JP6244862B2 - Laser radar equipment - Google Patents

Description

  The present invention relates to a laser radar device that irradiates a space with laser light, receives scattered light from an object, and measures the wind speed from this received light and measures the distance or shape to the measurement target. .

  Conventionally, a coherent Doppler lidar technique is known as a technique for measuring a wind speed or a wind direction using a laser beam. Coherent Doppler lidar technology irradiates a single-frequency laser beam into the atmosphere, receives backscattered light from aerosols (particulate matter suspended in the atmosphere), detects this received light heterodyne, and transmits it. It calculates the Doppler shift amount of the received light with respect to the frequency of the laser beam and obtains wind information such as wind speed or direction from this Doppler shift amount, and detects turbulence for weather observation, weather forecast, aviation / aviation safety Application to such as can be expected.

  The laser radar device using this coherent Doppler lidar technology can measure wind information if the measurement target is an aerosol as described above, but if the measurement target is a solid moving object, the above-described wind information can be measured. The moving speed and moving direction of the moving body can be measured by the same measurement principle as the measurement.

  In addition, the laser radar device irradiates an object existing in space or the sea surface or land surface with laser light and receives reflected light, and calculates the required time from the irradiation of the laser light to reception of the object or sea surface. It is also possible to measure distance information such as the distance from the laser radar device or the shape of the measurement target.

  As described above, the laser radar device can measure wind information when a soft target such as an aerosol is a measurement target, and measures distance information in addition to the moving speed when a hard target such as a solid is a measurement target. can do.

  The laser radar device described in Patent Document 1 pulsates laser light output from a CW laser (continuous wave laser) light source with an acoustooptic device, modulates the frequency, and further optically amplifies the light to a desired level. The amplified laser beam is irradiated into the atmosphere, the wind speed is calculated using the above-mentioned coherent Doppler lidar technology, and the moving speed and distance of the hard target are measured using a solid target such as a solid as a measurement target. ing.

JP 2010-127840 A

  In the laser radar device as described above, even in a situation where measurement objects are mixed, that is, in a situation where measurement of wind information and measurement of distance information regarding a hard target are performed, the wind information and the distance information are simultaneously used by the same device. In addition, there was a demand for measurement with high accuracy.

On the other hand, the resolution of the speed related to the measurement accuracy of the wind information and the resolution of the distance related to the measurement accuracy of the distance information are contradictory.
The speed resolution is determined by the frequency resolution at the time of FFT (Fast Fourier Transform), and this frequency resolution is proportional to the reciprocal of the observation time of the received signal. That is, if the observation time of the received signal becomes longer, the frequency resolution at the time of FFT becomes higher. However, the maximum value of the observation time of the received signal is the transmission pulse width of the transmission signal.
On the other hand, since the distance from the laser radar device to the measurement target is measured from the time difference between transmission and reception of the pulse laser, the distance resolution is determined by the transmission pulse width.
For this reason, if the transmission pulse width is short, the distance resolution is high. However, since the transmission pulse width is shortened, the observation time of the received signal is shortened, and the frequency resolution and the speed resolution at the time of FFT are low.

Thus, in order to solve the problem that the speed resolution and the distance resolution conflict, a method of mounting a coherent Doppler lidar device and a sensor for ranging and imaging on the laser radar device is conceivable.
However, the use of two types of devices increases the overall size of the applied laser radar device, complicates the structure and processing, and increases the addition of host devices and host systems to which the laser radar device is connected. There is.

  The present invention solves the above-described problems, and has a simpler structure for measuring wind information such as wind speed or direction and measuring distance information such as the distance to the measurement object or the shape of the measurement object. An object of the present invention is to provide a laser radar device that can be realized with high accuracy.

  The laser radar device according to the present invention generates a reception signal from an optical transmission unit that generates a pulse laser, an optical antenna unit that outputs the pulse laser as transmission light, receives the light, and received light received by the optical antenna unit And a wind measurement unit that calculates wind information from a Doppler shift frequency obtained based on a frequency peak obtained by performing analog-to-digital conversion of the received signal and fast Fourier transform of the converted digital signal and the frequency of the transmitted light And a distance measuring unit that calculates distance information of a measurement target based on a flight time from transmission to reception of received light corresponding to the received signal.

  According to the present invention, the reception signal is input to each of the wind measurement unit and the distance measurement unit, and the wind information or the distance information is calculated independently based on the reception signal in each of the wind measurement unit and the distance measurement unit. Wind information and distance information can be measured with a simple configuration.

1 is a configuration diagram of a laser radar device in Embodiment 1. FIG. In Embodiment 1, it is a figure for demonstrating the FFT process in an FFT process part. In Embodiment 1, it is a figure for demonstrating calculation of the Doppler frequency component in a wind information calculating part. FIG. 6 is a configuration diagram of a laser radar device in a second embodiment. In Embodiment 2, it is a flowchart which is a case where the characteristic information of a measuring object is known beforehand, Comprising: The process which changes the precision of distance measurement is shown. In Embodiment 2, it is a flowchart which is a case where the characteristic information of a measuring object is unknown, Comprising: The process which changes the precision of distance measurement is shown. FIG. 10 is a configuration diagram of a received signal distinction unit in a third embodiment. In Embodiment 3, it is a flowchart which shows the process which performs a wind measurement only about the periphery of a hard target. In Embodiment 3, it is a figure explaining the analog signal process in the case of performing a wind measurement only about the periphery of a hard target. FIG. 6 is a configuration diagram of a laser radar device in a fourth embodiment.

