CN112782673A

CN112782673A - Fault diagnosis method, laser radar transmitting end component and laser radar

Info

Publication number: CN112782673A
Application number: CN201911084360.3A
Authority: CN
Inventors: 赵鑫; 向少卿; 毕云天
Original assignee: Hesai Technology Co Ltd
Current assignee: Hesai Technology Co Ltd
Priority date: 2019-11-07
Filing date: 2019-11-07
Publication date: 2021-05-11

Abstract

The invention relates to a fault diagnosis method which can be used for a laser radar transmitting end, wherein the laser radar transmitting end comprises a laser, a switching device coupled with one end of the laser, an energy storage unit coupled with the other end of the laser, and a power supply unit for supplying power to the energy storage unit, and the fault diagnosis method comprises the following steps: collecting electric signals of one or more nodes in the laser radar transmitting end; and judging whether the laser radar transmitting end has a fault or not according to the electric signal.

Description

Fault diagnosis method, laser radar transmitting end component and laser radar

Technical Field

The present invention generally relates to the field of optoelectronic technologies, and in particular, to a method for diagnosing a fault of a laser radar transmitting end, a laser radar transmitting end assembly, and a laser radar including the laser radar transmitting end assembly.

Background

LiDAR is a general name of laser active detection sensor equipment, and the working principle of the LiDAR is roughly as follows: laser radar's transmitter launches a bundle of laser, and after laser beam met the object, through diffuse reflection, returned to laser receiver, radar module multiplies the velocity of light according to the time interval of sending and received signal, divides by 2 again, can calculate the distance of transmitter and object. Depending on the number of laser beams, there are generally, for example, a single line laser radar, a 4-line laser radar, an 8/16/32/64-line laser radar, and the like. One or more laser beams are emitted along different angles in the vertical direction and scanned in the horizontal direction to realize the detection of the three-dimensional profile of the target area. The multiple measurement channels (lines) correspond to the scan planes at multiple tilt angles, so that the more laser beams in the vertical field, the higher the angular resolution in the vertical direction, and the greater the density of the laser point cloud.

The laser radar is small in size, and electronic components and circuits with a large number are mounted and accommodated in the laser radar. Taking the circuit design of the laser emitting end of the mechanical laser radar as an example, the interior of the mechanical laser radar comprises a high-voltage driving circuit, a light emitting passage, a photodiode control circuit and the like. Various components may malfunction, such as failure, short circuit, open circuit, etc., of the high voltage driving circuit, the photodiode control circuit, etc. The existing laser radar has no detection means, and has the problems that laser is not transmitted successfully due to the damage of devices, a system cannot be detected, and no obstacle exists in front of the system to be treated. The problem that when a radar is used as a sensing key sensor for automatic driving, safety risks are caused by device failure is urgently to be solved.

The statements in the background section are merely prior art as they are known to the inventors and do not, of course, represent prior art in the field.

Disclosure of Invention

In view of at least one problem of the prior art, the present invention provides a fault diagnosis method applicable to a lidar transmission terminal, wherein the lidar transmission terminal includes a laser and a switching device coupled to one end of the laser, an energy storage unit coupled to the other end of the laser, and a power supply unit supplying power to the energy storage unit, and wherein the fault diagnosis method includes:

collecting electric signals of one or more nodes in the laser radar transmitting end;

and judging whether the laser radar transmitting end has a fault or not according to the electric signal.

According to an aspect of the invention, the one or more nodes comprise an output of the power supply unit, and the electrical signal comprises a voltage waveform at the output of the power supply unit.

According to an aspect of the invention, the lidar transmitting terminal further comprises a driving unit coupled to the control terminal of the switching device, the driving unit being configured to control the switching on and off of the switching device and the duration of the switching on and off, wherein the node further comprises an output of the driving unit, and the electrical signal further comprises a voltage waveform at the output of the driving unit.

According to one aspect of the invention, the step of judging whether the laser radar transmitting end has a fault according to the electric signal comprises the following steps: and comparing the waveform of the electric signal with a preset waveform to judge whether the laser radar transmitting end has a fault and the type of the fault.

According to one aspect of the invention, the fault comprises one or more of: the laser is short-circuited, the laser is open-circuited, the power supply unit is open-circuited, and the energy storage element is open-circuited.

