CN1273842C - Intelligent self-adaptive laser scanning distance-measuring imaging device - Google Patents

Abstract

The present invention relates to an intelligent self-adaptive laser scanning ranging and imaging device. The device analyzes data collection and the prediction algorithm of a master control board by a high-speed data collection circuit and controls the emergence energy and the emergence frequency of a laser. The device can realize nonuniform ground sampling with variable laser emergent power, the sampling defects of constant speed, uniform laser emergent power and poor imaging effect in existing scanning laser imaging are compensated, and thereby, the optimal laser ranging and imaging effects of a ground target are reached.

Description

Intelligent Adaptive Laser Scanning Ranging Imaging Device

technical field

The invention relates to a laser scanning ranging imaging system, in particular to an intelligent adaptive laser scanning ranging imaging device.

Background technique

Using high-brightness, high-coherence, and high-direction laser direct imaging technology for target detection, a three-dimensional laser direct imaging system for earth observation or ground scenes can be formed. Using laser as an active light source not only uses laser ranging, but also detects target reflection intensity information carried by laser echoes. By detecting the digital pulse and analog waveform of the laser echo, the target distance and reflection intensity information can be obtained, so as to obtain the high-resolution distance data and grayscale image of each pixel of the ground target. The earth observation scanning and ranging imaging system is developed from the airborne laser altimetry technology, and the off-machine point altimetry was realized in the early stage, but the accuracy is poor. Later, it developed into an airborne scanning height measurement imaging system, which is the current mainstream system. The latest development direction is the push broom type parallel height measurement imaging system. Most of these two types of systems use a diode-pumped solid-state laser as a pulsed laser radiation source, and the latter has greatly lower requirements on the repetition rate of the laser than the former.

The effect of laser ranging is closely related to the ground sampling interval of the laser. The smaller the sampling interval, the better the ranging effect. The size of the ground sampling interval (representing the size of the ground resolution) is inversely proportional to the pulse laser repetition frequency, and proportional to the scanning speed and the flight speed of the platform. The most ideal effect is to meet the speed-to-height ratio without overlapping between footprints. In order to reduce the ground sampling interval, only increase the pulse repetition frequency, or reduce the flight speed and scanning speed. Due to the limitations of the airborne laser manufacturing process and working environment, the repetition rate cannot reach the ideal situation, and it is also impossible to reduce the flight speed from a practical point of view. So how to obtain a satisfactory ground sampling interval has become one of the problems that need to be solved at present.

Laser imaging technology uses the energy of the laser echo to obtain the reflectivity of the outgoing laser band at the point on the ground. Because this method is not affected by sunshine, it is the frontier topic of active remote sensing research. However, due to the signal-to-noise ratio of the amplifying circuit, the echo detection circuit often cannot detect the echo signal in the case of low reflectivity, and the echo signal is oversaturated in the case of high reflectivity. Therefore, the imaging capabilities of these systems are currently unsatisfactory. At the same time, when the atmospheric conditions change, the imaging effect of the system is not good. How to make the system have a good imaging ability for various ground objects is another problem that needs to be solved.

Contents of the invention

The object of the present invention is to overcome the problems of the above-mentioned prior art and provide an intelligent self-adaptive laser scanning ranging imaging device. High-speed, uniform laser output power, and sampling defects with poor imaging effects, so as to achieve the best laser ranging imaging effect for ground targets.

Technical solution of the present invention is as follows:

An intelligent self-adaptive laser scanning ranging imaging device, including a transmitting and receiving coaxial optical system, a laser and a synchronous scanning mechanism, the laser emits laser light through the transmitting and receiving coaxial optical system, and the main wave signal of the laser is detected by a main wave photoelectric detection circuit , the main wave photoelectric detection circuit is connected to the distance measurement module through the main wave signal processing circuit, the laser echo reflected by the target is detected by the echo APD detector through the transmitting and receiving coaxial optical system, and the echo APD detector is connected to the echo signal processing The output terminal of the echo signal processor is connected to the distance measurement module on the one hand, and connected to the computer through the echo peak sampling AD conversion on the other hand. The distance measurement module is directly connected to the computer, and its characteristics are:

①. There is also a main control board, the main control board is provided with a data processing module, an energy control and a trigger frequency control module, the echo peak sampling circuit and the distance measurement module are connected with the data processing module of the main control board, and the The output power and trigger frequency control module of the main control board are connected to the laser and the stepping motor drive end of the synchronous scanning mechanism at the same time;

②. The main wave signal processor is also connected to the computer through main wave peak sampling AD conversion.

