KR20220083473A - Liadar system and controlling method of the same - Google Patents

Abstract

A lidar system and a control method thereof are provided. The lidar system includes a laser diode that emits laser light to a target object, a mirror unit positioned between the laser diode and the target object to generate a first reflected light by reflecting the laser beam, and a first reflected light by receiving the first reflected light. A photodiode generating a first reflected signal and receiving the second reflected light reflected from the target object to generate a second reflected signal, and comparing the first reflected signal with the second reflected signal to generate the second reflected signal It includes a PD signal processing unit for determining validity.

Description

LiDAR system and its control method

The present invention relates to a lidar system and a control method thereof, and more particularly, to a reference value generated using laser light emitted from a laser diode and an input generated from reflected laser light reflected from a target object and input to a photodiode. The present invention relates to a lidar system capable of filtering noise input to a photodiode by comparing values and determining whether the values are valid, and a method for controlling the same.

LIDAR (Light Detection and Ranging; LIDAR) refers to a technology that calculates distance information from a target by using time information between a laser that is fired and a laser that is reflected back from the target. Recently, as it is applied to automobiles, it is evaluated as an indispensable technology in the field of autonomous driving technology.

LiDAR detects the time-of-flight (ToF) of laser light by detecting the reflected laser light incident on the photodiode after the laser emitted from the laser diode is reflected from the target, and the distance between the LIDAR system and the target is measured from the time of flight. can However, not only the laser light reflected from the target but also other noise signals may be introduced into the photodiode of the lidar system, thereby reducing the distance measurement accuracy of the lidar system. In order to minimize the influence of the distance measurement precision due to the noise signal, a noise filtering technique has been introduced.

The technical problem to be solved by the present invention is to compare a reference value generated using laser light emitted from a laser diode with an input value generated from reflected laser light reflected from a target object and input to a photodiode to determine whether it is valid By doing so, it is to provide a lidar system capable of filtering noise that may be input to a photodiode.

Another technical problem to be solved by the present invention is to compare a reference value generated using laser light emitted from a laser diode with an input value generated from reflected laser light reflected from a target object and input to a photodiode to determine whether it is valid or not. An object of the present invention is to provide a control method of a lidar system capable of filtering noise that may be input to a photodiode by judging.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

A lidar system according to an embodiment of the present invention for achieving the above technical problem is a laser diode that emits a laser beam to a target object, is located between the laser diode and the target object, and reflects the laser beam to reflect the first reflected light a mirror unit generating and a PD signal processing unit configured to compare the second reflected signal to determine validity of the second reflected signal.

In some embodiments of the present invention, the PD signal processing unit includes an amplitude comparator comparing the magnitude of the first reflected signal and the magnitude of the second reflected signal, and a duration of the first reflected signal and the second reflected signal. A timing comparator for comparing durations, and a valid signal determining unit performing an AND operation on a comparison result of the amplitude comparator and the timing comparator, wherein the validity of the second reflected signal may be determined based on an output value of the effective signal determining unit .

In some embodiments of the present disclosure, the PD signal processing unit may output a time-of-flight (TOF) generated based on the second reflected signal when it is determined that the second reflected signal is valid.

In some embodiments of the present invention, An offset of the amplitude comparator and the timing comparator may be set to compare the first reflected signal with the second reflected signal attenuated within a predetermined range.

A control method of a lidar system for achieving the above technical problem includes emitting a laser beam from a laser diode to a target object, reflecting the laser beam through a mirror positioned between the laser diode and the target object generating a first reflected light; generating a first reflected signal by receiving the first reflected light; and generating a second reflected signal by receiving a second reflected light reflected from the target object; and comparing the second reflected signal to determine validity of the second reflected signal.

In some embodiments of the present disclosure, the comparing of the first reflected signal and the second reflected signal may include comparing the magnitude of the first reflected signal and the magnitude of the second reflected signal with the result of comparing the first reflected signal and the first reflected signal. and performing an AND operation on a result of comparing the duration of the second reflection signal with the duration of the second reflection signal.

In some embodiments of the present invention, the comparing of the first reflected signal and the second reflected signal comprises setting an offset to compare the first reflected signal and the second reflected signal attenuated within a predetermined range. may include steps.

In some embodiments of the present invention, the method may further include outputting a time-of-flight (TOF) based on the second reflected signal when it is determined that the second reflected signal is valid.

The details of other embodiments are included in the detailed description and drawings.

