OPTICAL MEASUREMENT APPARATUS FOR DETERMINING OBJECT INFORMATION OF OBJECTS IN AT LEAST ONE MONITORING REGION

Abstract

An optical measurement apparatus for determining object information of objects in at least one monitoring region is disclosed. The apparatus has a reception device for receiving light signals coming from at least one object. The reception device comprises at least one electro-optical receiver (34) for converting light signals into electrical signals. At least one light diffraction element (52) is arranged in a receiver light path of the at least one reception device upstream of the at least one receiver (34). The receiver (34) has a plurality of reception regions (40) that are arranged one behind another viewed in the direction of at least one receiver axis (42) and that is evaluated separately with respect to the respectively received light intensity. At least one boundary periphery (54) of at least one light diffraction element (52) at least regionally does not extend perpendicularly to the at least one receiver axis (42) viewed in the projection onto the receiver (34).

Claims

1. An optical measurement apparatus for determining object information of objects in at least one monitoring region, the optical measurement apparatus comprising: at least one reception device for receiving light signals coming from at least one object, wherein the at least one reception device comprises at least one electro-optical receiver for converting light signals into electrical signals, wherein at least one light diffraction element is arranged in a receiver light path of the at least one reception device upstream of the at least one receiver, wherein the at least one electro-optical receiver has a plurality of reception regions arranged one behind another viewed in the direction of at least one receiver axis and that are evaluated separately with respect to the respectively received light intensity, and wherein at least one boundary periphery of at least one light diffraction element at least regionally does not extend perpendicularly to the at least one receiver axis viewed in the projection onto the at least one receiver.

2. The optical measurement apparatus according to claim 1, wherein the at least one boundary periphery of the at least one light diffraction element is at least one periphery of at least one optical lens, a periphery of a stop or mask, a periphery of a heating wire, or a periphery of a window of a housing of the measurement apparatus.

3. The optical measurement apparatus according to claim 1, wherein more than 7/10 of the extent of at least one boundary periphery of at least one light diffraction element do not extend perpendicularly to the at least one receiver axis viewed in the projection onto the at least one receiver.

4. The optical measurement apparatus according to claim 1, wherein at least one boundary periphery of at least one light diffraction element extends at least regionally in a zigzag shape and/or at least regionally in a wave shape and/or at least regionally in a zigzag shape with flattened and/or rounded tips and/or at least regionally has a free curve profile.

5. The optical measurement apparatus according to claim 1, wherein the optical measurement apparatus has a housing in which at least one reception device is arranged, and the housing has at least one window through which light signals passes from the monitoring region to the at least one reception device.

6. The optical measurement apparatus according to claim 1, wherein the at least one receiver has a plurality of individual reception elements with in each case at least one reception region and/or the at least one receiver has at least one line-type or area-type arrangement of a plurality of reception regions.

7. The optical measurement apparatus according to claim 1, wherein at least one rectangular or square optical lens is arranged in the receiver light path.

8. The optical measurement apparatus according to claim 1, wherein the optical measurement apparatus is configured for determining at least one direction of at least one captured object relative to the measurement apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Further advantages, features and details of the invention are apparent from the following description, in which exemplary embodiments of the invention will be explained in greater detail with reference to the drawing. A person skilled in the art will also expediently consider individually the features that have been disclosed in combination in the drawing, the description and the claims and combine them to form further meaningful combinations. Schematically, in the drawings,

[0046] FIG. 1 shows a front view of a motor vehicle with an optical measurement apparatus for monitoring a monitoring region in front of the motor vehicle in the driving direction;

[0047] FIG. 2 shows a longitudinal section of an optical measurement apparatus according to a first exemplary embodiment, which can be used in the vehicle from FIG. 1;

[0048] FIG. 3 shows a view through a window of the optical measurement apparatus from FIG. 2;

[0049] FIG. 4 shows a view through a window of an optical measurement apparatus according to a second exemplary embodiment, which can be used in the vehicle from FIG. 1;

[0050] FIG. 5 shows a view through a window of an optical measurement apparatus according to a third exemplary embodiment, which can be used in the vehicle from FIG. 1;

[0051] FIG. 6 shows a view through a reception lens of the optical measurement apparatuses from FIG. 2;

[0052] FIG. 7 shows a view through a reception lens of an optical measurement apparatus according to a fourth exemplary embodiment, which can be used in the vehicle from the figure;

[0053] FIG. 8 shows a longitudinal section of an optical measurement apparatus, in which the invention is not used;

[0054] FIG. 9 shows a view through a window of the optical measurement apparatus from FIG. 8.