Said laser is a pulsed solid-state laser.

The main wave photodetection circuit uses a photodiode or an avalanche diode as a photoelectric conversion device.

The method for ranging imaging using the intelligent self-adaptive laser scanning ranging imaging device is characterized in that the working process of the data processing module of the main control board is as follows:

①. Choose an appropriate N value or a fixed N, N is a natural number greater than 1;

②. Elevation data and echo peak initialization;

③. Read in the current elevation data L _N , line up the elevation data in chronological order to form an elevation queue: L={L ₁ , L ₂ ... L _N };

Calculate difference queue: ΔL={L ₂ -L ₁ , L ₃ -L ₂ ,...L _N -L _N-1 };

Find the correction parameter X: $x={\mathrm{\Σ}}_1^{N-1}\mathrm{\ΔL};$

④. According to the correction parameter X and frequency control strategy selection, calculate the trigger frequency modification value F ₁ ;

⑤. When F ₁ ≤ F ₂ , then select the laser trigger frequency f _K = F ₁ ,

When F ₁ >F ₂ , the trigger frequency f _k of the selected laser = F ₂ ;

Among them: F ₂ is the upper limit frequency of the laser;

⑥. Read echo peak values A ₁ , A ₂ ... A _N , and calculate the average value of echo peak values:

${\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; AV</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; ;</span>$

⑦. Calculate the power modification value W _X according to A _AV deviation from the best response range of the AD converter and the laser power control strategy;

⑧. Set W _below and W _above as the upper and lower limits of laser power respectively. When W _below < W _X < W _above , select the output power control value of the laser (2) W _K = W _X . When W _above < W _X , then W _K = _above W; when W _X < _below W, W _K = _below W;

⑨. The main board outputs W _K and f _K to the drive end of the stepper motor of the laser and the synchronous scanning mechanism through the output power and trigger frequency control module to control the work of the laser and the stepping motor of the synchronous scanning mechanism.

The prediction algorithm of the data processing module of the main control board is as follows:

① Select different frequency modification values (Δf ₁ , Δf ₂ , Δf ₃ ) according to the observed terrain, plains/cities or hills or mountains, and select outgoing energy modification values (ΔP ₁ , ΔP ₂ , ΔP ₃ );

② According to the correction parameter X, select the frequency:

When _X≥Tuf ,

$\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; uf</span>}}}{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; the\; ceil</span>}}$

F ₁ =F ₀ +n×Δf

When X<T _df

$\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; df</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; the\; ceil</span>}}$

F ₁ =F ₀ -n×Δf

(T _uf > T _df )

Among them: _Tuf is the upper limit value of the frequency correction setting, T _df is the lower limit value of the frequency correction setting, F ₁ is the trigger frequency modification value, F ₀ is the trigger frequency original value, Δf is the preset frequency modification value , A is the subdivision coefficient, n is the frequency correction parameter, which is the upper integer divided by the absolute value of the difference between the correction parameter and the limit value divided by the subdivision coefficient;

③. According to the correction parameter A _AV , select the output power control value W _x of the laser:

When A _AV ≥ T _uP ,

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; AV</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; uP</span>}}}{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; the\; ceil</span>}}$

W _x = Wm x ΔP

When A _AV <T _dP , W _x is the output power control value

$\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; dP</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; AV</span>}}}{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; the\; ceil</span>}}$

W _x ＝W+m×ΔP

Among them: T _uP is the set echo peak power correction W _x is the positive upper limit value of the outgoing power control value, T _dP is the set echo peak power correction lower limit value, W _x is the outgoing power control value, W is The original value of the output power, ΔP is the preset output energy modification value, B is the subdivision coefficient, and m is the frequency correction parameter, which is the upper integer of dividing the absolute value of the difference between the energy correction parameter and the threshold value by the subdivision coefficient.

