CN115657058A - Laser radar ranging method, device and system and automatic driving vehicle - Google Patents

Laser radar ranging method, device and system and automatic driving vehicle Download PDF

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Publication number
CN115657058A
CN115657058A CN202211321053.4A CN202211321053A CN115657058A CN 115657058 A CN115657058 A CN 115657058A CN 202211321053 A CN202211321053 A CN 202211321053A CN 115657058 A CN115657058 A CN 115657058A
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laser signal
laser
intensity
ranging
scanning
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CN202211321053.4A
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王剑波
申耀明
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Apollo Intelligent Technology Beijing Co Ltd
Baidu USA LLC
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Apollo Intelligent Technology Beijing Co Ltd
Baidu USA LLC
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Priority to CN202211321053.4A priority Critical patent/CN115657058A/en
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Abstract

The disclosure provides a laser radar ranging method, a laser radar ranging device, a laser radar ranging system and an automatic driving vehicle, and relates to the technical field of automatic driving, in particular to the field of automatic driving hardware. The implementation scheme is as follows: determining a laser signal for emission, and a timing start time at which the laser signal is emitted to perform ranging, wherein the laser signal is configured to have at least two emission intensities that alternate; acquiring a laser signal reflected from an object; determining a timing end time by triggering a logic level flip based on a comparison between the received intensity of the reflected laser signal and an adjustable reference threshold, wherein the adjustable reference threshold is determined based on the received intensity of the laser signal; and determining the distance between the laser radar and the object based on the timing start time and the timing end time.

Description

Laser radar ranging method, device and system and automatic driving vehicle
Technical Field
The present disclosure relates to the field of autonomous driving technologies, and in particular, to the field of autonomous driving hardware, and more particularly, to a laser radar ranging method, apparatus, system, electronic device, computer-readable storage medium, computer program product, FPGA chip, and autonomous driving vehicle.
Background
With the development of the automatic driving technology, users have made higher demands on radar ranging in automatic driving vehicles. In radar ranging of an autonomous vehicle, the transmission process of a laser signal needs to be timed. In some cases, a large number of comparators are used in a circuit for timing, the circuit is very complex, signals are not easy to control, the accuracy of radar ranging of the automatic driving vehicle is influenced to a great extent, and the cost is high. How to realize more efficient autonomous vehicle radar ranging, improve the accuracy of autonomous vehicle radar ranging, reduce the cost of autonomous vehicle radar ranging, still be one of the research hotspot and the difficult point of industry.
The approaches described in this section are not necessarily approaches that have been previously conceived or pursued. Unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. Similarly, the problems mentioned in this section should not be considered as having been acknowledged in any prior art, unless otherwise indicated.
Disclosure of Invention
The present disclosure provides a lidar ranging method, apparatus, system, electronic device, computer-readable storage medium, computer program product, FPGA chip, and autonomous vehicle.
According to an aspect of the present disclosure, there is provided a laser radar ranging method, including: determining a laser signal for emission, and a timing start time at which the laser signal is emitted to perform ranging, wherein the laser signal is configured to have at least two emission intensities that alternate; acquiring a laser signal reflected from an object; determining a timing end time by triggering a logic level flip based on a comparison between the received intensity of the reflected laser signal and an adjustable reference threshold, wherein the adjustable reference threshold is determined based on the received intensity of the laser signal; and determining the distance between the laser radar and the object based on the timing start time and the timing end time.
According to another aspect of the present disclosure, there is provided a laser radar ranging apparatus including: a laser emission determination module configured to determine a laser signal for emission, and a timing start time at which the laser signal is emitted to perform ranging, wherein the laser signal is configured to have at least two emission intensities that alternate; a laser reflection acquisition module configured to acquire a laser signal reflected from an object; a time determination module configured to determine a timing end time by triggering a logic level flip based on a comparison result between the received intensity of the reflected laser signal and an adjustable reference threshold, wherein the adjustable reference threshold is determined based on the received intensity of the laser signal; and a distance determination module configured to determine a distance between the lidar and the object based on the timing start time and the timing end time.
According to another aspect of the present disclosure, there is provided a laser radar system including: an FPGA chip configured to perform the method provided above; the transmitting device is used for transmitting a laser signal and is connected with the FPGA chip, wherein the laser signal and the timing starting time of the transmitted laser signal are determined by the FPGA chip, and the laser signal is configured to have at least two intensities which are alternately changed; the receiving device is used for receiving the laser signal reflected from the object and is connected with the FPGA chip so as to provide the reflected laser signal to the FPGA chip; the scanning device comprises a micro-electro-mechanical system galvanometer and is connected with the FPGA chip, and the micro-electro-mechanical system galvanometer is configured to adjust the scanning angle of the laser signal by rotating on a horizontal axis and a vertical axis, wherein the scanning angle is determined by the FPGA chip; the voltage adjusting device is used for generating an adjustable reference threshold value and is connected with the FPGA chip so as to provide the adjustable reference threshold value for the FPGA chip, and the adjustable reference threshold value is used for determining the timing ending time of the laser radar for ranging; wherein at least one of the FPGA chip, the transmitting device, the receiving device, the scanning device and the voltage regulating device is monitored in a closed loop.
According to another aspect of the present disclosure, there is provided an electronic device comprising at least one processor; and a memory communicatively coupled to the at least one processor; wherein the memory stores instructions executable by the at least one processor to cause the at least one processor to perform the method of the present disclosure as provided above.
According to another aspect of the present disclosure, there is provided a non-transitory computer readable storage medium having stored thereon computer instructions for causing a computer to perform the method of the present disclosure as provided above.
According to another aspect of the present disclosure, a computer program product is provided, comprising a computer program, wherein the computer program, when executed by a processor, implements the method of the present disclosure as provided above.
According to another aspect of the present disclosure, there is provided an FPGA chip comprising circuitry implementing the method as provided above of the present disclosure.
According to another aspect of the present disclosure, there is provided an autonomous vehicle comprising an FPGA chip, wherein the FPGA chip is configured to perform the method of the present disclosure as provided above.
According to one or more embodiments of the present disclosure, more accurate laser ranging can be achieved at lower cost.
It should be understood that the statements in this section do not necessarily identify key or critical features of the embodiments of the present disclosure, nor do they limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the embodiments and, together with the description, serve to explain the exemplary implementations of the embodiments. The illustrated embodiments are for purposes of illustration only and do not limit the scope of the claims. Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.
FIG. 1 illustrates a schematic diagram of an exemplary system in which various methods described herein may be implemented, according to an embodiment of the present disclosure;
FIG. 2 shows a flow diagram of a method of lidar ranging in accordance with an embodiment of the present disclosure;
FIG. 3 shows a schematic diagram of determining a timing end time based on a comparison of the received intensity of a laser signal to an adjustable reference threshold in accordance with an embodiment of the present disclosure;
FIG. 4 shows a schematic diagram of short-range object and long-range object ranging, according to an embodiment of the present disclosure;
FIG. 5 shows a schematic of a scanning waveform of a MEMS galvanometer cross-axis according to an embodiment of the present disclosure;
FIG. 6 shows a schematic diagram of a superposition of MEMS galvanometer transverse axis and longitudinal axis scanning waveforms, in accordance with an embodiment of the present disclosure;
FIG. 7 shows a block diagram of a lidar ranging device according to an embodiment of the disclosure;
FIG. 8 shows a block diagram of a lidar ranging apparatus according to another embodiment of the present disclosure;
FIG. 9 shows a schematic structural diagram of a lidar system in accordance with an embodiment of the disclosure;
FIG. 10 illustrates a block diagram of an exemplary electronic device that can be used to implement embodiments of the present disclosure.
