A method and system for adaptive segmented gain multi-wavelength laser ranging

Abstract

The application discloses a kind of self-adapting segmented gain multi-wavelength laser ranging method and system, method includes: multi-wavelength laser is under the control of trigger signal, laser pulse is emitted by emission optical system, trigger mode has synchronization, equal interval and coded emission.Laser echo is guided to detector by receiving system, and digital signal is generated after conversion by segmented gain module.Control processing module includes the information of ranging value, echo intensity in signal processing calculation.By self-adapting segmented gain, low magnification gain circuit is used to suppress strong signal in short distance, high magnification gain circuit is switched to improve weak signal detection ability in long distance, and step gain is formed by gain partition, and segmented area is adaptively adjusted to avoid distortion according to echo ranging value.Control processing module will complete data transmission.Near distance signal distortion and long distance signal missing detection are avoided, and system reliability and detection ability are improved.

Description

Technical Field

[0001] This invention belongs to the field of laser ranging, and more specifically, relates to an adaptive segmented gain multi-wavelength laser ranging method and system. Background Technology

[0002] Pulsed laser ranging relies on measuring the time difference between the emitted laser and the echo reflected from the target to determine the distance. Therefore, a one-to-one correspondence between the emitted pulse and the echo is required. When the target distance is too far or the laser repetition frequency is too high, the next laser pulse may be triggered before the echo of the previous pulse is received by the detector, resulting in mismatched emitted pulses and echoes, leading to ranging ambiguity. This means there is a difficulty in simultaneously controlling the measurement frequency and measurement range. Unlike traditional microwave radar, due to the limitations of the laser and the range requirements, it is difficult to distinguish different emitted pulses through pulse modulation in hardware. Existing software processing methods all have a certain error rate, resulting in noise in the point cloud.

[0003] Traditional laser ranging still faces the challenge of insufficient dynamic range during use. The system needs to capture both strong echo signals from near-range, highly reflective targets and weak echo signals from far-range, low-reflective targets within a single pulse cycle, with an energy span of up to 120 dB. This causes nonlinear distortion due to signal saturation at the near-range end of the traditional fixed-gain receiver link, while at the far-range end, insufficient signal-to-noise ratio leads to missed detection of weak targets. Common methods employ a multi-channel receiver architecture (high-gain and low-gain channels in parallel) combined with adaptive gain control to extend the dynamic range. However, multiple channels increase the complexity of the optical system, requiring more detectors, signal conditioning circuits, and high-speed ADC channels. Adaptive gain control requires feedback adjustment of the gain based on the received signal magnitude, and in complex and variable environments, the dynamic response speed of this feedback mechanism is insufficient.

[0004] Meanwhile, a single laser wavelength has limitations in target detection. For example, the infrared band has strong propagation capabilities in the air but cannot penetrate the water surface medium, and the point cloud measured by the airborne lidar will form holes on the water surface. A single wavelength can only obtain the reflectivity of the target in that band, and more target spectral information needs to be obtained with the help of optical cameras or hyperspectral cameras.

[0005] Based on the aforementioned defects and shortcomings, there is an urgent need in this field for an adaptive segmented gain multi-wavelength laser ranging method to effectively improve the measurement frequency and dynamic range of large-area laser ranging, add multispectral information, and expand application scenarios such as water surface and underwater. Summary of the Invention

[0006] This invention aims to address the problems of traditional laser ranging, such as the difficulty in balancing measurement frequency and range, insufficient dynamic range, and limitations of single-wavelength detection. By proposing an adaptive piecewise gain multi-wavelength laser ranging method, it effectively improves the measurement frequency and dynamic range of large-area laser ranging, utilizes multiple wavelengths to acquire multispectral information of the target, expands application scenarios such as water surface and underwater, reduces point cloud noise, avoids near-range signal distortion and long-range signal missed detection, and enhances system reliability and detection capability.

[0007] To address the aforementioned deficiencies or improvement needs of existing technologies, as a first aspect of this invention, an adaptive piecewise gain multi-wavelength laser ranging method is provided, comprising:

[0008] S1. A multi-wavelength laser emits laser pulses via a transmitting optical system under the control of a trigger signal; the triggering methods include synchronous emission, equally spaced emission, and coded emission.

