Diagnostic device for a scanning lidar measuring device

Abstract

The present invention relates to a diagnostic device (10) for diagnosing a functionality of a scanning lidar measuring device (20), having: a communications interface (12) for receiving an input signal with information from the lidar measuring device (20) regarding a measuring direction and a determined distance in the measuring direction; a separation unit (14) for defining, on the basis of the measuring direction, a calibration range corresponding at least in sections with a dead zone of the lidar measuring device (20); and a diagnostic unit (16) for diagnosing a functionality of the lidar measuring device (20) on the basis of the input signal in the event of a measurement in the calibration range. The lidar measuring device 20 comprises the diagnostic device (10) and a housing in which the diagnostic device (10), a laser light source (22) and a detector (24) are disposed. The laser light source 22 transmits a laser light beam 26 to a rotating mirror 28. The laser light beam 26 is deflected by the rotating mirror 28, cast on an object to be measured and scattered back from the object to be measured, and preferably likewise cast back to a detector surface of the detector 24 by means of the rotating mirror 28. Consequently, the lidar system can be calibrated on an ongoing basis, and this can ensure a reliable measurement. The present invention also relates to a corresponding system (18), method and computer program product.

Description

[0001] Diagnostic device for a scanning lidar measuring device

[0002] The present invention relates to a diagnostic device for diagnosing the functionality of a scanning lidar measuring device. The present invention further relates to a corresponding system, method, and computer program product.

[0003] A LIDAR (light detection and ranging) system is based on the emission of light pulses and the detection of the reflected light. For example, a time-of-flight measurement can be used to calculate the distance to the location of the reflection. A target can be detected by analyzing the received reflections. Regarding the technical implementation of the corresponding sensor, a distinction is made between scanning systems, which usually function based on micromirrors, and non-scanning systems, in which several transmitting and receiving elements are arranged statically next to one another (especially so-called focal plane arrays).

[0004] Currently, LiDAR systems are known that determine distances based on, for example, a time-of-flight (ToF) method or based on the optical displacement of a laser beam. In this case, a reflection of a laser beam is directed onto a CMOS or CCD sensor, or a similar sensor, preferably using a lens or optical unit. This sensor can have a linear or matrix-like pixel structure.

[0005] A safety laser scanner with a light transmitter and receiver is known from published patent application DE 10 2019 111 852 B3. The light transmitter emits a light beam onto a rotating mirror. The safety laser scanner has a reference target for calibration.

[0006] Since such lidar systems are sometimes used in safety-relevant applications, such as road traffic, the task of verifying the data collected by such a lidar system arises. In particular, the functionality and reliability of the lidar system and its measurement results must be ensured.

[0007] This problem is solved by the subject matter of the subordinate claims.

[0008] Preferred embodiments of the invention are described in the dependent claims. It is understood that the features mentioned above and those to be explained below can be used not only in the respective combinations specified, but also in other combinations or alone, without departing from the scope of the present invention. In particular, the method and the computer program product can be implemented according to the embodiments described for the device in the dependent claims.

[0009] The accuracy of a lidar system's distance measurement is verified by periodically receiving the outgoing laser beam at a known distance from the lidar system's receiver using known measurement methods or measurement patterns. Consequently, the lidar system can be continuously calibrated, ensuring reliable measurements. Ambiguous measurements can be improved. It is understood that during a calibration measurement, every part of a detector in the lidar system can be illuminated and checked. By implementing the inventive concept in a diagnostic device, it is possible to use the inventive concept with existing lidar systems. A communication interface for receiving an input signal allows for efficient and rapid retrofitting of the diagnostic device into an existing lidar measuring device.

[0010] It is understood that the diagnostic device can also be implemented directly during the production of a lidar measuring device. In particular, the diagnostic device can be designed as part of a lidar measuring device and does not necessarily have to be arranged separately from it in a separate housing or the like.