Detailed Description
Exemplary embodiments of the present disclosure are described below with reference to the accompanying drawings, in which various details of the embodiments of the disclosure are included to assist understanding, and which are to be considered as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the present disclosure. Also, descriptions of well-known functions and constructions are omitted in the following description for clarity and conciseness.
In the present disclosure, unless otherwise specified, the use of the terms "first", "second", and the like to describe various elements is not intended to limit the positional relationship, the temporal relationship, or the importance relationship of the elements, and such terms are used only to distinguish one element from another. In some examples, a first element and a second element may refer to the same instance of the element, while in some cases they may refer to different instances based on the context of the description.
The terminology used in the description of the various described examples in this disclosure is for the purpose of describing particular examples only and is not intended to be limiting. Unless the context clearly indicates otherwise, if the number of elements is not specifically limited, the elements may be one or more. Furthermore, the term "and/or" as used in this disclosure is intended to encompass any and all possible combinations of the listed items.
Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.
Fig. 1 illustrates a schematic diagram of an exemplary system 100 in which various methods and apparatus described herein may be implemented in accordance with embodiments of the present disclosure. Referring to fig. 1, the system 100 includes a motor vehicle 110, a server 120, and one or more communication networks 130 coupling the motor vehicle 110 to the server 120.
In embodiments of the present disclosure, motor vehicle 110 may include a computing device and/or be configured to perform a method in accordance with embodiments of the present disclosure.
Server 120 may run one or more services or software applications that enable the lidar ranging methods according to embodiments of the disclosure. In some embodiments, the server 120 may also provide other services or software applications, which may include non-virtual environments and virtual environments. In the configuration shown in fig. 1, server 120 may include one or more components that implement the functions performed by server 120. These components may include software components, hardware components, or a combination thereof, which may be executed by one or more processors. A user of motor vehicle 110 may, in turn, utilize one or more client applications to interact with server 120 to take advantage of the services provided by these components. It should be understood that a variety of different system configurations are possible, which may differ from system 100. Accordingly, fig. 1 is one example of a system for implementing the various methods described herein and is not intended to be limiting.
The server 120 may include one or more general purpose computers, special purpose server computers (e.g., PC (personal computer) servers, UNIX servers, mid-end servers), blade servers, mainframe computers, server clusters, or any other suitable arrangement and/or combination. The server 120 may include one or more virtual machines running a virtual operating system, or other computing architecture involving virtualization (e.g., one or more flexible pools of logical storage that may be virtualized to maintain virtual storage for the server). In various embodiments, the server 120 may run one or more services or software applications that provide the functionality described below.
The computing units in server 120 may run one or more operating systems including any of the operating systems described above, as well as any commercially available server operating systems. The server 120 may also run any of a variety of additional server applications and/or middle tier applications, including HTTP servers, FTP servers, CGI servers, JAVA servers, database servers, and the like.
In some embodiments, server 120 may include one or more applications to analyze and consolidate data feeds and/or event updates received from motor vehicle 110. Server 120 may also include one or more applications to display data feeds and/or real-time events via one or more display devices of motor vehicle 110.
Network 130 may be any type of network known to those skilled in the art that may support data communications using any of a variety of available protocols, including but not limited to TCP/IP, SNA, IPX, etc. By way of example only, the one or more networks 130 may be a satellite communication network, a Local Area Network (LAN), an ethernet-based network, a token ring, a Wide Area Network (WAN), the internet, a virtual network, a Virtual Private Network (VPN), an intranet, an extranet, a blockchain network, a Public Switched Telephone Network (PSTN), an infrared network, a wireless network (including, for example, bluetooth, wiFi), and/or any combination of these and other networks.
The system 100 may also include one or more databases 150. In some embodiments, these databases may be used to store data and other information. For example, one or more of the databases 150 may be used to store information such as audio files and video files. The data store 150 may reside in various locations. For example, the data store used by the server 120 may be local to the server 120, or may be remote from the server 120 and may communicate with the server 120 via a network-based or dedicated connection. The data store 150 may be of different types. In certain embodiments, the data store used by the server 120 may be a database, such as a relational database. One or more of these databases may store, update, and retrieve data to and from the database in response to the command.
In some embodiments, one or more of the databases 150 may also be used by applications to store application data. The databases used by the application may be different types of databases, such as key-value stores, object stores, or regular stores supported by a file system.
Motor vehicle 110 may include sensors 111 for sensing the surrounding environment. The sensors 111 may include one or more of the following sensors: visual cameras, infrared cameras, ultrasonic sensors, millimeter wave radar, and laser radar (LiDAR). Different sensors may provide different detection accuracies and ranges. The camera may be mounted in front of, behind, or otherwise on the vehicle. The visual camera may capture conditions inside and outside the vehicle in real time and present to the driver and/or passengers. In addition, by analyzing the picture captured by the visual camera, information such as traffic light indication, intersection situation, other vehicle running state, and the like can be acquired. The infrared camera can capture objects under night vision conditions. The ultrasonic sensors can be arranged around the vehicle and used for measuring the distance between an object outside the vehicle and the vehicle by utilizing the characteristics of strong ultrasonic directionality and the like. The millimeter wave radar may be installed in front of, behind, or other positions of the vehicle for measuring the distance of an object outside the vehicle from the vehicle using the characteristics of electromagnetic waves. The lidar may be mounted in front of, behind, or otherwise of the vehicle for detecting object edges, shape information, and thus object identification and tracking. The radar apparatus can also measure a speed variation of the vehicle and the moving object due to the doppler effect.
Motor vehicle 110 may also include a communication device 112. The communication device 112 may include a satellite positioning module capable of receiving satellite positioning signals (e.g., beidou, GPS, GLONASS, and GALILEO) from the satellites 141 and generating coordinates based on these signals. The communication device 112 may also include modules to communicate with a mobile communication base station 142, and the mobile communication network may implement any suitable communication technology, such as current or evolving wireless communication technologies (e.g., 5G technologies) like GSM/GPRS, CDMA, LTE, etc. The communication device 112 may also have a Vehicle-to-Vehicle (V2X) networking or Vehicle-to-anything (V2X) module configured to enable, for example, vehicle-to-Vehicle (V2V) communication with other vehicles 143 and Vehicle-to-Infrastructure (V2I) communication with Infrastructure 144. Further, the communication device 112 may also have a module configured to communicate with a user terminal 145 (including but not limited to a smartphone, tablet, or wearable device such as a watch), for example, via wireless local area network using IEEE802.11 standards or bluetooth. Motor vehicle 110 may also access server 120 via network 130 using communication device 112.