Embodiment 1 FIG.
Hereinafter, preferred embodiments of the laser radar device according to the present invention will be described.
[Configuration of Laser Radar Device 1]
FIG. 1 is a configuration diagram of a laser radar device 1 according to Embodiment 1 of the present invention.
The laser radar device 1 includes an optical transmitter 10 that generates and outputs a pulse laser, an optical transmitter 10, an optical circulator 20 that is disposed between an optical antenna unit 30 described later, and an optical receiver 40 described later, An optical antenna unit 30 that outputs the pulse laser received from the transmission unit 10 to the outside as transmission light and receives the light, an optical reception unit 40 that generates a reception signal from the reception light received by the optical antenna unit 30, and an optical reception unit 40 The wind measurement unit 50 that calculates wind information such as wind speed or direction using the received signal generated by the receiver, and the distance information such as the distance to the measurement target and the shape of the measurement target using the received signal generated by the light receiving unit 40. A distance measuring unit 60 to calculate, and a control unit 70 for controlling the operation of each component constituting the laser radar device 1 such as the optical transmission unit 10 and the optical antenna unit 30 and communicating with an external device. .
Examples of the external device that communicates with the control unit 70 include the host device 80 shown in FIG. 1 and a user terminal (not shown). The control unit 70 and the host device 80 may be configured to connect both directly or via a network.

The optical transmitter 10 generates and outputs a pulse laser having a desired pulse width and desired output. The light source 11 oscillates and outputs a single frequency laser beam as a continuous wave, and the laser beam from the light source 11. Is shifted by a predetermined frequency, and a pulse modulation unit (pulse modulator) 12 that modulates laser light in a pulse shape, and a pulse laser modulated and output by the pulse modulation unit 12 is amplified to a desired output level. An optical amplifying unit (optical amplifier) 13 and an optical splitter 14 that divides the laser light output from the light source 11 into two parts and outputs the branched light to the pulse modulating unit 12 and the optical receiving unit 40 are provided.
Note that in the optical transmitter 10, like the above-described pulse modulator 12, one device has a function of shifting the optical frequency of the laser light by a predetermined frequency and a function of modulating the laser light in pulses. A configuration may be used, or a configuration in which each function is realized by each device.

  The optical circulator 20 gives different polarization characteristics to the pulse laser as the transmission light output from the optical transmission unit 10 and the reception light output from the optical antenna unit 30, and separates the path between the transmission light and the reception light. It is what has. By this optical circulator 20, the pulse laser output from the optical transmission unit 10 is input to the optical antenna unit 30, and the received light received by the optical antenna unit 30 is input to the optical reception unit 40.

The optical antenna unit 30 includes a transmission / reception optical system 31 that adjusts a desired beam divergence angle, a beam diameter, and a scanning direction of transmission light, and adjusts a reception field of view, and a scanner 32 that scans transmission light and reflected light.
In FIG. 1, an arrow directed from the transmission / reception optical system 31 to the outside via the scanner 32 indicates transmission light, is indicated by a broken line, and an arrow from the outside toward the scanner 32 indicates reception light. In FIG. 1, for the sake of convenience, the received light is shown only from the outside toward the scanner 32, but actually the light is directed from the scanner 32 toward the transmission / reception optical system 31.

  The optical receiver 40 operates as an optical coupler 41 that combines the laser light from the light source 11 and the received light from the optical antenna unit 30 and a gate function, and converts the received light from the optical coupler 41 into an electrical signal. In addition, a light receiving processing unit 42 for further multiplying and outputting is provided.

The wind measurement unit 50 includes an AD (analog-digital) conversion unit 51 that converts an analog electrical signal input from the light reception unit 40, particularly the light reception processing unit 42, into a digital signal.
The digital signal group converted by the AD conversion unit 51 is divided into fixed intervals on the time series, that is, predetermined range bins, and FFT (Fast Fourier Transform) processing is performed to decompose the digital signal group into frequency components for each range bin. And a wind information calculation unit 53 that calculates a Doppler frequency from frequency data obtained for each range bin and calculates a wind speed, and calculates a wind direction based on the calculated wind speed and the scanning direction of the antenna unit 30.

  The distance measurement unit 60 calculates the time of flight required for the transmitted pulse laser to reach the measurement target and return to the optical antenna unit 30 from the timing at which the pulse laser is transmitted and the light is received. TOF (Time Of Flight) ) The distance from the laser radar device 1 to the measurement target is calculated from the flight time calculated by the measurement unit 61 and the TOF measurement unit 61, and the measurement target is calculated from the calculated distance information and the scanning direction information of the optical antenna unit 30. The distance information calculation unit 62 for calculating the three-dimensional coordinate information is provided.

The control unit 70 communicates with the host device 80, adjusts the control parameters of each component of the laser radar device 1 such as the optical transmission unit 10 and the optical antenna unit 30, and the data related to each component or the laser radar device 1 The calculated measurement information is output to the host device 80.
In FIG. 1, a solid line connecting each component indicates information related to transmission / reception light and reception signals actually used in calculation of wind information and distance information, or calculated measurement information. The control unit 70 and each component A broken line connecting the two points indicates information related to the control of each component exchanged between the two, and a one-dot chain line connecting the control unit 70 and the host device 80 indicates the measurement information calculated by the radar laser device 1 and the information of the laser radar device 1. Indicates information about control.

Next, the operation of the laser radar device 1 will be described.
[Operation when sending]
When the light source 11 outputs laser light, the laser light is branched into two by the optical splitter 14, one being input to the pulse modulator 12 and the other being input to the optical coupler 41.
The pulse modulation unit 12 shifts the optical frequency f ₀ of the input laser light by a predetermined frequency to the frequency f ₁ and modulates the laser light in a pulse shape in synchronization with the pulse trigger input from the control unit 70. .
The optical amplifying unit 13 optically amplifies and outputs the pulse-modulated laser light to a laser output level set by the control unit 70.

The pulse laser output from the optical amplification unit 13 is input to the optical antenna unit 30 via the optical circulator 20.
In the optical antenna unit 30, the input pulse laser is adjusted to a desired beam diameter and beam divergence angle by the transmission / reception optical system 31, and laser scanning is performed by the scanner 32.
Further, the control unit 70 captures the transmission timing of the pulse laser from the optical antenna unit 30.

[Reception behavior]
The laser light output to the outside from the optical antenna unit 30 is reflected by a particulate matter such as aerosol or a hard target drifting in the external space. The reflected light is received by the scanner 32 and input to the transmission / reception optical system 31 as received light.
Note that the reception visual field adjustment of the transmission / reception optical system 31 and the drive control of the scanner 32 are performed based on the control signal received from the control unit 70 as in the case of pulse laser transmission.

