WO2022206501A1

WO2022206501A1 - Radar-based distance measurement method and device, radar, and terminal

Info

Publication number: WO2022206501A1
Application number: PCT/CN2022/082440
Authority: WO
Inventors: 王超
Original assignee: 华为技术有限公司
Priority date: 2021-04-02
Filing date: 2022-03-23
Publication date: 2022-10-06
Also published as: CN115184946A

Abstract

Provided are a radar-based distance measurement method and apparatus, a radar, a terminal, a computer readable storage medium, and a computer program product. The distance measurement method comprises: determining a first time of flight according to echo data of at least one first frame received by a radar; determining a second time of flight according to echo data of at least one second frame received by the radar; eliminating some of the time of flight in the second time of flight according to the first time of flight to obtain a third time of flight; and determining distance information of a target according to the first time of flight and the third time of flight, wherein in a first measurement time corresponding to the first frame, the radar disables transmission within a plurality of transmission periods, and within a second measurement time corresponding to the second frame, the radar transmits within each transmission period. According to the distance measurement method, the distance ambiguity problem of the radar can be resolved, and the measurement capability and measurement accuracy of the target distance are improved.

Description

Radar-based distance detection method, device, radar and terminal

This application claims the priority of the Chinese patent application with the application number 202110361727.2 and the application title "Radar-based distance detection method, device, radar and terminal" filed with the China Patent Office on April 2, 2021, the entire contents of which are by reference Incorporated in this application.

technical field

The present application relates to the field of radar technology, and in particular, to a radar-based distance detection method, device, radar and terminal.

Background technique

By sending out emission signals to the environment, receiving echo signals reflected from target objects in the environment, and analyzing the echo signals, lidar can determine the distance and other information of the target objects in the environment. Among them, the laser radar has a ranging range, and the laser radar of the prior art has a range limit on the analysis and processing of the echo signal. Ideally, the echo signal is reflected by the target object within the ranging range of the lidar, and the distance information of the target object determined according to the echo signal analysis is within the ranging range. However, when there is a target object with high reflectivity or ultra-high reflectivity (1000%) in the environment outside the ranging range, since the intensity of the reflected echo signal is strong enough, it can also be received by the lidar. The echo signal reflected by the target outside the ranging range is mistakenly regarded as the echo signal of the target within the ranging range for analysis, resulting in the deviation of the analyzed target distance from the real distance of the target object. This phenomenon is called distance ambiguity or ambiguous distance reentry. This phenomenon may cause the radar to misjudge and trigger a false alarm, and transmit the wrong information of the target distance, causing potential safety hazards when lidar is applied to scenarios with high safety requirements such as autonomous driving.

The methods proposed in the prior art have some aspects that need to be improved in terms of ensuring no loss of ranging capability, computational complexity and computational power requirements, and most of them are suitable for laser radars and even millimeter-wave radars based on pulse ranging and analog signal output. The solid-state lidar based on the principle of single-photon detection is a kind of digital radar, and it is necessary to combine the characteristics of the principle of single-photon detection to study the solution to the distance ambiguity suitable for the lidar of this system.

SUMMARY OF THE INVENTION

In view of this, a radar-based distance detection method, device, radar, and terminal are proposed. The distance detection method of the embodiments of the present application can realize the resolution of the distance ambiguity problem of the radar, and improve the detection ability and detection accuracy of the target distance.

In a first aspect, an embodiment of the present application provides a radar-based distance detection method, the method comprising:

determining a first flight time according to echo data of at least one first frame received by the radar, where the first flight time includes the flight time of a target outside the ranging range of the radar;

determining the second time of flight according to the echo data of at least one second frame received by the radar;

According to the first flight time, eliminate part of the flight time in the second flight time to obtain a third flight time, and the part of the flight time corresponds to the flight time of the target outside the ranging range;

According to the first flight time and the third flight time, the distance information of the target is determined,

Wherein, in the first measurement time corresponding to the first frame, the radar turns off transmission in multiple transmission periods, and in the second measurement time corresponding to the second frame, the radar transmits in each transmission period.

According to the radar-based distance detection method according to the embodiment of the present application, during the first measurement time corresponding to the first frame, the radar turns off the transmission in multiple transmission periods, so that at least one of the echo data of the first frame has the transmission turned off. The echo data received in multiple transmission cycles has nothing to do with the target in the ranging range. By receiving the echo data of the first frame, the flight time of the target outside the ranging range in the first flight time can be determined without being affected by the target. Interference of targets within the ranging range; so that when the first flight time is used to determine the target distance information, the distance information of the targets outside the ranging range can be obtained according to the flight time of the targets outside the ranging range, and the ability of target distance detection can be improved. During the second measurement time corresponding to the second frame, the radar transmits in each transmission period, so that the echo data of at least one second frame is related to both the targets within the ranging range and the targets outside the ranging range. Therefore, according to the echo data of at least one second frame, the determined second flight time includes the flight time of the target outside the ranging range and the flight time of the target within the ranging range; combined with the first flight time, the second flight time can be removed The false flight time corresponding to the flight time of the target outside the ranging range is obtained, and the third flight time is obtained. And the third flight time does not include the flight time of the target outside the ranging range, so using the third flight time can determine the distance information of the target within the ranging range without interference from the target outside the ranging range, which can improve the accuracy of target distance detection. Spend. According to the radar-based distance detection method according to the embodiment of the present application, the finally obtained distance information of the target is more comprehensive, and the obtained distance information of the target does not have distance ambiguity, and the accuracy is high.

According to the first aspect, in a first possible implementation manner of the distance detection method, the method further includes:

During the first measurement time corresponding to the first frame, the radar is controlled to enter one or more off cycles, and each off cycle includes multiple emission cycles;

In each shutdown period, the radar is sequentially controlled to close the transmission for h transmission periods, open for 1 transmission period, and then close for a transmission period, where h and a are positive integers;

Wherein, the first echo data of the first frame is received in the a transmission cycles, and the first echo data is used to determine the flight time of the target outside the ranging range of the radar.

By controlling the radar to close the transmission for h transmission periods, the radar can prepare for the transmission of pulses within 1 transmission period. The first echo data of the first frame received in the period has nothing to do with the target within the ranging range, so that the first echo data of the first frame can be used to determine the target outside the ranging range in the first flight time flight time without interference from targets in the ranging range.

According to a first possible implementation manner of the first aspect, in a second possible implementation manner of the distance detection method, the method further includes:

In a transmission cycle after each said closing cycle ends, control the radar to start transmitting;

Wherein, the second echo data of the first frame is received in the one transmission cycle, the second echo data is used to determine the fourth flight time, the first flight time includes the fourth flight time, and the The fourth flight time represents the flight time of the target within the ranging range.

By controlling the radar to start transmitting in a transmitting period after each closing period, the first echo data of the first frame received in the one transmitting period is not interfered by the target outside the ranging range, and is consistent with the first frame. Therefore, the fourth time-of-flight determined according to the first echo data of the first frame can represent the target that cannot be detected in the entire off period of the first frame. Flight time to target in range. The processor can determine the distance information of the target within the ranging range according to the fourth flight time and the third flight time in the first flight time. In this way, the missed detection of the target by the radar can be avoided, so that the obtained distance information of the target within the ranging range is more accurate.

According to the first aspect, and any one possible implementation manner of the above first aspect, in a third possible implementation manner of the distance detection method, the radar receives echoes through one or more single-photon detectors photons, and the echo data is determined based on the count of received echo photons.

In this way, the radar can determine the distance information of the target outside the ranging range and the distance information of the target within the ranging range according to the echo data.

According to a third possible implementation manner of the first aspect, in a fourth possible implementation manner of the distance detection method, determining the first flight time according to echo data of at least one first frame received by the radar includes:

Determine a photon count histograms according to the counts of echo photons received in the a emission periods in all the off periods of the first frame, wherein each photon count histogram is based on the same The sequence of emission cycles is determined by the counts of echoed photons;

According to the flight time corresponding to the a peak positions of the a photon count histograms, the flight time of the target outside the ranging range of the radar in the first flight time is determined, wherein each photon count histogram includes one peak position .

By processing the a photon count histograms, the time of flight of the target outside the ranging range in each emission period in the entire shutdown period can be determined, so as to determine the target time out of the ranging range of the radar in the first flight time. The time-of-flight enables the processor to further determine the distance information of targets outside the radar's ranging range. The method of determining a photon count histogram can be applied to a fast moving scene, which makes the method of target distance detection more targeted, and can ensure the accuracy of the distance information determined by the distance detection.