Motor vehicle 110 may also include a control device 113. The control device 113 may include a processor, such as a Central Processing Unit (CPU) or a Graphics Processing Unit (GPU), or other special purpose processor, etc., in communication with various types of computer-readable storage devices or media. The control device 113 may include an autopilot system for automatically controlling various actuators in the vehicle. The autopilot system is configured to control a powertrain, steering system, and braking system, etc., of a motor vehicle 110 (not shown) via a plurality of actuators in response to inputs from a plurality of sensors 111 or other input devices to control acceleration, steering, and braking, respectively, without human intervention or limited human intervention. Part of the processing functions of the control device 113 may be realized by cloud computing. For example, some processing may be performed using an onboard processor while other processing may be performed using the computing resources of the cloud. The control device 113 may be configured to perform a method according to the present disclosure. Furthermore, the control apparatus 113 may be implemented as one example of a computing device on the motor vehicle side (client) according to the present disclosure.
The system 100 of fig. 1 may be configured and operated in various ways to enable application of the various methods and apparatus described in accordance with the present disclosure. The laser radar ranging method according to an embodiment of the present disclosure is described in detail below.
FIG. 2 shows a flow diagram of a lidar ranging method 200 according to an embodiment of the disclosure. As shown in fig. 2, the method 200 includes steps S201, S202, S203, and S204.
In step S201, a laser signal for transmission is determined, and a timing start time at which the laser signal is transmitted to perform ranging. The laser signal is configured to have at least two emission intensities that alternate.
In an example, the laser signal may be emitted by an emitting module for emitting laser light, which may comprise at least one laser. The laser may emit the laser signal directly toward the object or may emit the laser signal toward the object by reflection from a device such as a Micro-Electro Mechanical Systems (MEMS) galvanometer.
In an example, the current time may be recorded as the timing start time of the ranging while the laser light emitted from the emitting module is emitted, or the current time may be recorded as the timing start time of the ranging while the laser light emitted from the emitting module is reflected on a device such as a MEMS galvanometer.
In an example, the laser signal may be emitted with a regular pattern of alternating intensity and intensity. The power supply voltage of the transmitting module can be adjusted by adjusting the duty ratio of PWM (Pulse width modulation), so as to adjust the transmitting intensity of the laser signal.
In the ranging method according to the embodiment of the disclosure, the emission intensity of the laser signal and the distance between the object and the laser radar are positively correlated, so that the ranging accuracy of a long-distance object and a short-distance object can be automatically considered. For example, a laser signal with a large intensity is set to be used for ranging an object with a long distance because of a large detection distance; the laser signal with low intensity is less disturbed by reflection at the protective glass of the transmitting module and is arranged for ranging an object with a short distance. In addition, the laser signal may also be set to include more than two emission intensities, such as three intensities that decrease sequentially, for ranging to objects that are farther, medium, and closer, respectively.
In step S202, a laser signal reflected from an object is acquired.
In an example, a laser signal reflected from an object may be received by a receiving module, which may include at least one photoelectric converter for converting the received laser signal into an electrical signal.
In an example, since the transmitting module may be provided with a protective glass, when the laser signal is transmitted onto the protective glass, a reflection of the laser signal may be generated, and the reflected laser signal may be received by the receiving module, thereby affecting the determination of the distance between the laser radar and the object. The laser signal generated by reflecting the laser signal having a large intensity at the protective glass has a particularly large influence on the laser signal having a small intensity, and may even annihilate the laser signal having a small intensity. Thus, by emitting the laser signal in a regular alternating strong and weak manner, adverse effects of reflection of the laser signal at a non-ranging target object such as a cover glass can be reduced.
In step S203, a timing end time is determined by triggering a logic level flip based on a comparison between the received intensity of the reflected laser signal and an adjustable reference threshold. The adjustable reference threshold is determined based on the received intensity of the laser signal.
In an example, upon acquiring the laser signal reflected from the object, a range of received intensities of the laser signal may be determined, e.g., a strong signal or a weak signal, such that the adjustable reference threshold is determined based on the received intensities. For example, the range of the reception intensity of the laser signal may be determined by setting several threshold values in advance to compare the reception intensity with each threshold value.
In an example, the intensity of the received reflected laser signal may be compared to an adjustable reference threshold. If the intensity of the received reflected laser signal is greater than or equal to the adjustable reference threshold, triggering logic level inversion to finish timing of ranging; if the intensity of the received reflected laser signal is smaller than the adjustable reference threshold, the logic level inversion is not triggered, that is, effective ranging is not obtained at the moment.
In an example, the current time may be recorded while the logic level is flipped as the timing end time of the ranging. The logic levels may include both "0" and "1" states. The current time can be recorded as the timing end time of the ranging while the logic level is changed from "0" to "1"; the current time may also be recorded while the logic level is changed from "1" to "0" as the timing end time of the ranging.
In an example, the adjustable reference threshold may be a light intensity value for comparison with the intensity of the received laser signal to determine whether to trigger a logic level flip to determine the timing end time. The adjustable reference threshold may also be a voltage value determined based on the light intensity value for comparison with the voltage of the electrical signal into which the received laser signal is converted to determine whether to trigger a logic level flip to determine the timing end time.
In the ranging method according to the embodiment of the disclosure, the adjustable reference threshold is determined based on the intensity of the received laser signal, so that more dynamic ranging can be realized, and the ranging result is more accurate. For example, if the intensity of the received laser signal is small, it means that the corresponding laser signal may come from a close object, and therefore a smaller adjustable reference threshold may be used accordingly. Similarly, if the intensity of the received laser signal is high, it means that the corresponding laser signal may be from a distant object, and therefore a large adjustable reference threshold may be used accordingly.
In step S204, the distance between the laser radar and the object is determined based on the timing start time and the timing end time.
In an example, the total length of the optical path from the transmission of the laser signal to the reception of the laser signal may be calculated by multiplying the speed of light by the difference between the timing start time and the timing end time, and thus the distance between the laser radar and the object may be calculated by half the length of the optical path.
According to the laser radar ranging method disclosed by the embodiment of the disclosure, by emitting the laser signals with at least two emission intensities which are changed alternately, the ranging accuracy of a long-distance object and a short-distance object can be automatically considered. Meanwhile, the adjustable reference threshold is determined based on the receiving intensity of the reflected laser signal, and the timing end time is determined by triggering logic level inversion based on the comparison between the receiving intensity of the reflected laser signal and the adjustable reference threshold, so that not only can more dynamic ranging be realized for the distance, but also the influence of interference signals from non-ranging target objects can be eliminated to a certain extent, and more accurate laser radar ranging results can be realized.
Various aspects of lidar ranging methods according to embodiments of the disclosure are described further below.
According to some embodiments, determining the timing end time by triggering a logic level flip based on a comparison between the received intensity of the reflected laser signal and an adjustable reference threshold may comprise: and determining the time when the reflected laser signal is received as the timing end time in response to the received intensity of the reflected laser signal being greater than or equal to the adjustable reference threshold.
In an example, the intensity of the received reflected laser signal may be compared to an adjustable reference threshold. If the intensity of the received reflected laser signal is greater than or equal to the adjustable reference threshold, the current time may be recorded as the timing end time of the ranging. If the intensity of the received reflected laser signal is smaller than the adjustable reference threshold, logic level inversion is not triggered, that is, effective ranging is not obtained at the moment, so that the reflected laser signal can be continuously received, and the comparison process is repeated until effective ranging is obtained.
