KR102086025B1 - LIDAR signal processing apparatus and method - Google Patents

Abstract

The present invention relates to a lidar signal processing apparatus and method, and more particularly, a multi-pulse wave applying unit for applying pulse waves having various power values so that laser lights of various sizes can be generated in a laser diode; A power value selector configured to select a corresponding power value of the applied pulse wave when detecting a reflected wave by any one of the laser lights in the photodiode; And a power value limiter configured to limit the pulse waves to be applied by the multi-pulse wave application unit to below the corresponding power value.

Description

Lida signal processing apparatus and method

The present invention relates to a lidar signal processing apparatus and method, and more particularly, to an apparatus for measuring a distance and shape to an object to be measured using optical means.

LIDAR: Light Detection And Ranging (LIDAR) is a physical property such as distance, concentration, speed, and shape of a measurement object from the time, intensity, frequency change, polarization state change, etc. Refers to measure.

It is similar to a radar (RADAR: Radio Detection And Ranging) that uses a microwave to obtain a distance by observing the round-trip time to an object, but it has a difference that it uses light, unlike a radar that uses radio waves. It is also called.

Lidar devices have been dominated by aviation riders that emit laser pulses from satellites or aircraft and receive pulses backscattered by particles in the atmosphere from ground stations, and these aviation riders, along with wind information, are used to It has been used to measure the presence and movement of smoke, aerosols, cloud particles, etc., and to analyze the distribution of airborne dust particles or air pollution.

However, recently, both the transmission system and the reception system are installed on the ground to perform obstacle detection, terrain modeling, and location acquisition to the target. Research is being actively conducted with the application to civilian applications such as mobile robots for civilian use, intelligent vehicles, and unmanned vehicles in mind.

However, since the conventional lidar device emits a laser having a wide beam width to obtain an object and acquires reflected light to obtain a distance from the reflector, a laser module having a very high output is required, and in order to reduce detection errors By outputting multiple pulses, there is a problem in that performance due to heat of the laser diode is significantly reduced. In addition, the laser module having a high output has a large size and acts as a factor to increase the overall size of the lidar device.

The present invention has been devised to cope with the above-described technical problems, and the object of the present invention is to substantially compensate for various problems caused by limitations and disadvantages in the prior art, and minimizes power consumed by the laser diode. It was configured to be able to. Thus, to solve the problem of heat generation of the laser diode, and to provide an improvement in the maximum measurement distance through efficient use. The present invention is to solve a number of problems, including the above problems, an object of the present invention is to provide a lidar signal processing apparatus and method capable of reducing load and power consumption of a driving semiconductor of a laser diode. However, these problems are exemplary, and the scope of the present invention is not limited thereby.

In order to achieve the above object, the lidar signal processing apparatus according to an embodiment of the present invention, a multi-pulse wave applying unit for applying pulse waves having various power values so that laser lights of various sizes can be generated in a laser diode ; A power value selector configured to select a corresponding power value of the applied pulse wave when detecting a reflected wave by any one of the laser lights in the photodiode; And a power value limiter configured to limit the pulse waves to be applied by the multi-pulse wave application unit to below the corresponding power value.

In addition, the multi-pulse wave applying unit may repeatedly apply a plurality of multi-pulse wave sets consisting of N pulse waves, from low-power pulse waves to progressively high-power pulse waves.

In addition, the power value limiting unit, the multi-pulse wave application unit, while applying the low power value from the pulse wave to the pulse wave of the high power value gradually, when the power value is selected in the power value selection unit, the power The power value of the pulse wave can be limited until the N pulse waves are applied to the same power value.

In addition, the lidar signal processing apparatus may further include a power value recovery unit configured to restore power values of the pulse waves to the multi-pulse wave application unit when a reflected wave is not detected in the photodiode for a certain period of time. have.

In addition, the lidar signal processing apparatus may further include a ToF comparator that detects pulse waves applied by the multiple pulse wave applying unit and compares the detected pulse waves.

