CN-114563792-B - Laser-based detection device, motor vehicle and method for operating a laser-based detection device

Abstract

The invention relates to a detection device (10) for detecting the surroundings, wherein the detection device (10) has a transmission unit (14) with a laser light source (36) which is designed to transmit a pulse train (46) with a plurality of first light pulses (18 a) which have a predetermined time interval (T, T1, T2) from one another, and a receiving unit (16) which is designed to detect a second light pulse (18 b). The invention provides that the transmission unit (14) is designed to change a predetermined time interval (T, T1, T2) during the transmission of the pulse train (46) according to a predetermined modulation pattern (56), wherein the detection device (10) has an evaluation unit (24) which is designed to evaluate the second light pulses (18 b) detected by the receiving unit (16) according to the predetermined modulation pattern (56).

Inventors

• H. G. Kurtz
• MEINECKE MARC-MICHAEL

Assignees

• 大众汽车股份公司

Dates

Publication Date

20260512

Application Date

20211126

Priority Date

20201127

Claims (11)

1. 1. A detection device (10) for ambient detection, wherein the detection device (10) has a transmission unit (14) with a laser light source (36) designed to transmit a pulse train (46) with a plurality of first light pulses (18 a) having a predetermined time interval (T, T1, T2) from each other, and a receiving unit (16) designed to detect a second light pulse (18 b), characterized in that the transmission unit (14) is designed to change the predetermined time interval (T, T1, T2) during transmission of the pulse train (46) according to a preset modulation pattern (56), wherein the detection device (10) has an evaluation unit (24) designed to evaluate the second light pulses (18 b) detected by the receiving unit (16) according to the preset modulation pattern (56) to determine whether the predetermined time interval (T, T1, T2) changed according to the preset modulation pattern (56) is a random number of the resonant cavity (T1, T2) is provided during transmission of the pulse train (46), wherein the resonant cavity (T1) is designed to change the resonant cavity (T2) according to the preset modulation pattern (56), wherein the transmission unit (14) is designed to change the optical path length in time in order to change the predetermined time interval (T, T1, T2) during the transmission of the pulse train (46), wherein the resonant cavity (42) has an active medium (38) with an optical density, wherein the transmission unit (14) is designed to change the optical density of the active medium (38) in time in order to change the optical path length in time.
2. 2. The detection device (10) according to claim 1, characterized in that the evaluation unit (24) is designed to check whether the detected second light pulses (18 b) and/or which of the detected second light pulses (18 b) are at least part of at least some of the first light pulses (18 a) transmitted by the transmission unit (14) and reflected at objects (20) in the environment, according to the preset modulation pattern (56).
3. 3. The detection device (10) according to any one of the preceding claims 1 to 2, characterized in that the evaluation unit (24) is designed to transform the detected temporal intensity profile (48 a,48 b) of the detected second light pulse (18 b) into a frequency space by means of a fourier transformation (50) for evaluating the second light pulse (18 b), and to determine the respective time interval (T, T1, T2) of the second light pulse (18 a) as a function of the result (54 a,54 b) of the fourier transformation (50).
4. 4. A detection device (10) according to claim 3, characterized in that the evaluation unit (24) is designed to determine a frequency spacing (f rep ,f1 rep ,f2 rep ) from the result (54 a,54 b) of the fourier transformation (50), which is a frequency comb with a plurality of frequencies (54 a,54 b) having the frequency spacing from each other, and to determine a corresponding time spacing (T, T1, T2) of the second light pulses (18 b) from the frequency spacing (f rep ,f1 rep ,f2 rep ).
5. 5. The detection device (10) according to any of the preceding claims 1 to 2, characterized in that the transmission unit (14) is designed to mechanically change the resonator length (L) of the resonator (42) in time in order to change the optical path length in time.
6. 6. The detection device (10) according to any of the preceding claims 1 to 2, characterized in that the transmission unit (14) is designed to change the transmission power of the detection device (10) in order to change the predetermined time interval (T, T1, T2) during the transmission of the pulse train (46).
7. 7. The detection device (10) according to any of the preceding claims 1 to 2, characterized in that the modulation pattern (56) is designed such that the time interval (T, T1, T2) is changed based on a barker code.
8. 8. The detection device (10) according to any of the preceding claims 1 to 2, characterized in that the modulation pattern (56) is designed such that the time interval (T, T1, T2) is changed based on a barker code with a length 13.
9. 9. The detection device (10) according to any of the preceding claims 1 to 2, characterized in that the detection device (10) is configured as a lidar system (10).
10. 10. A motor vehicle (12) with a detection device (10) according to any one of the preceding claims.
11. 11. Method for operating a detection device (10) for ambient detection, wherein the detection device (10) has a transmission unit (14) with a laser light source (36) which transmits a pulse train (46) with a plurality of first light pulses (18 a) which have a predetermined time interval (T, T1, T2) from one another, and a reception unit (16) which is designed to detect a second light pulse (18 b), characterized in that the transmission unit (14) changes the predetermined time interval (T, T1, T2) during transmission of the pulse train (46) according to a predetermined modulation pattern (56), wherein the detection device (10) has an evaluation unit (24) which evaluates the second light pulses (18 b) detected by the reception unit (16) according to the predetermined modulation pattern (56) to determine whether the predetermined time interval (T, T1, T2) which has been changed according to the predetermined modulation pattern (56) is reflected in the second light pulses (18 b), wherein the resonant frequency (T1, T2) is designed to have a random frequency of the resonant frequency of the laser light source (46) which has been provided for the purpose of changing the resonant frequency (56), wherein the transmission unit (14) is designed to change the optical path length in time in order to change the predetermined time interval (T, T1, T2) during the transmission of the pulse train (46), wherein the resonant cavity (42) has an active medium (38) with an optical density, wherein the transmission unit (14) is designed to change the optical density of the active medium (38) in time in order to change the optical path length in time.