Fig. 3 shows a schematic diagram of determining a timing end time based on a comparison of the received intensity of the laser signal to an adjustable reference threshold according to an embodiment of the present disclosure. This process of determining the timing end time may correspond to step S203 described in fig. 2, for example.
As previously mentioned, the adjustable reference threshold is determined based on the received intensity of the laser signal. In an example, the adjustable reference threshold may be a voltage value for comparison with a voltage of an electrical signal into which the received laser signal is converted to determine whether to trigger a logic level flip to determine the timing end time.
As shown in fig. 3, in an example, the received reflected laser signal may be converted into a pulse signal in the form of a voltage. Fig. 3 schematically shows that a laser signal L1 with a smaller intensity and a laser signal L2 with a larger intensity are received. The electrical signal into which the laser signal L1 is converted may have a voltage V1, and the electrical signal into which the laser signal L2 is converted may have a voltage V2. The first adjustable reference threshold V may be determined based on the voltages V1 and V2, respectively th1 And a second adjustable reference threshold V th2 . The voltages V1 and V2 of the laser signal L1 and the laser signal L2, respectively, may be compared to a first adjustable reference threshold V th1 And a second adjustable reference threshold V th2 And comparing to determine the timing end time.
In an example, the voltage V1 of the electrical signal into which the laser signal L1 with smaller intensity is converted is smaller than the first adjustable reference threshold V th1 Therefore, the logic level inversion is not triggered, and the time T1 when the laser signal L1 is received is not recorded as the timing end time. The voltage V2 of the electrical signal converted from the laser signal L2 with larger intensity is larger than the second adjustable reference threshold value V th2 Thus triggering a logic level flip, the time T2 at which the laser signal L2 is received can be recorded as the timing end time.
In an example, a logic level may include two states, "0" and "1". Logic level flipping may include a situation where the logic level changes from a state of "0" to "1"; it is also possible to include a case where the logic level changes from "1" to "0".
It will be appreciated that figure 3 illustrates one situation in which the received intensity of the reflected laser signal is compared to an adjustable reference threshold. The adjustable reference threshold may also be a light intensity value for comparison with the intensity of the received laser signal to determine whether to trigger a logic level flip to determine the timing end time. The received laser signal may be at other times and/or have other intensity levels. The adjustable reference threshold may also have other values and/or manifestations.
In some embodiments, the lidar ranging of a vehicle may be performed in special weather such as rain, snow, or fog, where the water droplets or snowflakes in the air at a short distance may reflect a stronger laser signal intended for ranging of a distant object, which may affect the accuracy of the lidar ranging. In such special weather, the adjustable reference threshold for distant objects may be adjusted higher than in normal clear weather to avoid interference from water droplets or snowflakes and thus influence the ranging results.
According to the timing end time process determining method and device, when the receiving intensity of the reflected laser signal is larger than or equal to the adjustable reference threshold, the received time of the reflected laser signal is determined as the timing end time, the timing end of ranging can be accurately triggered, and therefore a more accurate laser radar ranging result can be achieved.
According to some embodiments, the distance between the lidar and the object may be calculated by the formula L = c (t 2-t 1)/2, where L is the distance, c is the speed of light, t1 is the timing start time, and t2 is the timing end time.
In an example, the total length of the optical path from the transmission of the laser signal to the reception of the laser signal may be calculated by multiplying the speed of light by the difference between the timing start time and the timing end time, and the distance between the laser radar and the object may be calculated by half the length of the optical path.
According to the calculation process of the distance between the laser radar and the object, the distance between the laser radar and the object can be calculated by utilizing the propagation time and the speed of light of the light path, and the accurate distance between the laser radar and the object can be obtained.
According to some embodiments, the laser signal may be emitted alternately at a first intensity and a second intensity, the second intensity being greater than the first intensity.
In an example, the magnitude of the supply voltage of the transmitting module may be adjusted by adjusting the magnitude of the duty cycle of the PWM, thereby adjusting the intensity of the transmitted laser signal to the first intensity or the second intensity.
In an example, the laser signal with the second intensity can be used for ranging objects with longer distances due to the larger detection distance; the laser signal of the first intensity can be used for ranging an object at a short distance because the reflection effect at the protective glass of the transmitting module is small.
FIG. 4 shows a schematic diagram of short-range object and long-range object ranging, in accordance with an embodiment of the present disclosure.
As shown in fig. 4, a vehicle 410 for laser radar ranging using the laser radar ranging method of the embodiment of the present disclosure is shown, and an object 420 having a small distance from the vehicle 410 and an object 430 having a large distance from the vehicle 410 are shown.
In an example, the vehicle 410 may emit a plurality of laser signals, each set to have a first intensity and a second intensity that alternately vary, the second intensity may be greater than the first intensity. Next, the first laser signal 411 and the second laser signal 412 schematically shown in fig. 4 will be described as an example.
In an example, the first laser signal 411 with the lower first intensity may be used to measure a distance to a closer object 420 because the reflection at the cover glass of the transmitting module is less, and the distance measurement to the closer object is more accurate. However, the first laser signal 411 may not detect the object 430 at a longer distance because of its smaller intensity and smaller detection distance. The second laser signal 412 with the higher second intensity can detect the object 430 with a longer distance due to the larger detection distance, and therefore can be used for accurately measuring the distance of the object 430.
According to the short-distance object and long-distance object ranging process disclosed by the embodiment of the disclosure, the accuracy of laser radar ranging of the long-distance object and the short-distance object can be considered in a simple manner by emitting laser signals with two kinds of intensities which are changed alternately.
According to some embodiments, the lidar may include a MEMS galvanometer having a transverse axis and a longitudinal axis, the transmitted laser signal being scanned via the MEMS galvanometer in the transverse axis and the longitudinal axis, respectively. The laser signals are scanned on the horizontal axis at unequal time intervals so that the scanning angle between two scanning paths of adjacent two-shot laser signals is the same.
The transverse and longitudinal axes of the MEMS galvanometer are also referred to as the fast and slow axes. I.e. the scanning frequency on the horizontal axis is fast, while the scanning frequency on the vertical axis is slow.
In some embodiments, the angular range over which the emitted laser signal is scanned on the horizontal axis may be, for example, 30 degrees, such as an up and down 15 degree range centered on the horizontal position of the MEMS galvanometer.
In some embodiments, the scan angle between two scan paths of adjacent twice-emitted laser signals scanned on the horizontal axis may be, for example, 0.1 degrees, 0.2 degrees, etc.
According to the scanning process of the laser radar disclosed by the embodiment of the disclosure, the scanning angles between two scanning paths for transmitting the laser signals twice are the same in the scanning process, so that the point cloud distribution of the laser signals is uniform, the subsequent data processing is facilitated, and the laser radar ranging result can be calculated more conveniently.
According to some embodiments, the scanning waveform on the horizontal axis may be a sine wave and the scanning waveform on the vertical axis may be a triangle wave.
FIG. 5 shows a schematic of a scanning waveform of a transverse axis of a MEMS galvanometer in accordance with an embodiment of the present disclosure.