[0011] A separation unit for defining a calibration range enables rapid functionality of the diagnostic device; in particular, a calibration measurement can be performed preferably before the first measurement. Because the calibration range corresponds, at least in part, to a dead zone of the lidar measuring device, a high data yield can be achieved despite calibration, especially despite regular calibration.

[0012] The calibration range is, in particular, a directional range relative to a measurement direction of the lidar measuring device. Therefore, calibration is advantageously performed when no other measurement is possible with the lidar measuring device, since the current measurement direction lies within the dead band of the lidar measuring device during calibration.

[0013] A diagnostic unit for diagnosing the functionality of a lidar measuring device enables a quick and reliable determination of the reliability of the measurements of a lidar measuring device. The diagnostic unit can take various forms. In particular, the diagnostic unit can comprise a computer chip, in particular a special chip, e.g., a 1oo2 architecture, such as an FPGA, a comparator, or even software running on the special chip.

[0014] In particular, direct laser beams can be used for calibration. Preferably, a direct laser beam path runs from the laser light source to a reflection body of the lidar measuring device, and from this reflection body directly to a detector of the lidar measuring device. Therefore, calibration can preferably be performed without an additional reference target. Reference target-free calibration is performed. The reflection body is the unit of the lidar measuring device used to deflect a laser beam for a measurement.

[0015] The lidar measuring device preferably has a dead zone, wherein the calibration measurement is carried out within this dead zone, so that the field of view of the lidar measuring device is not restricted by the calibration.

[0016] The diagnostic device can therefore be used particularly advantageously with lidar measuring devices that already have a dead zone. Preferably, the diagnostic unit is designed to compare an expected predefined distance and an actually measured distance during a measurement in the calibration range and, based on the comparison, to diagnose the functionality of the lidar measuring device. A comparison allows the functionality of the lidar measuring device to be determined in a technically simple and, in particular, rapid manner. It is understood that all common methods of determining distances in a lidar measurement can be applied. In particular, the distance can correspond to a phase shift and / or a time-of-flight and / or be converted into these.

[0017] It goes without saying that calibration can also be performed based on raw data. The received data does not necessarily have to be converted into a distance. For example, calibration can also be performed based on a ToF, ADC (analog digital counter) entries, or similar. It is clear that a distance results from various parameters, such as a propagation time, a phase shift, etc., and in this respect, distance is preferably used synonymously for the aforementioned quantities.

[0018] Particularly preferred is to mark all measurements of the lidar measuring device that were performed between two successful calibrations as trustworthy. This allows calibration to be performed before and after a measurement, so that preferably two successful calibrations can be assigned to one measurement. Trust and security are increased.

[0019] Calibration can be understood, in particular, as the performance of a measurement within the calibration range, and this measurement, within predefined limits, agrees with an expected result. A calibration cycle therefore preferably involves a comparison of a measurement with an expected result and is preferably successful if the functionality can be confirmed by the calibration cycle.

[0020] Advantageously, the diagnostic device can be configured to determine the measurement direction based on the angular position of a reflective body of the lidar measuring device. Angular position refers, in particular, to the diagnostic device being able to determine the angle at which a laser light beam incident on the reflective body is deflected or reflected. The term "reflective body" is to be understood broadly, so that any optical unit that deflects the incident laser light beam can be considered a reflective body.

[0021] For example, the reflection body can comprise a rotating mirror or rotating micromirrors. It is understood that materials with a variable refractive index can also deflect a laser light beam and can be considered reflection bodies in this sense. Those skilled in the art are familiar with various options for deflecting light beams, in particular laser light beams, which can be subsumed under the term "reflection body" in the present application.

[0022] In the case of a rotating mirror, the angular position of the reflecting body can be detected using a rotary encoder, for example. Furthermore, the angular position can also be extracted from a control signal for the rotating mirror.