[0009] S2. The laser pulse is reflected by the target to form an echo, and the receiving system makes each wavelength echo receive the detector separately;

[0010] S3. Echoes of different wavelengths are converted into electrical signals by a segmented gain module, and then into digital signals by a high-speed analog-to-digital converter. The control processing module processes the digital signals and calculates information including ranging values ​​and echo intensity according to design requirements.

[0011] S4. The problem of simultaneously detecting weak signals at long distances and strong signals at close range is solved by adaptive segmented gain settings: In the close range, a low amplification gain circuit is used to suppress the echo intensity of the close-range signal; outside the close range, a high amplification gain circuit is switched to improve the detection capability of weak signals at long distances; at the same time, the number of gain segments is further increased according to the needs of the measurement range to form a stepped gain; and the segmented regions are adaptively adjusted according to the echo ranging value, etc., to avoid signal distortion.

[0012] S5. The control processing module communicates and transmits the processed data to the host computer.

[0013] Furthermore, the scenarios for synchronous transmission, equally spaced transmission, and coded transmission distribution adaptation in S1 are as follows:

[0014] Synchronous transmission method, used for simultaneous detection of different media;

[0015] The purpose of the equal-interval emission method is to ensure the uniformity of the laser trigger interval, thereby ensuring the uniformity of the measured point cloud and facilitating the subsequent point cloud processing.

[0016] The coded transmission method can further expand the unambiguous ranging range and the ability to resist interference from other lidar systems. By encoding the trigger interval of lasers of different wavelengths, and based on the relative positional relationship between the ranging values ​​of the received echoes of different wavelengths, it can determine which laser trigger match the echo, thus breaking through the ambiguity range limitation of single-pulse ranging, or determining whether the echo belongs to the laser pulse echo emitted by this system, avoiding interference from other laser measurement systems.

[0017] Furthermore, in the receiving system of S2, beam splitting and narrowband filtering are used to ensure that echoes of different wavelengths are received by the detectors separately, thus avoiding mutual interference between laser pulses of different wavelengths.

[0018] Furthermore, the method for setting the gain partition in S4 is as follows:

[0019] The system's ranging range is designed to be d min ~d max If the total number of gain levels is L, then the distance d at the boundary between the i-th gain level and the (i+1)-th gain level is... g-i Set as:

[0020]

[0021] In the formula, d max and d min These represent the maximum and minimum distances at the boundary, corresponding to the upper and lower limits of the boundary adjustment range.

[0022] Furthermore, in step S4, the segmented region is adaptively adjusted based on the echo ranging value, etc., to avoid signal distortion. The specific method is as follows:

[0023] Let the echo ranging value obtained from the previous laser trigger be d. measured ;

[0024] Let the time interval between the echo and the boundary position be Δt. e-b It is obtained by converting the echo ranging value and the boundary distance through the speed of light c, that is:

[0025]

[0026] Let the adjustment threshold be T. adj The lower limit of the boundary adjustment range is T. org The upper limit of the boundary adjustment range is T. org +ΔT, the distance between the boundary between the adjusted i-th gain and the (i+1)-th gain is

[0027] Determine |Δt e-b |with T adj The magnitude relationship, and Δt e-bThe relative position of the boundary adjustment range;

[0028] When |Δt e-b | <T adj And Δt e-b When it approaches the lower limit of the range, that is Adjust the boundary to the distance corresponding to the upper limit of the range:

[0029]

[0030] When |Δt e-b | <T adj And Δt e-b When approaching the upper limit of the range, i.e. Adjust the boundary to the distance corresponding to the upper limit of the range:

[0031]

[0032] When |Δt e-b |≥T adj The position of the boundary remains unchanged, that is:

[0033]

[0034] When the boundary position is adjusted to the upper or lower limit of the allowable adjustment range, the boundary position can be readjusted to the lower limit, upper limit, initial position, or any position without echoes. reset :

[0035] like or but

[0036] Furthermore, the interval emission mode of the multi-wavelength laser in S1 is specifically as follows:

[0037] For a laser transceiver module with M wavelengths, after setting the trigger frequency of the single-wavelength laser to PRR, the trigger interval between lasers of different wavelengths is set to...

[0038] According to the calculated trigger interval, lasers of different wavelengths are triggered to emit laser pulses in sequence; that is, after the first wavelength laser is emitted, the second wavelength laser is triggered to emit after a specific time interval, and so on, until all M wavelength lasers have completed one emission; then a new round of emission is started again from the first wavelength laser, and so on, to ensure that the laser trigger interval is uniform.