According to a third possible implementation manner of the first aspect, in a fifth possible implementation manner of the distance detection method, determining the first flight time according to echo data of at least one first frame received by the radar includes:

According to the counts of echo photons received in the a emission periods in all the off periods of the first frame, determine a photon count histogram;

According to the flight time corresponding to the e peak positions of one photon count histogram, the flight time of the target outside the ranging range of the radar in the first flight time is determined, where e is a positive integer less than or equal to a.

In this way, the flight time of the target outside the ranging range of the radar in the first flight time can be determined, so that the processor can further determine the distance information of the target outside the ranging range of the radar. The method of determining a photon count histogram can be applied to a moving scene where the radar is in a slow speed, or when the radar is in a stationary scene, which makes the method of target distance detection more targeted and can ensure the accuracy of the distance information determined by the distance detection. And it is determined that the data processing cost of one photon count histogram is low, which can save the data processing cost of the processor and improve the data processing efficiency.

According to a third possible implementation manner of the first aspect, in a sixth possible implementation manner of the distance detection method, the method further includes:

Determine a photon count histogram according to the count of the echo photons in an emission period after each of the off periods ends;

The fourth flight time in the first flight time is determined according to the flight time corresponding to at least one peak position in the multiple flight time intervals in the one photon count histogram, and the multiple flight time intervals are based on the radar The time-of-flight of targets outside the ranging range is determined.

The fourth flight time interval is determined according to the flight time of the target outside the ranging range of the radar, and the fourth flight time interval is determined according to the flight time corresponding to at least one peak position in the multiple flight time interval in a photon count histogram. time, so that the flight time of the target within the ranging range close to the flight time of the target outside the ranging range can be detected, that is, the fourth flight time. In this way, the missed detection caused by the flight time of the target in the ranging range during the entire off period of the first frame can be avoided, and the ranging capability of the radar can be improved.

According to a first possible implementation manner of the first aspect, in a seventh possible implementation manner of the distance detection method, the power of the transmission pulse within one transmission period of the start transmission is higher than that of the second measurement transmit pulse power over time.

The purpose of increasing the transmit pulse power is to capture the photons of the echo pulses of the targets at longer distances. In this way, the ranging capability of the radar system can be improved.

In a second aspect, an embodiment of the present application provides a distance detection device, the device comprising:

a first determining module, for determining a first flight time according to echo data of at least one first frame received by the radar, where the first flight time includes the flight time of a target outside the ranging range of the radar;

The second determining module determines the second flight time according to the echo data of at least one second frame received by the radar;

The third determination module, according to the first flight time, eliminates part of the flight time in the second flight time to obtain a third flight time, and the part of the flight time corresponds to the flight time of the target outside the ranging range;

the fourth determination module, according to the first flight time and the third flight time, to determine the distance information of the target,

According to the second aspect, in a first possible implementation manner of the distance detection device, the device further includes:

The first control module, during the first measurement time corresponding to the first frame, controls the radar to enter one or more shutdown periods, and each shutdown period includes multiple emission periods;

The second control module, in each off cycle, sequentially controls the radar to turn off the transmission for h firing cycles, turn on the firing for 1 firing cycle, and then turn off the firing for a firing cycle, where h and a are positive integers;

According to a first possible implementation manner of the second aspect, in a second possible implementation manner of the distance detection apparatus, the apparatus further includes:

The third control module controls the radar to start transmitting in a transmitting period after each closing period ends;

According to the second aspect, and any one possible implementation manner of the above second aspect, in a third possible implementation manner of the distance detection device, the radar receives echoes through one or more single-photon detectors photons, and the echo data is determined based on the count of received echo photons.

According to a third possible implementation manner of the second aspect, in a fourth possible implementation manner of the distance detection device, the first determining module includes:

The first determination sub-module determines a photon count histograms according to the counts of echo photons received in the a emission periods in all the off periods of the first frame, wherein each photon count histogram is based on In all off periods, the counts of echo photons of emission periods in the same order are determined;

The second determination sub-module determines the time of flight of a target outside the ranging range of the radar in the first time of flight according to the time of flight corresponding to the a peak positions of the a photon count histograms, wherein each photon count histogram The graph includes 1 peak position.

According to a third possible implementation manner of the second aspect, in a fifth possible implementation manner of the distance detection device, the first determining module includes:

The third determination sub-module determines a photon count histogram according to the counts of echo photons received in the a emission period in all the off periods of the first frame;

The fourth determination sub-module, according to the flight time corresponding to the e peak positions of one photon count histogram, determines the flight time of the target outside the ranging range of the radar in the first flight time, wherein e is less than or equal to a positive integer of .

According to a third possible implementation manner of the second aspect, in a sixth possible implementation manner of the distance detection apparatus, the apparatus further includes:

The fifth determination module, according to the count of the echo photons in an emission period after each said shutdown period ends, to determine a photon count histogram;

The sixth determination module, according to the flight time corresponding to at least one peak position in the multiple flight time intervals in the one photon count histogram, determines the fourth flight time in the first flight time, the multiple flight time intervals. The flight time interval is determined according to the flight time of the target outside the ranging range of the radar.

According to a first possible implementation manner of the second aspect, in a seventh possible implementation manner of the distance detection apparatus, the power of the transmit pulse within one transmit period of the start-to-transmit is higher than that of the second measurement transmit pulse power over time.

In a third aspect, embodiments of the present application provide a distance detection device, including:

processor;

memory for storing processor-executable instructions;

Wherein, the processor is configured to implement the first aspect or one or more of the distance detection methods in multiple possible implementation manners of the first aspect when executing the instruction.

In a fourth aspect, embodiments of the present application provide a non-volatile computer-readable storage medium on which computer program instructions are stored, and when the computer program instructions are executed by a processor, the above-mentioned first aspect or the first aspect is implemented One or more of the various possible implementations of the distance detection method.

In a fifth aspect, embodiments of the present application provide a computer program product, comprising computer-readable codes, or a non-volatile computer-readable storage medium carrying computer-readable codes, when the computer-readable codes are stored in an electronic When running in the device, the processor in the electronic device executes the first aspect or one or more of the distance detection methods in the multiple possible implementation manners of the first aspect.

In a sixth aspect, an embodiment of the present application provides a radar, including the second aspect or a distance detection device of one or more of the multiple possible implementations of the second aspect, or including the above-mentioned third aspect. distance detection device.

In a seventh aspect, an embodiment of the present application provides a terminal, including the radar of the sixth aspect.

These and other aspects of the present application will be more clearly understood in the following description of the embodiment(s).

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features and aspects of the application and together with the description, serve to explain the principles of the application.

FIG. 1 shows a schematic structural diagram of a direct time-of-flight radar system.

FIG. 2 shows an exemplary schematic diagram of how a direct time-of-flight radar system works when transmitting in each transmission cycle.

FIG. 3 shows an exemplary schematic diagram of how the distance detection method according to an embodiment of the present application works within the first frame measurement time.

Fig. 4 shows an exemplary schematic diagram of determining the first flight time in a fast motion scene according to the distance detection method according to an embodiment of the present application.

FIG. 5 shows an exemplary schematic diagram of determining the first flight time in a slow moving scene or a static scene by the distance detection method according to an embodiment of the present application.

FIG. 6 shows an exemplary structural diagram of a distance detection apparatus according to an embodiment of the present application.

Detailed ways

Various exemplary embodiments, features and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numbers in the figures denote elements that have the same or similar functions. While various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

In addition, in order to better illustrate the present application, numerous specific details are given in the following detailed description. It should be understood by those skilled in the art that the present application may be practiced without certain specific details. In some instances, methods, means, components and circuits well known to those skilled in the art have not been described in detail so as not to obscure the subject matter of the present application.

Hereinafter, terms that may appear in the embodiments of the present application are explained.

LiDAR (light detection and ranging, LiDAR): A radar that uses a laser as a radiation source. Its working principle is to detect the corresponding target object by transmitting the detection signal through the laser and receiving the echo signal reflected by the target object.