The received light input to the transmission / reception optical system 31 is input to the optical coupler 41 via the optical circulator 20.
The optical coupler 41 combines the laser light from the light source 11 branched by the optical splitter 14 and the received light transmitted from the optical circulator 20, and converts the high frequency into a low frequency, that is, receives the light after down-conversion processing. The data is output to the processing unit 42.

When the light reception processing unit 42 receives a signal indicating that the gate should be opened, that is, a gate opening signal from the control unit 70, the light reception processing unit 42 opens the gate between the optical coupler 41 and the light reception processing unit 42 and receives from the optical coupler 41. Get light.
The control unit 70 acquires the transmission timing of the pulse laser from the optical antenna unit 30, and sends a gate opening signal to the light receiving processing unit 42 at a timing when a predetermined delay time is given to the transmission timing of the pulse laser. Send.
As a result, the light receiving processing unit 42 captures the received light with a predetermined time delay from the transmission timing of the pulse laser. However, as described above, the control unit 70 performs the delay operation for opening the gate by the pulse laser. The gate opening signal may be transmitted after a predetermined delay time elapses from the transmission timing, or the control unit 70 transmits a gate opening signal to which the delay time information is added to the light reception processing unit 42, and the light reception processing unit 42. Alternatively, after receiving the gate opening signal, the gate may be opened after waiting for the delay time added to the command signal.

Next, the light reception processing unit 42 converts the received light taken from the optical coupler 41 into an electrical signal with a desired multiplication factor. The multiplication degree is adjusted by the control unit 70.
This photoelectrically converted received signal is branched into two and input to the wind measuring unit 50 and the distance measuring unit 60. The wind measuring unit 50 calculates wind information, and the distance measuring unit 60 calculates the distance to the measurement target. Used to calculate distance information such as shape.

[Wind Information Calculation Processing by Wind Measuring Unit 50]
Next, the calculation process of the wind information by the wind measurement part 50 is demonstrated.
As described above, the reception signal from the light reception processing unit 42 is input to the wind measurement unit 50.
When the control unit 70 transmits a signal indicating that AD conversion should be started, that is, an AD conversion start signal to the AD conversion unit 51 at a timing given a predetermined delay time with respect to the transmission timing of the pulse laser, the AD conversion unit 51 Starts AD conversion of the received signal based on the AD conversion start signal received from the control unit 70, and outputs the converted digital received signal to the FFT processing unit 52.
The AD conversion unit 51 ends AD conversion after a predetermined time has elapsed from the start of AD conversion, and waits for the next AD conversion start signal to be input from the control unit 70.

FIG. 2 is a diagram for explaining the FFT processing in the FFT processing unit 52.
The FFT processing unit 52 first divides the received data group input from the AD conversion unit 51 for each predetermined range bin.
FIG. 2A shows the signal strength I (Intensity) of the analog reception signal input from the AD conversion unit 51 in time series, and shows how the reception signal is divided into predetermined range bins. Show.

In the received signal, the reflected light from the hard target and the reflected light from the soft target are mixed.
Since soft targets such as aerosols are widely present in the atmosphere, reflected waves from the soft target are included over the entire received signal, as shown in a region S surrounded by a dashed-dotted line in FIG. Some degree of signal strength always appears.
On the other hand, when a hard target is present on the pulse laser transmission path, the reception intensity of the reflected wave from the hard target is higher than the reception intensity of the soft target. In FIG. 2A, the signal intensity I in a region H surrounded by a two-dot chain square indicates a reflected wave from the hard target.
As shown in FIG. 2A, when the FFT processing unit 52 divides the received data for each predetermined range bin, depending on the range bin, only the received signal related to the reflected wave from the soft target may be included, or from the hard target and the soft target. In other words, the received signal concerning both reflected waves is included.

Next, the FFT processing unit 52 performs FFT for each divided range bin.
FIG. 2B shows a frequency spectrum in a certain range bin, and shows the intensity for each frequency by performing FFT processing on the received signal in the range bin.
FFT processing unit 52, for each divided range bin to determine the peak frequency f _r of the frequency spectrum and spectrum as in FIG. 2 (b).

The wind information calculation unit 53 performs signal processing in consideration of the influence of background light and system noise on the data subjected to the FFT processing by the FFT processing unit 52 to extract the maximum intensity frequency component _fr , and the Doppler frequency component _fd is calculated.
FIG. 3 is a diagram for explaining calculation of the Doppler frequency component f _d in the wind information calculation unit 53. FIG. 3A shows the frequency (f ₁ − when the reflected light is not subjected to Doppler shift. f ₀ ) and the intensity thereof, and FIG. 3B shows the frequency component (f ₁ −f ₀ ) + f _d and the intensity of the maximum intensity when the reflected light undergoes Doppler shift. It is a thing.

If the frequency not subjected to Doppler shift (f ₁ −f ₀ ) is known, the frequency component (f ₁ −f ₀ ) ± f _{d of} the maximum intensity obtained by FFT processing and the frequency not subjected to Doppler shift ( By calculating the difference from f ₁ −f ₀ ) , the Doppler frequency component f _d can be obtained.

Further, the Doppler frequency component _fd and the wind speed V have the relationship of Expression (1), and the wind information calculation unit 53 calculates the wind speed V based on Expression (1).
In equation (1), c represents the speed of light, and f ₀ represents the case where no Doppler shift is applied, that is, the original frequency.

  Moreover, the wind information calculating part 53 calculates a wind direction using the wind speed data calculated as mentioned above with respect to the transmission direction of each pulse laser. An example of a wind direction calculation method is a VAD (Velocity Azimuth Display) method.

[Distance Information Calculation Processing by Distance Measuring Unit 60]
Next, a calculation process of distance information such as the distance from the laser radar device 1 to the measurement target and the shape of the measurement target by the distance measurement unit 60 will be described.
When the control unit 70 transmits a signal indicating that the time measurement should be started, that is, a time measurement start signal to the TOF measurement unit 61 at a timing when a predetermined delay time is given to the transmission timing of the pulse laser, the TOF measurement unit 61 is transmitted. Starts time measurement, starts detection of a received signal having an intensity equal to or greater than a predetermined threshold, measures flight time for the detected received signal, and obtains information on the obtained flight time as distance information calculation unit 62. Output to.