[0039] The emitted laser pulse is reflected by the target to form an echo, which is collected by the receiving optical system. The echoes of different wavelengths are split by the beam splitting system and received by the corresponding detectors and converted into electrical signals. Then, they are converted into digital signals by high-speed analog-to-digital conversion. The control processing module processes these digital signals and calculates information including the corresponding ranging value and the echo intensity of different wavelengths.

[0040] Since laser pulses of different wavelengths are not emitted simultaneously in the equal-interval emission method, the echoes of different wavelengths do not measure the same target. Therefore, the spectral registration of the same target is achieved by upsampling interpolation of point clouds of different wavelengths.

[0041] Furthermore, the method for achieving spectral registration of the same target by upsampling interpolation of point clouds at different wavelengths is specifically as follows:

[0042] Upsampling interpolation and spectral registration of point clouds at different wavelengths only need to consider the scan line direction;

[0043] Assume the echo intensity of the j-th laser trigger at wavelength λ1 is Then for the echo intensity sequence The interpolated echo intensity sequence is obtained by performing M-fold interpolation. The calculation formula is as follows:

[0044]

[0045] In the formula, k represents the interpolated sequence. And the index values ​​of the relevant intermediate interpolation sequences; The sequence is If M-1 zeros are inserted between each pair of values ​​in the sequence, then... The length of the sequence becomes The sequence is M times the original sequence; for the echo intensity sequences before and after interpolation, we have:

[0046]

[0047] Therefore, for an echo intensity sequence of M wavelengths emitted at equal intervals, the target spectral information obtained by the j-th laser trigger at the m-th wavelength is:

[0048]

[0049] In the formula, each parameter represents λ1, which represents I. jThe vector representing the interpolated echo intensity values ​​of each wavelength in the sequence of M equally spaced echo intensity signals, obtained during the j-th laser trigger, represents the target spectral information obtained in this trigger. M represents the interpolation factor, which is the factor by which the data density of the original echo intensity sequence is increased when interpolating. m represents the m-th wavelength used to identify the multi-wavelength system, where m = 1, 2, ..., M.

[0050] Furthermore, the specific method for adaptive segmented gain in S4 is as follows: Multiple resistors with varying resistance values ​​are connected in parallel in the transimpedance amplifier circuit at the back end of the detector. Each parallel resistor is connected in series with a switching device to control the switching on and off of the resistor in the transimpedance amplifier circuit. The switching device is controlled by the control and processing module via high and low level signals.

[0051] The equivalent transimpedance of the transimpedance amplifier circuit is:

[0052]

[0053] Where g(i) = 0, 1 represents the state of the i-th switch, and R i Let be the resistance value of the i-th resistor.

[0054] As a second aspect of the present invention, an adaptive piecewise gain multi-wavelength laser ranging system is provided, characterized in that it comprises:

[0055] The laser emitting unit is used to emit laser pulses from a multi-wavelength laser via an emitting optical system under the control of a trigger signal; the triggering methods include synchronous emission, equally spaced emission, and coded emission.

[0056] The echo receiving unit is used to generate echoes when laser pulses are reflected by the target, and the receiving system enables the detectors to receive the echoes of each wavelength separately.

[0057] The signal conversion and processing unit is used to convert echoes of different wavelengths into electrical signals via a segmented gain module, and then generate digital signals via a high-speed analog-to-digital converter. The control processing module processes the digital signals and calculates information including ranging values ​​and echo intensity according to design requirements.

[0058] The gain adjustment unit is used to solve the problem of simultaneously detecting weak signals at long distances and strong signals at close range through adaptive segmented gain settings: within the close range, a low amplification gain circuit is used to suppress the echo intensity of the close-range signal; outside the close range, a high amplification gain circuit is switched to improve the detection capability of weak signals at long distances; at the same time, the number of gain segments is further increased according to the needs of the measurement range to form a stepped gain; and the segmented regions are adaptively adjusted based on echo ranging values, etc., to avoid signal distortion.

[0059] The control processing unit is used to control the processing module to communicate and transmit the processed data with the host computer.

[0060] As a third aspect of the invention, a computer-readable storage medium is also provided, on which a computer program is stored, which is executed by a processor of any step of the adaptive segmented gain multi-wavelength laser ranging method.