The lidar system according to an embodiment of the present invention may determine whether the laser light input to the photodiode is a valid signal or noise by comparing it with the laser light output through the laser diode. In addition, in the comparison, the laser light reflected through the mirror unit and input to the photodiode without going outside is used as a reference value and compared with the input value, but the accuracy is improved by comparing it in the form of a digital value converted through an analog-to-digital converter. can

Effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a view for explaining a lidar system according to some embodiments of the present invention.
2 is a diagram for explaining the configuration of a PD signal processing unit included in a lidar system according to some embodiments of the present invention.
3 is a flowchart illustrating a method of controlling a lidar system according to some embodiments of the present invention.
4 is a timing diagram for explaining the operation of the lidar system according to some embodiments of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

When one component is referred to as “connected to” or “coupled to” with another component, it means that it is directly connected or coupled to another component or intervening another component. including all cases. On the other hand, when one component is referred to as “directly connected to” or “directly coupled to” with another component, it indicates that another component is not interposed therebetween. “and/or” includes each and every combination of one or more of the recited items.

The terminology used herein is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise in the phrase. As used herein, “comprises” and/or “comprising” refers to the presence of one or more other components, steps, operations, and/or elements mentioned. or addition is not excluded.

Although the first, second, etc. are used to describe various elements, these elements are not limited by these terms, of course. These terms are only used to distinguish one component from another. Accordingly, it goes without saying that the first component mentioned below may be the second component within the spirit of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein may be used with the meaning commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not to be interpreted ideally or excessively unless clearly defined in particular.

The term 'unit' or 'module' used in this embodiment means software or hardware components such as FPGA or ASIC, and 'unit' or 'module' performs certain roles. However, 'unit' or 'module' is not meant to be limited to software or hardware. A 'unit' or 'module' may be configured to reside on an addressable storage medium or may be configured to reproduce one or more processors. Thus, by way of example, a 'part' or 'module' refers to software components, object-oriented software components and functions, subroutines, segments of program code, microcode, circuitry, data, databases, data structures, It can include tables, arrays, and variables. Components and functionality provided in 'units' or 'modules' may be combined into a smaller number of components and 'units' or 'modules' or additional components and 'units' or 'modules' can be further separated.

1 is a view for explaining a lidar system according to some embodiments of the present invention.

Referring to FIG. 1 , a lidar system according to some embodiments of the present invention includes a laser diode 110 , a mirror unit 120 , a transmitting end lens 130 , a receiving end lens 150 , a photodiode 160 , and signal amplification. It may include a unit 170 , a time-digital conversion unit 180 , a laser diode driving unit 190 , and a photo diode (PD) signal processing unit 200 .

The laser diodes LD and 110 may emit laser light for detecting a distance from the target object 140 under the control of the laser diode driver 190 . As the emitted laser light passes through the transmitting end lens 130 , a viewing angle and each resolution may be secured.

The laser diode driver 190 may provide a laser diode driving signal to the laser diode 110 . The laser diode driving signal may be, for example, a current signal provided to the laser diode 110 .

The laser diode driving signal may also be provided to the PD signal processing unit 200 . As will be described later, the laser diode driving signal may function as a trigger signal for generating a reference value using laser light reflected by the mirror unit 120 and input to the photodiode 160 .

A portion of the laser light emitted from the laser diode 110 may be provided to the photodiode 160 without going out through the mirror unit 120 . As will be described later, the photodiode 160 may generate a reference value using the laser light reflected by the mirror unit 120 .

Here, the reference value may be a reference for determining whether the received signal is valid when the laser light reflected by the target object 140 is received by the photodiode 160 . The lidar system 10 according to the embodiment of the present invention compares the reference value generated using the laser beam reflected by the mirror unit 120 and the input value generated using the laser beam reflected from the target object 140 . can be compared

The photodiode PD 160 may receive laser light reflected from the target object 140 . The laser light reflected from the target object 140 may be condensed through the receiving end lens 150 to be incident on the photodiode 160 .

The photodiode 160 may generate a photodiode signal by receiving laser light reflected from the mirror unit 120 or the target object 140 . The photodiode signal may be amplified by the signal amplifying unit 170 and provided to the PD signal processing unit 200 .

The time-to-digital conversion unit 180 may encode the effective signal output from the PD signal processing unit 200 to generate time information for time-of-flight (ToF) calculation. The generated time information may be used to calculate a distance to the target object 140 .

2 is a diagram for explaining the configuration of a PD signal processing unit included in a lidar system according to some embodiments of the present invention.

Referring to FIG. 2 , the PD signal processing unit 200 includes a reference generation input buffer 210 , a PD signal amplification buffer 225 , a PD signal buffer 235 , analog-to-digital converters 215 and 240 , a counter 220 , 245 ), an amplitude comparator 250 , a timing comparator 255 , a valid signal determiner 260 , and a valid signal buffer 270 .