Maximum ranging distance: or the maximum detection distance, which is a parameter related to the configuration of the radar itself (factory-set parameters or related to factory-set parameters). For example, the maximum ranging distance of long-range adaptive cruise control (ACC) radar is 250m, and the maximum ranging distance of medium-range radar is 70-100m.

Distance ambiguity: Distance ambiguity means that when the distance between the target and the lidar is greater than the maximum ranging distance, the echo signal reflected by the target does not fall within the ranging time period corresponding to the transmitted signal, and the measured target distance at this time is unreal. distance, this phenomenon is called distance blurring.

Dynamic range: an important parameter of a photodetector, which indicates the detection capability of the photodetector, which can be expressed by the number of incident photons that the photodetector can respond to at the same time. In some scenarios, a detector array is used for simultaneous data acquisition, and the detector array may include multiple photodetectors. The greater the number of incident photons that can respond at the same time, the greater the dynamic range of the detector array. If the dynamic range of the photodetector is insufficient, it will greatly limit the accuracy and range of the detection system. Among them, the photodetector is used to capture photons and output a current pulse signal when the photons are captured. If the photodetector captures photons of ambient light, the dynamic range of the detector array is "occupied" by photons of ambient light from the moment the photons are captured, and it will take some time to recover to the state where photons can be captured. Therefore, when the ambient light is strong, the number of photodetectors in the detector array that can capture effective signal photons will decrease, resulting in the inability to read out effective signals and reducing the accuracy of the overall system.

Electrical scanning: an array light source lighting sequence, a lighting method determined by the driving current injection sequence and working area, without any mechanical scanning components.

Range blur is a common problem with lidars. In the prior art, the commonly used solutions for distance ambiguity are as follows: The first strategy is to balance the ratio of the laser emission pulse period to the ranging range of the system, and to increase the ranging corresponding to two adjacent emission pulses as much as possible. The interval of the window time, the number of pulses received in one ranging window time will inevitably decrease, which limits the ranging performance of the radar to a certain extent, especially for long-distance lidar and other radar systems with high performance requirements are more unfavorable . The second common strategy is to optimize through various post-processing algorithms. The basic idea is to identify false signals and filter them out. The implementation methods and costs of system algorithms with different architectures are different, such as the "pulse-cut" method. This method is computationally complex and requires high computing power of the system. The third strategy is to use transmit power modulation to change or reduce the pulse peak power of the laser to reduce the probability of the system detecting photon signals beyond the ambiguous distance. This method may increase the complexity of hardware adjustment. The fourth strategy is to perform pulse code modulation at the transmitter, but doing so may lose system performance and increase the complexity of hardware circuit control.

According to the above description, the existing methods have some aspects that need to be improved in terms of ensuring no loss of ranging capability, computational complexity and computational power requirements, and most of them are suitable for lidar based on pulse ranging and analog signal output. Even mmWave radar. The solid-state lidar based on the principle of single-photon detection is a kind of digital radar, and it is necessary to combine the characteristics of the principle of single-photon detection to study the solution to the distance ambiguity suitable for the lidar of this system.

In order to solve the above technical problems, the present application provides a radar-based distance detection method. The distance detection method of the embodiments of the present application can achieve the resolution of the radar's distance ambiguity problem and improve the detection capability and detection accuracy of target distance.

FIG. 1 shows a schematic structural diagram of a direct time-of-flight radar system. The distance detection method of the embodiment of the present application can be applied to, for example (but not limited to) the processor of the radar system shown in FIG. 1 .

The following describes the ranging principle of the direct time-of-flight radar system based on the single-photon detection principle. As shown in Figure 1, the transmitting end of the direct time-of-flight radar system may include a laser, for example, a vertical cavity surface emitting laser (Vcsel), an electroluminescence display (ELD) or a pulsed laser Diodes (pulsed laser diodes, PLDs) can be used to provide optical signals. The optical signal emitted by the laser is used as the emission signal, which is emitted into the environment by the emission optical system, and is reflected by the target object in the environment to obtain an echo pulse, that is, the echo signal, which is received by the receiving optical system. The radar receiver may include a detector, such as a single photon avalanche diode (SPAD) or a digital silicon photomultiplier (SIPM), which has single-photon sensitivity and can capture photons of reflected echo pulses , when the detector captures the first photon, a current pulse signal is generated, which is output to the time-to-digital converter (TDC), and the time-of-flight is generated and recorded by the time-to-digital converter.

According to the ranging range of the radar system, the ranging window time of the radar system can be determined. The transmitting end of the radar transmits the transmit pulse, reaches the maximum ranging distance specified by the range, and then returns to the receiving end of the radar from the maximum ranging distance, which is the ranging window time. For example, when the ranging range is 150 meters, the ranging window time may be equal to, for example, 1 microsecond (ranging range*2/speed of light). The ranging window time can be set to be less than or equal to the transmit period. The time-to-digital converter reports the delay to the processor, which is the difference between the current pulse signal input by the detector to the time-to-digital converter within the ranging window after each transmit pulse is transmitted relative to the transmit pulse. Delay, the processor stores the delay, that is, records a flight time.

After multiple transmit pulses are fired at the transmitter, multiple times of flight may be recorded at the receiver of the radar. The processor may perform histogram statistics on the stored times of the same flight time based on time-correlated single photon counting (TCSPC), and obtain a histogram with the abscissa as the flight time and the ordinate as the number. By detecting the peak position of the histogram, the flight time with the highest number of times can be found, and the distance information of the target object can be determined according to the flight time.

In the case of no distance blurring, the target distance R ₀ corresponding to the echo pulse can be calculated according to formula (1):

R ₀ =ct ₀ /2 Formula (1)

Among them, c is the speed of light, and t ₀ is the flight time with the highest number of times determined according to the histogram in the current scene.

The formula (1) is applicable to the case where the detector only receives the echo pulses reflected by the target within the ranging range. When the echo pulse photons reflected by the target outside the ranging range are also captured by the detector, the distance information of the target object determined by the processor will appear distance blurred. The reason is that when the detector of the radar captures the echo pulse photons, the radar may have entered the ranging window time corresponding to the next or even the next transmitted pulse. In this case, the processor gets a flight time, which is a fake flight time. If the false flight time is brought into formula (1), the obtained distance information is wrong distance information, that is, distance ambiguity occurs.

In a possible implementation manner, in this embodiment of the present application, the frame data collected by the receiving end can be divided into detection frame data and non-detection frame data, and the detection frame data can be used to calculate the real distance of the target object outside the ranging range. information, and then use the detection frame data and non-detection frame data to calculate the real distance information of the target object within the ranging range to achieve distance blur removal. For example, the first frame may be used to represent the detection frame, and the second frame may be used to represent the non-detection frame. The radar-based distance detection method according to the embodiment of the present application includes:

The first flight time is determined according to the echo data of at least one first frame received by the radar, and the first flight time includes the flight time of the target outside the ranging range of the radar; according to the echo data of at least one second frame received by the radar The data determines the second flight time; according to the first flight time, eliminate part of the flight time in the second flight time to obtain the third flight time, and the part of the flight time corresponds to the flight time of the target outside the ranging range; According to the first flight time and the third flight time, the distance information of the target is determined, wherein, in the first measurement time corresponding to the first frame, the radar turns off the transmission in multiple transmission cycles, and in the second During the second measurement time corresponding to the frame, the radar transmits in each transmission period.

The radar-based distance detection method according to the embodiment of the present application will be described in detail below.

In one possible implementation, the radar receives echo photons through one or more single-photon detectors, and determines echo data according to the counts of the received echo photons.

For example, the radar-based distance detection method according to the embodiment of the present application can be aimed at a lidar using a single-photon device as a detector and based on time-correlated single-photon counting, and can calculate the target distance through direct flight time. The transmitter of the lidar is preferably a laser with a higher center frequency, and the form of the laser at the transmitter is not limited, such as a vertical cavity surface emitting laser, an electroluminescent display, or a pulsed laser diode; the form of the lidar is not limited, such as mechanical, solid-state, Hybrid solid-state or other types; the detector at the receiving end can be, for example, a single-photon avalanche diode, a digital silicon photomultiplier tube, etc.; the working mode of the lidar is not limited to electrical scanning, floodlighting, line scanning or two-dimensional scanning devices. Dot matrix scanning, etc.