As a method for realizing the measurement of the flight time of the received signal by the TOF measurement unit 61, there are a method using a TAC (Time to Analog Converter) circuit, a method using a TDC (Time to Digital Converter) circuit, and the like.
The TAC circuit detects the input of the time measurement start signal using the rise or fall of the time measurement start signal, or both the rise and fall, charges the internal capacitor from this detection timing, and exceeds the threshold value The input of the received signal is detected using the rising or falling edge of the received signal having strength, or both the rising and falling edges, charging is stopped at this detection timing, and time information is obtained from the charging voltage value at that time. It is to convert.
In addition, the TDC circuit passes the time measurement start signal through the gate array, and until the timing at which the input of the received signal is detected using the rising or falling edge of the received signal having the intensity equal to or higher than the threshold, or both the rising and falling edges. Time information is obtained from the number of gates through which the time measurement start signal passes.

The distance information calculation unit 62 calculates the distance information R from the laser radar device 1 to the measurement target using Expression (2) based on the time information t regarding the flight time input from the TOF measurement unit 61.
In equation (2), c represents the speed of light, and n represents the refractive index of the medium from the laser radar device 1 to the measurement target.

Further, the distance information calculation unit 62 can also obtain the shape of the measurement target based on the information regarding the flying direction of the reflected light received by the optical antenna unit 30 and the distance information calculated by the equation (2).
For example, as information on the reflected light flying direction, two-dimensional coordinates regarding the scanning direction of the scanner 32 when the reflected light is received, and information on the distance calculated by the equation (2) when the reflected light is received, By collecting each time the reflected light is received, three-dimensional information on the measurement target can be obtained, and information on the shape of the measurement target can also be obtained.

[Processing of wind information and distance information]
The wind information calculated by the wind measurement unit 50 and the distance information calculated by the distance measurement unit 60 or the distance information related to the shape of the measurement target are output to the control unit 70, and the control unit 70 transmits these measurement information to the host device 80. . By displaying this measurement information on the display unit connected to the host device 80, the monitor can check the status of the measurement target.

As described above, in the laser radar device 1 according to the first embodiment, the reception signal output from the light reception processing unit 42 of the light reception unit 40 is branched into two and input to both the wind measurement unit 50 and the distance measurement unit 60. Then, each of the wind measurement unit 50 and the distance measurement unit 60 independently calculates wind information or distance information using the received reception signal.
As a result, the distance between the range bins can be set separately in the FFT calculation processing required when performing wind measurement and the TOF measurement processing required when measuring distance information. It is possible to achieve both wind measurement and distance measurement without affecting the accuracy of information measurement.

As an application example of the laser radar device 1 according to the first embodiment, there is an aircraft that takes off and landing on the sea. In such an aircraft, it is necessary to determine whether the wind conditions near the sea surface and the ocean waves are safe for takeoff and landing.
In the conventional laser radar device, as described above, when the accuracy of the distance resolution is increased, the resolution of the velocity is lowered, and the measurement accuracy of the wind information such as the wind direction and the wind speed is lowered. However, if the laser radar device 1 according to the first embodiment is used, measurement processing of wind information such as wind speed and direction near the sea surface and measurement processing of the wave height shape of the sea surface (for example, resolution of several centimeters to several meters level). Since both are independent of each other, it is possible to secure both the measurement accuracy of wind information and the measurement accuracy of distance information, and abundant judgment materials for taking off and landing of aircraft can be obtained.

Embodiment 2. FIG.
In the first embodiment, the reception signal photoelectrically converted by the light reception processing unit 42 is input to the wind measurement unit 50 and the distance measurement unit 60. However, in the second embodiment, only a specific reception signal is measured by wind measurement. A case will be described in which the information is input to the unit 50 and the distance measuring unit 60, or the accuracy of the distance information is adjusted.
Note that the description of the same configuration and processing as those of the laser radar device 1 in the first embodiment will be omitted, and the configuration and processing different from those in the first embodiment will be described below.

FIG. 4 is a configuration diagram of the laser radar device 1 according to the second embodiment of the present invention, in which a received signal distinction unit 43 is added to the optical receiver 40 of the laser radar device 1 according to the first embodiment.
In the optical receiving unit 40 of FIG. 4, the received signal photoelectrically converted by the light receiving processing unit 42 is input to the received signal discriminating unit 43, and the received signal discriminating unit 43 uses the received signal selection parameter set by the control unit 70. Based on the input received signal, only a specific received signal is selected and output.
In addition, when a specific received signal is detected, the received signal distinguishing unit 43 outputs a signal indicating that the received signal has been detected, that is, a detection signal to the control unit 70.
Further, the reception signal distinction unit 43 switches the output destination of the reception signal based on a command from the control unit 70, for example, outputs the reception signal to the wind measurement unit 50 and the distance measurement unit 60, or measures the wind measurement unit 50 or the distance measurement. Switching between output to one of the units 60 is performed.

  The parameter for receiving signal selection is set differently depending on whether or not the information on the hard target to be measured is known. In the second embodiment, the information on the measurement target is known and the host device 80 performs the measurement. A case where target information is set in the control unit 70 and a case where measurement target information is unknown will be described.

[When hard target information is known]
First, the case where the information to be measured is known will be described with reference to FIGS. 4 and 5.
FIG. 5 is a flowchart showing a process for changing the accuracy of distance measurement in a case where the characteristic information of the measurement target is known in advance.

  The host device 80 sets prior information for measurement in the control unit 70 (S101). The prior information is information on the operating environment such as the rough distance from the laser radar device 1 or the light characteristics such as reflectance and light diffusivity of the hard target to be measured, or weather conditions and the altitude of the laser radar device 1. is there.