As shown in fig. 5, it is schematically shown that the laser signal is continuously emitted for scanning in a period from t0 to t 4. The scanning waveform on the horizontal axis may be a sine wave, and the dots on the sine wave may represent the emitted laser signal.
In an example, in order to make the scanning angle between two scanning paths of two adjacent laser signals emitted in the time period from t0 to t1 the same, the time interval of scanning the laser signals on the horizontal axis in the time period from t0 to t1 may be gradually reduced, i.e. the dot frequency is denser.
In an example, in order to make the scanning angle between two scanning paths of two adjacent laser signals emitted in the time period from t1 to t2 the same, the time interval of scanning the laser signals on the horizontal axis may gradually increase along with the scanning in the time period from t1 to t2, i.e. the dot frequency is more sparse.
In an example, in order to make the scanning angle between two scanning paths of two adjacent laser signals emitted in the time period from t2 to t3 the same, the time interval of scanning the laser signals on the horizontal axis in the time period from t2 to t3 may be gradually reduced, i.e. the dot frequency is denser.
In an example, in order to make the scanning angle between two scanning paths of two adjacent laser signals emitted in the time period from t3 to t4 the same, the time interval of scanning the laser signals on the horizontal axis may gradually increase along with the scanning in the time period from t3 to t4, that is, the dot frequency is more sparse.
It will be appreciated that fig. 5 shows one cycle of the scanning waveform on the horizontal axis, and that the emitted laser signal may follow the same law for scanning times other than the time periods shown.
It is also understood that the laser signal may be emitted several times, for example, several tens of times according to the scanning period of the horizontal axis within one scanning period of the horizontal axis as shown in fig. 5.
FIG. 6 shows a schematic diagram of a superposition of MEMS galvanometer transverse axis and longitudinal axis scanning waveforms, in accordance with an embodiment of the present disclosure.
As shown in fig. 6, the scanning waveform on the horizontal axis may be a sine wave, and the scanning waveform on the vertical axis may be a triangular wave. The time period from t5 to t7 may represent one cycle of the scanning waveform of the vertical axis, and the frequency may be, for example, 10 to 20Hz.
In an example, as shown in fig. 6, the frequency of the swept triangular wave on the vertical axis may be much greater than the frequency of the swept sinusoidal wave on the horizontal axis. Thus, a large number of laser signal shots can be performed within one scanning period of the vertical axis, for example, within a time period from t5 to t7, to form a dense laser signal point cloud.
According to the scanning process of the laser radar, the scanning waveform on the transverse axis is set to be the sine wave, and the scanning waveform on the longitudinal axis is set to be the triangular wave, so that the laser signal can be processed, and the laser radar ranging result can be obtained through calculation more conveniently.
According to some embodiments, the operation of determining a timing end time for ranging and the operation of determining a distance between the lidar and the object may be performed during a first waveform portion in which a slope of the triangular wave is greater than zero.
With continued reference to fig. 6, as shown in fig. 6, the first waveform portion may be a period of time t5 to t6 during which the slope of the triangular wave is greater than zero, that is, the operation of determining the timing end time for ranging and the operation of determining the distance between the laser radar and the object may be performed during the period of time t5 to t 6.
In an example, in one scanning cycle of the vertical axis, for example, a time period from t5 to t7, a period of the first waveform portion in which the slope of the triangular wave is greater than zero, that is, a time period from t5 to t6, may be set to be much greater than a period in which the slope of the triangular wave is less than zero, that is, a time period from t6 to t 7. In this way, the time ratio of the operation of determining the timing end time for ranging and the operation of determining the distance between the laser radar and the object can be made larger, enabling more efficient laser radar ranging.
According to the embodiment of the disclosure, by setting the operation of timing the end time for ranging and the operation of determining the distance between the laser radar and the object to be performed during the first waveform portion in which the slope of the triangular wave is greater than zero, it is possible to avoid the influence on data processing due to the error generated between the scanning from bottom to top and the scanning from top to bottom on the longitudinal axis, thereby improving the accuracy of laser radar ranging.
According to some embodiments, the lidar ranging method may further include: the transmission and reception of the laser signal is monitored during a second waveform portion in which the slope of the triangular wave is less than zero.
With continued reference to fig. 6, as shown in fig. 6, the second waveform portion may be, for example, a time period t6 to t7 during which the slope of the triangular wave is less than zero, e.g., the transmission and reception of the laser signal may be monitored during the time period t6 to t 7.
According to the embodiment of the disclosure, the transmitting and receiving of the laser signal are monitored during the second waveform part with the slope of the triangular wave being smaller than zero, so that the transmitting strength, the adjustable reference threshold value and other parameters of the laser signal can be adjusted in time according to the transmitting and receiving conditions of the laser signal, and the accuracy of laser radar ranging is improved.
Therefore, in one cycle of the scanning waveform of the vertical axis, one period of time (e.g., a period of time t5 to t 6) may be used for ranging, and another period of time (e.g., t6 to t 7) may not be used for ranging. The time period not used for ranging may be 1/20 to 1/8 of the period. The switching of the two operations described above may be performed, for example, by an analog switching gate.
According to some embodiments, the at least two intensities of the laser signal may be controlled by at least two duty cycles generated by PWM.
In an example, the amplitude magnitude of the pulse width modulated signal may be, for example, 3.3V, and the pulse frequency may be, for example, 400KHz. When the laser signal having a small intensity is emitted, the high level time of the pulse width modulation signal may be, for example, greater than or equal to 20ns, and less than or equal to 40ns. When a laser signal with a large intensity is emitted, the high level time of the pulse width modulation signal may be, for example, 40ns or more and 150ns or less.
According to the control process of the laser signal intensity of the embodiment of the present disclosure, the control of the laser signal intensity can be conveniently and reliably realized by controlling the intensity of the laser signal by using the duty ratio generated by the pulse width modulation.
According to another aspect of the present disclosure, a laser radar ranging device is also provided.
Fig. 7 shows a block diagram of a lidar ranging device 700 according to an embodiment of the disclosure.
As shown in fig. 7, laser radar ranging apparatus 700 includes: a laser emission determination module 710 configured to determine a laser signal for emission, and a timing start time at which the laser signal is emitted to perform ranging, wherein the laser signal is configured to have at least two emission intensities that alternate; a laser reflection acquisition module 720 configured to acquire a laser signal reflected from an object; a time determination module 730 configured to determine a timing end time by triggering a logic level flip based on a comparison result between the received intensity of the reflected laser signal and an adjustable reference threshold, wherein the adjustable reference threshold is determined based on the received intensity of the laser signal; and a distance determination module 740 configured to determine a distance between the lidar and the object based on the timing start time and the timing end time.
Since the laser emission determination module 710, the laser reflection acquisition module 720, the time determination module 730, and the distance determination module 740 in the lidar ranging device 700 may respectively correspond to steps S201 to S204 as described in fig. 2, details of various aspects thereof are not repeated here.
In addition, lidar ranging device 700 and the modules included therein may also include further sub-modules, which will be described in detail below in conjunction with fig. 8.