The post-processing process of the data by the computer:

①. Align the AD change value of the main wave peak sampling AD conversion sampling data with the AD change value of the echo peak sampling AD conversion sampling data;

②. Calculate the laser output power W _t according to the calibration data and the AD change data of the main wave peak sampling AD conversion sampling;

③. The surface reflectance ρ _tar of the target is calculated by inversion according to the following ranging equation:

${\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}}{<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; tar</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}$

In the formula, W _t is the energy of the emitting laser, τ _p is the pulse width of the laser, τ _t is the transmittance of the transmitting optical system, τ _a ² is the two-way transmittance of the atmosphere, τ _r is the transmittance of the receiving optical system ρ _tar is the surface reflectivity of the target, A _r is the effective receiving aperture of the receiving system, P _r is the detected power of the system, corresponding to the echo peak AD conversion value, τ _f is the filter before the echo detector The transmittance of the light sheet, R is the distance measurement.

Technical effect of the present invention:

1. In the conventional system of scanning laser ranging imaging for earth observation, the scanning laser samples the ground uniformly. In the optical-mechanical scanning system, the scanning motor in the head of the optical machine drives the scanning mirror to rotate at a certain speed. accomplish. In the present invention, the stepping motor is used as the scanning motor to realize the variable-speed scanning, and the control signal of the variable-speed scanning comes from the adaptive variable-speed driving signal generation circuit, and the variable-speed driving signal is subjected to the ground fluctuation prediction given by the distance measurement and fluctuation prediction circuit Control of results. In the push broom system, it is only necessary to use a variable external trigger signal to control the output frequency of the laser, and there is no need for a corresponding circuit to control the scanning motor;

2. Transform the laser control circuit so that it can control the laser output power. In the present invention, the control signal for variable output power scanning comes from the adaptive variable output power drive circuit, which is controlled by the main control board. Digital adjustable resistance Composed of a voltage divider circuit composed of fixed-value resistors, its function is to output a voltage signal proportional to the output power according to the result of the echo peak prediction algorithm;

3. Transform the main wave system, and change the original circuit that only generates digital main wave into a circuit that records main wave energy at the same time. After the main wave signal is sampled at the peak value, it is subjected to analog-to-digital conversion, and the data value obtained after the analog-to-digital conversion is sent to the computer for storage, and is used when inverting the image.

Description of drawings

Figure 1 is a structural block diagram of an existing laser scanning ranging imaging device

Fig. 2 is a structural block diagram of an intelligent self-adaptive laser scanning ranging imaging device of the present invention

Fig. 3 is a flow chart of the prediction work of the main control board of the device of the present invention.

Detailed ways

Please refer to Fig. 2 first. Fig. 2 is a structural block diagram of the intelligent adaptive laser scanning ranging imaging device of the present invention. As can be seen from the figure, the intelligent adaptive laser scanning ranging imaging device of the present invention includes a transmitting and receiving coaxial optical system 1, a laser 2 and a synchronous scanning mechanism 12, the laser 2 emits laser light through the transmitting and receiving coaxial optical system 1, the main wave signal of the laser is detected by the main wave photoelectric detection circuit 7, and the main wave photoelectric detection circuit 7 is connected to the main wave signal processor 8 The distance measurement module 10, the laser echo reflected by the target is detected by the echo APD detector 4 through the transmitting and receiving coaxial optical system 1, and the echo APD detector 4 is connected to the echo signal processor 5, and the echo signal processor 5 On the one hand, the output terminal is connected to the distance measurement module 10, and on the other hand is connected to the computer 11 through the echo peak sampling AD conversion 6, and the distance measurement module 10 is directly connected to the computer 11, and is characterized in that:

1. There is also a main control board 3, the main control board 3 is provided with a data processing module 31, an outgoing power and a trigger frequency control module 32, and the echo peak sampling AD conversion 6 and the distance measurement module 10 are connected with the main control board 3 The data processing module 31 of the main control board 3 is connected, and the output power and the trigger frequency control module 32 of the main control board 3 are respectively connected to the laser 2 and the synchronous scanning mechanism 12;

②. The main wave signal processor 8 is also connected to the computer 11 through the main wave peak sampling AD conversion 9 .

