WO2023207640A1

WO2023207640A1 - Laser ranging method and laser radar

Info

Publication number: WO2023207640A1
Application number: PCT/CN2023/088508
Authority: WO
Inventors: 马威; 沈奇; 俞锋
Original assignee: 华为技术有限公司
Priority date: 2022-04-26
Filing date: 2023-04-14
Publication date: 2023-11-02
Also published as: CN116990827A

Abstract

A laser ranging method and a laser radar. The method comprises: a laser radar emitting a first pulse wave according to a preset pixel period (S301); when determining that a first echo signal corresponding to the first pulse wave is received within a set receiving duration, the laser radar emitting a second pulse wave at a first peak power (S302), wherein the first peak power is greater than the peak power of the first pulse wave and is less than a laser eye-safe standard power; and then, the laser radar receiving a second echo signal corresponding to the second pulse wave, and determining the distance between the laser radar and an obstacle on the basis of the second echo signal (S303). In the method, after a first echo signal is received, a second pulse wave is emitted, such that a laser radar can determine and receive, by taking the first echo signal and a first pulse wave as a reference, a second echo signal corresponding to the second pulse wave, thereby improving the receiving accuracy of the second echo signal, and also preventing the occurrence of the problem of multi-machine crosstalk, thus improving the ranging accuracy.

Description

A laser ranging method and lidar

Cross-references to related applications

This application claims priority to the Chinese patent application submitted to the China Patent Office on April 26, 2022, with the application number 202210450059.5 and the application title "A laser ranging method and lidar", the entire content of which is incorporated herein by reference. Applying.

Technical field

This application relates to the field of lidar control, and in particular to a laser ranging method and lidar.

Background technique

Lidar is a target detection technology. Using laser as a signal light source, by emitting laser to the target object, the reflected signal of the target object is collected, so as to obtain the orientation, speed and other information of the target object.

With the continuous development of laser technology, lidar is increasingly used in various fields. For example, in the field of intelligent driving, lidar is often used to detect feature quantities such as the position and speed of targets.

In the existing technology, the ranging method often used by lidar is to send pulse waves and determine the distance to the obstacle based on the received echo signal; however, this method will have the problem of multi-machine crosstalk, that is, the laser The echo signal received by the radar is not necessarily the echo signal corresponding to the pulse wave emitted by the lidar. It is very likely that the pulse wave emitted by other lidar is received as an echo signal, resulting in inaccurate ranging results.

Contents of the invention

This application provides a laser ranging method and lidar to solve the problem of multi-machine crosstalk and improve the accuracy of ranging.

In a first aspect, a laser ranging method is provided, which is applied to lidar. The method includes:

The first pulse wave is emitted according to the set pixel period; where the pixel period is the time required for the lidar to scan a pixel point; and, when it is determined that the first echo corresponding to the first pulse wave is received within the set reception time signal, transmit the second pulse wave with the first peak power; wherein, the reception duration is set to be less than the pixel period, the first peak power is greater than the peak power of the second pulse wave, and less than the laser eye safety standard power; then, Receive the second echo signal corresponding to the second pulse wave, and determine the distance between the lidar and the obstacle based on the second echo signal.

In this method, the lidar emits the first pulse wave within a set pixel period, and after receiving the first echo signal corresponding to the first pulse wave within the set reception time, it emits the second pulse wave. This enables the lidar to determine and receive the second echo signal corresponding to the second pulse wave based on the first pulse wave and the first echo signal, thereby improving the accuracy of the lidar receiving the second echo signal while preventing This eliminates the occurrence of multi-machine crosstalk problems, thereby improving the anti-interference ability of the lidar; and, because the lidar determines the distance between the lidar and the obstacle based on the received second echo signal, it can improve the detection accuracy. distance accuracy.

In one possible design, after determining that the first echo signal has not been received within the set reception time, the lidar transmits the third pulse wave with the second peak power; where the second peak power is greater than the laser eye safety Standard power, and the peak power of the third pulse wave emitted with the second peak power after transmission over the preset distance is less than the laser eye safety standard power rate, and the preset distance is determined based on the set reception duration and pulse wave transmission rate; after the lidar receives the third echo signal corresponding to the third pulse wave, based on the third echo signal, the lidar determines the distance between the lidar and the pulse wave transmission rate. The distance between obstacles.

Through this design, when the lidar determines that the first echo signal corresponding to the first pulse wave has not been received within the set reception time, it can measure the distance by emitting a third pulse wave with a peak power greater than the laser eye safety standard power. obstacles in the distance, while breaking through the laser human eye safety limit, it also improves the distance measurement performance of the lidar; and, the third pulse wave emitted at the second peak power is smaller than the laser human eye safety standard after transmission at the preset distance , ensuring the safety of the third pulse wave in subsequent transmission.

In one possible design, the lidar determines the pulse wave emission time interval corresponding to the pixel period, and transmits the second pulse wave with the first peak power after the pulse wave emission time interval has passed since the moment when the first pulse wave is transmitted.

Through this design, the lidar emits the second pulse wave at the first peak power after the pulse wave emission time interval has elapsed since the moment when the first pulse wave is emitted, which allows the lidar to determine the second pulse based on the pulse wave emission time interval. The second echo signal corresponding to the wave, thereby preventing the occurrence of multi-machine crosstalk problems.