According to the embodiment of the present disclosure, by emitting the laser signal having the at least two emission intensities that are alternately changed, the ranging accuracy for the long-distance object and the short-distance object can be automatically taken into consideration. Meanwhile, the adjustable reference threshold is determined based on the receiving intensity of the reflected laser signal, and the timing end time is determined by triggering logic level inversion based on the comparison between the receiving intensity of the reflected laser signal and the adjustable reference threshold, so that not only can more dynamic ranging be realized for the distance, but also the influence of interference signals from non-ranging target objects can be eliminated to a certain extent, and more accurate laser radar ranging results can be realized.
Fig. 8 shows a block diagram of a lidar ranging apparatus 800 according to another embodiment of the present disclosure.
As shown in fig. 8, lidar ranging device 800 may include a laser emission determination module 810, a laser reflection acquisition module 820, a time determination module 830, and a distance determination module 840. The laser emission determination module 810, the laser reflection acquisition module 820, the time determination module 830, and the distance determination module 840 may correspond to the laser emission determination module 710, the laser reflection acquisition module 720, the time determination module 730, and the distance determination module 740 shown in fig. 7, and thus the details thereof will not be described herein.
In an example, the time determination module 830 can include: an execution module 831 configured to determine a time at which the reflected laser signal is received as a timing end time in response to the received intensity of the reflected laser signal being greater than or equal to the adjustable reference threshold.
Therefore, when the receiving intensity of the reflected laser signal is larger than or equal to the adjustable reference threshold, the time of receiving the reflected laser signal is determined as the timing end time, the timing end of ranging can be accurately triggered, and therefore a more accurate laser radar ranging result can be achieved.
In an example, the distance between the lidar and the object may be calculated by the formula L = c (t 2-t 1)/2, where L is the distance, c is the speed of light, t1 is the timing start time, and t2 is the timing end time.
Therefore, the distance between the laser radar and the object is calculated by utilizing the propagation time and the light speed of the light path, so that the accurate distance between the laser radar and the object can be obtained.
In an example, the laser signal may be emitted alternately at a first intensity and a second intensity, the second intensity being greater than the first intensity.
Therefore, by emitting laser signals with two kinds of intensity which are changed alternately, the accuracy of laser radar ranging of long-distance objects and short-distance objects can be considered in a simple mode.
In an example, the lidar may include a MEMS galvanometer having a transverse axis and a longitudinal axis, via which the emitted laser signals may be scanned on the transverse axis and the longitudinal axis, respectively, wherein the laser signals are scanned on the transverse axis at unequal time intervals such that a scanning angle between two scanning paths of adjacent two emitted laser signals is the same.
Therefore, the scanning angle between two scanning paths for emitting the laser signals twice in the scanning process is the same, point cloud distribution of the laser signals can be uniform, subsequent data processing is facilitated, and the laser radar ranging result can be obtained through calculation more conveniently.
In an example, the scanning waveform on the horizontal axis may be a sine wave and the scanning waveform on the vertical axis is a triangle wave.
Therefore, the scanning waveform on the transverse axis is set to be the sine wave, and the scanning waveform on the longitudinal axis is set to be the triangular wave, so that the laser signal can be processed, and the laser radar ranging result can be calculated more conveniently.
In an example, the operation of determining the timing end time and the operation of determining the distance between the lidar and the object may be performed during a first waveform portion in which the slope of the triangular wave is greater than zero.
Therefore, by setting the operation of timing the end time for ranging and the operation of determining the distance between the laser radar and the object to be performed during the first waveform portion in which the slope of the triangular wave is greater than zero, it is possible to avoid the influence on data processing due to the error generated between the scanning from bottom to top and the scanning from top to bottom on the longitudinal axis, and thus, the accuracy of laser radar ranging is improved.
In an example, lidar ranging device 800 may also include a laser signal monitoring module 850 configured to monitor the transmission and reception of laser signals during a second waveform portion where the slope of the triangular wave is less than zero.
Therefore, by monitoring the emission and the reception of the laser signals during the second waveform part with the slope of the triangular wave smaller than zero, the parameters such as the emission intensity of the laser signals and the adjustable reference threshold value can be adjusted in time according to the emission and the reception conditions of the laser signals, and the accuracy of laser radar ranging is improved.
In an example, the at least two intensities of the laser signal may be controlled by at least two duty cycles generated by pulse width modulation.
Thus, by controlling the intensity of the laser signal using the duty ratio generated by the pulse width modulation, the control of the intensity of the laser signal can be easily and reliably achieved.
According to another aspect of the present disclosure, there is also provided a lidar system.
Fig. 9 shows a schematic structural diagram of a lidar system 900 according to an embodiment of the disclosure.
As shown in fig. 9, laser radar system 900 includes: an FPGA chip 910 configured to perform the methods in the above embodiments; a transmitting device 920, configured to transmit a laser signal, and connected to the FPGA chip 910, wherein the laser signal and a timing start time of the laser signal are determined by the FPGA chip 910, and the laser signal is configured to have at least two intensities that are alternately changed; a receiving device 930 for receiving the laser signal reflected from the object and connected to the FPGA chip 910 to provide the reflected laser signal to the FPGA chip 910; a scanning device 940 including a MEMS galvanometer and connected to the FPGA chip 910, the MEMS galvanometer configured to adjust a scanning angle of the laser signal by rotating on a horizontal axis and a vertical axis, wherein the scanning angle is determined by the FPGA chip 910; and a voltage adjusting device 950, configured to generate an adjustable reference threshold, and connect with the FPGA chip 910 to provide the adjustable reference threshold to the FPGA chip 910, where the adjustable reference threshold is used to determine a timing end time of ranging performed by the laser radar; wherein at least one of the FPGA chip 910, the transmitting device 920, the receiving device 930, the scanning device 940 and the voltage regulating device 950 is monitored in a closed loop.
In an example, as shown in fig. 9, the FPGA chip 910 and the transmitting device 920, the FPGA chip 910 and the receiving device 930, the FPGA chip 910 and the scanning device 940, and the FPGA chip 910 and the voltage regulating device 950 may all be connected to each other.
In an example, there may be bi-directional information transfer between the FPGA chip 910 and the transmitting device 920. The FPGA chip 910 may transmit information indicating the intensity of the laser signal and the timing start time of the emission of the laser signal to the emitting device 920, for example. The FPGA chip 910 may adjust a transmission power boost circuit (transmission charge and discharge circuit) by PWM to make the transmitting device 920 transmit a laser signal having at least two intensities that are alternately changed. The transmitting device 920 may transmit, for example, information capable of indicating the intensity of the laser signal actually transmitted and the actual transmission time of the laser signal to the FPGA chip 910. The emitting device 920 may feed back the generated laser signal to the FPGA chip 910 through an optical coupler (voltage amplitude is, for example, 1.5V). Thus, the transmitting device 920 is monitored in a closed loop, so that the timing can be more accurately performed, and the adverse effect of electromagnetic interference on timing and distance measurement is avoided.
In an example, the FPGA chip 910 and the receiving device 930 may have a unidirectional information transfer relationship therebetween. The receiving device 930 may transmit, for example, information indicating the intensity of the received laser signal and the reception time of the laser signal to the FPGA chip 910.