[0055] In the figures, identical components are provided with the same reference signs.

EMBODIMENT(S) OF THE INVENTION

[0056] FIG. 1 illustrates a front view of a motor vehicle 10 by way of example in the form of a passenger vehicle. The motor vehicle 10 has a driver assistance system 12, with which the motor vehicle 10 can be operated autonomously or partially autonomously in a manner which is of no further interest here.

[0057] The motor vehicle 10 furthermore has an optical measurement apparatus 14, which is arranged, by way of example, in the front bumper. The optical measurement apparatus 14 can be used to monitor a monitoring region 16, designated in FIG. 2, in front of the motor vehicle 10 in the driving direction for objects 18. The optical measurement apparatus 14 can also be arranged at a different location of the motor vehicle 10 and with a different alignment.

[0058] The optical measurement apparatus 14 can be used to capture standing or moving objects 18, for example vehicles, persons, animals, plants, obstacles, road unevennesses, in particular potholes or rocks, roadway boundaries, traffic signs, free spaces, in particular free parking spaces or the like.

[0059] The optical measurement apparatus 14 can be used to ascertain object information, for example distances, directions and speeds of captured objects 18 relative to the optical measurement apparatus 14, that is to say relative to the motor vehicle 10. The measurement apparatus 14 can be designed for example as a laser-based distance measurement system, for example as a LiDAR system.

[0060] The optical measurement apparatus 14 is connected to the driver assistance system 12 for the transmission of signals. Object information of objects 18 captured with the optical measurement apparatus 14 is transmitted to the driver assistance system 12. The object information is processed with the driver assistance system 12 and can be used for controlling functions of the motor vehicle 10.

[0061] FIG. 2 shows a longitudinal section of an optical measurement apparatus 14 according to a first exemplary embodiment.

[0062] The optical measurement apparatus 14 comprises a housing 20. The housing 20 has, on its side facing the monitoring region 16, a window 22.

[0063] A transmission device 24, a reception device 26 and a control and evaluation device 28 are arranged in the housing 20.

[0064] During the operation of the measurement apparatuses 14, transmission light signals 30, for example in the form of laser pulses, are produced using the transmission device 24. The transmission light signals 30 may be invisible to the human eye, for example. The window 22 is made from a material that is transmissive to the transmission light signals 30. The transmission light signals 30 are transmitted through the window 22 into the monitoring region 16.

[0065] A light signal deflection device (not shown), for example a deflection mirror device or the like, with which the transmission light signals 30 can be steered into the monitoring region 16, can be optionally arranged in the housing 20.

[0066] The transmission light segments 30 are reflected at objects 18 in the monitoring region 16. The transmission light signals 30 reflected in the direction of the measurement apparatus 14 are below referred to as reception light signals 32 for the purposes of better differentiation. The reception light signals 32 pass through the window 22 to the reception device 26. The reception light signals 22 in the housing 20 can optionally be deflected using the deflection mirror device.

[0067] Using the reception device 26, the reception light signals 32 are converted into electrical signals and transmitted to the control and evaluation device 28. The object information, specifically the distance, the direction and the speed of the captured object 18 relative to the measurement apparatus 14, is ascertained from the captured reception light signals 32. The object information is transmitted to the driver assistance system 12 using the control and evaluation device 28.

[0068] The reception device 26 comprises, by way of example, a receiver 34 and an optical reception lens 36. The reception lens 36 and the window 22 are located in a receiver light path 38 of the receiver 34. The receiver light path 38 within the meaning of the invention is the path travelled by the reception light signals 32 coming from the object 18. For the sake of clarity, FIG. 2 indicates the receiver light path 38 merely as a dashed axis. This axis is intended to indicate the centre of the receiver light path 38. The receiver light path 38 is actually understood to mean a three-dimensional space that in FIG. 2 extends, by way of example, from the axis upwards, downwards, into the drawing plane and away from the drawing plane.