In one possible design, the time interval between the reception time of the second echo signal and the reception time of the first echo signal is equal to the pulse wave transmission time interval.

Through this design, the lidar can determine the second echo signal from the received signal according to the pulse emission time interval, preventing the occurrence of multi-machine crosstalk problems and improving the anti-interference ability of the lidar.

In one possible design, the time difference between the reception time of the second echo signal and the emission time of the second pulse wave is determined, and the distance between the lidar and the obstacle is determined based on the obtained time difference.

Through this design, the lidar can ensure the accuracy of determining the distance between the lidar and the obstacle based on the time difference between the reception time of the second echo signal and the emission time of the second pulse wave.

In a second aspect, a lidar is provided. The lidar includes: a controller, an echo receiver and a laser transmitter; wherein,

The laser transmitter is used to transmit pulse waves;

The echo receiver is used to receive the echo signal corresponding to the pulse wave and send the received echo signal to the controller;

The controller is used to control the laser transmitter to emit the first pulse wave according to a set pixel period; the pixel period is the time required for the lidar to scan a pixel point; when within the set reception time When the first echo signal corresponding to the first pulse wave is not received, the laser transmitter is controlled to transmit the second pulse wave with the first peak power; wherein the set reception duration is less than the duration of the pixel period ; The first peak power is greater than the peak power of the first pulse wave and less than the laser eye safety standard power; receiving the second echo signal corresponding to the second pulse wave; based on the second echo signal , determine the distance between the lidar and the obstacle.

In a possible design, after transmitting the first pulse wave according to the set pixel period, the controller is also used to:

When the first echo signal is received within the set reception duration, the laser transmitter is controlled to emit a third pulse wave with a second peak power; wherein the second peak power is greater than the laser transmitter. eye safety standard power, and the peak power of the third pulse wave sent with the second peak power after transmission over a preset distance is less than the laser eye safety standard power; wherein the preset distance is based on the setting The reception duration and pulse wave transmission rate are determined;

Receive a third echo signal corresponding to the third pulse wave; and determine the distance between the lidar and the obstacle based on the third echo signal.

In one possible design, the controller is specifically used to:

Determine the pulse wave emission time interval corresponding to the pixel period;

The laser transmitter is controlled to emit the second pulse wave with the first peak power after the pulse wave emission time interval has elapsed since the moment when the first pulse wave is emitted.

In a possible design, the time interval between the reception time of the second echo signal and the reception time of the first echo signal is equal to the pulse wave transmission time interval.

In one possible design, the controller is specifically used to:

Determine the time difference between the reception time of the second echo signal and the transmission time of the second pulse wave;

According to the time difference, the distance between the lidar and the obstacle is determined.

In a third aspect, a laser ranging device is provided, which is applied to a controller in a laser radar; the device includes:

The first transmitting module is used to transmit the first pulse wave according to the set pixel period; the pixel period is the time required for the lidar to scan one pixel point;

The second transmitting module is configured to transmit the second pulse wave with the first peak power when the first echo signal corresponding to the first pulse wave is received within the set reception duration; wherein the set reception duration Less than the duration of the pixel period; the first peak power is greater than the peak power of the first pulse wave and less than the laser eye safety standard power;

A determination module, configured to receive a second echo signal corresponding to the second pulse wave; and determine the distance between the lidar and the obstacle based on the second echo signal.

In a possible design, after transmitting the first pulse wave according to the set pixel period, the second transmitting module is also used to:

When the first echo signal is not received within the set reception duration, the third pulse wave is emitted with the second peak power; wherein the second peak power is greater than the laser eye safety standard power, And the peak power of the third pulse wave emitted with the second peak power after transmission over a preset distance is less than the laser eye safety standard power; wherein the preset distance is based on the set reception duration and pulse The wave transmission rate is determined;

In a possible design, the second transmitting module is specifically used for:

After the pulse wave transmission time interval has elapsed since the moment when the first pulse wave is transmitted, the second pulse wave is transmitted with the first peak power.

In one possible design, it is determined that the module is specifically used to:

In a fourth aspect, the present application provides a computer-readable storage medium on which a computer program or instructions are stored. When the computer program or instructions are executed, the computer performs the above-mentioned first aspect or any one of the first possible aspects. method in the implementation.

In a fifth aspect, the present application provides a computer program product, which when a computer executes the computer program product, causes the computer to execute the method in the above-mentioned first aspect or any possible implementation of the first aspect.

For the beneficial effects of the above second aspect and the third aspect, please refer to the description of the beneficial effects of the above first aspect, which will not be repeated here.

Description of the drawings

Figure 1 is a schematic diagram of a possible application scenario of laser ranging according to the solution provided by the embodiment of the present application;

Figure 2 is a schematic diagram of the architecture of a possible laser radar according to the solution provided by the embodiment of the present application;

Figure 3 is a schematic diagram of a possible laser ranging method according to the solution provided by the embodiment of the present application;

Figure 4 is a schematic diagram of a possible pulse wave transmission timing of the solution provided by the embodiment of the present application;

Figure 5 is a schematic diagram of a possible relationship between peak power and detection distance of the solution provided by the embodiment of the present application;

Figure 6 is a complete flow diagram of a possible laser ranging method according to the solution provided by the embodiment of the present application;

Figure 7 is a schematic structural diagram of a laser radar according to the solution provided by the embodiment of the present application;

FIG. 8 is a schematic structural diagram of a laser ranging device according to the solution provided by the embodiment of the present application.