On the other hand, the lidar signal processing method according to an embodiment of the present invention, a multi-pulse wave application step of applying pulse waves having various power values so that laser light of various sizes can be generated in a laser diode; A power value selection step of selecting a corresponding power value of the applied pulse wave when detecting the reflected wave by any one of the laser lights in the photodiode; And a power value limiting step of limiting the pulse waves to be applied in the multiple pulse wave applying step to below the corresponding power value.

The multi-pulse wave application step may include: a first pulse wave application step of applying a reference first pulse wave; An N-1 pulse wave application step of applying a N-1 pulse wave having a power value greater than the first pulse wave; And an Nth pulsed wave applying step of applying an Nth pulsed wave having a power value greater than that of the N-1th pulsed wave. Until the pulse wave application step, a plurality of multiple pulse wave sets consisting of N pulse waves can be repeatedly applied.

In addition, in the rider signal processing method, in the first pulse wave application step, the first pulse wave is formed of a plurality of pulse wave sets having the same power value, and the Nth pulse is applied in the N-1 pulse wave application step. The -1 pulse wave may be formed of a plurality of pulse wave sets having the same power value, and in the Nth pulse wave application step, the Nth pulse wave may be formed of a plurality of pulse wave sets having the same power value.

Further, in the step of limiting the power value, if the corresponding power value is selected in the power value selection step while applying from the first pulse wave to the Nth pulse wave in the multiple pulse wave application step, the corresponding power value The power value of the pulse wave may be limited until the N pulse waves are applied with the same power value as.

In addition, the rider signal processing method, after the power value limiting step, if a reflected wave is not detected in the photodiode for a certain period of time, a power value for recovering the power value of the pulsed waves in the multiple pulse wave application step Recovery step; may further include.

In addition, the rider signal processing method, after the multiple pulse wave application step, the ToF comparison step of comparing the pulse waves detected by detecting the pulse waves applied in the multiple pulse wave application step in the photodiode; further It can contain.

According to the present invention, it is possible to reduce the deterioration of rider characteristics by reducing the performance of the laser diode by thermally controlling the pulse size of the laser diode, and to reduce the load of the driving semiconductor of the laser diode. Measurement distance can be improved.

Thus, it solves the problem of heat generation of the laser diode, has an effect of improving the maximum measurement distance through efficient use, and can have an effect of reducing the physical size of the lidar device manufactured to produce a high output.

1 is a block diagram showing the structure of a lidar signal processing apparatus according to an embodiment of the present invention.
2 is a flowchart illustrating a method for processing a lidar signal according to an embodiment of the present invention.
3 is a flowchart illustrating a method for processing a lidar signal according to another embodiment of the present invention.
4 is an operation flowchart showing a lidar signal processing according to an embodiment of the present invention.
5 is a graph showing the power value of a pulse wave according to an object of a lidar signal processing apparatus according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and the following embodiments make the disclosure of the present invention complete, and the scope of the invention to those skilled in the art It is provided to inform you completely. In addition, for convenience of description, in the drawings, the size of components may be exaggerated or reduced.

However, the following embodiments are provided to those of ordinary skill in the art to fully understand the present invention and may be modified in various other forms, and the scope of the present invention is limited to the embodiments described below. It does not work.

1 is a configuration diagram showing the structure of a lidar signal processing apparatus 100 according to an embodiment of the present invention, and FIG. 5 is a graph showing the power value of a pulse wave according to an object of the lidar signal processing apparatus.

First, as shown in FIG. 1, the lidar signal processing apparatus 100 according to an embodiment of the present invention includes a multi-pulse wave application unit 10, a power value selection unit 20, and a power value limiting unit ( 30).

As shown in FIG. 1, the multi-pulse wave applying unit 10 may apply pulse waves having various power values so that laser lights of various sizes can be generated in the laser diode LD.

The multiple pulse wave applying unit 10 may repeatedly apply a plurality of multiple pulse wave sets including N pulse waves from a low power value pulse wave to a gradually high power pulse wave.

More specifically, for example, the multi-pulse wave applying unit 10 includes a second pulse wave and a third pulse wave, which are pulse waves with a gradually higher power value, from the first pulse, which is the lowest power pulse pulse, and the reflected wave signal It may include a fourth pulse wave, a fifth pulse wave, a sixth pulse wave, and a seventh pulse wave, which are pulse waves of the maximum power value set to detect.