[0023] By determining the measurement direction based on an angular position and diagnosing functionality based on a measurement in the measurement direction and an expected predefined distance in the measurement direction, the functionality of the lidar measuring device can be determined efficiently and quickly, for example, using lookup tables. This allows the required computing power to be kept low without influencing or compromising the reliability of the diagnosis. An energy-efficient and fast diagnostic device can be created.

[0024] In a particularly preferred embodiment, the diagnostic device and preferably the diagnostic unit are configured to determine wear, contamination, and / or aging of the lidar measuring device based on an expected predefined distance and an actually measured distance during a measurement in the calibration range. By determining wear, contamination, and / or aging, a confidence parameter for the reliability of the measurement can be created. In particular, the detection of contamination, wear, and / or aging of the lidar measuring device enables early detection of a risk of failure or a loss of reliability of the measurements.

[0025] Furthermore, insights into the durability and wear of individual components of the lidar measuring device can be obtained. Particularly preferably, the diagnostic unit is configured to provide an indication of a required adjustment of the lidar measuring device based on the determined wear, contamination, and / or aging of the lidar measuring device. Additionally or alternatively, the diagnostic unit is configured to adjust the lidar measuring device.

[0026] Adjustment, for example, refers to adjusting the current and / or voltage of a laser light source and / or the current and / or voltage of a receiver unit. It is understood that, depending on the lidar measuring device, further adjustments are conceivable, which can preferably be carried out and / or initiated partially or fully automatically by the diagnostic unit.

[0027] For example, if contamination is detected, the light intensity can be increased to achieve a sufficient signal-to-noise ratio during a measurement with the lidar measuring device. It is understood that control commands are preferably transmitted via the communication interface between the diagnostic device and the lidar measuring device for this purpose.

[0028] A control command can also be a voltage and / or a current. In particular, it is conceivable that the diagnostic device does not actively instruct a control unit of the lidar measuring device, but instead applies an additional voltage or current to the measuring diode or laser light source in addition to the voltage supplied by the control unit of the lidar measuring device or a current supplied by the control unit of the lidar measuring device. This allows an existing lidar measuring device to be advantageously retrofitted with a diagnostic device without interfering with the control electronics.

[0029] By issuing a warning, the replacement of aged or worn components, or the cleaning of contaminated components, can also be initiated. This allows for sustainable, reliable measurements using the Lidar measuring device.

[0030] Particularly preferably, a calibration measurement can also be performed between a laser light source, a reflection surface of a reflection body, in particular a mirror of the lidar measuring device, and at least one other surface. This allows the frequency of calibration measurements to be increased, since not only direct but also partially reflected laser light beams can be used for calibration. For example, calibration can be performed at shorter intervals. The reliability of the measurements can be confirmed more frequently, and potential measurement errors can be detected more quickly.

[0031] This also allows a longer distance to be used for calibration.

[0032] The invention is described and explained in more detail below using selected embodiments in conjunction with the accompanying drawings. They show:

[0033] Figure 1: a schematic representation of a diagnostic device;

[0034] Figure 2a: a schematic perspective view of a lidar measuring device with a diagnostic device during a measuring process;

[0035] Figure 2b: a top view of the lidar measuring device according to Figure 2a;

[0036] Figure 3a: a perspective view of a lidar measuring device during a calibration measurement;

[0037] Figure 3b: a schematic top view of the lidar measuring device according to Figure 3a; Figure 4a: a schematic perspective view of a lidar measuring device during a further calibration measurement;

[0038] Figure 4b: a top view of the lidar measuring device according to Figure 4a.

[0039] Figure 1 shows a diagnostic device 10 for diagnosing the functionality of a scanning lidar measuring device (not shown).

[0040] The diagnostic device 10 has a communication interface 12, a separation unit 14, and a diagnostic unit 16. The communication interface 12 is configured to receive an input signal containing information from the lidar measuring device (not shown) regarding a measuring direction in which the lidar measuring device is measuring, and a result of the measurement in this measuring direction, for example, a determined distance in the measuring direction.