[0061] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0062] 1. The adaptive segmented gain multi-wavelength laser ranging method of the present invention determines the trigger interval between lasers of different wavelengths by setting the trigger frequency of a single-wavelength laser, and triggers the emission of laser pulses sequentially according to the interval. The echo of the laser after reflection from the target is collected, split, converted and processed by the system. Since the laser pulses of different wavelengths are not emitted simultaneously, spectral registration is achieved by upsampling interpolation of point clouds of different wavelengths. This method can simultaneously acquire multi-wavelength information, increase the data dimension, ensure the uniformity and stability of laser emission, improve the accuracy of multispectral information acquisition, and achieve comprehensive and accurate perception of target characteristics.

[0063] 2. The adaptive segmented gain multi-wavelength laser ranging method of this invention utilizes a specific transimpedance amplifier circuit built in hardware. Multiple resistors of different resistance values ​​are connected in parallel and a switching device is connected in series, controlled by a control module via high and low level signals. At the algorithm level, the total number of gain levels and the boundaries between each level are calculated based on the system's ranging range. Simultaneously, the segmented regions are adaptively adjusted based on the time relationship between the echo and the boundary position. The hardware and algorithm work together to allow the segmented gain to be flexibly adjusted according to actual ranging requirements, ensuring that the circuit can reasonably amplify the signal in different distance segments, providing an efficient and stable gain adjustment mechanism for laser ranging systems. Attached Figure Description

[0064] Figure 1 This is a flowchart of an adaptive segmented gain multi-wavelength laser ranging method according to an embodiment of the present invention;

[0065] Figure 2 This is a system block diagram illustrating an adaptive piecewise gain multi-wavelength laser ranging method according to an embodiment of the present invention.

[0066] Figure 3 This is a schematic diagram of the circuit segmented gain principle according to an embodiment of the present invention;

[0067] Figure 4 This is an example diagram of an equal-interval transmission method according to an embodiment of the present invention;

[0068] Figure 5 This is an example diagram of the segmented gain of the circuit according to an embodiment of the present invention;

[0069] Figure 6 This is a system unit diagram of an embodiment of the present invention. Detailed Implementation

[0070] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0071] Example 1

[0072] Please refer to Figure 1 This embodiment 1 provides an adaptive piecewise gain multi-wavelength laser ranging method, including:

[0073] S1. A multi-wavelength laser emits laser pulses via a transmitting optical system under the control of a trigger signal; the triggering methods include synchronous emission, equally spaced emission, and coded emission.

[0074] S2. The laser pulse is reflected by the target to form an echo, and the receiving system makes each wavelength echo receive the detector separately;

[0075] S3. Echoes of different wavelengths are converted into electrical signals by a segmented gain module, and then into digital signals by a high-speed analog-to-digital converter. The control processing module processes the digital signals and calculates information including ranging values ​​and echo intensity according to design requirements.

[0076] S4. The problem of simultaneously detecting weak signals at long distances and strong signals at close range is solved by adaptive segmented gain settings: In the close range, a low amplification gain circuit is used to suppress the echo intensity of the close-range signal; outside the close range, a high amplification gain circuit is switched to improve the detection capability of weak signals at long distances; at the same time, the number of gain segments is further increased according to the needs of the measurement range to form a stepped gain; and the segmented regions are adaptively adjusted according to the echo ranging value, etc., to avoid signal distortion.

[0077] S5. The control processing module communicates and transmits the processed data to the host computer.

[0078] This embodiment 1 provides a detailed explanation of the above method steps:

[0079] Please refer to Figure 2This embodiment 1 includes a multi-wavelength laser transceiver module, a segmented gain module, and a control processing module. Under the control of a trigger signal, the multi-wavelength laser emits laser pulses through the transmitting optical system. These laser pulses are reflected by the target, forming echoes that are received by the receiving optical system. The echoes of different wavelengths are split by the beam splitting system and then converted into electrical signals by the segmented gain module. These signals are then converted into digital signals by a high-speed analog-to-digital converter and processed by the control processing module to obtain corresponding ranging values, echo intensities of different wavelengths, and other information. Finally, the control processing module communicates with the host computer and transmits data.

[0080] Multi-wavelength laser transceiver module. By using lasers of different wavelengths to emit light alternately, and employing beam splitting and narrowband filtering in the receiving system, the echoes of different wavelengths are received by separate detectors, avoiding mutual interference between laser pulses of different wavelengths.