The multi-pulse wave applying unit 10 may continuously apply the multi-pulse wave set consisting of one set of the first pulse wave to the seventh pulse wave repeatedly to sense the object T. .

In addition, all of the first to seventh pulsed waves emitted from the multiple pulsed wave applying unit 10 may each include pulsed waves having the same size or more power values.

The power value selection unit 20 may select a corresponding power value of the pulse wave applied at the time of detection when the reflected wave by any one of the laser lights is detected in the photodiode PD.

More specifically, for example, when the object T is present among the pulse waves emitted from the multi-pulse wave applying unit 10, the power value selecting unit 20 detects the reflected wave signal reflected on the object T The detected pulse wave can be selected as a corresponding power value.

The laser diode LD may be a semiconductor laser having two electrodes for laser operation. More specifically, the laser diode LD is composed of three layers, and the active layer GaAs may be formed in a form sandwiched by AlxGa1-xAs. The refractive index n1 of the GaAs and the refractive index n2 of AlxGa1-xAs may be designed to contain light generated in the active layer, and the generated light may be emitted from the side of the active layer. In addition, the thickness of the active layer can be made smaller than the wavelength of light that normally occurs, and it is different from excitation by light or electrons. have.

As described above, the pulse wave generated by the laser diode LD may be transmitted toward an object through an optical system. More specifically, the optical system may be formed of a combination of a reflective mirror, a lens, and a prism for transmitting light energy using reflection and refraction of light.

The photodiode PD may receive the reflected wave from which the laser light is reflected by the object and return, and convert the reflected wave into an electrical signal.

More specifically, a photodiode (PD) is a semiconductor that converts an optical signal into an electrical signal, and has a PN junction or PIN structure, and when sufficient photon energy strikes the diode, mobile electrons and positive charge holes are generated. When the electrons are active and absorb in the depletion region of the junction, these carriers can flow through the erected field of the depletion layer to generate photocurrent.

The power value limiting unit 30 may limit the pulse waves to be applied by the multiple pulse wave applying unit 10 to be less than or equal to the corresponding power value.

The power value limiting unit 30, while the multiple pulse wave applying unit 10 is applied from a low power value pulse wave to a gradually high power value pulse wave, the power value selecting unit 20 applies the corresponding power value. When selected, the power value of the pulse wave can be limited until the N pulse waves are applied with the same power value as the corresponding power value.

More specifically, for example, the power value limiter 30 may limit all pulse waves applied after the corresponding power value selected by the power value selector 20 to apply a power value of the same pulse wave. .

In addition, as shown in FIG. 1, the lidar signal processing apparatus 100 according to an embodiment of the present invention may further include a power value recovery unit 40 and a ToF comparison unit 50.

The power value recovery unit 40 may restore the power values of the pulse waves to the multi-pulse wave application unit 10 when a reflected wave is not detected in the photodiode PD for a certain period of time.

More specifically, for example, in the power value recovery unit 40, the power value of the corresponding power value and the pulse waves applied thereafter in the power value limiting unit 30 is reflected on the object T and reflected waves are generated. When it is detected, when the distance of the object T increases and the reflected wave is no longer detected, the power value of the pulse wave can be increased again to detect other objects.

The ToF comparator 50 may compare the pulse waves detected by detecting the pulse waves applied by the multiple pulse wave applying unit 10 by the photodiode PD.

ToF (Time Of Flight) means the flight time of a pulse wave, and can be calculated by a flight time distance measurement method. More specifically, the flight time distance measurement method may be a principle of measuring a distance by measuring a time difference between a reference time point at which a pulse wave is fired and a detection time point of a reflected wave reflected back from an object.

Such a flight time distance measurement method has an advantage of being able to measure a distance without distance ambiguity in a long area of several m to several hundred km, and is relatively simple to implement, such as the shipbuilding industry and the aviation industry. It is applied to the groundborne or airborne geodetic survey required for civil engineering, architecture, and urban development, as well as 3D shape measurement in the field of large manufacturing industry, especially satellite laser tracking system (SLR) ), Laser altimeter, and artificial satellites.