[0041] The separation unit 14 is designed to define a calibration range. The calibration range corresponds, at least in part, to a dead zone of the lidar measuring device. Particularly preferably, the calibration range is completely contained within the dead zone. The calibration range is determined based on the measuring direction of the lidar measuring device.

[0042] The diagnostic unit 16 is configured to diagnose the functionality of the lidar measuring device. The diagnostic unit 16 diagnoses the functionality based on the input signal during a measurement of the lidar measuring device 20 in the calibration range.

[0043] Figure 2a shows a schematic perspective view of a system 18 comprising a lidar measuring device 20 and a diagnostic device 10 during a measurement.

[0044] In the example shown, the lidar measuring device 20 comprises the diagnostic device 10 and a housing in which the diagnostic device 10, a laser light source 22, and a detector 24 are arranged. The laser light source 22 transmits a laser light beam 26 onto a rotating mirror 28. The laser light beam 26 is deflected by the rotating mirror 28, projected onto an object to be measured, and scattered back by the object to be measured, preferably also reflected back onto a detector surface of the detector 24 by means of the rotating mirror 28.

[0045] In this case, the distance between the object to be measured and the lidar measuring device 20 can be determined both by determining the time of flight and by a phase shift.

[0046] It is understood that the laser light source 22 can comprise several individual laser light sources, allowing multiple measurements to run in parallel. It is also understood that, depending on the measurement method, individual laser light pulses can also be emitted.

[0047] Figure 2b shows a top view of the measurement according to Figure 2a for clarity. Like reference numerals refer to like features and will not be explained again.

[0048] For clarity, the laser light beam 26 has been shown only in the area of ​​the lidar measuring device 20. It is understood that the laser light beam 26 continues to an object or target to be measured and is scattered back to the detector 24.

[0049] The term "laser light beam 26" is to be understood broadly; in particular, a laser pulse can also be encompassed by the term "laser light beam 26." Preferably, the laser light beam 26 indicates a direction along which the laser light propagates.

[0050] Figure 3a shows a schematic perspective view of a calibration measurement using the lidar measuring device 20. A laser light beam 26 is directed from the laser light source 22 directly onto a detector surface of the detector 24 by means of the rotating mirror 28. A signal generated by the detector 24 is processed by the diagnostic device 10. The distance between the laser light source 22, the rotating mirror 28, and the detector 24 is known. Consequently, a determined distance, a determined light propagation time, or a determined phase shift is also known.

[0051] Based on these known measured values, the diagnostic unit 16 can determine the functionality of the lidar measuring device 20. For this purpose, expected measured values ​​are preferably compared with actual measured values.

[0052] It is conceivable that the diagnostic unit 16 is only activated when a measurement is carried out in the determined calibration range.

[0053] The calibration range is understood to mean, in particular, the measurement range in which laser light from the laser light source 22 is directed directly onto the detector 24. Directed directly means, in particular, that it is not reflected or backscattered laser light that falls onto the detector 24, but rather that the laser beam is directed from the laser light source 22, for example, by means of the mirror 28, to the detector 24, whereby a distance between the laser light source 22 and the detector 24 is known in advance.

[0054] Consequently, a reference measurement or calibration measurement with a known expected measurement result can be carried out and the functionality of the lidar measuring device 20 can be determined by comparing expected and measured values.

[0055] For clarity, Figure 3b shows the calibration measurement according to Figure 3a in plan view.

[0056] Based on an angular position of the rotating mirror 28, the diagnostic unit 16 can determine the measuring direction, i.e., among other things, the direction in which a laser light is deflected by the rotating mirror 28.

[0057] The diagnostic device 10 can preferably be configured to determine contamination, wear, and / or aging of the lidar measuring device 20 based on the measurement data obtained during a calibration measurement. Contamination or aging can, in particular, lead to a decrease in the light intensity of the laser light source 22 or a reduced detection sensitivity of the detector 24.