The working process of the device of the present invention is as follows:

1. The main control board 3 sends an external trigger signal to the laser 2. The laser 2 emits laser light through the transmitting and receiving coaxial optical system 1. The main wave signal of the laser is detected by the photodiode detection circuit 7 and processed by the main wave signal processor 8. Finally, the digital main wave is generated, divided into two channels, and one channel is sent to the distance measurement module 10 with a time resolution of 120 ps to start counting. All the way into the main wave peak sampling AD conversion 9 sampling and analog-to-digital conversion, to obtain the main wave peak sampling data, sent to the computer 11 for storage.

2. The emitted laser echoes reflected by the ground are received by the receiving optical system of the transmitting and receiving coaxial optical system 1, detected by the echo APD detector 4, and processed by the echo signal processor 5, and then divided into two paths, All the way, the generated digital echo is sent to the distance measurement module 10, and the counting is stopped. The time from the main wave start counting to the echo stop counting is the flight time Δt of the laser, so as to obtain the distance h from the flying platform to the ground distance measuring point =C·Δt, on the one hand, the distance value h is sent to the computer 11 for storage, and at the same time, it is sent to the main control board 3 for prediction and calculation of ground elevation fluctuations. One way is sent to the echo peak sampling AD conversion 6 for sampling and analog-to-digital conversion to obtain the echo peak adoption data, which are respectively sent to the computer 11 for storage and the main control board 3 for prediction and calculation of the ground echo peak fluctuation.

3. Based on the distance measurement data and echo peak data, the main control board combines the prediction algorithm to predict the change trend of the ground elevation and the echo peak value. According to the prediction result of the elevation change, the trigger frequency of the laser 2 and the synchronous scanning mechanism 12 are controlled. According to the prediction result of the echo peak change, the operating voltage of the laser 2 is controlled to achieve the effect of controlling the output power of the laser.

4. According to the measured digital main wave peak value, the digital echo peak value at the corresponding moment and the distance measurement value, according to the ranging formula (1), the surface reflectance ρ _tar of the corresponding target object is inverted.

${\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}{<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; tar</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; min</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, W _t is the energy of the emitting laser, τ _p is the pulse width of the laser, τ _t is the transmittance of the transmitting optical system, τ _a ² is the two-way transmittance of the atmosphere, τ _r is the transmittance of the receiving optical system ρ _tar is the surface reflectance of the target, _Ar is the effective receiving aperture of the receiving system, P _rmin is the minimum detectable power of the system under test, τ _f is the transmittance of the filter before the echo detector , R is the distance measurement value. In order to measure the absolute reflectivity, we need to calibrate W _t and the sampling data of the peak value of the main wave, so the sampling data of the peak value of the main wave and the sampling data of the echo peak must be sent to the computer 11 for processing.

The prediction workflow of the main control board 3 of the device of the present invention is as shown in Figure 3:

After starting to work, first perform data initialization, read in the current elevation data L _N , form an elevation queue, calculate the queue difference value of the elevation queue (flight height or target distance value), and correct the calculated difference distance queue Parameter X

Elevation queue: L={L ₁ , L ₂ ...L _N }

Distance difference queue: $\mathrm{\&Delta;\; L}=\{L_2-L_1,L_3-L_2...L_N-L_{N-1}\}$

Find the correction parameter X: $x={\mathrm{\&Sigma;}}_1^{N-1}\mathrm{\&Delta;L}$

According to the correction parameter X and the frequency control strategy (plain/urban, hilly, mountainous), calculate the frequency modification value. Then judge whether the modified frequency value satisfies the upper limit frequency of laser operation, and if it exceeds the upper limit frequency, fix the frequency modification value to the upper limit frequency of the laser.

Read in the current echo peak A _N to form the echo peak queue A, calculate the average value A _AV of the echo peak queue, and judge whether A _AV falls within the optimal range of AD change, if not, according to the power control strategy ( Strong/medium/weak), calculate the power modification value, and judge whether the modified output power meets the limit power (upper limit and lower limit) of the laser. If the limit is exceeded, the output power modification value is fixed to the limit output power of the laser.