The control unit 70 sets received signal selection parameters for selecting received signals based on prior information set from the host device 80 and control parameters for system control of the laser radar device 1 stored in advance. Calculate and set in the received signal distinction unit 43 (S102).
The reception signal distinction unit 43 processes the reception signal from the light reception processing unit 42 based on the set reception signal selection parameter. Here, the received signal selection parameter is a lower limit threshold regarding the voltage value of the received signal from the light receiving processing unit 42. In this case, when the voltage value of the received signal from the light receiving processing unit 42 is smaller than the threshold value, the received signal discriminating unit 43 does not consider that the desired received signal is received, and the received signal voltage value is equal to or higher than the threshold value. In this case, it is determined that a desired signal has been received. Thereby, the reception signal of a noise level can be excluded from the reception signal group, the accuracy of each information in the wind measurement part 50 and the distance measurement part 60 after this can be improved, and calculation load can be suppressed.

  Next, the laser radar apparatus 1 starts measurement (S103). The operations at the time of pulse laser transmission and the photoelectric conversion processing of the light receiving processing unit 42 at the time of reception of reflected light are the same as in the first embodiment.

Received signal distinction circuit 43, the received signal from the light receiving unit 42 is input, the voltage value of the received signal, compared to the set lower threshold as a parameter for the received signal sorting (S104), the received signal Is equal to or greater than the threshold value (Y in S104), it is determined that a desired received signal has been detected, and a detection signal is transmitted to the control unit 70 to notify that the received signal has been detected ( S105).
Further, the control unit 70 that has received the detection signal from the received signal distinction unit 43 considers that the measurement target has been detected, and causes the host device 80 to measure the distance information such as the detection of the measurement target and the distance or shape. Queries whether accuracy needs to be improved.

  If there are a plurality of received signals that the received signal discriminating circuit 43 determines to be equal to or greater than the threshold value in step S104, the last received signal that is the latest data in the detected received signal group is regarded as a signal from the hard target. Note that the first received signal in the received signal group may be a signal from the hard target.

  In step S104, if the reception signal distinction circuit 43 does not detect a reception signal having a voltage value equal to or higher than the threshold value even after a predetermined time has elapsed (N in S104), the detection signal from the reception signal distinction circuit 43 is received. The control unit 70 that does not transmits a warning message indicating that the measurement target is not detected or that prior information or the like should be reset to the higher-level device 80 (S106).

  When the host device 80 that has received the warning message resets the prior information in the control unit 70 (S101), the control unit 70 resets the received signal selection parameter in the received signal distinction circuit 43 (S102), and the laser. The radar apparatus 1 restarts the measurement (S103), and the received signal distinction circuit 43 performs a received signal discrimination process with the newly set parameters (S104).

Here, although the reception signal selection parameter is the lower threshold value of the voltage value of the reception signal, the reception signal selection parameter is the upper limit threshold value of the reception signal voltage. When the voltage value of the received signal from the light receiving processing unit 42 is equal to or lower than the upper limit value, it may be determined that the desired signal is received. In this case, reception signals reflected from other objects closer to the radar laser device 1 than the measurement target are excluded, and the subsequent wind measurement unit 50 and distance measurement are not affected without being affected by the measurement target outside. While improving the accuracy of each information in the part 60, calculation load can be suppressed.
The received signal selection parameter is not a single value such as the upper limit value or the lower limit value of the voltage value described above, but indicates the range of the voltage value of the received signal. When the voltage value of the received signal from the processing unit 42 is included within a predetermined range, it may be configured to determine that a desired signal has been received. In this case, as described above, the lower limit value can be provided to eliminate noise, and the upper limit value can be provided to eliminate the influence from an object near the radar laser apparatus 1 outside the measurement target.

  The process returns to the case where the received signal distinction circuit 43 in S105 notifies the control unit 70 that the received signal has been detected. When the control unit 70 inquires the host device 80 whether or not the accuracy of the distance information measurement needs to be improved, the host device 80 determines that the accuracy of the distance information measurement needs to be improved (Y in S107). Then, information regarding the measurement accuracy of the distance information is set to the control unit 70 (S108).

  The control unit 70 calculates parameters of the transmission laser such as the pulse width and pulse peak value of the transmission laser in the optical transmission unit 10 based on the new accuracy regarding the measurement of the distance information (S109).

Further, the control unit 70 determines whether or not the laser parameter newly calculated in S109 secures a lower limit value of the accuracy of wind information calculation by the wind measurement unit 50 (S110).
When the new laser parameter secures the lower limit of the accuracy of wind information calculation (Y in S110), the control unit 70 sets the new laser parameter in the optical transmission unit 10 (S111), and the optical transmission unit 10 outputs a laser pulse with the set new laser parameter, and the laser radar apparatus 1 performs measurement (S112).

  When the new laser parameter does not secure the lower limit value of the wind information calculation accuracy (N in S110), the control unit 70 instructs the higher-level device 80 that the new laser parameter is the lower limit value of the wind information calculation accuracy. Inquiries are made as to whether or not to perform measurement with new laser parameters, in other words, whether or not to give priority to the accuracy of the distance information measurement even if the accuracy of the wind information measurement is lowered (S113).

  When the response from the host device 80 gives priority to the measurement of the distance information over the measurement of the wind information (Y in S114), the control unit 70 sets this new laser parameter in the optical transmission unit 10 ( S112). Further, in order to perform only distance information measurement, the control unit 70 causes the reception signal distinguishing unit 43 to output the reception signal from the light reception processing unit 42 only to the TOF calculation unit 61 of the distance measurement unit 60, and The operations of the AD conversion unit 51 and the FFT processing unit 52 in the measurement unit 50 are stopped, and the calculation results of the wind information calculation unit 53 so far are presented to the host device 80. In this way, calculation of wind information with low accuracy by the wind measurement unit 50 is not performed, and only the distance information is measured, and the calculation load of the entire laser radar device 1 can be suppressed.

  Even if the response from the host device 80 gives priority to the measurement of distance information over the measurement of wind information (Y in S114), the received signal distinction unit 43 performs the light receiving process as in the first embodiment. The reception signal from the unit 42 is output to both the AD conversion unit 51 of the wind measurement unit 50 and the TOF calculation unit 61 of the distance measurement unit 60, and the wind information calculation result of the wind measurement unit 50 is used as reference information. You may output to the high-order apparatus 80. FIG.