[0069] The reception lens 36 is located between the window 22 and the receiver 34. The reception light signals 32 are focused onto the receiver 34 using the reception lens 36.

[0070] The receiver 34 has a plurality of reception regions 40. The reception regions 40 can in each case be implemented as an avalanche photodiode, by way of example. The reception regions 40 are arranged one behind another viewed in the direction of a receiver axis 42. In the exemplary embodiment shown, the receiver axis 42 extends, with a normal alignment of the motor vehicle 10, as shown in FIG. 2, spatially vertically, with the result that the reception regions 40 are arranged there one above another. With the vertical arrangement of reception regions 40 according to the exemplary embodiment, spatial height information with respect to the captured object 18 can be ascertained using the receiver 34.

[0071] Rather than with separate avalanche photodiodes, the receiver 34 can also be implemented in the form of a line sensor having a plurality of image points arranged correspondingly along the receiver axis 42.

[0072] The reception lens 36 has, for example, a quadrangular, specifically a square or rectangular, design. The reception lens 36 is shown in front of the receiver 34 in FIG. 6. The illustration of the window 22 was omitted for clarity reasons in FIG. 6. The reception lens 36 is aligned such that two of its peripheries, specifically the upper periphery 46 and the lower periphery 48, extend perpendicularly to the receiver axis 42 viewed in the projection onto the receiver 34.

[0073] Two masks 44 are arranged on the reception lens 36. The masks 44 are located, by way of example, on the side of the reception lens 36 facing the receiver 34. One of the masks 44 extends along the upper periphery 46 of the reception lens 36 and covers the upper periphery 46. The other mask 44 extends along the lower periphery 48 of the reception lens 36 and covers the lower periphery 48. On their sides facing one another, the masks 44 each have a zigzag-shaped boundary periphery 50.

[0074] The masks 44 in each case act as light diffraction elements for the reception light signals 32. It is known that lines and edges produce diffraction patterns according to their alignment. Diffraction patterns that expand in the reception regions 40 in the direction of the receiver axis 42 can lead to crosstalk between the reception regions 40. None of the zigzag-shaped boundary peripheries 50 of the masks 44 extend perpendicularly to the receiver axis 42 viewed in the projection onto the receiver 34. In this way it is ensured that expansions of the diffraction patterns, brought about by the boundary peripheries 50, in the reception regions 40 in the direction of the receiver axis 42 are reduced.

[0075] By way of example, two heating wires 52 are arranged at the window 22. The heating wires 52 are located, protected with respect to the environment, for example at the inner side of the window 22 facing the interior of the housing 20. The heating wires 52 are connected to a power supply, which is not shown for the sake of clarity. The heating wires 52 can be used to control the temperature of the window 22 in order to prevent for example that the window 22 fogs up or ices over.

[0076] The heating wires 52 are located in the receiver light path 38 and thus likewise act as light diffraction elements for the reception light signals 32. The upper peripheries of the heating wires 52 in FIGS. 2 and 3 in each case form boundary peripheries 54. The heating wires 52 and the boundary peripheries 54 have a zigzag-shaped profile. The boundary peripheries 54 do not in any portion extend perpendicularly to the receiver axis 42 viewed in the projection onto the receiver 34. In this way it is ensured that expansions of the diffraction patterns, caused by the boundary peripheries 54, in the reception regions 40 in the direction of the receiver axis 42 are reduced.

[0077] Rather than one common window 22 for transmission light signals 30 and reception light signals 32, separate transmission windows and reception windows may be provided.

[0078] During a measurement with the measurement apparatus 14, transmission light signals 30 are produced with the transmission device 24 and transmitted through the window 22 into the monitoring region 16.

[0079] The reception light signals 32 reflected at an object 18 initially pass through the window 22. In the process, diffraction patterns are produced at the boundary peripheries 54 of the heating wires 52. Owing to the zigzag-shaped profile of the boundary peripheries 52, the diffraction patterns extend substantially at an angle with respect to the receiver axis 42.