[0058] Contamination can also lead to scattering of the laser light during a calibration measurement, so that neighboring pixels of the detector 24 also receive a weak signal.

[0059] In particular, aging can lead to individual light emitters of the laser light source 22 emitting less strongly or individual detector pixels of the detector 24 receiving a lower signal.

[0060] It is understood that the effects described above are only examples. A person skilled in the art is familiar with the various effects and can draw conclusions about the condition of the lidar measuring device 20 based on them.

[0061] If such wear, contamination and / or aging of the lidar measuring device 20 is determined, the diagnostic unit 16 can output an indication of a required adjustment of the lidar measuring device 20.

[0062] In the simplest case, an indication can be, for example, a warning tone, a visual signal, or digitally transmitted information that informs a user of the lidar measuring device 20 that the measurement is classified as untrustworthy or that the lidar measuring device 20 is operating at a limit of trustworthiness. Indications / information can be transmitted, for example, via communication interfaces such as RS232, I2C, CAN, IoT, Ethernet in cars, etc. It is understood that the indication can be transmitted both wirelessly and via cable. A person skilled in the art knows the necessary means for this. The laser light source 22 or the detector 24 can then be readjusted or cleaned. Preferably, the indication can also contain information regarding the component to be readjusted, cleaned, and / or replaced.

[0063] Additionally or alternatively, the diagnostic unit 16 can adjust the lidar measuring device 20. This can be done, for example, via a control command. In particular, an adjustment of the operating voltage of the laser light source 22 and / or the detector 24 can be performed.

[0064] Figure 4a shows a schematic perspective view of a lidar measuring device 20 during a further measurement in the calibration range.

[0065] In contrast to the measurement shown in Figure 3a, a path of the laser light runs between the laser light source 22, the rotating mirror 28 and another surface of the lidar measuring device 20.

[0066] Since an angle of the laser light path when emitted by the laser light source 22 is known, the path that the laser light takes between the light source 22, the rotating mirror 28 and the detector 24 can be determined.

[0067] This allows the diagnostic device 10 to calculate an expected running time or an expected measured distance or to retrieve a pre-calculated distance or a pre-calculated running time in a memory and compare it with a distance or a running time in a measurement.

[0068] Consequently, a measurement in which a reflection occurs inside and / or outside the lidar measuring device 20 can also be used for calibration or functional diagnosis.

[0069] Figure 4b shows a top view of the measurement shown in Figure 4a for clarity. It should be understood that a longer light propagation time is preferably expected for a calibration measurement shown in Figure 4b than for the calibration measurement shown in Figure 3b. This allows a wider time range to be measured. Drifts in a clock generator can be more easily detected.

[0070] Despite the longer light travel time, the calibration measurement preferably takes place completely within the lidar measuring device 20 so that external interference is minimized.

[0071] The invention has been described in detail using a simple exemplary embodiment. A person skilled in the art will recognize that, in addition to the simple design of a lidar measuring device chosen here for clarification, the diagnostic device 10 according to the invention can be used with a variety of known lidar measuring devices 20. This simple illustration serves to facilitate understanding of the invention and is in no way to be understood as limiting.

[0072] A person skilled in the art will recognize, in particular, that laser light sources are available in numerous forms on the market and can be used with the invention. The same applies to detectors and the rotating mirror 28. In particular, the rotating mirror 28 can be designed as a micromirror. In an alternative embodiment, it is also conceivable for the laser light source 22 itself to be designed to rotate.

[0073] The invention has been comprehensively described and explained with reference to the drawings and the description. The description and explanation are to be understood as exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other embodiments or variations will become apparent to those skilled in the art upon use of the present invention and upon careful analysis of the drawings, the disclosure, and the following claims.