  If the response from the host device 80 does not give priority to the measurement of distance information (N in S114), the control unit 70 recalculates the laser parameter that secures the lower limit value of the wind information calculation accuracy and transmits the light. The unit 10 is set (S115), and measurement is performed (S112).

  The control unit 70 does not detect the received signal, for example, for a predetermined time or longer until a predetermined time elapses from the start of measurement (S103), until an end instruction is received from the host device 80, or until no received signal is detected. Until the measurement is continued, the measurement with the accuracy of distance / shape measurement being changed is continued (N in S116). If the measurement does not need to be continued or the above-mentioned continuation conditions are not satisfied (Y in S116) ) And finish the measurement.

[When hard target information is unknown]
Next, the case where the measurement target information is unknown will be described with reference to FIGS. 4 and 6. In this case, when the measurement is started, the host device 80 provisionally sets a threshold value and the like for the received signal distinction circuit 43 to detect the received signal.
FIG. 6 is a flowchart showing a process for changing the accuracy of distance measurement when the characteristic information of the measurement target is unknown.

In FIG. 5, if the host device 80 sets the prior information related to the hard target in the control unit 70 (S101 in FIG. 5), the control unit 70 calculates a reception signal selection parameter (threshold), and receives the received signal. This is set in the distinction section 43 (S102 in FIG. 5).
In FIG. 6, since the prior information regarding the hard target is unknown, the host device 80 tentatively determines a received signal selection parameter and sets it in the received signal discriminating unit 43 via the control unit 70 (S201). ).

  Next, the laser radar device 1 starts measurement (S202). The operations at the time of pulse laser transmission and the photoelectric conversion processing of the light receiving processing unit 42 at the time of reception of reflected light are the same as in the first embodiment.

  When a received signal subjected to photoelectric conversion is input, the received signal distinction circuit 43 compares the voltage value of the received signal with a threshold value temporarily set as a received signal selection parameter (S203). If the voltage value is equal to or greater than the threshold value (Y in S203), it is determined that a desired received signal has been detected, and a detection signal is transmitted to the control unit 70 to notify that the received signal has been detected ( S204).

In step S203, when the reception signal distinction circuit 43 does not detect a reception signal having a voltage value equal to or higher than the threshold value even after a predetermined time has elapsed (N in S203), the detection signal from the reception signal distinction circuit 43 is received. The control unit 70 that does not transmit a warning message or warning signal indicating that the measurement target is not detected or that the parameter for receiving signal selection should be reset is transmitted to the host device 80 (S205).
If the host device 80 that has received the warning message resets the received signal selection parameter to the received signal distinction circuit 43 via the control unit 70 (S201), the laser radar device 1 restarts the measurement (S202) and receives the signal. The signal distinction circuit 43 performs reception signal discrimination processing with the newly set parameters (S203).

The control unit 70 counts the number of receptions of the detection signal (S204) from the reception signal distinction circuit 43, and determines whether or not the number of receptions within a predetermined time is smaller than a preset reference number of receptions. Determination is made (S206).
If the number of receptions within the predetermined time is greater than the threshold (N in S206), the threshold for comparison with the voltage value of the received signal is too low in step S203, and the received signal selection parameter is reset. A warning message indicating that it should be sent is notified to the host device 80 (S205).

If the number of receptions of the received signal detection signal within the predetermined time is smaller than the threshold value (Y in S206), the process proceeds with the currently set threshold value.
The subsequent process for improving the measurement accuracy of the distance information is the same as S107 to S116 in FIG.

  As described above, the laser radar device 1 according to the second embodiment includes the reception signal distinction unit 43 as a detection circuit for a desired reception signal, and the reception signal distinction unit 43 and the control unit 70 detect the reception signal according to the detection status of the reception signal. Since the host apparatus 80 is urged to reset the reception signal selection parameter (threshold value), it is possible to extract only an appropriate reception signal for a distance information calculation process for a desired measurement target.

Further, when the measurement target information is known, the control unit 70 automatically calculates a threshold value for detection of the received signal based on the input measurement target information and sets it to 43 in the received signal discrimination unit. Therefore, the measurement target can be appropriately detected by inputting the measurement target information.
Even if the information to be measured is unknown, if the host device 80 provisionally sets the reception signal selection parameter in the control unit 70, the control unit 70 receives the reception status of the received signal, for example, the received signal. Since the host apparatus 80 is urged to reset the threshold value based on the detection frequency of the signal, the reception accuracy of the signal from the measurement target can be improved.

Furthermore, when changing the parameters of the transmission laser to improve the measurement accuracy of distance information, after calculating what the measurement accuracy of wind information will be, we will inquire whether to increase the accuracy of distance information calculation, Since parameter setting for distance information calculation and measurement processing of distance information, etc. proceed according to the answer to the inquiry, it is possible to improve the distance information calculation accuracy while ensuring the wind information calculation accuracy.
In addition, since the distance information calculation process proceeds according to the response from the higher-level device 80 as to whether or not the accuracy of calculating the distance information is increased or whether the calculation accuracy of the wind information is ensured, the operation of the higher-level device 80 A flexible measuring device can be provided according to the situation.

Embodiment 3 FIG.
In the first embodiment, the wind signal calculation process and the distance information calculation process are separately performed by processing the received signal in each of the wind measurement unit 50 and the distance measurement unit 60. In Embodiment 3, a case where only wind measurement in the vicinity of the hard target is performed will be described.
In the third embodiment, the description of the same configuration and processing as those of the laser radar device 1 according to the first or second embodiment will be omitted, and the configuration and processing different from the first or second embodiment will be mainly described hereinafter. Shall be explained.

FIG. 7 is a configuration diagram of the received signal distinction unit 43 of the laser radar apparatus 1 according to the third embodiment of the present invention. The received signal distinction unit 43 according to the second embodiment performs only wind measurement in the vicinity of the hard target. The structure for this is described.
The reception signal distinction unit 43 includes a reception determination unit 431, a switching circuit 432, and a delay circuit 433, and the reception signal input from the light reception processing unit 42 to the reception determination unit 431 has passed through the reception determination unit 431. After that, one branch is input to the wind measuring unit 50 via the switching circuit 432 and the other is input to the distance measuring unit 60.