The ToF comparator 50 may calculate the distance by calculating the detected pulse waves when the pulse waves applied from the laser diode LD are reflected and detected, and compare the detected pulse waves to change the distance of the object T Can be calculated.

2 and 3 are flowcharts illustrating a method for processing a lidar signal according to various embodiments of the present invention.

2 and 3, according to an embodiment of the present invention, the lidar signal processing method includes a multi-pulse wave application step (S10), a power value selection step (S20), and a power value limiting step (S30). ), A power value recovery step (S40), and a ToF comparison step (S50).

The multiple pulse wave application step S10 may apply pulse waves having various power values so that laser lights of various sizes may be generated in the laser diode LD.

In the multi-pulse wave application step (S10), a first pulse wave application step (S11) of applying a reference first pulse wave and a N-1 pulse wave having a power value greater than the first pulse wave are applied. The N-1 pulse wave application step (S12) and the Nth pulse wave application step (S13) of applying the Nth pulse wave having a power value greater than the N-1 pulse wave may be included.

In the multi-pulse wave application step S10, a plurality of multi-pulse wave sets consisting of N pulse waves may be repeatedly applied from the first pulse wave application step S11 to the N-th pulse wave application step S13. .

In this case, the first pulse wave may be formed of a plurality of pulse wave sets having the same power value in the first pulse wave application step (S11), and the N-1 pulse wave is applied to the N-1 pulse wave step (S12). ) May be formed of a plurality of pulse wave sets having the same power value, and the Nth pulse wave may be formed of a plurality of pulse wave sets having the same power value in the Nth pulse wave application step (S13).

In the power value selection step (S20), when a reflected wave by any one of the laser lights is detected in the photodiode PD, a corresponding power value of the pulse wave applied upon detection may be selected.

In the power value limiting step S30, the pulse waves to be applied in the multi-pulse wave application step S10 may be limited to below the corresponding power value.

More specifically, the power value limiting step (S30), while applying from the first pulse wave to the Nth pulse wave in the multiple pulse wave application step (S10), the corresponding power value in the power value selection step (S20) When is selected, the power value of the pulse wave can be limited until the N pulse waves are applied with the same power value as the corresponding power value.

As shown in FIG. 3, in the power value recovery step (S40), if a reflected wave is not detected in the photodiode PD for a period of time after the power value limiting step (S30), a multi-pulse wave application step (S10) In the power value of the pulse waves can be recovered.

3, the ToF comparison step (S50) is detected by detecting the pulse waves applied in the multiple pulse wave application step (S10) after the multiple pulse wave application step (S10) in the photodiode (PD). Pulse waves can be compared.

4 is an operation flowchart showing a lidar signal processing according to an embodiment of the present invention.

As illustrated in FIG. 4, the first pulse wave may be applied, and a pulse wave having a power greater than that of the first pulse wave may be repeatedly applied to apply the pulse wave up to the Nth pulse wave.

When an effective reflection pulse, which is a reflection wave of a pulse wave applied from the first pulse wave to the Nth pulse wave, is received, the reflected wave may be analyzed to output a distance to the object T.

When the effective reflected pulse is received and the object T is sensed, a pulse wave having a power value lower than that of the received pulsed wave is applied by using the rider signal processing apparatus 100 as described above. The object T can be detected.

However, if the effective reflection pulse is not received, the next pulse wave may be repeatedly applied. If the object does not exist, the effective reflection pulse may not be continuously received.

5 is a graph showing the power value of a pulse wave according to an object of a lidar signal processing apparatus according to an embodiment of the present invention.

1 and 5, the second pulse wave and the third pulse wave, which are the pulse waves of the higher power value, are gradually applied from the first pulse, which is the lowest power pulse pulse, in the multiple pulse wave applying unit 10. In addition, the fourth pulse wave, the fifth pulse wave, the sixth pulse wave, and the seventh pulse wave, which are pulse waves of the maximum power value set to detect the reflected wave signal, may be applied.

As described above, after the first set is applied from the first pulse wave to the seventh pulse wave, pulse waves having a power value of the same pattern are repeated so that a plurality of pulse waves, such as a second set, a third set, and a fourth set This can be applied.