Among them, the center frequency is also called the point frequency. The higher the center frequency of the laser, the more transmit pulses it can transmit per unit time, which means that more echo pulses can be received, which makes the time-of-flight information recorded by the radar system. It is more sufficient, which can improve the computational redundancy of the radar system. Due to structural reasons, the center frequency of the vertical cavity surface emitting laser has no upper limit, which is usually 500KHz-1MHz, and can even be several GHz or even tens of GHz. The center frequency of electroluminescent displays and pulsed laser diodes is usually 100KHz-300KHz. There is a heat dissipation problem in the actual radar system, so it can be considered to choose a laser with a narrower pulse width. The fast response capability of the vertical cavity surface emitting laser itself is relatively high, so it is easy to realize narrow pulse width emission.

According to the ranging range and ranging requirements of the radar system, the measurement angle, working frame rate, repetition period of the transmission pulse (referred to as the transmission period) and measurement time (such as the first measurement time and the second measurement time) of the radar system can be preset. Wait. Among them, the measurement angle can be set according to the actual scene; the working frame rate can be set according to the actual scene, the high frame rate can be set in the scene with high precision requirement, and the low frame rate can be set in the scene with low precision requirement; It can be set to a value greater than or equal to the ranging window time. The measurement time is the time to complete a frame of data collection when the lidar system collects data in units of frames. The measurement time is much longer than the emission period and ranging time. Within the measurement time , the radar may send out hundreds or even thousands of transmit pulses. In this embodiment of the present application, the first measurement time may be equal to the second measurement time, for example.

Among them, the working frame rate is related to the actual application scenario. For example, the working frame rate is defined as f. In high-speed and medium-speed scenarios, in order to ensure the ranging performance, the working frame rate can be set to more than 25 frames/second. In low-speed scenes, the working frame rate can be set from 10 frames/sec to 15 frames/sec. According to the actual scene and ranging requirements, the working frame rate can also be set to other values, which are not limited in this application.

As shown in Figure 2, the repetition period of the transmission pulse (transmission period for short) is set as t, the ranging window time is T, and the measurement time T0 is equal to the time of m transmission cycles, T0=m*t. Among them, T0>>t≥T, the value of the ranging window time T can be determined according to the speed of light and the ranging range of the system. For example, the ranging range is 150 meters, and the ranging window time may be equal to, for example, 1 microsecond. Assuming that there is a target object within the ranging range and a target object outside the ranging range, within the first ranging window time T1 (T1=T) after the first transmit pulse is sent, the The flight time of the photons of the echo pulse 1 reflected by the target object may be t1. In the second ranging window time T2 (T2=T) after the second emission pulse is sent, the flight time of the photons of the echo pulse 2 reflected by the target object within the ranging range may be t2. During the second ranging window, the radar can also obtain the flight time t3 of the photons of the echo pulse 3 of the first transmitted pulse reflected by the target outside the ranging range. Until the mth ranging window time Tm (Tm=T) after the mth transmit pulse is sent, the radar system completes the acquisition of one frame of data, and can record multiple flight times.

For example, within 1 second, the radar may eg be able to receive N+M frames of echo data. The echo data of the N first frames received by the radar may be set as N frame detection frame data for processing to determine the first flight time. Correspondingly, the echo data of M second frames received by the radar are set as M frames of non-detected frame data for processing to determine the second flight time. However, a part of the second flight time determined according to the echo data of the M second frames is the unreal flight time of the target outside the ranging range, which can be obtained according to the echo data of the N first frames In the first flight time, the flight time of the target outside the ranging range corresponding to the first flight time in the second flight time determined by the echo data of the M second frames is excluded to obtain the third flight time. In this way, according to the first flight time The first time of flight can determine the distance information of the target outside the ranging range, and the distance information of the target within the ranging range can be determined according to the third time of flight. The echo data of the first frame is processed, and finally the distance information of the targets within the ranging range and outside the ranging range is obtained. Wherein, the echo data of the N first frames received by the radar can be set to have a flag bit, and the processor can distinguish whether the received data is the echo data of the first frame or the echo data of the second frame based on this. For fast-moving scenes, the radar can be set to continuously receive echo data of N first frames as detection frame data. For slow-moving scenes or static scenes, the radar can be set to continuously receive N first frames The echo data is used as the detection frame data, and it can also be set to receive the echo data of N discontinuous first frames as the detection frame data. This application does not limit this.

In a possible implementation manner, the received echo data of N consecutive first frames have correlation. For example, when the working frame rate is 25 frames per second, the radar system receives 25 frames of data (including echo data of the first frame and echo data of the second frame) per second. Since after receiving the echo data of the N first frames, the processor also needs to perform operations on the received echo data of the N first frames, so theoretically, in every second when the radar system performs distance detection, The earlier the echo data of the N first frames is received, the better. In practical applications, due to the non-ideal hardware of the system, as well as frame loss and packet loss during data transmission, data verification can be performed before the radar system is used for distance detection. Through the verification, the accuracy of the distance information obtained by processing the echo data of the N first frames can be improved. After the verification is passed, for example, within the first second of the radar system performing distance detection, several consecutive frames (for example, 1-5 frames) in the 25 frames can be selected as the detection frame (the first frame), and 6-25 frames can be selected. as a non-detected frame (second frame). In the second second when the radar system performs distance detection, several consecutive frames (such as 6-10 frames) in the 25 frames can be selected as the detection frame (the first frame), and 1-5 and 11-25 frames are taken as non-detection frames. frame (second frame). The present application does not limit the specific selection manner of the detection frame (the first frame).

In a possible implementation manner, the radar system of the embodiment of the present application may include multiple radars arranged at different positions of the vehicle. For example, it may include a first radar suitable for distance detection in a fast moving scene and a second radar suitable for distance detection in a slow moving scene or a stationary scene. In practical applications, a suitable radar can be selected for distance detection according to the speed of the vehicle to reduce the cost of data processing; the first radar and the second radar can also be used at the same time to improve the detection accuracy. The radar system of the embodiment of the present application may further include more radars, which is not limited in the present application.

In a possible implementation manner, M may be preset according to the working frame rate f. For example, when N=5 and f=25 frames/sec, M can be set to be equal to 20 frames, so that at least 5 echo data of the first frame can be received every second, so as to calculate the out-of-range range In this way, within the first second of the radar system's operation, the distance information (including within and outside the ranging range) can be calculated and obtained, and within the second second of the radar system's operation, the vehicle It can work according to the distance information obtained in the first second when the radar system is working. During the third second when the radar system is working, the vehicle can work according to the distance information obtained in the second second when the radar system is working, so that terminals such as vehicles can work. The distance information on which the vehicle is based is kept up-to-date, thereby improving the safety of autonomous driving of the vehicle.

Wherein, M and N may also be set so that the lidar completes the reception of N echo data of the first frame and the reception of M echo data of the second frame at other times. For example, it can be ensured that at least N echo data of the first frame can be received every 2 seconds or every 0.5 seconds. This application does not limit this.

In a possible implementation manner, when the radar transmits in each transmission period, the data received within the ranging window corresponding to each transmission period may include the echo photon count and ranging of the target within the ranging range. Echo photon counts for out-of-range targets. In the embodiment of the present application, the pulse transmission mode in the first measurement time can be set, so that the echo data of the first frame received in a fixed time period in each first measurement time only includes the echo data outside the ranging range. The echo photon count of the target. Based on this, the flight time of the target outside the ranging range can be determined according to the echo data of the first frame received in this time period. The distance detection method of the embodiment of the present application further includes:

During the first measurement time corresponding to the first frame, the radar is controlled to enter one or more off cycles, and each off cycle includes multiple emission cycles; in each off cycle, the radar is sequentially controlled to turn off and transmit for h firing cycles, turn on One transmit cycle is transmitted, and then a transmit cycle is turned off, where h and a are positive integers; wherein, the first echo data of the first frame is received in the a transmit cycle, and the first echo data is Used to determine the time of flight of targets outside the radar's range.

For example, referring to FIG. 3 , the start time tt of the first closing period of each first frame can be preset, so that the start time tt corresponding to any first frame is reached and the preset time tt elapses, the The first off period of the frame. It can be defined that the time corresponding to one off period is equal to the time corresponding to a+h+1 emission periods, where h≥1 and an integer, and a≥1 and an integer.