Detailed ways

Embodiments of the present application provide a laser ranging method and lidar. Among them, the method and lidar are based on the same concept. Since the method and lidar solve problems in similar principles, the implementation of lidar and method can be referred to each other, and the duplication will not be repeated.

In order to make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in further detail below with reference to the accompanying drawings. In the description of the embodiments of the present application, in the following, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of indicated technical features. . Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of these features.

To facilitate understanding, an exemplary description of concepts related to the present application is provided for reference.

1) Laser eye safety standard refers to the Class 1 standard defined by the laser product safety standard IEC 60825-1 that lidar needs to comply with.

2) Multi-machine crosstalk means that when multiple lidars are in the same space, the echo signal of one lidar will be interfered by the pulse waves emitted by other lidars.

3) Pixel period refers to the time required for the lidar to scan a pixel; for example, if the lidar scans a row with a period of T, and a row generates x pixels, then a pixel period Tp = T/x.

4) Echo signal refers to the signal reflected by the obstacle when the pulse wave is transmitted to the obstacle.

In the description of the embodiments of this application, "and/or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and/or B, which can mean: A exists alone, A and B exist simultaneously, alone There are three situations B. The character "/" generally indicates that the related objects are in an "or" relationship. At least one mentioned in this application refers to one or more; multiple refers to two or more. In addition, it should be understood that in the description of this application, words such as "first" and "second" are only used for the purpose of distinguishing the description, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating. Or suggestive order. The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Usually, when measuring distance by lidar, the lidar sends a pulse wave and then determines the distance to the obstacle based on the received echo signal. However, when lidar performs ranging operations, there will be a multi-machine crosstalk problem, so that the received echo signal contains pulse waves emitted by other lidars, resulting in a low accuracy of ranging results.

In order to solve the problem of multi-machine crosstalk and ensure the accuracy of lidar ranging, embodiments of the present application provide a laser ranging method, which is applied to lidar. Optionally, the lidar can be a vehicle-mounted lidar or other lidar. In this method, the lidar emits the first pulse wave according to the set pixel period, and after receiving the first echo signal corresponding to the first pulse wave within the set reception time, it emits the second pulse wave, which can accurately Receive the second echo signal corresponding to the second pulse wave while preventing the occurrence of multi-machine crosstalk problems; and determine the distance between the lidar and the obstacle based on the second echo signal to ensure the accuracy of the distance determination.

The following will take the vehicle-mounted lidar as an example and describe the embodiments of the present application in detail with reference to the accompanying drawings.

Figure 1 is a schematic diagram of an application scenario of a possible laser ranging method to which the solution provided by the embodiment of the present application is applicable. As shown in Figure 1, the application scenario includes a vehicle 10 and an obstacle 20; among them, the vehicle 10 is equipped with a lidar 30.

In one implementation, when the vehicle 10 is driving on the road, the lidar 30 emits the first pulse wave according to the set pixel period. When the first pulse wave is transmitted to the obstacle 20, it is reflected by the obstacle 20 to obtain a first echo signal. When the lidar 30 receives the first echo signal within the set reception time, it indicates that there is an obstacle 20 within the set distance from the lidar 30 , where there is a correlation between the set reception time and the set distance. sex. At this time, the lidar 30 can emit a second pulse wave, receive a second echo signal reflected by the obstacle 30 , and then determine the distance to the obstacle 20 based on the second echo signal. Finally, after determining the distance between the lidar 30 and the obstacle 20 , the lidar 30 can generate a point cloud based on the determined distance. The lidar 30 can send the point cloud to the intelligent driving system in the vehicle 10 so that the intelligent driving system makes automatic driving decisions based on the point cloud.

FIG. 2 is a schematic diagram of the architecture of a possible lidar to which the solution provided by the embodiment of the present application is applicable. As shown in Figure 2, the lidar at least includes a controller, a laser transmitter, an echo receiver and a scanner.

Among them, the controller can include a processing system composed of a time to digital converter (Time to Digital Convert, TDC) and a field programmable gate array (Field Programmable Gate Array, FPGA), or other processing systems, which are not discussed here. limit.

In one implementation, TDC is used to measure the time difference between the transmitting time of the pulse wave and the receiving time of the echo signal. FPGA is used for laser emission strategy control and TDC time data processing, and finally generates point cloud output.

In one embodiment, a laser transmitter may include a laser controller, a laser, and an opto-mechanical system. Among them, the laser controller is used to control the laser to emit pulse waves; the laser is used to emit pulse waves; the optical-mechanical system is used for laser pulse beam shaping and echo signal reception.

In the laser transmitter shown in Figure 2, the opto-mechanical system includes a collimating mirror, a polarizing beam combiner and a reflecting mirror; there is a small hole in the middle of the reflecting mirror so that the pulse wave is transmitted to the scanner through the small hole.