Description

Laser-based detection device, motor vehicle and method for operating a laser-based detection device Technical Field The invention relates to a detection device for detecting the surroundings, wherein the detection device has a transmission unit with a laser light source, which is designed to transmit a pulse train (Pulszug) with a plurality of first light pulses, which have a predetermined time interval from one another, and a detection device, which is designed to detect a second light pulse. The invention also relates to a motor vehicle having such a detection device and to a method for operating the detection device. Background Laser-based Detection devices, such as laser radar (Light Detection AND RANGING) systems, are known from the prior art. At the same time, such systems are increasingly used in the automotive field, since it is precisely for autopilot that as reliable as possible ambient perception is essential. In particular, lidar plays a critical role in redundant, robust ambient detection, since this sensor type can accurately measure distance in ambient detection and can also be used for classification. Conventional lidar systems rely, inter alia, on Time-of-Flight (Time-of-Flight) measurement methods in which light travel Time (Lichtlaufzeit) is measured in order to determine the distance traversed. In this case, light pulses are emitted which are reflected and detected by the surroundings. The maximum range of the system is related to the number of photons reflected. The more photons are sent back from the surface of an object or obstacle, the earlier the object or obstacle is detected by a photodiode mounted in the sensor, which is an example of a receiving unit. The number of photons that can be detected here scales linearly with the emitted power. Thus, time-of-flight lidar systems typically operate near maximum power that can be emitted in use for autopilot functions. The number of photons emitted is correspondingly so high that these systems are particularly susceptible to interactions with other lidar systems or emission sources of the same wavelength. Thus, for example, ghost objects (Geisterziele) appear as interactions with spatially adjacent systems (e.g., systems used on other vehicles). It is therefore desirable to be able to distinguish the light pulses emitted and detected by one lidar as reliably as possible from the light pulses of the other lidar in order to avoid ghost targets and thus improve the detection quality. Disclosure of Invention The object of the present invention is therefore to provide a laser-based detection device for detecting the surroundings, a motor vehicle and a method for operating a laser-based detection device, which achieve a detection quality as high as possible during the detection of the surroundings. This object is achieved by a detection device, a motor vehicle and a method according to the invention. An advantageous embodiment of the invention is the content of the description and of the drawing. The inventive detection device for detecting the surroundings has a transmission unit with a laser light source, which is designed to transmit a pulse train with a plurality of first light pulses, which have a predetermined time interval from one another, and a reception unit, which is designed to change the predetermined time interval during the transmission of the pulse train according to a predetermined modulation pattern (Modulationsschema), wherein the detection device furthermore has an evaluation unit, which is designed to evaluate the second light pulses detected by the reception unit according to the predetermined modulation pattern. By varying the time intervals of the transmitted light pulses according to a predetermined modulation pattern, it is advantageously possible to distinguish these light pulses from the light pulses of other detection devices according to the predetermined modulation pattern when received by the transmission unit. By varying the light pulse spacing over time, ghost objects can be effectively avoided and thus the detection quality in the detection of the surroundings by the detection device can be significantly improved. The maximum possible range of action of the detection device remains substantially unaffected compared to other modulation variants (e.g. amplitude modulation), since the amplitude of the light pulses is directly related to the intensity of the light pulses, rather than to the pulse spacing. The pulse train is a sequence of a plurality of individual light pulses. The pulse train here comprises at least two light pulses. The pulse train may also have a plurality of sub-pulse trains, which in turn each comprise a plurality of (that is to say at least two) light pulses, wherein, for example, the light pulses within a sub-pulse train may be emitted at a constant time interval from one another and the time interval between the light pulses of different sub-pulse trains may be modulated according to a modu