In each off cycle, the following operations are completed: Taking the first off cycle as an example, the processor controls the laser to turn off the pulse emission during the time corresponding to the first firing cycle to the h-th firing cycle in the first off cycle. (defined as pre-off emission); within the time corresponding to the h+1th emission period, the processor controls the laser to start pulse emission (defined as detection emission); the h+2th emission period to the a+h+1th emission During the time corresponding to the period, the processor controls the laser to turn off pulse emission (defined as continuous turn-off emission). There are several (c) off periods within the data receiving time (first measurement time T0) of each first frame, and the time interval between two adjacent off periods may be equal to b transmitting periods.

In a possible implementation manner, the power of the transmission pulse within one transmission period (detection transmission) when the transmission is turned on is higher than the transmission pulse power in the second measurement time. The purpose of increasing the power of the transmitted pulse when detecting the emission is to capture the photons of the echo pulse of the target at a longer distance. In this way, the ranging capability of the radar system can be improved.

Among them, the purpose of setting the pre-shutdown emission is to charge the laser in advance within the time corresponding to the pre-shutdown emission, so that a transmission pulse that increases the transmission power can be emitted when the emission is detected. The purpose of continuously shutting down the transmission is to make the data information received by the radar system come from the echo pulses of the targets outside the range within a period corresponding to a transmission period of the continuous shut-down transmission, so that the data can be received according to the data in the continuous shut-down transmission time. The information (the first echo data of the first frame) calculates the distance information of the target outside the range.

For example, in the application scenario of FIG. 3, h=2 can be set, then in the 1-2 emission period of the first shutdown period, the laser pulse emission is turned off, that is, the pre-shutdown emission; the third emission period During the corresponding time, turn on the laser pulse emission, that is, detect the emission, and increase the emission pulse power when detecting the emission; you can set a=6, then the laser pulse emission is turned off within the time corresponding to the 4th emission cycle to the 9th emission cycle. That is, the emission is turned off continuously.

Among them, the value of h can be preset according to the power of the emission pulse within one emission period (detection emission) when the emission is turned on, and the time required for the laser to be charged to be able to emit the emission pulse of this power, and the value of a can be determined according to Ranging requirements, adjust before ranging. For example, if the center frequency is 500kHz, and the ranging range is 300 meters, the transmission period is 2 microseconds (1/center frequency), and the ranging window time T is also 2 microseconds (measurement range). Distance range*2/speed of light). If you want to measure the distance information of the target within 300 meters and the target with high reflectivity within 300 meters to 1500 meters, take the high reflectivity target at 1500 meters as an example, from the radar system sending out the transmit pulse, to the time when the transmit pulse is affected by the high reflectivity The target is reflected, and then the echo pulse returns to the radar system. The real flight time of the pulsed photon can be equal to 10 microseconds (1500m*2/speed of light). And 10 microseconds is equal to 5 emission periods, and the emission period is equal to the ranging window time, that is to say, for the pulses emitted in the first emission period, the echo pulse photons reflected by the target have a flight time equal to five emission periods. , captured by the detector within the sixth emission cycle at the latest. In this case, it suffices to make the continuous off emission time of one off period equal to the time of 6 emission periods (a=6). In practical applications, 1500 meters is already a relatively large distance. Therefore, the value of a does not need to be preset to be large, and it is usually set within 10. This application does not limit the specific value of a.

In this way, the first flight time determined by the radar system includes the flight time of the target outside the ranging range of the radar determined in a transmission cycle of each shutdown period, so that the flight time of the target outside the ranging range of the radar can be determined according to the flight time of the target outside the ranging range of the radar. time, to determine the real flight time of the echo pulse photons of the target outside the ranging range, so as to determine the real distance information of the target object outside the ranging range.

In a possible implementation manner, a specific encoding method can be used to constrain the start time tt of the first off period of any first frame and the number of periods b of the time interval between two off periods to form specificity feature. For any first frame, b can take one value or multiple values, for example, it can take one value b ₀ , and the time interval between any two off periods of the first frame is equal and equal to b ₀ *t ; If multiple values b ₁ , b ₂ , b ₃ ......b _c-1 are taken, the time intervals of the two off periods of the first frame are respectively b ₁ *t, b ₂ *t, b ₃ *t ...b _c-1 *t. For the N first frames, the value of the interval time of the off period of each first frame may be different, that is, the value of b of each first frame may be different.

For example, if the working frame rate of the radar system is 25 frames per second, the radar system receives 25 frames of data in 1 second. For example, the 6th to 10th frames may be determined as the first frame (N=5). The time to receive the echo data of each first frame (the first measurement time T0 ) is equal to 200 (m=200) transmission cycles. For example, the start time tt of the first off period of the first first frame (6th frame) can be preset to be 0.1s, and the next off period is entered every 10 (b=10) emission periods. For example, after reaching the first first frame start time and after 0.1s (tt=0.1s), the first off period is entered. In the first off period, the pre-off emission is completed first, for example, the laser pulse emission is turned off for two emission periods (h=2). Then, the detection emission is completed, for example, the laser pulse emission is turned on for one emission period, and the power of the emission pulse is increased. Then, the laser pulse emission was continuously turned off for a period of three emission cycles (a=3). The first shutdown cycle ends. There is a time interval of 10 emission cycles (b=10), and the second off cycle is entered. By analogy, until the end time of the first first frame is reached, the reception of the echo data of the first first frame is completed.

For example, the start time tt of the first off period of the second first frame (the seventh frame) can be preset to be 0.2s (tt=0.2s), and every 8 (b=8) transmission periods, into the next shutdown cycle. For example, after the second first frame start time is reached and 0.2s has passed, the first off period is entered. In the first off period, the pre-off emission is completed first, for example, the laser pulse emission is turned off for one emission period (h=1). Then, the detection emission is completed, for example, the laser pulse emission is turned on for one emission period, and the power of the emission pulse is increased. Then, the laser pulse emission was continuously turned off for a period of four emission cycles (a=4). The first shutdown cycle ends. There is a time interval of 8 emission cycles (b=8), and the second off cycle is entered. By analogy, until the end time of the second first frame is reached, the reception of the echo data of the second first frame is completed.

In this way, the anti-jamming capability of the radar system can be improved, thereby improving the accuracy of the finally obtained distance information. Those skilled in the art should understand that the time interval between any two off periods of any first frame and the start time of the first off period of any first frame can be selected in various ways, as long as the measurement can be satisfied This is not limited in this application.

In a possible implementation manner, the echo data of the first frame is also used to determine the flight time of the target within the ranging range, and the distance detection method of the embodiment of the present application further includes:

In a transmission period after each shutdown period, the radar is controlled to start transmitting; wherein, the second echo data of the first frame is received in the one transmission period, and the second echo data is used to determine the fourth flight time, The first flight time includes the fourth flight time, and the fourth flight time represents the flight time of the target within the ranging range.

For example, the processor may control the laser to turn on and emit one firing period after each off period ends. Therefore, the second echo data of the first frame received in this one transmission period includes the count of echo pulse photons within the ranging range. Moreover, at the end of each shutdown period, the radar has not sent any pulses for a continuous transmission period. Therefore, it can be considered that the second echo data of the first frame received in this one transmission period does not include the out-of-ranging range. Counts of echo pulse photons. The second echo data of the first frame can be used to determine the fourth flight time. Therefore, the fourth flight time represents the flight time of the target within the ranging range, and the fourth flight time can be used to determine the distance information of the target within the ranging range.

Based on this, the first flight time includes the flight time of the target outside the ranging range, and the flight time of the target within the ranging range, that is, the fourth flight time. Then, according to the first flight time and the third flight time, the distance information of the target is determined. It can be considered that according to the flight time of the target outside the ranging range in the first flight time, the distance information of the target outside the ranging range can be determined; The third flight time and the fourth flight time in the first flight time can determine the distance information of the target within the ranging range.

An exemplary method for determining the first flight time in this embodiment of the present application is described below.

In a possible implementation manner, after receiving the echo data of the N first frames, the processor may analyze and process the received data based on the time-correlated single-photon counting method to determine the first time of flight.