[0080] The reception light signals 32 are focused onto the receiver 34 using the reception lens 36. In the process, diffraction patterns are produced at the boundary peripheries 50 of the masks 44. Owing to the zigzag-shaped profile of the boundary peripheries 50, the diffraction patterns extend substantially at an angle with respect to the receiver axis 42.

[0081] Depending on the height at which the object 18 is located, the corresponding reception light signals 32 illuminate the receiver 34 at the corresponding height in a full-illumination region 56, which is indicated in FIG. 2. The shape of the full-illumination region 56 is influenced by the diffraction patterns produced at the boundary peripheries 50 and 54. FIG. 3 indicates, by way of example, the full-illumination region 56 merely for illustration purposes in the form of a star, wherein the spikes of the star in each case extend at an angle with respect to the receiver axis 42. The actual shape of the full-illumination region 56 depends, among other things, on the profile of the boundary peripheries 50 and 54 and their arrangement. In FIG. 3, the illustration of the reception lens 36 and of the transmission device 24 is omitted for the sake of clarity.

[0082] Owing to the reduction according to the invention of the extent of the above-described diffraction patterns in the direction of the receiver axis 42, the full-illumination region 56 fully illuminates only the second reception regions 40 from the top in the exemplary embodiment shown. The in each case zigzag-shaped profile of the boundary peripheries 50 and 54 ensures that no crosstalk, or at least greatly reduced crosstalk, to the adjacent, specifically the first and the third reception regions 40 from the top occurs.

[0083] Height information relating to the object 18 can be acquired from the reception light signals 32, which are captured with the reception region 40 that is struck by the full-illumination region 56.

[0084] FIG. 4 shows a window 22 with heating wires 52 according to a second exemplary embodiment. The elements that are similar to those of the first exemplary embodiment from FIGS. 2 and 3 are provided with the same reference signs. The second exemplary embodiment differs from the first exemplary embodiment in that the heating wires 52 extend in a sawtooth shape.

[0085] FIG. 5 shows a window 22 with heating wires 52 according to a third exemplary embodiment. The elements that are similar to those of the first exemplary embodiment from FIGS. 2 and 3 are provided with the same reference signs. The third exemplary embodiment differs from the first exemplary embodiment in that the zigzag-shaped heating wires 52 have flattened tips in their reversal points. By way of example, more than 7/10 of the extent of the respective boundary peripheries 54 do not extend perpendicularly to the receiver axis 42 viewed in the projection onto the receiver 34.

[0086] FIG. 7 shows a reception lens 36 with masks 44 and a receiver 34 of a measurement apparatus 14 according to a fourth exemplary embodiment. The elements that are similar to those of the first exemplary embodiment from FIGS. 2 and 3 are provided with the same reference signs. The fourth exemplary embodiment differs from the first exemplary embodiment in that the reception regions 40 of the receiver 34 are arranged two-dimensionally in rows and columns. The receiver 34 has a vertical reception axis 42a and a horizontal reception axis 42b. Using the two-dimensional receiver 34, spatially horizontal and spatially vertical direction information relating to the object 18 relative to the measurement apparatus 14 can be ascertained.

[0087] In order to reduce in respective measurements the influence of diffraction patterns brought about by the lateral peripheries 58 of the receiver lens 22 on the extent of the respective full-illumination regions, the lateral peripheries 58 are covered with in each case vertically extending masks 44. The lateral masks 44 have, similar to the horizontally extending masks 44 at the upper periphery 46 and the lower periphery 48, in each case zigzag-shaped boundary peripheries 54.

[0088] FIGS. 8 and 9 show merely for comparison purposes a measurement apparatus 14 that is not in accordance with the invention, in which the heating wires 52 do not extend in a zigzag shape but straight and perpendicularly to the receiver axis 42 viewed in the projection, that is to say not in accordance with the invention. Without the masks 44, the upper periphery 46 and the lower periphery 48 extending perpendicularly to the receiver axis 42 viewed in the projection bring about diffraction patterns that expand the full-illumination region 56 in the direction of the receiver axis 42 for example over three reception regions 40. This results in crosstalk of the reception light signals 32 for example into the first and the third reception region 40 from the top and thus to a loss of accuracy when determining the height information of objects 18.