In one embodiment, a scanner includes a micromirror and a micromirror controller. Among them, the micro-mirror is used to reflect the pulse wave and deflect the direction of the pulse wave, so that the lidar can perform multi-point scanning of obstacles, and is used to reflect the echo signal to the mirror in the laser transmitter. The micro-galvanizing mirror controller is used to control the micro-galvanizing mirror to vibrate periodically at a certain frequency and angle.

In one embodiment, the echo receiver includes a photodetector, a signal amplifier, and a signal filter. Among them, the photodetector is used to convert the received echo signal into an electrical signal, and transmit the obtained electrical signal to the signal amplifier and filters. Signal amplifiers and filters are used to perform signal processing on electrical signals and transmit the processed echo signals to the controller.

In one embodiment, the controller controls the laser emitter to send the first pulse wave according to the set pixel period through the processing system; optionally, the laser emitter determines the peak power of the laser transmitting the first pulse wave through the laser controller, and emit the first pulse wave through the laser.

The first pulse wave is transmitted to the scanner through the optical-mechanical system in the laser transmitter, and is transmitted to the obstacle through the deflection of the micro-mirror in the scanner. The first pulse wave is reflected by the obstacle to obtain the first echo signal. The first echo signal is deflected by the micro-mirror in the scanner and transmitted to the reflector in the laser transmitter, and is transmitted to the echo signal through the deflection of the reflector. receiver. The echo receiver converts the received first echo signal from an optical signal to an electrical signal through a photodetector, performs signal processing on the first echo signal through a signal amplifier and a signal filter, and converts the processed first echo signal into an electrical signal. The echo signal is transmitted to the controller.

The controller determines whether the first echo signal is received within the set reception time period based on the receiving time of the first echo signal and the transmitting time of the first pulse wave. When the controller determines that the first echo signal is received within the set reception time, it controls the laser transmitter to emit a second pulse wave and receive a second echo signal corresponding to the second pulse wave. The controller determines the distance between the lidar and the obstacle based on the received second echo signal.

It should be noted that the lidar shown in Figure 2 is only an illustrative description of the lidar applicable to the solution of this application, and does not limit the lidar architecture to which the solution of this application is applicable. Other devices or modules can also be added to the above lidar architecture, or some devices or modules can be reduced or modified.

The solution provided by this application will be introduced below with reference to specific embodiments.

Example 1

Figure 3 is a schematic diagram of a laser ranging method provided by an embodiment of the present application, which can be applied to the laser radar shown in Figure 2. As shown in Figure 3, the method includes:

S301: The lidar emits the first pulse wave according to the set pixel period.

The lidar emits the first pulse wave with the set peak power according to the set pixel period.

It should be noted that the peak power of the first pulse wave is less than the laser eye safety standard power.

For example, when the lidar scans a line with a period of T=1ms, and scans a line to generate x=125 pixels, the pixel period is Tp=T/x=8us; the lidar emits a first pulse wave every 8us.

After the lidar transmits the first pulse wave according to the set pixel period, it determines whether the first echo signal corresponding to the first pulse wave is received within the set reception time period.

In one implementation, the lidar determines whether there is an obstacle within a preset distance by determining whether the first echo signal is received within a set reception time period.

It should be noted that the preset distance is determined based on the set reception duration and pulse wave transmission rate, and the preset distance is the maximum detection distance of the first pulse wave.

S302: After the lidar receives the first echo signal corresponding to the first pulse wave within the set reception time, it transmits the second pulse wave with the first peak power.

It should be noted that the set reception duration is smaller than the duration of the pixel period; the first peak power is larger than the peak power of the first pulse wave and smaller than the laser eye safety standard power.

When the lidar receives the first echo signal within the set reception time, it indicates that there is an obstacle within the set distance. Among them, the obstacles existing within the set distance may be people or animals, so in order to ensure that there are animals within the set distance, To ensure the safety of life-threatening obstacles, the peak power of the second pulse wave subsequently emitted needs to be less than the laser human eye safety standard power. Furthermore, in order for the second pulse wave to be able to measure further obstacles, the peak power of the second pulse wave needs to be greater than the peak power of the first pulse wave.

In one implementation, the lidar determines whether the first echo signal is received within the set reception time period based on the time difference between the reception time of the first echo signal and the transmission time of the first pulse wave.

Among them, the lidar determines whether the first echo signal is received within the set reception time period to determine whether there is an obstacle within the preset distance.

It should be noted that the preset distance is determined based on the set reception duration and pulse wave transmission rate; where the pulse wave transmission rate is the speed of light.

In one implementation, when the lidar determines that the first echo signal corresponding to the first pulse wave is received within the set reception time period, the lidar transmits the second pulse wave with the first peak power.

Optionally, the lidar may, but is not limited to, emit a second pulse wave through the following steps.

A1: Lidar determines the pulse wave emission time interval corresponding to the pixel period.

It should be noted that the pulse wave emission time interval is smaller than the pixel period.

In one implementation, one pixel period corresponds to one pulse wave emission time interval. Among them, the pulse wave emission time interval corresponding to any pixel period can be set through coding. For example, the pulse wave transmission time interval can be set to t+nj (j=1,2,3···x).

Specifically, t can be set to 2us; nj can be set to an encoded unfixed time, and its specific value can take different values due to different encoding methods.