Further, each of the first pulse wave to the seventh pulse wave may be one output pulse, or may be a plurality of output pulses having the same size or more.

As shown in FIGS. 1 and 5, the object T approaches the lidar signal processing apparatus 100 and the fourth pulse wave of the third set among the pulse waves emitted from the multi-pulse wave application unit 10 If it is reflected and detected as a reflected wave signal, the fourth pulse wave, which is the power value applied when detected by the power value selector 20, may be selected as the corresponding power value.

The fifth pulse wave, the sixth pulse wave, and the seventh pulse wave applied after the fourth pulse wave, which is the corresponding power value selected by the power value selector 20, apply a power value of the same pulse wave as the fourth pulse wave. So the power value limiter 30 may be limited. Thus, the fifth pulse wave, the sixth pulse wave, and the seventh pulse wave may be applied to the object T with the same power value as the fourth pulse wave detected as the reflected wave.

Subsequently, if the object T is further approached to the lidar signal processing apparatus 100 and is reflected by the third pulse wave of the fourth set among the pulse waves emitted from the multi-pulse wave applying unit 10, it is detected as a reflected wave signal. , A third pulse wave, which is a power value applied upon detection by the power value selector 20, may be reselected as a corresponding power value. Thus, the fourth pulse wave, the fifth pulse wave, the sixth pulse wave, and the seventh pulse wave applied after the third pulse wave of the fourth set, which is the reselected corresponding power value, are the third pulse wave. The power value limiter 30 is limited to apply the same pulse wave power value, and the target object T may be applied with the same power value as the third pulse wave detected as the reflected wave.

Subsequently, the object T is further approached to the lidar signal processing apparatus 100 to be reflected by the second pulse wave of the fifth set of pulse waves emitted from the multi-pulse wave application unit 10 and detected as a reflected wave signal. If so, the second pulse wave, which is the power value applied upon detection by the power value selector 20, may be reselected as the corresponding power value. Thus, the fifth pulse wave, the fourth pulse wave, the fifth pulse wave, the sixth pulse wave, and the seventh pulse wave applied after the second pulse wave of the fifth set, the reselected corresponding power value, The power value limiter 30 is limited to apply the power value of the same pulse wave as that of the second pulse wave, so that it can be applied to the object T with the same power value as the second pulse wave detected as a reflected wave.

As described above, when the object T approaches the lidar signal processing apparatus 100 and the reflected wave is detected, the power value of the laser diode is minimized by limiting the power value to the detected reflected wave and the output below, and the laser diode Can minimize the fever.

Subsequently, although not shown, the third pulse wave, the fourth pulse wave, the fifth pulse wave, the sixth pulse wave, and the seventh pulse wave, which are the corresponding power values last limited by the power value limiter, are the object T ) When the reflected wave is detected and the distance of the object (T) is farther away and the reflected wave is no longer detected, the power value recovery unit (40) is able to detect the object (T) or another object again. Spa power values can be restored.

Accordingly, the pulse size of the laser diode can be controlled stepwise to prevent performance degradation due to heat of the laser diode, reduce the load of the driving semiconductor of the laser diode, improve the maximum measurement distance, and improve the laser diode. It solves the problem of heat generation, has the effect of improving the maximum measurement distance through efficient use, and can have the effect of reducing the physical size of the lidar device manufactured to produce a high output.

Although the present invention has been described with reference to the embodiments shown in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

10: multiple pulse wave application unit
20: power value selection unit
30: power value limiter
40: power value recovery unit
50: ToF comparison unit
LD: laser diode
PD: photo diode

Claims (11)