Echo peak queue: A={A ₁ , A ₂ ... A _N }

Echo Peak Average: $A_{\mathrm{AV}}=\frac{\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{A}_i}{N}$

Finally, execute the frequency and output power control amount, and modify the elevation and echo peak queue to prepare for the next control.

This part of the work can also be done by the computer 11 .

Compared with the prior art, the present invention has obvious practical pertinence and significant progress. The outgoing laser beam is directed to the ground target through the deflection or beam splitting mechanism of the scanning mirror, and the back-reflected laser signal of the ground target passes through the scanning mirror. Turning back to the telescope, it is received by the detector located on the focal plane of the telescope, and after processing, the distance and reflectivity information of the target can be obtained. By processing this moment and several such distance information in the past, it is possible to make predictions about the fluctuations of future ground targets. The prediction result can then be used as a control parameter for the subsequent point or the next scan line. Through the closed-loop control of this parameter, the rotation rate of the motor is adjusted to realize variable speed scanning. By processing the echo peak information at this moment and several previous ones, it is possible to make a prediction of the change of the reflectivity of the ground target in the future. The prediction result is used as a control parameter of the laser emission energy of the subsequent point or the next scanning line. Use this parameter to control the laser output energy or the attenuation coefficient of the attenuation sheet, so that the echo energy can fall within the optimal range of the echo circuit. At the same time, the peak value of the main wave is used to record the control parameters. Finally, intelligent adaptive variable speed and variable energy scanning ranging imaging is realized. In the case of constant laser repetition frequency, intensive sampling is carried out on areas with large ground fluctuations, and the actual ranging effect is significantly improved. At the same time, the ability of laser imaging is deeply explored. For areas with large fluctuations in ground reflectivity, lasers with variable output power are used as active light sources, which significantly improves the imaging ability of different ground objects.

Claims (6)