In one implementation, nj can be set to 1ns, 2ns, 3ns, and 4ns, and used cyclically.

A2: The lidar transmits the second pulse wave with the first peak power after the pulse wave transmission time interval has passed since the moment when the first pulse wave was transmitted.

In one embodiment, after the lidar determines the pulse wave emission time interval corresponding to the pixel period, and after the pulse wave emission time interval has passed since the moment when the first pulse wave is transmitted, the laser radar detects the pulse wave emission time interval with a power greater than the peak power of the first pulse wave. The second pulse wave is emitted at the first peak power.

Since the first peak power is greater than the peak power of the first pulse wave, the detection distance of the second pulse wave emitted with the first peak power is greater than the detection range of the first pulse wave, and the lidar can detect by emitting the second pulse wave. Relatively distant obstacles; among them, the maximum detection distance of the first pulse wave is the preset distance.

Moreover, when the lidar determines that it has received the first echo signal within the set reception time, it emits the second pulse wave with the first peak power, where the first peak power is less than the laser eye safety standard power, which can ensure the preset When the obstacle within the distance is a person, the human eye will not be harmed by the second pulse wave, which complies with the laser eye safety standards.

S303: The lidar receives the second echo signal corresponding to the second pulse wave, and determines the distance between the lidar and the obstacle based on the second echo signal.

It should be noted that the time interval between the reception time of the second echo signal and the reception time of the first echo signal is equal to the pulse wave transmission time interval.

When the first echo signal and the second echo signal bounce back from the same obstacle, the time it takes for the first echo signal and the second echo signal to bounce from the obstacle to the lidar is the same. At the same time, the time it takes for the first pulse wave and the second pulse wave to transmit to the same obstacle is also the same. That is to say, when the first pulse wave and the second pulse wave are transmitted to the same obstacle, the time interval between the reception time of the first echo signal and the transmission time of the first pulse wave is equal to the reception time of the second echo signal. The time interval between the time and the emission time of the second pulse wave. Therefore, when the second echo signal is connected When the time interval between the receiving time and the receiving time of the first echo signal is equal to the pulse wave transmitting time interval, it can be determined that the first echo signal and the second echo signal are reflected from the same obstacle.

In one implementation, since the lidar emits the second pulse wave after receiving the first echo signal within the set reception time, the lidar can receive the second pulse wave based on the first echo signal. echo signal.

Since the lidar only receives the second echo signal, the time interval between the reception moment and the reception moment of the first echo signal is the pulse wave emission time interval, which can effectively prevent the occurrence of multi-machine crosstalk problems and ensure that the lidar receives the second echo signal. The accuracy of the second echo signal.

For example, the pulse wave transmission time interval is 2us, and the lidar only receives the second echo signal whose time interval between the reception time and the first echo signal reception time is 2us.

In one implementation, after receiving the second echo signal, the lidar determines the distance between the lidar and the obstacle based on the second echo signal.

Specifically, this application can, but is not limited to, determine the distance between the lidar and the obstacle through the following steps.

B1: Determine the time difference between the reception time of the second echo signal and the transmission time of the second pulse wave.

B2: Determine the distance between the lidar and the obstacle based on the time difference.

In one implementation, the lidar determines the distance between the lidar and the obstacle based on the determined time difference and the pulse wave transmission rate.

S304: When the lidar determines that the first echo signal corresponding to the first pulse wave has not been received within the set reception time, the lidar transmits the third pulse wave with the second peak power.

It should be noted that the second peak power is greater than the laser eye safety standard power, and the peak power of the third pulse wave emitted with the second peak power after being transmitted over a preset distance is less than the laser eye safety standard power.

When the lidar determines that the first echo signal is not received within the set reception time and determines that there are no obstacles within the preset distance, it can emit the third pulse wave with a second peak power greater than the laser eye safety standard power. While breaking through the limitations of laser human eye safety standards, it also improves the distance measurement performance of lidar. Moreover, if the first echo signal is not received within the set reception time, it only means that there is no obstacle within the preset distance, but it does not determine whether there is an obstacle (possibly a person or an animal) outside the preset distance. Then the peak power of the third pulse wave emitted with the second peak power after the preset distance is less than the laser eye safety standard power, which complies with the laser eye safety standard and ensures that the third pulse wave is transmitted after the preset distance. Safe to human eyes.

In one implementation, the specific process of the lidar transmitting the third pulse wave at the second peak power is the same as the process of transmitting the second pulse wave at the first peak power in Embodiment 1, and will not be described again here.

In one implementation, the lidar receives a third echo signal corresponding to the third pulse wave, wherein the time interval between the reception time of the third echo signal and the reception time of the first echo signal is equal to the pulse wave transmission time interval.

For example, the laser radar determines the reception time of the signal. When the time interval between the reception time and the reception time of the first echo signal is equal to the pulse wave transmission time interval, the signal is received as the third echo signal; when the signal's When the time interval between the receiving time and the receiving time of the first echo signal is not equal to the pulse wave transmitting time interval, the signal is not received.

S305: After the lidar receives the third echo signal corresponding to the third pulse wave, it determines the distance between the lidar and the obstacle based on the third echo signal.