The principle of time-correlated single-photon counting is introduced first. During the measurement time T0, there may be m times of pulse transmission and reception, and the time-to-digital converter can record n times (n < m) of the light flight time, and generate a photon count histogram of the flight time with respect to the number of counts. Using the extreme value solving algorithm to detect the peak position of the photon count histogram can calculate the flight time value with the most occurrences, which is the final flight time. If multiple peak positions with different intensities are found when detecting peak positions, it can be considered that multiple flight times corresponding to multiple peak positions come from different targets, and the flight time values of multiple peak positions of the photon count histogram can be calculated, is the final flight time. By using the time-correlated single-photon counting technology, the detector can effectively remove the inherent noise of the device and ambient light noise under the condition that the incident single photon is captured, so that the number of counts caused by noise will be much lower than that caused by valid signals. , which can be easily identified from the photon count histogram. At the same time, the time-correlated single-photon counting technology performs repeated measurement of the target object's time of flight for multiple times, which can further improve the time resolution of the system.

In a possible implementation manner, determining the first flight time according to echo data of at least one first frame received by the radar includes:

Determine a photon count histograms according to the counts of echo photons received in a emission cycles in all off cycles of the first frame, wherein each photon count histogram is based on the emission cycles in the same order in all off cycles is determined by the counts of the echo photons of ; according to the flight times corresponding to the a peak positions of the a photon count histograms, the flight time of the target outside the ranging range of the radar in the first flight time is determined, wherein each photon counts The histogram includes 1 peak position.

For example, for any first frame, within the time of each OFF period, one continuous OFF transmission is completed, and the continuous transmission time is equal to a transmission period. In a fast moving scene, see FIG. 4 , the N first frames (detection frames) may include c1, c2, . The device can determine the first photon count histogram (1Th) according to the single photon count of the received echo data within the time corresponding to the first emission period (1th) of the continuous shutdown emission of each shutdown period; In the time (2th) corresponding to the second emission period of continuous shutdown emission of one shutdown period, the single photon count of the received echo data determines the second photon count histogram (2Th); During the time (ath) of the a-th emission period of the continuous-off emission of one off period, the single-photon count of the received echo data determines the a-th photon count histogram (aTh). After obtaining a photon count histograms, peak positions can be detected for the a photon count histograms respectively. It can be seen from the above description that the ordinate of the photon count histogram is the number of single photon counts. Therefore, the time information corresponding to the single photon with the largest number of times is the flight time of the target outside the ranging range determined by the radar system. Assuming that each photon count histogram detects a peak position, the flight times of targets outside the ranging range determined by the radar system are Tt1, Tt2...Tta, that is, the first flight time determined by the radar includes Tt1, Tt2... Tta.

In a possible implementation, when echo pulses from two different targets with high reflectivity are received within the time corresponding to the same emission period, multiple peaks can be detected in the photon count histogram corresponding to the emission period For example, the flight time of the target outside the ranging range determined by the radar system is Tt11, Tt12, Tt2...Tta. Among them, Tt11 and Tt12 are both from the first photon count histogram. That is, the first flight time determined by the radar includes Tt11 , Tt12 , Tt2 . . . Tta.

In a possible implementation manner, the first flight time further includes a fourth flight time, and the distance detection method in this embodiment of the present application further includes:

One photon count histogram is determined according to the count of echo photons in one emission period after each off period; according to the one photon count histogram, the flight corresponding to at least one peak position in multiple flight time intervals time, the fourth flight time in the first flight time is determined, and the multiple flight time intervals are determined according to the flight time of the target outside the ranging range of the radar.

For example, the processor can obtain a histogram of photon counts according to the single-photon counts within one emission period immediately following each off period in the N first frames, and obtain a photon count histogram according to the above-mentioned method. The flight time Tt1, Tt2...Tta of the target can determine a flight time interval. For example, when the pulse width of the transmitted pulse is P, a flight time interval [Tt1-P, Tt1+P], [Tt2-P can be determined according to the flight time Tt1, Tt2...Tta of the target outside the ranging range ,Tt2+P]…[Tta-P,Tta+P].

In a possible implementation manner, a flight time interval [Tt1-P, Tt1+P], [Tt2-P, Tt2+P]...[Tta-P, Tta+P] in the range of Part of the photon count histogram detects the peak position. If at least one peak position can be detected, it can be considered that the radar system has missed detection of the target within the ranging range during the entire off period of the N first frames. In this case, the flight time corresponding to the detected at least one peak position represents the flight time of the target in the ranging range that cannot be detected in the entire closing period of the first frame, and can be determined as the first flight time in the first flight time. Four flight times. For example, if three peak positions are detected in multiple flight time intervals, and the corresponding flight times are Tq1, Tq2, and Tq3, respectively, the determined fourth flight time includes Tq1, Tq2, and Tq3.

In this way, in a fast motion scenario, the flight time of the target outside the ranging range and the flight time of the target within the ranging range can be determined respectively, that is, the first flight time can be determined. The distance information of the target outside the ranging range can be calculated according to the flight time of the target outside the ranging range, and the ranging capability of the radar is improved.

An exemplary method for determining the distance information of the target according to the first flight time and the third flight time is described below.

In a possible implementation manner, according to the first flight time, the processor may determine the distance information of the target outside the ranging range. Referring to Figure 4, for example, in a fast motion scene, the flight time Tt1 corresponding to the peak position of the first photon count histogram (1Th) is in the first emission cycle when the emission is continuously turned off. The time-of-flight determined by the echo photon count of the arriving echoes can be seen from the ranging principle of the direct time-of-flight radar system described above. The radar system counts the emission time of the transmitted pulse corresponding to a ranging window time and counts the ranging window time. The captured echo photons are counted, and the flight time is determined according to the count of the echo photons, that is to say, the flight time determined by the radar system must be less than or equal to the ranging window time T. However, in the first emission period of the continuous shutdown emission, the echo photons captured by the radar system are actually the echo photons of the emission pulses detected and emitted before the continuous shutdown emission. Therefore, the actual flight time of the echo photons can be increased by one emission period t compared to the flight time determined by the radar system based on the counts of the captured echo photons. In this way, according to the flight time Tt1 corresponding to the peak position of the first photon count histogram (1Th), a flight time Tt1+t can be determined.

The flight time Tt2 corresponding to the peak position of the second photon count histogram (2Th) is the flight time Tt2 determined by the radar according to the captured echo photon counts in the second emission period of the continuous shutdown emission, and the flight time Tt2 of the continuous shutdown emission During the 2 emission periods, the echo photons captured by the radar system are actually the echo photons of the emission pulses that are continuously turned off before the emission is detected. Therefore, the actual flight time of the echo photons can be increased by 2 emission periods t compared to the flight time determined by the radar system based on the counts of captured echo photons. In this way, according to the flight time Tt2 corresponding to the peak position of the second photon count histogram (2Th), a flight time Tt2+2t can be determined.

By analogy, the flight time Tta corresponding to the peak position of the a-th photon count histogram (aTh) is the flight time Tta determined by the radar according to the captured echo photon counts in the a-th emission cycle when the emission is continuously turned off. In the a-th emission period of the shutdown emission, the echo photons captured by the radar system are actually the echo photons of the emission pulses detected and emitted before the continuous shutdown emission. Therefore, the actual flight time of the echo photons can be increased by a transmission period t compared to the flight time determined by the radar system based on the counts of captured echo photons. In this way, according to the flight time Tta corresponding to the peak position of the a-th photon count histogram (aTh), a flight time Tta+at can be determined.

Based on this, according to Tt1+t, Tt2+2t...Tta+at, substitute into formula (1), so that t ₀ is equal to Tt1+t, Tt2+2t...Tta+at respectively, then the distance information of the out-of-range target can be calculated .

In a possible implementation, multiple peak positions are detected in the photon count histogram corresponding to the same emission period. For example, the flight time of the target outside the ranging range determined by the radar system is Tt11, Tt12, Tt2...Tta , and when Tt11 and Tt12 come from the first photon count histogram, Tt11 and Tt12 are the time of flight determined by the radar according to the captured echo photon counts in the first emission period of the continuous shutdown of the emission. It can be seen from the above description that, The actual flight time of the echo photons can be increased by one emission period t compared to the flight time determined by the radar system based on the counts of the captured echo photons. Therefore, according to the flight times Tt11 and Tt12 corresponding to the peak position of the first photon count histogram, two flight times Tt11+t and Tt12+t can be determined. By analogy, the flight times Tt11+t, Tt12+t, Tt2+2t...Tta+at can be obtained, and substituted into formula (1), so that t0 is equal to Tt11+t, Tt12+t, Tt2+2t...Tta+ at, the distance information of the out-of-range target can be calculated.