In an example, the FPGA chip 910 and the scanning device 940 may have a bi-directional information transfer relationship. The FPGA chip 910 may, for example, send information (e.g., scan angle, frequency, period, etc.) to the scanning device 940 regarding the ability to direct the laser signal to scan across the lateral and vertical axes of the MEMS galvanometer. The scanning device 940 may collect and transmit the feedback voltage through a D/a (Digital/Analog converter) to the FPGA chip 910, for example, through a feedback module provided therein. In this way, the scanning device 940 is monitored in a closed loop, so that the scanning angle can be controlled more accurately, and the accuracy of laser radar ranging is improved.
In an example, there may be bi-directional information transfer between the FPGA chip 910 and the voltage regulation device 950. The FPGA chip 910 may, for example, send information to the voltage adjustment device 950 that can indicate the strength of the received laser signal. The voltage adjustment device 950 may, for example, send the magnitude of the adjustable reference threshold determined according to the intensity of the received laser signal to the FPGA chip 910. In this way, the voltage regulation device 950 is monitored in a closed loop, enabling more accurate control of the adjustable reference threshold.
In an example, the adjustable reference threshold may be generated by a D/a and an operational amplifier. The weaker adjustable reference threshold may be set, for example, to 0.4-0.5V, while the stronger adjustable reference threshold may be set, for example, to 0.6-0.7V, for detection of different reception intensities, i.e., different distances, of the laser signal, respectively. The received laser signal and the adjustable reference threshold may be compared at an LVDS (Low-Voltage Differential Signaling) terminal of the FPGA chip 910 to trigger logic level inversion, thereby triggering timing of the ranging to be ended.
In an example, lidar system 900 may further include a power monitoring module connected to FPGA chip 910 to collect power supply via D/a for closed loop monitoring.
In an example, the FPGA chip 910 may be monitored in a closed loop via an external watchdog program or chip. Thus, closed loop monitoring of the entire lidar system 900 may be achieved.
According to the laser radar system of the embodiment of the disclosure, the FPGA chip, the transmitting device, the receiving device, the scanning device and the voltage adjusting device in the closed-loop monitoring laser radar system can adjust the intensity of laser signals and links such as transmitting opportunity, power supply voltage, scanning direction and data processing in time according to actual conditions, and the accuracy of laser radar ranging is improved.
According to another aspect of the present disclosure, there is also provided an electronic device including: at least one processor; and a memory communicatively coupled to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of the above embodiments.
According to another aspect of the present disclosure, there is also provided a non-transitory computer readable storage medium storing computer instructions for causing a computer to perform the method in the above-described embodiments.
According to another aspect of the present disclosure, there is also provided a computer program product comprising a computer program, wherein the computer program, when executed by a processor, implements the method in the above embodiments.
According to another aspect of the present disclosure, there is also provided an FPGA chip including a circuit implementing the method in the above embodiments.
According to another aspect of the present disclosure, there is also provided an autonomous vehicle comprising an FPGA chip, wherein the FPGA chip is configured to perform the method of the above embodiments.
Referring to fig. 10, a block diagram of a structure of an electronic device 1000, which may be a server or a client of the present disclosure, which is an example of a hardware device that may be applied to aspects of the present disclosure, will now be described. Electronic device is intended to represent various forms of digital electronic computer devices, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other suitable computers. Electronic devices may also represent various forms of mobile devices, such as personal digital processors, cellular telephones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions, are meant to be examples only, and are not meant to limit implementations of the disclosure described and/or claimed herein.
As shown in fig. 10, the electronic device 1000 includes a computing unit 1001 that can perform various appropriate actions and processes according to a computer program stored in a Read Only Memory (ROM) 1002 or a computer program loaded from a storage unit 1008 into a Random Access Memory (RAM) 1003. In the RAM 1003, various programs and data necessary for the operation of the electronic apparatus 1000 can also be stored. The calculation unit 1001, the ROM 1002, and the RAM 1003 are connected to each other by a bus 1004. An input/output (I/O) interface 1005 is also connected to bus 1004.
A number of components in the electronic device 1000 are connected to the I/O interface 1005, including: input section 1006, output section 1007, storage section 1008, and communication section 1009. The input unit 1006 may be any type of device capable of inputting information to the electronic device 1000, and the input unit 1006 may receive input numeric or character information and generate key signal inputs related to user settings and/or function controls of the electronic device, and may include, but is not limited to, a mouse, a keyboard, a touch screen, a track pad, a track ball, a joystick, a microphone, and/or a remote controller. Output unit 1007 may be any type of device capable of presenting information and may include, but is not limited to, a display, speakers, a video/audio output terminal, a vibrator, and/or a printer. The storage unit 1008 may include, but is not limited to, a magnetic disk, an optical disk. The communication unit 1009 allows the electronic device 1000 to exchange information/data with other devices via a computer network, such as the internet, and/or various telecommunications networks, and may include, but is not limited to, modems, network cards, infrared communication devices, wireless communication transceivers, and/or chipsets, such as bluetooth (TM) devices, 802.11 devices, wiFi devices, wiMax devices, cellular communication devices, and/or the like.
Computing unit 1001 may be a variety of general and/or special purpose processing components with processing and computing capabilities. Some examples of the computing unit 1001 include, but are not limited to, a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), various dedicated Artificial Intelligence (AI) computing chips, various computing units running machine learning model algorithms, a Digital Signal Processor (DSP), and any suitable processor, controller, microcontroller, and so forth. The calculation unit 1001 performs the respective methods and processes described above, such as the laser radar ranging method. For example, in some embodiments, the lidar ranging method may be implemented as a computer software program tangibly embodied in a machine-readable medium, such as storage unit 1008. In some embodiments, part or all of the computer program may be loaded and/or installed onto electronic device 1000 via ROM 1002 and/or communications unit 1009. When the computer program is loaded into RAM 1003 and executed by computing unit 1001, one or more steps of the lidar ranging method described above may be performed. Alternatively, in other embodiments, the calculation unit 1001 may be configured to perform the lidar ranging method in any other suitable manner (e.g., by means of firmware).
Various implementations of the systems and techniques described here above may be implemented in digital electronic circuitry, integrated circuitry, field Programmable Gate Arrays (FPGAs), application Specific Integrated Circuits (ASICs), application Specific Standard Products (ASSPs), system on a chip (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and/or combinations thereof. These various embodiments may include: implemented in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, receiving data and instructions from, and transmitting data and instructions to, a storage system, at least one input device, and at least one output device.
Program code for implementing the methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowchart and/or block diagram to be performed. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package partly on the machine and partly on a remote machine or entirely on the remote machine or server.
In the context of this disclosure, a machine-readable medium may be a tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
To provide for interaction with a user, the systems and techniques described here can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to a user; and a keyboard and a pointing device (e.g., a mouse or a trackball) by which a user can provide input to the computer. Other kinds of devices may also be used to provide for interaction with a user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form, including acoustic, speech, or tactile input.
The systems and techniques described here can be implemented in a computing system that includes a back-end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front-end component (e.g., a user computer having a graphical user interface or a web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: local Area Networks (LANs), wide Area Networks (WANs), the internet, and blockchain networks.
The computer system may include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. The server may be a cloud server, a server of a distributed system, or a server with a combined blockchain.