[0074] In the claims, the words "comprising" and "having" do not exclude the presence of further elements or steps. The undefined article "a" or "an" does not exclude the presence of a plurality. A single element or unit can perform the functions of several of the units recited in the claims. An element, unit, device, and system can be partially or completely implemented in hardware and / or software. The mere mention of some measures in several different dependent claims should not be understood to mean that a combination of these measures cannot also be used advantageously. A computer program can be stored / distributed on a non-volatile data carrier, for example on an optical memory or on a solid-state drive (SSD).A computer program may be distributed together with hardware and / or as part of hardware, for example, via the Internet or via wired or wireless communication systems. Reference signs in the patent claims are not to be construed as limiting.

[0075] List of reference symbols

[0076] 10 Diagnostic device

[0077] 12 Communication interface 14 Separation unit

[0078] 16 Diagnostic unit

[0079] 18 systems

[0080] 20 Lidar measuring device

[0081] 22 Laser light source 24 Detector

[0082] 26 laser light beam

[0083] 28 rotating mirrors

Claims

Patent claims 1. A diagnostic device (10) for diagnosing the functionality of a scanning lidar measuring device (20), comprising: a communication interface (12) for receiving an input signal with information from the lidar measuring device (20) regarding a measuring direction and a determined distance in the measuring direction; a separation unit (14) for defining a calibration range, which corresponds at least partially to a dead zone of the lidar measuring device (20), based on the measuring direction; and a diagnostic unit (16) for diagnosing the functionality of the lidar measuring device (20) based on the input signal during a measurement in the calibration range.

2. Diagnostic device (10) according to claim 1, wherein the diagnostic unit (16) is designed to compare an expected predefined distance and an actual measured distance during a measurement in the calibration range and to diagnose a functionality of the lidar measuring device (20) based on the comparison.

3. Diagnostic device (10) according to one of the preceding claims, wherein the diagnostic unit (16) is designed to mark all measurements between two successful diagnoses as trustworthy.

4. Diagnostic device (10) according to one of the preceding claims, wherein the diagnostic unit (16) is designed to determine the measuring direction based on an angular position of a reflection body of the lidar measuring device (20).

5. Diagnostic device (10) according to one of the preceding claims, wherein the diagnostic unit (16) is designed to determine wear, contamination and / or aging of the lidar measuring device (20) based on an expected predefined distance and an actual measured distance during a measurement in the calibration range.

6. Diagnostic device (10) according to the preceding claim, wherein the diagnostic unit (16) is designed to output an indication of a required adjustment of the lidar measuring device (20) based on the determined wear, the determined contamination and / or the determined aging of the lidar measuring device (20) and / or to adjust the lidar measuring device (20).

7. Diagnostic device (10) according to one of the preceding claims, wherein the diagnostic unit (16) diagnoses a functionality of the lidar measuring device (20) based on the expected predefined distance and the actual measured distance in a measurement between a laser light source (22) of the lidar measuring device (20), a reflection surface of a mirror of the lidar measuring device (20) and preferably at least one further surface of the lidar measuring device (20) in the calibration range.

8. System (18) comprising a diagnostic device (10) according to one of the preceding claims and a lidar measuring device (20).

9. A method for diagnosing the functionality of a scanning lidar measuring device (20), preferably by means of a diagnostic device (10) according to one of the preceding claims, comprising the steps: Receiving an input signal with information from the lidar measuring device (20) about a measuring direction and a determined distance in the measuring direction; Defining a calibration range which corresponds at least partially to a dead zone of the lidar measuring device (20) based on the measuring direction; and Diagnosing a functionality of the lidar measuring device (20) based on the input signal at a Measurement in the calibration range.

10. Method according to the preceding claim, comprising the steps of: comparing an expected predefined distance and an actually measured distance in a measurement in the calibration range and diagnosing a functionality of the lidar measuring device (20) based on the comparison.

11. A computer program product comprising program code for performing the steps of the method according to the preceding claim when the program code is executed on a computer.

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