In this way, the distance information of the target outside the range can be obtained.

In a possible implementation manner, according to the third flight time, the processor may determine the distance information of the target within the ranging range.

For example, according to the method described above, the obtained first flight time may include, for example, the flight time Tt1 , Tt2 , . . . Tta of the target outside the ranging range. And, according to the echo data of at least one second frame, the second flight time may be determined, and the second flight time may for example include Tt1, Tt2...Tta, Tk1, Tk2...Tks. In this case, the flight time corresponding to the flight time of the out-of-range target in the second flight time can be removed first to obtain the third flight time, for example, the third flight time includes Tk1, Tk2...Tks. The third flight time is the flight time of the target in the ranging range. Therefore, by substituting Tk1, Tk2...Tks into formula (1), so that t0 is equal to Tk1, Tk2...Tks, respectively, the distance information of the target in the range can be calculated. .

Further, according to the first flight time and the third flight time, the processor can obtain the distance information of the target within the ranging range with higher accuracy.

For example, according to the method described above, in the first flight time obtained, in addition to the flight time Tt1, Tt2, ... Tta of the target outside the ranging range, the flight time Tq1 of the target within the ranging range can also be included. , Tq2, Tq3 (fourth flight time). The third flight time and the fourth flight time may be ORed to obtain, for example, Tq1, Tq2, Tq3, Tk1, Tk2...Tks. In this case, the OR operation result of the third flight time and the fourth flight time is the flight time of the target within the ranging range. Therefore, Tq1, Tq2, Tq3, Tk1, Tk2...Tks can be substituted into formula (1), Make t0 equal to Tq1, Tq2, Tq3, Tk1, Tk2... Tks respectively, then the distance information of the target in the range can be calculated.

In this way, the distance information of the target within the ranging range with higher accuracy can be obtained.

In a possible implementation manner, the distance information of the target within the range and the distance information of the target outside the range can be output as the point cloud depth map of the target within the range and the point cloud depth map of the target outside the range respectively, or It is integrated into a point cloud depth map including in-range targets and out-of-range targets and then output.

The distance detection method of the embodiment of the present application can obtain the distance information of the target outside the ranging range and the distance information of the target within the ranging range with high accuracy, and the acquisition of the two can be realized by calculation, and does not need to be in the radar. New hardware is added, so the ranging capability of the radar can be improved without increasing the hardware cost.

In a possible implementation, in a fast motion scene, if a photon counting histogram detects the peak position, it is found that in any photon counting histogram, there are similar intensities but the flight time distribution is larger than the emission pulse The multiple peak positions of the pulse width t can be considered as the flight time of the echo pulse from the moving target rather than the noise. In this case, the detection window and the threshold of the peak position can be set, and all the peak positions and their flight times that exceed the threshold can be collected, and then the time information ( That is, the minimum and maximum values in the flight time of the peak position that exceeds the threshold) are used as the time information of the target. If the direction is the same, the minimum value is taken, and the maximum value is taken if the direction is opposite. The relationship between the difference between the values and the speed of the vehicle is used to calculate the possible change law of the spatial distance relationship between the target and the lidar system over a period of time, and report the predicted law to the control system of the terminal. The control system of the terminal can apply the pre-judgment rule to the echo data of the second frame received subsequently, such as predicting the possible distance information of the moving object within the second measurement time, so as to plan the driving according to the possible distance information of the moving object route etc.

Another exemplary method for determining the first flight time in this embodiment of the present application is described below.

According to the counts of echo photons received in a emission period in the entire off period of the first frame, a photon count histogram is determined; according to the flight times corresponding to e peak positions of a photon count histogram, the first photon count histogram is determined. Time-of-flight time-of-flight of targets outside the radar's ranging range, where e is a positive integer less than or equal to a.

For example, for any first frame, within the time of each OFF period, one continuous OFF transmission is completed, and the continuous transmission time is equal to a transmission period. In a moving scene where the radar is in a slow speed, referring to FIG. 5 , the N first frames (detection frames) may, for example, include c1, c2, . The value of the number of off cycles c1, c2, . , in this case, for N first frames, single-photon counts obtained for a emission period of continuous off-emission of all off periods can be combined into one photon count histogram (Th). Since the 1 photon count histogram (Th) is obtained during the continuous off emission time, there is no echo pulse photon of the target in the real range. By detecting the peak of the photon count histogram, e can be detected, for example. peak positions with different intensities, e≤a. The flight times corresponding to the strongest peak to the weakest peak are Tt1, Tt2...Tte. That is, the first flight time determined by the radar includes Tt1 , Tt2 . . . Tte.

In a possible implementation manner, when the radar is in a slow motion scene, or the radar is in a stationary scene, the fourth flight time may be determined by referring to the fourth flight time in the fast motion scene above. The description of the determination method will not be repeated here.

In this way, the flight time of the target outside the ranging range and the flight time of the target within the ranging range, that is, the first flight time, can be determined respectively in a slow moving scene or a static scene. The distance information of the target outside the ranging range can be calculated according to the flight time of the target outside the ranging range, and the ranging capability of the radar is improved.

The following introduces an exemplary method for determining the distance information of the target according to the first flight time and the third flight time in a slow moving scene or a static scene.

In a possible implementation manner, according to the first flight time, the processor may determine the distance information of the target outside the ranging range. Referring to Figure 5, for example, the flight times Tt1, Tt2... are different. In this case, it can be considered that the flight time Tt1 corresponding to the strongest peak is the flight time determined by the radar according to the captured echo photon counts in the first emission cycle when the emission is continuously turned off. The flight time Tt1 corresponding to the peak can be determined as a flight time Tt1+t. It can be considered that the flight time Tt2 corresponding to the sub-strong peak is the flight time determined by the radar according to the captured echo photon counts in the second emission cycle when the emission is continuously turned off. Tt2, a flight time Tt2+2t can be determined. By analogy, Tt1+t, Tt2+2t...Tte+et can be determined respectively, and substituted into formula (1), so that t0 is equal to Tt1+t, Tt2+2t...Tte+et, respectively, and the out-of-range target can be calculated. distance information.

In a possible implementation manner, the processor may determine the distance information of the target within the ranging range according to the third flight time, or according to the first flight time and the third flight time. For the specific method, reference may be made to the description of the method for determining the distance information of the target within the ranging range in the above-mentioned motion scene with a relatively high speed, which will not be repeated here.

According to the distance detection method of the embodiment of the present application, the distance information of the target outside the ranging range and the distance information of the target within the ranging range can be obtained at the same time, thereby expanding the system performance. In addition, the acquisition of the above distance information does not come at the expense of complex design and regulation. The hardware control and implementation are relatively simple. Only the on and off of the laser pulse emission is designed, and the receiving end does not need to be modified, and the data can be collected normally. The strategy of the embodiment of the present application does not require complex data post-processing, and only needs to perform the processing of the N first frames of echo data received during the corresponding continuous off-transmission time before obtaining a complete photon count histogram. The first echo data of one frame and the second echo data of N first frames received in the next first transmission period are stored and processed, and the complexity of the strategy and the implementation cost are small.

An embodiment of the present application provides a distance detection device, see FIG. 6 , the device includes:

The first determination module 101 determines a first flight time according to echo data of at least one first frame received by the radar, where the first flight time includes the flight time of a target outside the ranging range of the radar;

The second determining module 102 determines the second flight time according to the echo data of at least one second frame received by the radar;

The third determination module 103, according to the first flight time, eliminates part of the flight time in the second flight time to obtain a third flight time, and the part of the flight time corresponds to the flight time of the target outside the ranging range;

The fourth determination module 104 determines the distance information of the target according to the first flight time and the third flight time,

In a possible implementation, the apparatus further includes:

In a possible implementation manner, the radar receives echo photons through one or more single-photon detectors, and determines the echo data according to the count of the received echo photons.

In a possible implementation manner, the first determining module includes:

In a possible implementation, the apparatus further includes:

In a possible implementation manner, the power of the transmit pulse within one transmit period when the transmit is turned on is higher than the power of the transmit pulse within the second measurement time.

An embodiment of the present application provides a distance detection apparatus, comprising: a processor and a memory for storing instructions executable by the processor; wherein the processor is configured to implement the above method when executing the instructions.

Embodiments of the present application provide a radar, including the above distance detection device.

An embodiment of the present application provides a terminal including the above radar.