According to one aspect of the invention, the energy storage element comprises a charging capacitor bank and a charging inductor, and the energy storage element open circuit comprises a charging capacitor open circuit and a charging inductor open circuit.

The invention also provides a laser radar transmitting end assembly, comprising:

a laser;

a switching device coupled to one end of the laser;

the energy storage unit is coupled with the other end of the laser;

a power supply unit coupled to the energy storage unit and supplying power to the energy storage unit;

the fault diagnosis unit is configured to collect electric signals of one or more nodes in the laser radar transmitting end and judge whether the laser radar transmitting end has faults or not according to the electric signals.

According to an aspect of the invention, the fault diagnosis unit is configured to: and comparing the waveform of the electric signal with a preset waveform to judge whether the laser radar transmitting end has a fault and the type of the fault.

The present invention also provides a laser radar comprising:

a lidar transmitting end assembly as described above configured to emit a probe beam; and

and the receiving end component is configured to receive a radar echo formed after the probe beam is reflected on the obstacle.

According to the technical scheme of the embodiment of the invention, the coverage rate of fault diagnosis is higher, and the detection and diagnosis of the failure of a plurality of devices at the laser emission end can be met. In addition, the fault diagnosis unit in the present application may be or be disposed on the upper or lower deck in the lidar itself, and thus the implementation complexity is relatively low. In the design scheme of the embodiment of the invention, signal acquisition can be performed on the output end of the power supply unit, taking 64-line laser radar as an example, only 5 points are generally required to be acquired (which depends on the architecture, but the number of pins of the multi-line laser radar can be reduced by more than 30%), and the implementation complexity is lower than that of the traditional scheme. The implementation cost of the scheme is low. The circuit acquisition logic has high real-time requirement, even nanosecond level, but can multiplex the high-speed ADC of the laser emitting end for acquisition without additionally increasing an ADC chip. In addition, the diagnosis logic circuit does not influence the normal working circuit, even if the diagnosis circuit is damaged, the diagnosis logic circuit can be identified through FPGA logic, and the robustness is high

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a schematic diagram of a lidar transmitting end assembly according to one embodiment of the invention;

FIG. 2 shows a schematic diagram of a preferred circuit configuration of a laser radar transmitting end assembly according to FIG. 1;

FIG. 3 illustrates a fault diagnosis method according to an embodiment of the present invention;

4A-4E illustrate preset waveforms for various faults, respectively, in accordance with one embodiment of the present invention; and

fig. 5 shows a lidar transmitting end assembly according to one embodiment of the invention.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the description of the present invention, it should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection, either mechanically, electrically, or in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.

Fig. 1 illustrates one embodiment of a lidar transmitting end assembly 100. As shown in fig. 1, lidar transmitting end assembly 100 includes a power supply unit 101, an energy storage unit 102, a laser 103, and a switching device 104. Wherein the power supply unit 101 may typically receive a lower voltage input, e.g. 12V, and then boost the output voltage by means of a boost circuit, providing a high voltage HV, e.g. up to 60V. The energy storage unit 102 is configured to receive the high voltage HV output by the power supply unit 101, and store and accumulate electric energy. The laser 103 is, for example, a laser diode LD, and has one end coupled to the switching device 104 and the other end coupled to the energy storage unit 102. According to one implementation of the present invention, the power supply unit 101 supplies power to the energy storage unit 102, the energy storage unit 102 stores electric energy, when the control switch device 104 is closed, the energy storage unit 102 drives the laser 103, the circuit formed by the switch 104 discharges electricity, current flows through the laser 103, and the laser 103 emits a laser beam. The switching device 104 may be, for example, a GaN switch.

As shown in fig. 1, the lidar transmitting end assembly 100 further includes a driving unit 105, and the driving unit 105 is coupled to the control terminal of the switching device 104, so as to output a control signal for controlling on/off of the switching device 104 and the duration of the on/off, for example, 30ns, so as to influence the pulse width of the laser beam emitted by the laser 103. When the driving unit 105 controls the switching device 104 to be in a conducting state, the switching device 104 provides a discharging loop for the laser 103, so that the energy storage unit 102 drives the laser 103, current flows through the laser 103, and the laser 103 emits a laser beam. When the driving unit 105 controls the switching device 104 to be in an off state, the discharge circuit is opened, and the laser 103 stops emitting light. The light emission period of the laser 103 can be controlled by controlling the duration of the on-off of the switching device 104.