  The reception determination unit 431 determines whether or not the voltage value of the reception signal input from the light reception processing unit 42 is equal to or greater than a preset threshold value, and determines that the voltage value of the reception signal is equal to or greater than the threshold value. In this case, the control unit 70 is notified that a reception signal having a voltage value equal to or higher than the threshold value has been received.

  The switching circuit 432 switches whether to output the output destination of the signal input from the reception determination unit 431 to the wind measurement unit 50 or to the delay circuit 433 based on the switching signal from the control unit 70, 433 delays the input signal from the switching circuit 432 by a predetermined time based on the signal from the control unit 70 and outputs the delayed signal.

Next, the operation will be described.
FIG. 8 is a flowchart illustrating a process of performing wind measurement only on the periphery of a hard target that is a distance measurement target in the third embodiment.

  After starting the operation of the laser radar device 1, the control unit 70 does not instruct the first embodiment 80 to perform wind information calculation processing only around the hard target (N in S 301). The operation similar to 2 is continued (S302).

  On the other hand, when the control unit 70 receives an instruction from the host device 80 to calculate the wind information only around the hard target (Y in S301), the control unit 70 inputs the input to the switching circuit 432 from the reception determination unit 431. The received signal is instructed to switch from the path directly input to the wind measuring unit 50 until the instruction is received from the host device 80 to the path input to the delay circuit 433 from the switching circuit 432. (S303). Thereafter, the reception signal output from the delay circuit 433 is input to the wind measuring unit 50.

In addition, the control unit 70 receives the measurement range of the wind information from the host device 80 in order to define the measurement range for measuring the wind information around the hard target (S304). Based on the measurement range information, the signal propagation delay amount T _delay of the delay circuit 433 is calculated and set in the delay circuit 433 (S305).
Note that the control unit 70 calculates a signal propagation delay amount T _delay , a time amount T _TOF corresponding to the distance from the flight time of the received signal calculated by the TOF calculation unit 61 to the measurement target, and a TOF calculation unit. The hard target detection processing time T _det 61 is received from the TOF calculation unit 61, and the control unit 70 obtains a corresponding time amount T _range based on the measurement range of the wind information received from the host device 80. Then, a signal propagation delay amount T _delay is calculated using these T _TOF , T _det , and T _range and the following equation (3).

Thereafter, the control unit 70 starts measurement (S306).
At this time, the control unit 70 generates the timing at which the AD conversion process is performed by the AD conversion unit 51 in order to perform the wind information calculation process only for the designated hard target peripheral range, and the AD conversion 51 is performed at the generated timing. Are subjected to AD conversion processing (S307). Specifically, the following processing is performed.

FIG. 9 is a diagram illustrating analog signal processing when wind measurement is performed only around the hard target, and is a diagram illustrating that the AD conversion processing unit 51 operates only in the hard target peripheral range. Similarly to (a), the signal intensity I (Intensity) of the analog reception signal input from the AD conversion unit 51 is shown in time series.
In FIG. 9, the signal intensity I in the portion surrounded by the dashed-dotted square is higher than the signal intensity I other than the portion enclosed by the dotted square, indicating that a hard target exists. The wind information around the hard target can be calculated by using the signal intensity I from the time earlier than the time zone in which the signal intensity I becomes higher to the time later than the time zone.

The control unit 70 calculates the start timing T _start and the end timing T _stop of the AD conversion processing using the equation (4), and the AD conversion unit 51 from the calculated start timing T _start to the end timing T _stop. Then, AD conversion processing of the received signal is performed.

The processing after AD conversion at the predetermined timing calculated as described above is the same as in the first embodiment. That is, the FFT processing unit 52 and the wind information calculation unit 53 operate to calculate the wind information based on the digital signal AD-converted at a predetermined timing, and the distance measurement unit to which the reception signal is input from the reception determination unit 431 In 60, the distance information of the hard target is calculated. Then, the control unit 70 transmits the wind information only around the hard target calculated by the wind measurement unit 50 and the distance information calculated by the distance measurement unit 60 to the host device 80 (S308).
The wind information calculation process only around the hard target continues until a predetermined time elapses or a process end command is received from the host device 80 (S309).

  As described above, since the laser radar device 1 according to the third embodiment performs wind power calculation by performing AD conversion of the received signal only around the hard target, the wind in the minimum necessary area around the hard target is calculated. While measuring the information, it is possible to reduce the AD conversion operation time and the load for the conversion process, as compared with the first or second embodiment, as compared with the AD conversion of all the received signals. In addition, power consumption required for AD conversion can be suppressed. Furthermore, since the amount of memory for storing AD converted data is also reduced, the load for memory processing can also be reduced.

Embodiment 4 FIG.
In the first to third embodiments, the wind measurement unit 50 calculates the wind information. In the fourth embodiment, a case will be described in which the distance measurement unit 60 estimates the wind speed based on the calculated distance information.
The description of the same configuration and processing as those of the laser radar device 1 in the first embodiment will be omitted, and the configuration and processing different from those in the first embodiment will be described below.

FIG. 10 is a configuration diagram of the laser radar device 1 according to the fourth embodiment of the present invention, in which a wind information estimation unit 63 is added to the distance measurement unit 60 of the laser radar device 1 according to the first embodiment.
In the fourth embodiment, the wind information estimation unit 63 calculates the wind speed in the vicinity of the calculated shape from the shape of the terrain calculated by the distance information calculation unit 62 based on the relationship between the predefined terrain shape information and the wind speed. It is what you want.
Here, as the fourth embodiment, a configuration in which the wind information estimation unit 63 is added to the laser radar device 1 of the first embodiment will be described. However, the wind information estimation unit 63 is added to the laser radar device 1 of the second or third embodiment. May be added.

  As in the first embodiment, the received signal photoelectrically converted by the light receiving processing unit 42 is input to the distance measuring unit 60, and the distance measuring unit 60 calculates distance information using the TOF measuring unit 61 and the distance information calculating unit 62. To do. The distance information calculation unit 62 calculates the shape information of the terrain from the three-dimensional coordinates of the terrain of the measurement area that is the measurement target, and outputs the information to the wind information estimation unit 63.