It should be understood that various forms of the flows shown above may be used, with steps reordered, added, or deleted. For example, the steps described in the present disclosure may be performed in parallel, sequentially or in different orders, and are not limited herein as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved.
Although embodiments or examples of the present disclosure have been described with reference to the accompanying drawings, it is to be understood that the above-described methods, systems and apparatus are merely exemplary embodiments or examples and that the scope of the present invention is not limited by these embodiments or examples, but only by the claims as issued and their equivalents. Various elements in the embodiments or examples may be omitted or may be replaced with equivalents thereof. Further, the steps may be performed in an order different from that described in the present disclosure. Further, various elements in the embodiments or examples may be combined in various ways. It is important that as technology evolves, many of the elements described herein may be replaced by equivalent elements that appear after the present disclosure.

Claims (24)

1. A laser radar ranging method, comprising:
determining a laser signal for emission and a timing start time at which the laser signal is emitted for ranging, wherein the laser signal is configured to have at least two emission intensities that alternate;
acquiring the laser signal reflected from an object;
determining a timing end time by triggering a logic level flip based on a comparison between a received intensity of the reflected laser signal and an adjustable reference threshold, wherein the adjustable reference threshold is determined based on the received intensity of the laser signal; and
determining a distance between the lidar and the object based on the timing start time and the timing end time.
2. The method of claim 1, wherein the determining a timing end time by triggering a logic level flip based on a comparison between a received intensity of the reflected laser signal and an adjustable reference threshold comprises:
determining a time at which the reflected laser signal is received as the timing end time in response to the received intensity of the reflected laser signal being greater than or equal to the adjustable reference threshold.
3. The method according to claim 1 or 2, wherein the distance between the lidar and the object is calculated by the formula L = c (t 2-t 1)/2, where L is the distance, c is the speed of light, t1 is the timing start time, and t2 is the timing end time.
4. The method of any one of claims 1 to 3, wherein the laser signal is emitted alternately at a first intensity and a second intensity, the second intensity being greater than the first intensity.
5. The method according to any one of claims 1 to 4, wherein the lidar comprises a micro-electromechanical system galvanometer having a transverse axis and a longitudinal axis, the emitted laser signals being scanned via the micro-electromechanical system galvanometer over the transverse axis and the longitudinal axis, respectively,
wherein the laser signals are scanned on the horizontal axis at unequal time intervals so that scanning angles between two scanning paths which emit the laser signals adjacently twice are the same.
6. The method of claim 5, wherein the scanning waveform on the horizontal axis is a sine wave and the scanning waveform on the vertical axis is a triangle wave.
7. The method of claim 6, wherein the operations of determining a timing end time for ranging and determining a distance between the lidar and the object are performed during a first waveform portion in which a slope of the triangular wave is greater than zero.
8. The method of claim 5 or 6, further comprising: monitoring the transmission and reception of the laser signal during a second waveform portion in which the slope of the triangular wave is less than zero.
9. The method of any of claims 1 to 7, wherein the at least two intensities of the laser signal are controlled by at least two duty cycles generated by pulse width modulation.
10. A lidar ranging device comprising:
a laser emission determination module configured to determine a laser signal for emission, and a timing start time at which the laser signal is emitted to perform ranging, wherein the laser signal is configured to have at least two emission intensities that alternate;
a laser reflection acquisition module configured to acquire the laser signal reflected from an object;
a time determination module configured to determine a timing end time by triggering a logic level flip based on a comparison between a received intensity of the reflected laser signal and an adjustable reference threshold, wherein the adjustable reference threshold is determined based on the received intensity of the laser signal; and
a distance determination module configured to determine a distance between the lidar and the object based on the timing start time and the timing end time.
11. The apparatus of claim 10, wherein the time determination module comprises:
an execution module configured to determine a time at which the reflected laser signal is received as the timing end time in response to the received intensity of the reflected laser signal being greater than or equal to the adjustable reference threshold.
12. The apparatus according to claim 10 or 11, wherein the distance between the lidar and the object is calculated by the formula L = c (t 2-t 1)/2, where L is the distance, c is the speed of light, t1 is the timing start time, and t2 is the timing end time.
13. The apparatus of any one of claims 10 to 12, wherein the laser signal is emitted alternately at a first intensity and a second intensity, the second intensity being greater than the first intensity.
14. The apparatus of any one of claims 10 to 13, wherein the lidar includes a mems galvanometer having a transverse axis and a longitudinal axis, the emitted laser signals being scanned over the transverse axis and the longitudinal axis, respectively, via the mems galvanometer,
wherein the laser signals are scanned on the transverse axis at unequal time intervals so that the scanning angles between two scanning paths which emit the laser signals twice adjacently are the same.
15. The apparatus of claim 14, wherein the scanning waveform on the horizontal axis is a sine wave and the scanning waveform on the vertical axis is a triangle wave.
16. The apparatus of claim 15, wherein the operation of determining a timing end time and the operation of determining a distance between the lidar and the object are performed during a first waveform portion in which a slope of the triangular wave is greater than zero.
17. The apparatus of claim 14 or 15, further comprising:
a laser signal monitoring module configured to monitor transmission and reception of the laser signal during a second waveform portion in which a slope of the triangular wave is less than zero.
18. The apparatus of any one of claims 10 to 16, wherein the at least two intensities of the laser signal are controlled by at least two duty cycles generated by pulse width modulation.
19. A lidar system comprising:
an FPGA chip configured to perform the method of any one of claims 1-9;
the transmitting device is used for transmitting a laser signal and is connected with the FPGA chip, wherein the laser signal and the timing starting time for transmitting the laser signal are determined by the FPGA chip, and the laser signal is configured to have at least two intensities which are alternately changed;
the receiving device is used for receiving the laser signal reflected from an object and is connected with the FPGA chip to provide the reflected laser signal to the FPGA chip;
a scanning device comprising a MEMS galvanometer and coupled to the FPGA chip, the MEMS galvanometer configured to adjust a scanning angle of the laser signal by rotation on a lateral axis and a longitudinal axis, wherein the scanning angle is determined by the FPGA chip; and
the voltage adjusting device is used for generating an adjustable reference threshold value and is connected with the FPGA chip to provide the adjustable reference threshold value for the FPGA chip, and the adjustable reference threshold value is used for determining the timing ending time of the laser radar for ranging;
wherein at least one of the FPGA chip, the transmitting device, the receiving device, the scanning device, and the voltage regulating device is monitored in a closed loop.
20. An electronic device, comprising:
at least one processor; and
a memory communicatively coupled to the at least one processor; wherein
The memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-9.
21. A non-transitory computer readable storage medium having stored thereon computer instructions for causing the computer to perform the method of any one of claims 1-9.
22. A computer program product comprising a computer program, wherein the computer program realizes the method according to any of claims 1-9 when executed by a processor.
23. An FPGA chip comprising circuitry implementing the method of any one of claims 1-9.
24. An autonomous vehicle comprising an FPGA chip, wherein the FPGA chip is configured to perform the method of any of claims 1-9.
CN202211321053.4A 2022-10-26 2022-10-26 Laser radar ranging method, device and system and automatic driving vehicle Pending CN115657058A (en)

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