Embodiments of the present application provide a non-volatile computer-readable storage medium on which computer program instructions are stored, and when the computer program instructions are executed by a processor, implement the above method.

Embodiments of the present application provide a computer program product, including computer-readable codes, or a non-volatile computer-readable storage medium carrying computer-readable codes, when the computer-readable codes are stored in a processor of an electronic device When running in the electronic device, the processor in the electronic device executes the above method.

For exemplary descriptions of the above embodiments, reference may be made to FIG. 1 to FIG. 5 and the related descriptions, which will not be repeated here.

A computer-readable storage medium may be a tangible device that can hold and store instructions for use by the instruction execution device. The computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read only memory (ROM), erasable type programmable read-only memory (electrically programmable read-only-memory, EPROM or flash memory), static random-access memory (static random-access memory, SRAM), portable compact disc read-only memory (compact disc read-only memory, CD - ROM), digital video discs (DVDs), memory sticks, floppy disks, mechanically encoded devices, such as punch cards or raised structures in grooves on which instructions are stored, and any suitable combination of the foregoing .

Computer readable program instructions or code described herein may be downloaded to various computing/processing devices from a computer readable storage medium, or to an external computer or external storage device over a network such as the Internet, a local area network, a wide area network and/or a wireless network. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer-readable program instructions from a network and forwards the computer-readable program instructions for storage in a computer-readable storage medium in each computing/processing device .

Computer program instructions for carrying out the operations of the present application may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or in one or more source or object code written in any combination of programming languages, including object-oriented programming languages such as Smalltalk, C++, etc., and conventional procedural programming languages such as the "C" language or similar programming languages. The computer readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer, or entirely on the remote computer or server implement. In the case of a remote computer, the remote computer can be connected to the user's computer through any kind of network—including a local area network (LAN) or a wide area network (WAN)—or, can be connected to an external computer (e.g., use an internet service provider to connect via the internet). In some embodiments, electronic circuits, such as programmable logic circuits, field-programmable gate arrays (FPGAs), or programmable logic arrays (programmable logic arrays), are personalized by utilizing state information of computer-readable program instructions logic array, PLA), the electronic circuit can execute computer-readable program instructions to implement various aspects of the present application.

Aspects of the present application are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the present application. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions.

These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer or other programmable data processing apparatus to produce a machine that causes the instructions when executed by the processor of the computer or other programmable data processing apparatus , resulting in means for implementing the functions/acts specified in one or more blocks of the flowchart and/or block diagrams. These computer readable program instructions can also be stored in a computer readable storage medium, these instructions cause a computer, programmable data processing apparatus and/or other equipment to operate in a specific manner, so that the computer readable medium on which the instructions are stored includes An article of manufacture comprising instructions for implementing various aspects of the functions/acts specified in one or more blocks of the flowchart and/or block diagrams.

Computer readable program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other equipment to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other equipment to produce a computer-implemented process , thereby causing instructions executing on a computer, other programmable data processing apparatus, or other device to implement the functions/acts specified in one or more blocks of the flowcharts and/or block diagrams.

The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatuses, systems, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more functions for implementing the specified logical function(s) executable instructions. In some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

It is also noted that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented in hardware (eg, a circuit or an ASIC (application) that performs the corresponding function or action. specific integrated circuit, application-specific integrated circuit)), or can be implemented with a combination of hardware and software, such as firmware, etc.

While the invention has been described herein in connection with various embodiments, those skilled in the art will understand and understand from a review of the drawings, the disclosure, and the appended claims in practicing the claimed invention. Other variations of the disclosed embodiments are implemented. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that these measures cannot be combined to advantage.

Various embodiments of the present application have been described above, and the foregoing descriptions are exemplary, not exhaustive, and not limiting of the disclosed embodiments. Numerous modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the various embodiments, the practical application or improvement over the technology in the marketplace, or to enable others of ordinary skill in the art to understand the various embodiments disclosed herein.

Claims

A radar-based distance detection method, characterized in that the method comprises:

determining a first flight time according to echo data of at least one first frame received by the radar, where the first flight time includes the flight time of a target outside the ranging range of the radar;

determining the second time of flight according to the echo data of at least one second frame received by the radar;

According to the first flight time, eliminate part of the flight time in the second flight time to obtain a third flight time, and the part of the flight time corresponds to the flight time of the target outside the ranging range;

According to the first flight time and the third flight time, the distance information of the target is determined,

Wherein, in the first measurement time corresponding to the first frame, the radar turns off transmission in multiple transmission periods, and in the second measurement time corresponding to the second frame, the radar transmits in each transmission period.
The method according to claim 1, wherein the method further comprises:

During the first measurement time corresponding to the first frame, the radar is controlled to enter one or more off cycles, and each off cycle includes multiple emission cycles;

In each shutdown period, the radar is sequentially controlled to close the transmission for h transmission periods, open for 1 transmission period, and then close for a transmission period, where h and a are positive integers;

Wherein, the first echo data of the first frame is received in the a transmission cycles, and the first echo data is used to determine the flight time of the target outside the ranging range of the radar.
The method according to claim 2, wherein the method further comprises:

In a transmission cycle after each said closing cycle ends, control the radar to start transmitting;

Wherein, the second echo data of the first frame is received in the one transmission cycle, the second echo data is used to determine the fourth flight time, the first flight time includes the fourth flight time, and the The fourth flight time represents the flight time of the target within the ranging range.
The method according to any one of claims 1-3, wherein the radar receives echo photons through one or more single-photon detectors, and determines the echo photons according to the count of the received echo photons. wave data.
The method according to claim 4, wherein determining the first time of flight according to echo data of at least one first frame received by the radar comprises:

Determine a photon count histograms according to the counts of echo photons received in the a emission periods in all the off periods of the first frame, wherein each photon count histogram is based on the same The sequence of emission cycles is determined by the counts of echoed photons;

According to the flight time corresponding to the a peak positions of the a photon count histograms, the flight time of the target outside the ranging range of the radar in the first flight time is determined, wherein each photon count histogram includes one peak position .
The method according to claim 4, wherein determining the first time of flight according to echo data of at least one first frame received by the radar comprises:

According to the counts of echo photons received in the a emission periods in all the off periods of the first frame, determine a photon count histogram;

According to the flight time corresponding to the e peak positions of one photon count histogram, the flight time of the target outside the ranging range of the radar in the first flight time is determined, where e is a positive integer less than or equal to a.
The method according to claim 4, wherein the method further comprises:

Determine a photon count histogram according to the count of the echo photons in an emission period after each of the off periods ends;

The fourth flight time in the first flight time is determined according to the flight time corresponding to at least one peak position in the multiple flight time intervals in the one photon count histogram, and the multiple flight time intervals are based on the radar The time-of-flight of targets outside the ranging range is determined.
The method according to claim 2, characterized in that, the power of the transmission pulse within one transmission period of the start-up transmission is higher than the power of the transmission pulse within the second measurement time.
A distance detection device, characterized in that the device comprises:

a first determining module, for determining a first flight time according to echo data of at least one first frame received by the radar, where the first flight time includes the flight time of a target outside the ranging range of the radar;

The second determining module determines the second flight time according to the echo data of at least one second frame received by the radar;

The third determination module, according to the first flight time, eliminates part of the flight time in the second flight time to obtain a third flight time, and the part of the flight time corresponds to the flight time of the target outside the ranging range;

the fourth determination module, according to the first flight time and the third flight time, to determine the distance information of the target,

Wherein, in the first measurement time corresponding to the first frame, the radar turns off transmission in multiple transmission periods, and in the second measurement time corresponding to the second frame, the radar transmits in each transmission period.
A distance detection device, comprising:

processor;

memory for storing processor-executable instructions;

Wherein, the processor is configured to implement the method of any one of claims 1-8 when executing the instructions.
A non-volatile computer-readable storage medium on which computer program instructions are stored, characterized in that, when the computer program instructions are executed by a processor, the method of any one of claims 1-8 is implemented.
A computer program product, characterized by comprising computer-readable codes, or a non-volatile computer-readable storage medium carrying computer-readable codes, when the computer-readable codes are executed in an electronic device, the A processor in the electronic device performs the method of any one of claims 1-8.
A radar, characterized by comprising the distance detection device according to any one of claims 9-10.
A terminal, characterized by comprising the radar of claim 13 .