In this Embodiment 4, the control part 70, the distance measurement part 60, or the wind information estimation part 63 has memorize | stored the database and relational expression regarding the relationship between the shape of a topography, and a wind speed.
The wind information estimation unit 63 extracts a feature amount necessary for wind speed estimation from the above-described topographic information calculated by the distance information calculation unit 62, and based on the relationship between the predefined topographic shape information and the wind speed, Obtain the wind speed value for the area.

  As a relational expression for this wind speed estimation, there is a relational expression calculated from, for example, a Pierson-Moskowitz type spectrum. Specifically, when the sea level is measured and the wave height is grasped, it is known that the relationship between the significant wave height and the wind speed is defined as equation (5) (R. Stewart “ “Introduction to Physical Oceanography”).

In Equation (5), H is the significant wave height, g is the gravitational acceleration, U _19.5 and U ₁₀ are the altitudes of 19.5 m and 10 m respectively, and the landform information calculated using this Equation (5) The wind speed in the vicinity can be obtained.

In addition to the estimated wind speed information, the wind information estimation unit 63 may also calculate the wind direction using the VAD method as performed by the wind information calculation unit 53.
The wind information estimation unit 63 calculated by estimating the wind information outputs wind information such as the estimated wind speed and direction to the control unit 70. Thereby, the control unit 70 receives the wind information estimated by the wind speed estimation unit 63 in addition to the wind information calculated by the wind measurement unit 50.

  When the echo of the particulate matter such as aerosol is weak and the wind speed value calculated by the wind measurement unit 50 is not sufficient measurement accuracy, the control unit 70 replaces the wind information such as the wind speed calculated by the wind measurement unit 50. By providing the wind information calculated by the wind information estimation unit 63 to the host device 80, the measurement accuracy of the wind information can be improved.

  Further, the control unit 70 collects estimated wind information such as wind speed obtained from the wind information estimation unit 63, and determines whether or not the system parameters of the laser radar device 1 need to be changed based on the estimated wind information. Judgment may be made or system parameters may be set.

  As described above, according to the fourth embodiment, it is possible to provide wind information estimated from the shape even in a situation where wind measurement by the wind measurement unit 50 is difficult due to weak echo from aerosol or the like.

  Even when the wind measurement unit 50 can calculate the wind information, it takes time to calculate the wind information from the result of the AD conversion and the FFT processing performed by the wind measurement unit 50. Therefore, the wind measurement unit 50 calculates the wind information. In the meantime, it is possible to set the system parameters in the next measurement using the estimated wind speed information, and the operation time can be improved.

  Even when the distance between the laser radar device 1 and the target is short, a range bin with sufficient calculation accuracy cannot be set and wind information cannot be calculated with sufficient accuracy. The value can be provided to the host device 80, and measurement of distance information to be measured and wind measurement can be made compatible without being affected by the measurement situation.

  In the above-described first to fourth embodiments, the optical transmitter 10, the optical antenna 30, the optical receiver 40, the wind measuring unit 50, the distance measuring unit 60, etc., the light source 11, the pulse modulator 12, etc., the laser radar device The processing and control method of each component of 1 may be realized by a digital signal processing circuit, or may be realized by software processing executed by a microcomputer or the like.

DESCRIPTION OF SYMBOLS 1 Laser radar apparatus, 10 light transmission part, 30 optical antenna part, 40 light receiving part, 50 wind calculation part, 60 position calculation part, 70 control part

Claims (7)

An optical transmitter for generating a pulsed laser;
An optical antenna unit that outputs the pulse laser as transmission light and receives light;
An optical receiver for generating a reception signal from the received light received by the optical antenna unit;
The received signal is converted from analog to digital, and wind information is calculated from the Doppler shift frequency obtained based on the frequency peak obtained by fast Fourier transform of the converted digital signal and the frequency when the received light is not subjected to Doppler shift. Wind measurement unit to
A distance measuring unit that calculates distance information of a measurement target based on a flight time from transmission to reception of received light corresponding to the received signal;
A control unit for controlling a transmission parameter for generating the pulse laser in the optical transmission unit;
The controller is
Determining whether or not the transmission parameter falls below a lower limit of accuracy of calculation of the wind information in the wind measurement unit;
When the transmission parameter is below the lower limit value and the accuracy of the distance information calculation by the distance measurement unit has priority over the accuracy of the wind information calculation, the transmission parameter is set in the optical transmission unit. ,
When the transmission parameter is below the lower limit value and the accuracy of calculation of the wind information is to be ensured, the transmission parameter within a range to ensure the lower limit value is set in the optical transmission unit. Laser radar device. The wind information is information on wind speed and direction,
The said wind measurement part calculates the said wind direction based on the said wind speed and the information regarding the scanning direction of the said optical antenna part while calculating the said wind speed based on the said Doppler shift frequency, The said wind direction is characterized by the above-mentioned. Laser radar device. The distance information is a distance to the measurement object and three-dimensional information of the measurement object,
The distance measuring unit calculates the distance based on the flight time, and calculates the three-dimensional information based on the distance and information related to the flight direction of the received light. Laser radar device. The optical receiver includes a received signal distinction circuit that outputs a detection signal notifying that the received signal exceeding the threshold is detected when the received signal exceeds the threshold;
When the control unit receives the detection signal from the reception signal distinction circuit, the control unit determines whether or not the transmission parameter is below a lower limit value of the calculation accuracy of the wind information in the wind measurement unit. The laser radar device according to claim 1, wherein 5. The laser according to claim 4, wherein the control unit outputs a signal for prompting the resetting of the threshold when it is determined that the detection signal from the reception signal distinction circuit is not received. Radar device. The control unit measures the frequency of receiving the detection signal from the received signal distinction circuit, and when the frequency falls below a lower limit value related to the reception frequency or when the frequency exceeds an upper limit value related to the reception frequency 5. The laser radar device according to claim 4, wherein a message for prompting resetting of the threshold value is output. The laser radar apparatus according to claim 1, wherein the distance measurement unit includes a wind information estimation unit that estimates a wind direction of a predetermined range of the measurement target based on the calculated distance information.

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