1. An intelligent self-adaptive laser scanning ranging imaging device, comprising a transmitting and receiving coaxial optical system (1), a laser (2) and a synchronous scanning mechanism (12), and the laser (2) is passed through a transmitting and receiving coaxial optical system ( 1) Laser emission, the main wave signal of the laser is detected by the main wave photoelectric detection circuit (7), and the main wave photoelectric detection circuit (7) is connected to the distance measurement module (10) through the main wave signal processor (8), and the target reflection The laser echo is detected by the echo APD detector (4) through the transmitting and receiving coaxial optical system (1), and the echo APD detector (4) is connected to the echo signal processor (5), and the echo signal processor ( 5) the output terminal is connected to the distance measurement module (10) on the one hand, and connected to the computer (11) through the echo peak sampling AD conversion (6) on the other hand, and the distance measurement module (10) is directly connected with the computer (11), It is characterized by: 1. There is also a main control board (3), the main control board (3) is provided with a data processing module (31), an energy control trigger frequency control module (32), and the echo peak sampling AD conversion (6) and distance The measurement module (10) is connected to the data processing module (31) of the main control board (3), and the energy control trigger frequency control module (32) of the main control board (3) is simultaneously connected with the laser (2) and the synchronous scanning mechanism (12) The drive end of the stepper motor is connected; ②. The main wave signal processor (8) is also connected to the computer (11) through the main wave peak sampling AD conversion (9). 2. The intelligent adaptive laser scanning ranging imaging device according to claim 1, characterized in that the laser (1) is a pulsed solid-state laser. 3. The intelligent adaptive laser scanning ranging imaging device according to claim 1, characterized in that the main wave photodetection circuit (7) uses a photodiode or an avalanche diode as a photoelectric conversion device. 4. Utilize the method for ranging imaging of the intelligent self-adaptive laser scanning ranging imaging device according to claim 1, characterized in that the working process of the data processing module (31) of the main control board (3) is as follows: ①. Choose an appropriate N value or a fixed N, N is a natural number greater than 1; ②. Elevation data and echo peak initialization; ③. Read in the current elevation data L _N , and queue up the elevation data in chronological order to form an elevation queue: L={L ₁ , L ₂ ... L _N }; Calculate difference queue: ΔL={L ₂ -L ₁ , L ₃ -L ₂ ,...L _N -L _N-1 }; Find the correction parameter X: $x={\mathrm{\&Sigma;}}_1^{N-1}\mathrm{\&Delta;L};$ ④. According to the correction parameter X and frequency control strategy selection, calculate the trigger frequency modification value F ₁ ; ⑤. When F ₁ ≤ F ₂ , then select the laser trigger frequency f _K = F ₁ , When F ₁ >F ₂ , the trigger frequency f _k of the selected laser = F ₂ ; Among them: F ₂ is the upper limit frequency of the laser; ⑥. Read echo peak values A ₁ , A ₂ ... A _N , and calculate the average value of echo peak values: ${\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; AV</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; ;</span>$ ⑦. Calculate the power modification value W _X according to A _AV deviation from the best response range of the AD converter and the laser power control strategy; ⑧. Set W _below and W _above as the upper and lower limits of laser power respectively. When W _below < W _X < W _above , select the output power control value of the laser (2) W _K = W _X . When W _above < W _X , then W _K = _above W; when W _X < _below W, W _K = _below W; ⑨. The main board (3) outputs W _K and f _K to the laser (2) and the stepper motor drive end of the synchronous scanning mechanism (12) through the output power and trigger frequency control module (32) to control the laser (2) and synchronous scanning The work of mechanism (12) stepper motor. 5. The ranging imaging method according to claim 4, characterized in that the prediction algorithm of the data processing module (31) of the main control board (3) is as follows: ① Select different frequency modification values (Δf ₁ , Δf ₂ , Δf ₃ ) according to the observed terrain, plains/cities or hills or mountains, and select outgoing energy modification values (ΔP ₁ , ΔP ₂ , ΔP ₃ ); ② According to the correction parameter X, select the frequency: When _X≥Tuf , $\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; uf</span>}}}{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; the\; ceil</span>}}$ F ₁ =F ₀ +n×Δf When X<T _df $\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; df</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; the\; ceil</span>}}$ F ₁ =F ₀ -n×Δf (T _uf >T _df ) Among them: _Tuf is the upper limit value of the frequency correction setting, T _df is the lower limit value of the frequency correction setting, F ₁ is the trigger frequency modification value, F ₀ is the trigger frequency original value, Δf is the preset frequency modification value , A is the subdivision coefficient, n is the frequency correction parameter, which is the upper integer divided by the absolute value of the difference between the correction parameter and the limit value divided by the subdivision coefficient; ③. According to the correction parameter A _AV , select the output power control value W _x of the laser (1): When A _AV ≥ T _uP , $\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; AV</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; uP</span>}}}{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; the\; ceil</span>}}$ W _x = Wm x ΔP When A _AV <T _dP , W _x is the output power control value $\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; dP</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; AV</span>}}}{\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; )</span>}_{\mathrm{<span\; class="notranslate">\; the\; ceil</span>}}$ W _x ＝W+m×ΔP Among them: T _uP is the set echo peak power correction W _x is the positive upper limit value of the outgoing power control value, T _dP is the set echo peak power correction lower limit value, W _x is the outgoing power control value, W is The original value of the output power, ΔP is the preset output energy modification value, B is the subdivision coefficient, m is the frequency correction parameter, and ceil is the expression of dividing the absolute value of the difference between the energy correction parameter and the threshold value by the subdivision coefficient and rounded up. 6. The ranging imaging method according to claim 4 or 5, characterized in that the post-processing process of the data by the computer (11) is: ①. Align the AD change value of the main wave peak sampling AD conversion (9) sampling data with the AD change value of the echo peak sampling AD conversion (6) sampling data; ②. Calculate the laser output power W _t according to the calibration data and the AD change data sampled by the main wave peak sampling AD conversion (9); ③. The surface reflectance ρ _tar of the target is calculated by inversion according to the following ranging equation: ${\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; tar</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}$ In the formula, W _t is the energy of the emitting laser, τ _p is the pulse width of the laser, τ _t is the transmittance of the transmitting optical system, τ _a ² is the two-way transmittance of the atmosphere, τ _r is the transmittance of the receiving optical system ρ _tar is the surface reflectivity of the target, A _r is the effective receiving aperture of the receiving system, P _r is the detected power of the system, corresponding to the echo peak AD conversion value, τ _f is the filter before the echo detector The transmittance of the light sheet, R is the distance measurement.

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