The reference generation input buffer 210 may receive a reference generation signal generated from laser light reflected from the mirror unit 120 and input to the photodiode 160 . The photodiode 160 receives the laser light reflected from the mirror unit 120 and outputs a reflected signal. The signal amplifying unit 170 may amplify the reflected signal and provide it to the PD signal processing unit 200 . The reference generation input buffer 210 may receive the amplified reflected signal, be triggered by an input of a laser diode driving signal, and output the reference generation signal to the analog-to-digital converter 215 and the counter 220 .

The analog-to-digital converter 215 may output a level reference value generated by quantifying the magnitude of the reference generation signal, and the counter 220 may output a timing reference value generated by quantifying the timing, that is, the duration of the reference generation signal. . Both the level reference value and the timing reference value may be configured in the form of a digital signal. The level reference value and the timing reference value are then provided to the amplitude comparator 250 and the timing comparator 255 to be compared with other input signals.

When the generation of the reference value is completed using the laser light reflected by the mirror unit 120 , the PD signal generated from the laser light reflected from the target object 140 may be provided to the PD signal processing unit 200 . The photodiode 160 receives the laser light reflected from the target object 140 and outputs a reflected signal. The signal amplifying unit 170 may amplify the reflected signal and provide it to the PD signal processing unit 200 .

The PD signal input to the PD signal processing unit 200 may be provided to the analog-to-digital converter 240 and the counter 245 through the PD signal buffer 235 . Here, the PD signal is input to the PD signal buffer 235 through a constant delay 230 , and the PD signal buffer 235 is triggered by the PD enable in which the PD signal amplification buffer 235 amplifies the PD signal to generate the PD signal. may be provided to the analog-to-digital converter 240 and the counter 245 .

The analog-to-digital converter 240 may output a level input value generated by digitizing the size of the PD signal, and the counter 245 may output a timing input value generated by digitizing the timing, that is, the duration of the PD signal. . Both the level input value and the timing input value may be configured in the form of a digital signal. The level input value and the timing input value are then provided to the amplitude comparator 250 and the timing comparator 255 to be compared with other reference signals.

The amplitude comparator 250 may compare the level reference value with the level input value and provide the comparison result to the valid signal determination unit 260 . The amplitude comparator 250 may receive a level reference value and a level input value, and may be triggered by a PD enable generated from a PD signal to provide a comparison result to the valid signal determiner 260 .

The timing comparator 255 may compare the timing reference value with the timing input value and provide the comparison result to the valid signal determiner 260 . The timing comparator 255 may receive a timing reference value and a timing input value, be triggered by a PD enable generated from the PD signal, and provide a comparison result to the valid signal determiner 260 .

In some embodiments of the present invention, the amplitude comparator 250 and the timing comparator 255 may be set with an offset for comparing amplitude and timing. That is, compared to the laser light reflected by the mirror unit 120 , the laser light reflected from the target object 140 may include some attenuation. Accordingly, in some embodiments, the amplitude comparator 250 and the timing comparator 255 may be offset to compare the attenuated amplitude input value and the timing input value with the level reference value and the timing reference value within a predetermined range.

The valid signal determination unit 260 may output a valid signal determination result from the comparison results of the amplitude comparator 250 and the timing comparator 255 . The valid signal determiner 260 may include, for example, an AND gate that performs an AND operation on the comparison results of the amplitude comparator 250 and the timing comparator 255 . For example, the amplitude comparator 250 determines that the level reference value and the level input value are the same and outputs a logic value '1', and the timing comparator 255 determines that the timing reference value and the timing input value are the same and determines the logic value '1' By outputting ', the valid signal determination result may be output as a logical value of '1'.

Finally, the valid signal determination result may trigger to output the valid signal stored in the valid signal buffer 270 as a time-of-flight (ToF) to the time-digital converter 180 . Through this, it is determined that the laser light input to the photodiode 160 is a valid signal, and the time-digital converter 180 may calculate the distance from the flight time to the target object 140 .

The lidar system 10 according to the embodiment of the present invention can determine whether the laser light input to the photodiode 160 is a valid signal or noise by comparing it with the laser light output through the laser diode 110 . have. In addition, in the comparison, the laser light reflected through the mirror unit 120 and input to the photodiode 160 without going to the outside is used as a reference value and compared with the input value, but in the form of a digital value converted through an analog-to-digital converter By comparing with , accuracy can be improved.

3 is a flowchart for explaining a method of controlling a lidar system according to some embodiments of the present invention, and FIG. 4 is a timing diagram for explaining an operation of a lidar system according to some embodiments of the present invention. An offset of the amplitude comparator 250 and the timing comparator 255 may be set to compare the attenuated amplitude input value and the timing input value with the level reference value and the timing reference value within a predetermined range.

