Distance F Target field L Laser beam P Position S Beam direction Y Transverse direction Z Vertical direction

Claims

1. Device for calibrating a laser scanner (3), in particular of a vehicle (2), said device comprising at least one reflection unit (21, 22) for reflecting a laser beam (L) of the laser scanner (3), the at least one reflection unit (21, 22) comprising a first plate (7), a second plate (8) and a screen (5), the first plate (7) being arranged between the second plate (8) and the screen (5) in a beam direction (S), the first plate (7) having a first reflection surface (31) extending at least approximately at right angles to the beam direction (S), and the second plate (8) having a second reflection surface (32) extending at least approximately at right angles to the beam direction (S), and the screen (5) having a third reflection surface (33) extending at least approximately at right angles to the beam direction (S), the first plate (7) being arranged at an offset from the second plate (8) in a vertical direction (Z) in such a way that a gap (9) is formed between the first plate (7) and the second plate (8), said gap extending in the vertical direction (Z) and in a transverse direction (Y), and the screen (5) being formed and arranged such that a projection of the gap (9) in the beam direction (S) lands entirely on the third reflection surface (33) of the screen (5), the vertical direction (Z) extending at right angles to the beam direction (S) and to the transverse direction (Y), characterised in that the vertical direction (Z) runs at right angles to a floor on which the reflection unit stands, and in that an extent of the third reflection surface (33) of the screen (5) in the vertical direction (Z) is greater than an extent of the gap (9) in the vertical direction (Z), and in that an extent of the third reflection surface (31) of the screen (5) in the transverse direction (Y) is greater than an extent of the gap (9) in the transverse direction (Y).

2. Device according to claim 1, characterised in that the device comprises a first reflection unit (21) and a second reflection unit (22), which are oriented such that the beam direction (S) of the first reflection unit (21) extends at least approximately at right angles to the beam direction (S) of the second reflection unit (22).

3. Device according to claim 2, characterised in that the first reflection unit (21) and the second reflection unit (22) are oriented such that the beam direction (S) of the first reflection unit (21) extends at least approximately in parallel with the transverse direction (Y) of the second reflection unit (22).

4. Device according to any of claims 2 to 3, characterised in that the first reflection unit (21) and the second reflection unit (22) are oriented such that the vertical direction (Z) of the first reflection unit (21) extends in parallel with the vertical direction (Z) of the second reflection unit (22).

5. Device according to any of claims 2 to 4, characterised in that the first reflection unit (21) and the second reflection unit (22) are oriented such that the gap (9) of the first reflection unit (21) and the gap (9) of the second reflection unit (22) are aligned in the vertical direction (Z).

6. Device according to at least one of the preceding claims, characterised in that the at least one reflection unit (21, 22) has at least one spacer (10) which is arranged such that the first plate (7) and the screen (5) are arranged so as to be offset from one another by a first spacing (A1) in the beam direction (S). PT7. Device according to at least one of the preceding claims, characterised in that the at least one reflection unit (21, 22) has at least one footing (6) which extends predominantly in the vertical direction (Z) and which is arranged such that the first plate (7) and the second plate (8) are arranged so as to be offset from one another by a second spacing (A2) in the beam direction (S).

8. Device according to at least one of the preceding claims, characterised in that the at least one reflection unit (21, 22) has at least one shield (11) which is arranged next to the second plate (8) and / or next to the first plate (7) in the transverse direction (Y), and in that the at least one shield (11) has at least two reflection surfaces which are arranged at an angle to one another.

9. Device according to at least one of the preceding claims, characterised in that the first reflection surface (31) of the first plate (7) and / or the second reflection surface (32) of the second plate (8) comprise(s) a first reflection region (12) and a second reflection region (13), the reflection regions (12, 13) having different reflective properties, in particular different colours and / or different surface materials.

10. Device according to at least one of the preceding claims, characterised in that the first reflection surface (31) of the first plate (7) and / or the first reflection region (12) of the second reflection surface (32) of the second plate (8) is / are covered with black foam.

11. Device according to at least one of the preceding claims, characterised in that at least the edges of the first plate (7) and / or of the second plate (8) that adjoin the gap (9) of the reflection unit (21, 22) are covered with black foam.

12. Method for calibrating a laser scanner (3), in particular of a vehicle (2), by means of a device according to at least one of the preceding claims, characterised in that a laser beam (L) of the laser scanner (3) is directed at the at least one reflection unit (21, 22) at least approximately in the beam direction (S), and the laser beam (L) is moved along the at least one reflection unit (21, 22) in the transverse direction (Y), and in that for each of a plurality of positions (P) of the laser beam (L) in the transverse direction (Y), a distance (D) from the laser scanner (3) to the reflection surface (31, 32, 33) that reflects the laser beam (L) is measured, and in that an orientation of the laser scanner (3) is determined from the measured distances (D) from the laser scanner (3) to each reflection surface (31, 32, 33).

13. Method according to claim 12, characterised in that the device comprises a first reflection unit (21) and a second reflection unit (22), which are oriented such that the beam direction (S) of the first reflection unit (21) extends at least approximately at right angles to the beam direction (S) of the second reflection unit (22), the laser beam (L) of the laser scanner (3) being directed at the first reflection unit (21) at least approximately in the beam direction (S) of the first reflection unit (21), and the laser beam (L) being moved along the first reflection unit (21) in the transverse direction (Y) of the first reflection unit (21), and in that for each of a plurality of positions (P) of the laser beam (L) in the transverse direction (Y), a distance (D) from the laser scanner (3) to that reflection surface (31, 32, 33) of the first reflection unit (21) which reflects the laser beam (L) is measured, and in that the laser beam (L) of the laser scanner (3) is directed at the second reflection unit (22) at least approximately in the beam direction (S) of the second reflection unit (22), and the laser beam (L) is moved along the second reflection unit (22) in the transverse direction (Y) of the second reflection unit (22), and in that for each of a plurality of positions (P) of the laser beam (L) in the transverse direction (Y), a distance (D) between the laser scanner (3) and that reflection surface (31, 32, 33) of the second reflection unit (22) which reflects the laser beam (L) is measured.

14. Method according to any of claims 12 to 13, characterised in that the determined orientation of the laser scanner (3) is displayed optically and / or acoustically.