A multiple pulse wave applying unit for applying pulse waves having various power values so that laser lights of various sizes can be generated in the laser diode;
A power value selector configured to select a corresponding power value of the applied pulse wave when detecting a reflected wave by any one of the laser lights in the photodiode; And
A power value limiter configured to limit the pulse waves to be applied by the multi-pulse wave application unit to below the corresponding power value;
Including,
The multiple pulse wave applying unit,
A plurality of multiple pulse wave sets consisting of N pulse waves are repeatedly applied from a low power value pulse wave to a gradually high power value pulse wave,
It further includes a power value recovery unit for recovering the power value of the pulse waves to the multi-pulse wave application unit when a reflected wave is not detected in the photodiode for a certain period of time,
If the reflected wave by any one of the laser lights is not detected in the photodiode, the multi-pulse wave application unit repeatedly applies the multi-pulse wave set,
When the reflected wave by any one of the laser lights is detected in the photodiode, the powers of the pulses of the multi-pulse wave set to be applied by the multi-pulse wave application unit are equal to or less than the corresponding power value selected by the power value selection unit. Limited by the value limit,
When the photodiode detects a reflected wave having a distance closer to the target than the reflected wave applied to the target power of the pulse wave selected by the power value selector and reflected to the target object, the power value limiter selects the power value A lidar signal processing device for limiting to a power value of a pulse wave lower than a corresponding power value of the pulse wave selected by the unit. delete According to claim 1,
The power value limiting unit,
When the multi-pulse wave application unit applies a low power value pulse wave to a progressively high power value pulse wave, and when the corresponding power value is selected in the power value selection unit, the N has the same power value as the corresponding power value. A lidar signal processing device that limits the power value of a pulse wave until two pulse waves are applied. delete According to claim 1,
A ToF comparator that detects pulse waves applied by the multiple pulse wave applying unit and compares the detected pulse waves by the photodiode;
The lidar signal processing apparatus further comprising a. A multiple pulse wave application step of applying pulse waves having various power values so that laser lights of various sizes can be generated in the laser diode;
A power value selection step of selecting a corresponding power value of the applied pulse wave when detecting the reflected wave by any one of the laser lights in the photodiode; And
A power value limiting step of limiting the pulse waves to be applied in the multiple pulse wave application step to below the corresponding power value;
Including,
The multi-pulse wave application step,
A first pulse wave application step of applying a reference first pulse wave;
An N-1 pulse wave application step of applying a N-1 pulse wave having a power value greater than the first pulse wave; And
An N-th pulse wave application step of applying an N-th pulse wave having a power value greater than that of the N-1 pulse wave;
Including,
In the multi-pulse wave application step, a plurality of multi-pulse wave sets consisting of N pulse waves are repeatedly applied from the first pulse wave application step to the N-th pulse wave application step,
After the power value limiting step,
Further comprising, if a reflected wave is not detected in the photodiode for a certain period of time, a power value recovery step of restoring the power values of the pulse waves in the step of applying the multiple pulse waves;
If the reflected wave by any one of the laser lights is not detected in the photodiode, the multiple pulse wave set is repeatedly applied in the multiple pulse wave application step,
When the reflected wave by any one of the laser lights is detected in the photodiode, the power of the pulse waves of the multi-pulse wave set to be applied in the multi-pulse wave application step is equal to or less than the corresponding power value selected in the power value selection step. Limit in the value limit phase,
If the photodiode detects a reflected wave having a distance closer to the object than the reflected wave applied to the object with the corresponding power value of the pulse wave selected by the power value selector, in the power value limiting step, the power value selecting step A method for processing a lidar signal, limiting to a power value of a pulse wave lower than a corresponding power value of the pulse wave selected in. delete The method of claim 6,
In the first pulse wave application step, the first pulse wave is formed of a plurality of pulse wave sets having the same power value,
In the step of applying the N-1 pulse wave, the N-1 pulse wave is formed of a plurality of pulse wave sets having the same power value,
In the Nth pulse wave application step, the Nth pulse wave is formed of a plurality of pulse wave sets having the same power value. The method of claim 6,
The power value limiting step,
During the application from the first pulse wave to the Nth pulse wave in the multiple pulse wave application step, if the corresponding power value is selected in the power value selection step, the N pearls have the same power value as the corresponding power value. A lidar signal processing method for limiting the power value of a pulse wave until a spar is applied. delete The method of claim 6,
After the step of applying the multiple pulse wave,
A ToF comparison step of comparing the pulse waves detected by detecting the pulse waves applied in the multiple pulse wave application step in the photodiode;
Further comprising, a lidar signal processing method.

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