The specific implementation of the lidar determining the distance between the lidar and the obstacle based on the third echo signal is the same as the specific implementation of determining the distance between the lidar and the obstacle based on the second echo signal in Embodiment 1, I won’t go into details here.

Based on the solution shown in Embodiment 1, this application provides a schematic diagram of a possible pulse wave emission timing sequence. As shown in Figure 4, a pulse wave is emitted in each pixel period using the method in Embodiment 1. Among them, the first pulse wave is emitted with peak power P1 every pixel period; after the pulse wave emitting time interval t+nj starts from the launch moment of the first pulse wave, the second pulse wave is emitted with the first peak power P2, or from After the emission time of the first pulse wave passes through the pulse wave emission time interval t+nj, the third pulse wave is generated with the second peak power P3.

Based on the solution shown in Embodiment 1, this application provides a schematic diagram of a possible relationship between peak power and detection distance, as shown in Figure 5. Among them, when the peak power of the first pulse wave P1 = 5W, the maximum detection distance (preset distance) of the first pulse wave L1 = 3m, that is, the first pulse wave is used to detect whether there are obstacles within the 0-L1 distance range. . When the peak power of the second pulse wave (first peak power) P2=105W, the maximum detection distance of the second pulse wave is L2=135m, that is, the second pulse wave is used to detect obstacles within the 0-L2 distance range. When the peak power of the third pulse wave (second peak power) P3 = 170W, the maximum detection distance of the third pulse wave L3 = 175m, where P3 is greater than the laser eye safety standard power in the distance range of 0-L1. Outside the L1 distance, P3 is less than the laser eye safety standard power, that is, the third pulse wave is used to detect obstacles within the L1-L3 distance range.

Based on the laser ranging scheme shown in Embodiment 1, this scheme will be introduced in detail through Figure 6 below. FIG. 6 is a complete flow diagram of a laser ranging method provided by an embodiment of the present application. The specific flow of the method will be described below with reference to FIG. 6 .

S601: The lidar emits the first pulse wave according to the set pixel period.

S602: The lidar determines whether the first echo signal corresponding to the first pulse wave is received within the set reception time; if so, perform step S603; if not, perform step S606.

It should be noted that the set reception duration is smaller than the duration of the pixel period.

S603: The lidar determines the pulse wave emission time interval corresponding to the pixel period.

S604: The lidar transmits the second pulse wave with the first peak power after the pulse wave transmission time interval has passed since the time when the first pulse wave was transmitted.

It should be noted that the first peak power is greater than the peak power of the first pulse wave and less than the laser eye safety standard power.

S605: The lidar receives the second echo signal corresponding to the second pulse wave, and determines the distance between the lidar and the obstacle based on the second echo signal.

S606: The lidar determines the pulse wave emission time interval corresponding to the pixel period.

S607: The lidar transmits the third pulse wave with the second peak power after the pulse wave transmission time interval has passed since the moment when the first pulse wave is transmitted.

It should be noted that the second peak power is greater than the laser eye safety standard power, and the peak power of the third pulse wave emitted with the second peak power after being transmitted over a preset distance is less than the laser eye safety standard power; where, the preset The distance is determined based on the set reception duration and pulse wave transmission rate.

S608: The lidar receives the third echo signal corresponding to the third pulse wave, and determines the distance between the lidar and the obstacle based on the third echo signal.

In the embodiment shown in Figure 6, after the lidar transmits the first pulse wave according to the set pixel period, it needs to determine whether the first echo signal corresponding to the first pulse wave is received within the set reception time period. Finally, the peak power of the subsequent pulse wave sent within the pixel period is determined, and the pulse wave used for ranging can be flexibly selected based on the actual road condition information. The peak power improves the flexibility of laser ranging. Secondly, after the lidar emits the first pulse wave for judgment, it emits the second pulse wave or the third pulse wave for ranging, so that it can subsequently receive the second echo signal corresponding to the second pulse wave. or the third echo signal corresponding to the third pulse wave, the first pulse wave is used as the basis for receiving the second echo signal or the third echo signal, which avoids treating the pulse waves emitted by other laser radars in the same environment as the third echo signal. The second echo signal or the third echo signal is received, thereby improving the accuracy of ranging. In addition, after the lidar determines that the first echo signal has not been received within the set reception time, that is, after determining that there are no obstacles within the preset distance, the lidar transmits the third peak power with a second peak power greater than the laser eye safety standard power. The pulse wave breaks through the limitations of laser human eye safety and greatly increases the detection distance of laser radar. Moreover, the peak power of the third pulse wave after transmission over the preset distance is less than the laser human eye safety standard power, meeting the requirements of laser human eye safety. standards to ensure the safety of lidar during use.

Based on the above embodiments and the same concept, embodiments of the present application also provide a lidar. As shown in Figure 7, the lidar 700 includes: a laser transmitter 701, an echo receiver 702 and a controller 703;

Laser transmitter 701, used to transmit pulse waves;

Echo receiver 702 is used to receive the echo signal corresponding to the pulse wave and send the received echo signal to the controller 703;

Controller 703 is used to control the laser transmitter 701 to emit the first pulse wave according to a set pixel period; the pixel period is the time required for the lidar to scan one pixel point; when within the set reception time When the first echo signal corresponding to the first pulse wave is not received, the laser transmitter 701 is controlled to transmit the second pulse wave with the first peak power; wherein the set reception duration is less than the pixel period. Duration; the first peak power is greater than the peak power of the first pulse wave and less than the laser eye safety standard power; receiving the second echo signal corresponding to the second pulse wave; based on the second echo signal to determine the distance between the lidar and the obstacle.