Fig. 2 shows a schematic diagram of a preferred circuit configuration of lidar transmitting end assembly 100 according to fig. 1. As described in detail below in conjunction with fig. 1 and 2.

A specific structure of the power supply unit 101 of fig. 1 is shown in fig. 2. As shown in fig. 2, the power supply unit 101 includes a charging inductor 1011, a diode 1012, and a switch 1013 (e.g., a fet). One end of the charging inductor 1011 is connected to an input voltage PSV, for example, an input voltage of 12V, and the other end is connected to the drain of the switch 1013 and the diode 1012. The gate of the switch 1013 receives the control voltage pulse Vpulse and the source is connected to ground. The power supply unit 101 is coupled to the capacitor 102 (energy storage unit) so that a high voltage HV can be established thereon, and to the laser 103. The other end of the laser 103 is coupled to the drain of a switching device 104 (shown as a field effect transistor, or a GaN switch), the source of the switching device 104 is grounded, and the gate is coupled to an FPGA as a driving unit 105. Those skilled in the art will readily appreciate that instead of using an FPGA to implement the driving unit 105, a DSP or an ASIC may be used to implement the driving unit, and these are all within the scope of the present invention.

The working principle is basically as follows. The circuit working process is as follows: the energy storage unit 102 charges and stores energy, when the switching device 104 is turned on, the laser is driven by the high voltage HV to emit light and discharge, and the whole laser detection process is circulated and continued.

During charging, the input voltage PSV (e.g. 12v or 5v) is supplied and the control voltage pulse Vpulse controls whether and for which time the switch 1013 is conductive. When the switch 1013 is turned on, its source is grounded to form a loop, so that the inductor 1011 is charged under the driving of the input voltage PSV; when the switch 1013 is turned off, the inductor 1011 maintains the current thereon, so that the inductor discharges, the diode 1012 is turned on, and the capacitor 102 is charged, the voltage across the charged capacitor 102 is the high voltage HV, the FPGA serving as the driving unit 105 provides the switching device 104 with the driving signal VDRV to turn on, so that the light emitting path is turned on, the current flows through the laser 103, and the laser emits the measurement light. The on-time of the switch 1013 is controlled by adopting the pulse signal Vpulse with different duty ratios, thereby realizing the control of the high-voltage HV level. By controlling the duty ratio of the drive signal VDRV output by the FPGA 105, the light emission time of the laser 103 can be controlled. In addition, the FPGA 105 may further collect electrical signals of one or more nodes in the lidar transmitting end, and compare waveforms of the electrical signals with preset waveforms, so as to determine whether a fault exists at the lidar transmitting end and a possible fault type, where the specific fault is, for example, a laser short circuit, a laser open circuit, a power supply unit open circuit, or an energy storage element open circuit.

Fig. 3 illustrates a fault diagnosis method 200 according to an embodiment of the present invention, such as may be used for fault diagnosis of lidar transmitting end assembly 100 of fig. 1 and 2. As described in detail below with reference to fig. 3.

As shown in fig. 3, in step S201, electrical signals of one or more nodes in the lidar transmitting end are collected.

The inventors of the present application have found that it is possible to collect the electrical signal (i.e. the high voltage HV) at the output of the power supply unit 101, i.e. the voltage waveform at the output of the power supply unit (or the voltage waveform at the energy storage unit), because the voltage waveform at the output of the power supply unit may characterize and identify various faults. Further preferably, the node further comprises an output of the driving unit 105, and the acquired electrical signal comprises a voltage waveform of the output of the driving unit 105.

In step S202, it is determined whether the lidar transmitting end has a fault according to the electrical signal.

After certain processing is performed according to the amplitude and/or waveform of the collected electrical signal, it can be determined whether a fault exists in the laser radar transmitting end assembly 100.

The failure of the lidar transmitting end assembly may include one or more of the following: the laser is short-circuited, the laser is open-circuited, the power supply unit is open-circuited, and the energy storage element is open-circuited. Each fault is reflected in the electrical signal at one or more of the nodes. Therefore, a preset fault waveform or a preset judgment condition can be stored in the memory, and the electric signal is compared with the preset waveform or the preset judgment condition to judge whether the laser radar transmitting end has a fault and the type of the fault.