Referring first to FIG. 3 , the control method of the lidar system according to some embodiments of the present invention includes driving a laser diode ( S110 ), generating a reference signal using a signal reflected through a mirror unit, and a target object. Comparing the input signal generated by reflection from the reference signal, comparing the reference signal and the input signal (S140), and determining the input signal as a valid signal (S150) or noise (S160) according to the comparison result may include

Referring to FIG. 4 , a laser driving signal is output from the laser diode driving unit 190 at time t1 and provided to the laser diode 110 and the PD signal processing unit 200 . The laser driving signal provided to the PD signal processing unit 200 may enable the LD trigger signal to be high.

A reflected signal generated from the laser light reflected from the mirror unit 120 at time t2 is provided to the PD signal processing unit 200 . The reflected signal generated from the laser light reflected from the mirror unit 120 is determined as a reference generation signal by the LD trigger signal, so that the level reference value and the timing reference value are generated from the analog-to-digital converter 215 and the counter 220, respectively. have. At this time, the reflected signal generated from the laser light reflected from the mirror unit 120 is provided to the analog-to-digital converter 240 and the counter 245 as a PD signal, and the analog-to-digital converter 240 and the counter 245 are Since the level input value and the timing input value generated through the same are values related to the laser light reflected from the same mirror unit 120 , the first flight time ToF may be output from the PD signal processing unit 200 .

Subsequently, the laser light reflected from the target object 140 is input to the photodiode 160 at time t3 . Since this is the laser light normally reflected from the target object 140 , the level reference value and the level input value, the timing reference value and the timing input value are the same, so that the second time of flight (ToF) may be output from the PD signal processing unit 200 . The time-digital converter 180 may measure the distance to the target object 140 using the first flight time and the second flight time.

On the other hand, at time t4, at time t1, the laser driving signal is output from the laser diode driving unit 190 and provided to the laser diode 110 and the PD signal processing unit 200, and at time t5, the first flight time is the PD signal processing unit ( 200) is output. However, before the laser light reflected from the target object 140 at time t6 is input to the photodiode 160, noise is introduced into the output AF Out of the signal amplifier 170 between times t5 and t6. is shown

However, despite the incoming noise, when the noise has the same level and duration as the level reference value and the timing reference value determined at time t5, they are ignored and the flight time is not output from the PD signal processing unit 200 . Only when a normal PD signal is input at time t6 , the PD signal processing unit 200 outputs the second flight time so that the time-digital converter 180 can measure the distance to the target object 140 .

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains can realize that the present invention can be embodied in other specific forms without changing the technical spirit or essential features. you will be able to understand Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

110: laser diode 120: mirror unit
130, 150: lens 160: photodiode
200: control unit

Claims (8)

a laser diode that emits laser light to the target;
a mirror unit positioned between the laser diode and the target object to generate a first reflected light by reflecting the laser light;
a photodiode that receives the first reflected light to generate a first reflected signal and receives the second reflected light reflected from the target object to generate a second reflected signal; and
Comprising a PD signal processing unit to determine the validity of the second reflected signal by comparing the first reflected signal and the second reflected signal,
lidar system. The method of claim 1,
The PD signal processing unit,
an amplitude comparator comparing the magnitude of the first reflected signal and the magnitude of the second reflected signal;
a timing comparator for comparing a duration of the first reflected signal with a duration of the second reflected signal; and
and a valid signal determining unit performing AND operation on the comparison result of the amplitude comparator and the timing comparator,
determining the validity of the second reflected signal based on the output value of the valid signal determining unit;
lidar system. The method of claim 1,
The PD signal processing unit outputs a time-of-flight (TOF) generated based on the second reflected signal when it is determined that the second reflected signal is valid,
lidar system. 3. The method of claim 2,
wherein the amplitude comparator and timing comparator are offset set to compare the first reflected signal with the second reflected signal attenuated within a predetermined range;
lidar system. emitting a laser beam from a laser diode to a target object;
generating a first reflected light by reflecting the laser light through a mirror positioned between the laser diode and the target object;
generating a first reflected signal by receiving the first reflected light, and generating a second reflected signal by receiving the second reflected light reflected from the target object; and
determining validity of the second reflected signal by comparing the first reflected signal with the second reflected signal;
How to control the lidar system. According to claim 4,
Comparing the first reflected signal and the second reflected signal comprises:
Comprising an AND operation of a comparison result of the magnitude of the first reflection signal and the magnitude of the second reflection signal, and the comparison result of the duration of the first reflection signal and the duration of the second reflection signal,
How to control the lidar system. 7. The method of claim 6,
Comparing the first reflected signal and the second reflected signal comprises:
setting an offset to compare the first reflected signal with the second reflected signal attenuated within a predetermined range;
How to control the lidar system. 7. The method of claim 6,
outputting a time-of-flight (TOF) based on the second reflected signal when it is determined that the second reflected signal is valid;
How to control the lidar system.

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