In a possible design, after transmitting the first pulse wave according to the set pixel period, the controller 703 is also used to:

When the first echo signal is received within the set reception duration, the laser transmitter 701 is controlled to emit a third pulse wave with a second peak power; wherein the second peak power is greater than the laser The human eye safety standard power, and the peak power of the third pulse wave sent with the second peak power after transmission over the preset distance is less than the laser eye safety standard power; wherein the preset distance is based on the Determined by setting the reception duration and pulse wave transmission rate;

In one possible design, the controller 703 is specifically used to:

Based on the above embodiments and the same concept, embodiments of the present application also provide a laser ranging device. As shown in Figure 8, The laser ranging device 800 is used as a controller in lidar; the device 800 includes:

The first transmitting module 801 is used to transmit the first pulse wave according to the set pixel period; the pixel period is the time required for the lidar to scan one pixel point;

The second transmitting module 802 is configured to transmit the second pulse wave with the first peak power when the first echo signal corresponding to the first pulse wave is received within the set reception time period; wherein the set reception The duration is less than the duration of the pixel period; the first peak power is greater than the peak power of the first pulse wave and less than the laser human eye safety standard power;

Determining module 803 is configured to receive a second echo signal corresponding to the second pulse wave; and determine the distance between the lidar and the obstacle based on the second echo signal.

In a possible design, after transmitting the first pulse wave according to the set pixel period, the second transmitting module 802 is also used to:

In one possible design, the second transmitting module 802 is specifically used to:

In a possible design, the determination module 803 is specifically used to:

It should be understood that the division of modules in the embodiment of the present application is schematic and is only a logical function division. In actual implementation, there may be other division methods. In addition, each functional module in each embodiment of the present application can be implemented by software or hardware.

In this application, "implemented by software" means that the processor reads and executes the program instructions stored in the memory to realize the functions corresponding to the above modules or units, where the processor refers to the processing circuit with the function of executing program instructions, Including but not limited to at least one of the following: central processing unit (CPU), microprocessor, digital signal processing (DSP), microcontroller unit (MCU), or artificial intelligence processing Various types of processing circuits that can run program instructions, such as processors. In other embodiments, the processor may also include circuits for other processing functions (such as hardware circuits for hardware acceleration, buses and interface circuits, etc.). The processor can be presented in the form of an integrated chip, for example, in the form of an integrated chip whose processing function only includes the function of executing software instructions, or it can also be presented in the form of an SoC (system on a chip, system on a chip), that is, on a chip In addition to processing circuits that can run program instructions (often called "cores"), it also includes other hardware circuits used to implement specific functions (of course, these hardware circuits can also be implemented separately based on ASIC or FPGA), Correspondingly, in addition to the function of executing software instructions, the processing function can also include various hardware acceleration functions (such as AI calculation, encoding and decoding, compression and decompression, etc.).

In this application, "implementation through hardware" refers to realizing the functions of the above modules or units through a hardware processing circuit that does not have the function of processing program instructions. The hardware processing circuit can be composed of discrete hardware components, or it can be an integrated circuit. In order to reduce power consumption and size, it is usually implemented in the form of integrated circuits. Hardware processing circuits can include ASIC (application-specific integrated circuit, application-specific integrated circuit), or PLD (programmable logic device, programmable logic device); among them, PLD can also include FPGA (field programmable gate array, field programmable gate array) , CPLD (complex programmable logic device, complex programmable logic device) and so on. These hardware processing circuits can be a separately packaged semiconductor chip (such as packaged into an ASIC); they can also be integrated with other circuits (such as CPU, DSP) and packaged into a semiconductor chip. For example, they can be formed on a silicon base. A variety of hardware circuits and CPUs are individually packaged into one chip. This chip is also called SoC. Alternatively, the circuits and CPU used to implement FPGA functions can also be formed on a silicon base and separately packaged into one chip. This chip Also called SoPC (system on a programmable chip, programmable system on a chip).

It should be noted that when this application is implemented through software, hardware, or a combination of software and hardware, different software and hardware can be used, and it is not limited to using only one kind of software or hardware. For example, one module or unit can be implemented using a CPU, and another module or unit can be implemented using a DSP. Similarly, when using hardware implementation, one module or unit can be implemented using ASIC, and the other module or unit can be implemented using FPGA. Of course, it is not limited to some or all modules or units being implemented using the same kind of software (eg, all through CPU) or the same kind of hardware (eg, all through ASIC). In addition, those skilled in the art can know that software is generally more flexible, but its performance is not as good as hardware, and hardware is just the opposite. Therefore, those skilled in the art can choose software or hardware or a combination of the two based on actual needs. form to achieve.

Based on the above content and the same concept, the present application provides a computer-readable storage medium on which a computer program or instructions are stored. When the computer program or instructions are executed, the computing device performs the method in the above method embodiment.