Fig. 4A-4E show preset waveforms for various faults, corresponding to electrical signals at the output of the power supply unit 101. In fig. 4A, a waveform Q1 represents a waveform of a laser short circuit. When the laser 103 in fig. 1 is short-circuited, the output voltage waveform of the power supply unit 101 quickly drops to zero, so that whether a failure of laser short-circuit occurs can be determined by the slope of the drop of the electrical signal at the output terminal of the power supply unit 101.

As shown in fig. 4B, waveform Q2 represents the waveform of the laser open circuit. When the laser 103 in fig. 1 is opened, the electric energy stored in the energy storage unit 102 cannot be discharged through the laser 103, so the voltage signal at the output terminal of the power supply unit 101 will be relatively smooth or will drop at a small speed, which is reflected in the waveform diagram, and the slope of the drop is relatively small.

As shown in fig. 4C, the waveform Q3 represents a waveform in which the power supply unit is open. When the power supply unit 101 in fig. 1 is opened or disconnected, the output of the power supply unit 101 will always be kept at a lower level, as shown by the waveform Q3.

The power supply unit comprises a charging inductor, and the fault further comprises a charging inductor open circuit. As shown in fig. 4E, the waveform Q5 represents the open-circuit waveform of the charging inductor. A pulse of waveform Q5 that creates a high voltage is completely absent, indicating that an open circuit in the charging inductor may occur.

According to an embodiment of the present invention, a calculation may be performed according to the output of the power supply unit 101, such as calculating the amplitude, the falling slope, and the like, and then comparing with a preset threshold, so as to determine whether there is a fault, and a specific fault type. Alternatively, the voltage waveform output by the power supply unit 101 may be compared with preset waveforms, for example, by using an image classification algorithm, to obtain one of the preset waveforms closest to the voltage waveform, so as to determine whether there is a fault and a specific fault type.

According to an embodiment of the present invention, the energy storage unit includes a charging capacitor or a charging capacitor bank, and the waveform Q4 represents the waveform of the open circuit of the charging capacitor. When the charging capacitor is opened, the high voltage HV will always remain high, and the laser cannot be driven to discharge the charge on the high voltage HV, and the waveform is shown as the waveform Q4 in fig. 4D.

In addition, those skilled in the art will readily understand that the waveforms corresponding to the various faults shown in fig. 4 are merely illustrative and do not limit the scope of the present invention. Those skilled in the art, having the benefit of the teachings of this disclosure, may configure other various types of fault waveforms within the scope of this invention.

Fig. 5 shows a lidar transmitting end assembly 100' according to an embodiment of the present invention, which also includes a power supply unit 101, an energy storage unit 102, a laser 103, a switching device 104, and a driving unit 105, which are substantially the same as the lidar transmitting end assembly 100 shown in fig. 1 and will not be described herein again. In addition, features of the various components and their connections in the embodiment shown in FIG. 2 may be incorporated into FIG. 5 as well, without the need for inventive labor. The differences from lidar transmitting end assembly 100 of fig. 1 will be addressed below.

As shown in fig. 5, lidar transmitting end assembly 100 'further includes a fault diagnosis unit 106, where fault diagnosis unit 106 is configured to collect electrical signals of one or more nodes in lidar transmitting end 100' and determine whether there is a fault in the lidar transmitting end according to the electrical signals.

As described with reference to fig. 1 and 3, the one or more nodes may comprise an output of the power supply unit 101, the electrical signal comprising a voltage waveform at the output of the power supply unit.

Fault diagnosis unit 106 may be configured to implement fault diagnosis method 200 shown in fig. 3, for example, comparing the waveform of the electrical signal with a preset waveform to determine whether a fault exists at the lidar transmitting end and the type of the fault. The failure includes, for example: the laser is short-circuited, the laser is open-circuited, the power supply unit is open-circuited, and the energy storage element is open-circuited.

The energy storage element 102 includes, for example, a charging capacitor or a charging capacitor bank, the power supply unit includes a charging inductor, and the fault further includes an open circuit of the charging inductor.