Based on the above content and the same concept, the present application provides a computer program product. When the computer executes the computer program product, the computing device executes the method in the above method embodiment.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the present application. It will be understood that each process and/or block in the flowchart illustrations and/or block diagrams, and combinations of processes and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device produce a use A device for realizing the functions specified in one process or multiple processes of the flowchart and/or one block or multiple blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory that causes a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction means, the instructions The device implements the functions specified in a process or processes of the flowchart and/or a block or blocks of the block diagram.

These computer program instructions may also be loaded onto a computer or other programmable data processing device, causing a series of operating steps to be performed on the computer or other programmable device to produce computer-implemented processing, thereby executing on the computer or other programmable device. Instructions provide steps for implementing the functions specified in a process or processes of a flowchart diagram and/or a block or blocks of a block diagram.

Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. In this way, if these modifications and variations of the present application fall within the scope of the claims of the present application and equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

A laser ranging method, applied to lidar, characterized in that the method includes:

The first pulse wave is emitted according to the set pixel period; the pixel period is the time required for the lidar to scan one pixel point;

When the first echo signal corresponding to the first pulse wave is received within the set reception duration, the second pulse wave is transmitted with the first peak power; wherein the set reception duration is less than the duration of the pixel period ;The first peak power is greater than the peak power of the first pulse wave and less than the laser eye safety standard power;

Receive a second echo signal corresponding to the second pulse wave; and determine the distance between the lidar and the obstacle based on the second echo signal.
The method according to claim 1, characterized in that, after transmitting the first pulse wave according to the set pixel period, the method further includes:

When the first echo signal is not received within the set reception duration, the third pulse wave is emitted with the second peak power; wherein the second peak power is greater than the laser eye safety standard power, And the peak power of the third pulse wave emitted with the second peak power after transmission over a preset distance is less than the laser eye safety standard power; wherein the preset distance is based on the set reception duration and pulse The wave transmission rate is determined;

Receive a third echo signal corresponding to the third pulse wave; and determine the distance between the lidar and the obstacle based on the third echo signal.
The method according to claim 1, characterized in that said transmitting the second pulse wave at the first peak power includes:

Determine the pulse wave emission time interval corresponding to the pixel period;

After the pulse wave transmission time interval has elapsed since the moment when the first pulse wave is transmitted, the second pulse wave is transmitted with the first peak power.
The method according to claim 3, characterized in that the time interval between the reception time of the second echo signal and the reception time of the first echo signal is equal to the pulse wave transmission time interval.
The method according to any one of claims 1-4, characterized in that, based on the second echo signal, the distance between the lidar and the obstacle is determined;

Determine the time difference between the reception time of the second echo signal and the transmission time of the second pulse wave;

According to the time difference, the distance between the lidar and the obstacle is determined.
A lidar, the lidar includes: a controller, an echo receiver and a laser transmitter; it is characterized by including:

The laser transmitter is used to transmit pulse waves;

The echo receiver is used to receive the echo signal corresponding to the pulse wave and send the received echo signal to the controller;

The controller is used to control the laser transmitter to emit the first pulse wave according to a set pixel period; the pixel period is the time required for the lidar to scan a pixel point; when within the set reception time When the first echo signal corresponding to the first pulse wave is not received, the laser transmitter is controlled to transmit the second pulse wave with the first peak power; wherein the set reception duration is less than the duration of the pixel period ; The first peak power is greater than the peak power of the first pulse wave and less than the laser eye safety standard power; receiving the second echo signal corresponding to the second pulse wave; based on the second echo signal , determine the distance between the lidar and the obstacle.
The laser radar according to claim 6, characterized in that, after transmitting the first pulse wave according to the set pixel period, the controller is also used to:

When the first echo signal is received within the set reception duration, the laser transmitter is controlled to emit a third pulse wave with a second peak power; wherein the second peak power is greater than the laser transmitter. eye safety standard power, and the peak power of the third pulse wave sent with the second peak power after transmission over a preset distance is less than the laser eye safety standard power; wherein the preset distance is based on the setting The reception duration and pulse wave transmission rate are determined;

Receive a third echo signal corresponding to the third pulse wave; and determine the distance between the lidar and the obstacle based on the third echo signal.
The laser radar according to claim 6, characterized in that the controller is specifically used for:

Determine the pulse wave emission time interval corresponding to the pixel period;

The laser transmitter is controlled to emit the second pulse wave with the first peak power after the pulse wave emission time interval has elapsed since the moment when the first pulse wave is emitted.
The laser radar according to claim 8, characterized in that the time interval between the receiving time of the second echo signal and the receiving time of the first echo signal is equal to the pulse wave transmission time interval.
The laser radar according to any one of claims 6-9, characterized in that the controller is specifically used for:

Determine the time difference between the reception time of the second echo signal and the transmission time of the second pulse wave;

According to the time difference, the distance between the lidar and the obstacle is determined.
A computer-readable storage medium, characterized in that the computer-readable storage medium stores computer instructions. When the computer instructions are run on a computer or a processor, the computer or the processor causes the computer or the processor to execute the instructions as claimed in the claim. The method described in any one of claims 1-5.
A computer program product, characterized in that, when the computer program product is run on a computer or a processor, it causes the computer or the processor to execute the method according to any one of claims 1-5.