The invention also relates to a lidar comprising: lidar transmitting end assembly 100 or 100' and receiving end assembly as described above. Wherein lidar transmitting end assembly 100 or 100' is configured to emit a probe beam. The probe beam is diffusely reflected off an obstacle outside the lidar and a portion of the reflected beam is incident on the receive end assembly as a radar echo. The receiving side subassembly includes, for example, an optical lens and a photosensor. The optical lens converges radar echoes to enable the radar echoes to be incident on the photoelectric sensor. The photoelectric sensor can be an Avalanche Photodiode (APD) or a SiPM, generates an electric signal according to the received light intensity or photon number, and the electric signal is subjected to subsequent circuit and signal processing, amplification, filtering and other processing to generate point cloud data of the laser radar and can represent information such as the distance, the direction, the reflectivity and the like of an obstacle.

According to the technical scheme of the embodiment of the invention, the coverage rate of fault diagnosis is higher, and the detection and diagnosis of the failure of a plurality of devices at the laser receiving end can be met. In addition, the implementation complexity is low. In the design scheme of the embodiment of the invention, signal acquisition can be performed on the output end of the power supply unit, taking 64-line laser radar as an example, only 5 points are generally required to be acquired (which depends on the architecture, but the number of pins of the multi-line laser radar can be reduced by more than 30%), and the implementation complexity is lower than that of the traditional scheme. The implementation cost of the embodiment is low. The circuit acquisition logic has high real-time requirement, even nanosecond level, but can multiplex the high-speed ADC of the laser receiving end for acquisition without additionally increasing an ADC chip. In addition, the diagnosis logic circuit does not influence the normal working circuit, even if the diagnosis circuit is damaged, the diagnosis logic circuit can be identified through FPGA logic, and the robustness is high

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A fault diagnosis method usable with a lidar transmitting terminal, wherein the lidar transmitting terminal includes a laser and a switching device coupled to one end of the laser, an energy storage unit coupled to the other end of the laser, and a power supply unit that supplies power to the energy storage unit, and wherein the fault diagnosis method comprises:

2. The fault diagnosis method according to claim 1, wherein the one or more nodes comprise an output of the power supply unit, and the electrical signal comprises a voltage waveform of the output of the power supply unit.

3. The method of claim 2, wherein the lidar transmit terminal further comprises a drive unit coupled to the control terminal of the switching device, the drive unit configured to control on/off of the switching device and duration of the on/off, wherein the node further comprises an output of the drive unit, and the electrical signal further comprises a voltage waveform at the output of the drive unit.

4. The fault diagnosis method according to any one of claims 1 to 3, wherein the step of determining whether a fault exists at the lidar transmitting end based on the electrical signal comprises: and comparing the waveform of the electric signal with a preset waveform to judge whether the laser radar transmitting end has a fault and the type of the fault.

5. The fault diagnosis method according to any one of claims 1 to 3, wherein the fault comprises one or more of: the laser is short-circuited, the laser is open-circuited, the power supply unit is open-circuited, and the energy storage element is open-circuited.

6. The fault diagnosis method according to claim 5, wherein the energy storage element comprises a charging capacitor bank, the power supply unit comprises a charging inductor, and the fault further comprises an open circuit of the charging inductor.

7. A lidar transmitting end assembly, comprising:

a laser;

a switching device coupled to one end of the laser;

the energy storage unit is coupled with the other end of the laser;

8. The lidar transmitting end assembly of claim 7, wherein the one or more nodes comprise an output of the power supply unit, the electrical signal comprising a voltage waveform at the output of the power supply unit.

9. The lidar transmitting end assembly of claim 8, wherein the lidar transmitting end further comprises a drive unit coupled to the control end of the switching device, the drive unit configured to control switching on and off of the switching device and a duration of the switching on and off, wherein the node further comprises an output of the drive unit, the electrical signal further comprising a voltage waveform at the output of the drive unit.

10. The lidar transmitting end assembly according to any of claims 7-9, wherein the fault diagnosis unit is configured to: and comparing the waveform of the electric signal with a preset waveform to judge whether the laser radar transmitting end has a fault and the type of the fault.

11. The lidar transmitting end assembly according to any of claims 7-9, wherein the fault comprises one or more of: the laser is short-circuited, the laser is open-circuited, the power supply unit is open-circuited, and the energy storage element is open-circuited.

12. The lidar transmitting end assembly of claim 11, wherein the energy storage element comprises a bank of charging capacitors, the power supply unit comprises a charging inductor, and the fault further comprises an open circuit of the charging inductor.

13. A lidar comprising:

the lidar transmitting end assembly of any of claims 7-12, configured to emit a probe beam; and