[0081] There are three main ways to trigger lasers of different wavelengths: synchronous emission, equally spaced emission, and coded emission, each corresponding to different application scenarios and purposes.

[0082] Synchronous transmission is mainly used for simultaneous detection of different media, such as airborne blue-green depth sounding lidar that simultaneously detects the water surface and underwater, or in scenarios where high spectral and time synchronization is required, such as high-speed scanning or situations where the carrier is moving at high speed and the target is far away. This avoids measurement inaccuracies caused by different laser pulses hitting different targets due to asynchronous transmission.

[0083] The purpose of the equally spaced emission method is to ensure the uniformity of the laser trigger interval, thereby ensuring the uniformity of the measured point cloud and facilitating subsequent point cloud processing. Within the same ranging ambiguity range, the number of lasers of different wavelengths determines the multiple of the maximum measurement frequency of this invention compared to traditional single-wavelength laser ranging.

[0084] The coded transmission method further expands the unambiguous ranging range and enhances resistance to interference from other lidar systems. By encoding the trigger intervals of lasers of different wavelengths and determining the relative positional relationship between the ranging values ​​received from echoes of different wavelengths, it identifies which laser trigger to match the echo, overcoming the ambiguity limitations of single-pulse ranging or determining whether the echo belongs to a laser pulse emitted by this system, thus avoiding interference from other laser measurement systems. In terms of increasing the measurement frequency, the coded transmission method requires fewer lasers of different wavelengths compared to the equal-interval transmission method, but it does require an additional encoding / decoding processing module.

[0085] Furthermore, the echoes of each wavelength carry the reflectivity information of the target at that wavelength. By measuring different wavelengths, multispectral information of the target can be obtained, generating a colored point cloud. Since the laser pulses of different wavelengths are not emitted simultaneously in the equal-interval emission method and the coded emission method, the echoes of different wavelengths do not represent the same target. Therefore, it is necessary to achieve spectral registration of the same target by upsampling interpolation of point clouds of different wavelengths.

[0086] An adaptive segmented gain module addresses the challenge of simultaneously detecting weak signals at long distances and strong signals at close range. Within the close-range range, a low-amplification gain circuit suppresses the echo intensity of the nearby signal. Outside this range, a high-amplification gain circuit is switched on to enhance the detection capability of weak signals at long distances. Since the feedback mechanism for echo signal intensity in adaptive gain control is not required, issues related to dynamic response speed and complex control algorithms are avoided, thus improving system reliability. Depending on the required measurement range, the number of gain segments can be further increased to create a stepped gain.

[0087] To ensure a reasonable gain range and signal quality, if the system's ranging range is designed to be d min ~d max If the total number of gain levels is L, then the boundary between the i-th gain level and the (i+1)-th gain level is defined as:

[0088]

[0089] Furthermore, in order to avoid distortion of the echo signal during gain switching between adjacent regions, it is necessary to adaptively adjust the segmented regions within a certain range.

[0090] Please refer to Figure 3 Based on the echo ranging value obtained from the previous laser trigger and the boundary position of the segmented gain region, the time interval between the echo and the boundary position is calculated. If the absolute value of the time interval is less than a threshold, the position of the boundary position on the time axis is increased / decreased accordingly, so that the boundary position is far away from the effective echo region. When the boundary position is adjusted to the upper (lower) limit of the allowable adjustment range, the boundary position is readjusted to the lower (upper) limit, the initial position, or any position without echo.

[0091] In a preferred embodiment, the segmented region is adaptively adjusted based on echo ranging values ​​to avoid signal distortion. The specific method is as follows:

[0092] Let the echo ranging value obtained from the previous laser trigger be d. measured ;

[0093] Let the time interval between the echo and the boundary position be Δt. e-b It is obtained by converting the echo ranging value and the boundary distance through the speed of light c, that is:

[0094]

[0095] Let the adjustment threshold be T. adj The lower limit of the boundary adjustment range is T. org The upper limit of the boundary adjustment range is T. org +ΔT, the distance between the boundary between the adjusted i-th gain and the (i+1)-th gain is

[0096] Determine |Δt e-b |with T adj The magnitude relationship, and Δt e-b The relative position of the boundary adjustment range;

[0097] When |Δt e-b | <T adj And Δt e-b When it approaches the lower limit of the range, that is Adjust the boundary to the distance corresponding to the upper limit of the range:

[0098]

[0099] When |Δt e-b | <T adj And Δt e-b When approaching the upper limit of the range, i.e. Adjust the boundary to the distance corresponding to the upper limit of the range:

[0100]

[0101] When |Δt e-b |≥T adj The position of the boundary remains unchanged, that is:

[0102]

[0103] When the boundary position is adjusted to the upper or lower limit of the allowable adjustment range, the boundary position can be readjusted to the lower limit, upper limit, initial position, or any position without echoes. reset :

[0104] like or but

[0105] Please refer to Figure 4 The specific implementation of the multi-wavelength equally spaced transmission method in a multi-wavelength laser transceiver module is shown in the figure below: For a laser transceiver module with M wavelengths, after setting the trigger frequency of the single-wavelength laser to PRR, the trigger interval between different wavelength lasers is set to... This increases the laser measurement frequency by M times.

[0106] Because airborne lidar systems strive to maintain uniformity in point density directly below the target area by adjusting parameters such as rotation speed, point frequency, and flight speed during scanning, upsampling interpolation and spectral registration of point clouds at different wavelengths only require consideration of the scan line direction. Assume the echo intensity of the j-th laser trigger at wavelength λ1 is... Then for the echo intensity sequence The interpolated echo intensity sequence is obtained by performing M-fold interpolation. The calculation formula is as follows:

[0107]

[0108] In the formula, k represents the interpolated sequence. And the index values ​​of the relevant intermediate interpolation sequences; The sequence is If M-1 zeros are inserted between each pair of values ​​in the sequence, then... The length of the sequence becomes The sequence is M times the original sequence; for the echo intensity sequences before and after interpolation, we have:

[0109]

[0110] Therefore, for an echo intensity sequence of M wavelengths emitted at equal intervals, the target spectral information obtained by the j-th laser trigger at the m-th wavelength is:

[0111]

[0112] In the formula, each parameter represents λ1, which represents I. j The vector representing the interpolated echo intensity values ​​of each wavelength in the sequence of M equally spaced echo intensity signals, obtained during the j-th laser trigger, represents the target spectral information obtained in this trigger. M represents the interpolation factor, which is the factor by which the data density of the original echo intensity sequence is increased when interpolating. m represents the m-th wavelength used to identify the multi-wavelength system, where m = 1, 2, ..., M.

[0113] The above is only one example of upsampling interpolation and spectral registration; other interpolation algorithms can also be used.

[0114] Please refer to Figure 5 In a preferred implementation, the specific method for achieving segmented gain in the circuit is as follows: Multiple resistors with varying resistance values ​​are connected in parallel in the transimpedance amplifier circuit at the back end of the detector. Each parallel resistor is connected in series with a switching device to control the switching on and off of the resistor in the transimpedance amplifier circuit. The switching device is controlled by the control and processing module via high and low level signals.

[0115] The equivalent transimpedance of the transimpedance amplifier circuit is:

[0116]

[0117] Where g(i) = 0, 1 represents the state of the i-th switch, and R i Let be the resistance value of the i-th resistor. Through proper resistance value design, a maximum value of 2 can be obtained. N -1 different resistance range.

[0118] For a simple example, two resistors, a 1k ohm and a 10k ohm, are designed for range switching. The 10k ohm resistor's switch is normally closed, while the 1k ohm resistor's switch is activated by high / low level signals from the control and processing module. This avoids the race condition that could occur if both resistors switch simultaneously, leading to a simultaneous open circuit. In this example, the gain is divided into two levels: a 10k level with a single 10k ohm resistor, and a 0.9k level with a 10k ohm resistor and a 1k ohm resistor connected in parallel. If the system's ranging range is designed to be 5m to 1500m, the boundary between the two gain levels is set as follows:

[0119]

[0120] The boundary between the two gain levels is determined by the time difference Δt between the center time of the previous echo and the boundary. e-b The decision to adjust is limited to a certain area at the initial boundary. A specific adjustment strategy is given below:

[0121] Directly set the upper and lower limits of the boundary adjustment range [T] org ,T org +200ns], when |Δt e-b | Less than the adjustment threshold T adj Furthermore, when the value approaches the lower limit of the range, adjust the boundary to the upper limit of the range, and vice versa. Adjust the threshold T. adj The minimum value is determined based on the echo pulse width; otherwise, the boundary would fall within the echo waveform. For example, the threshold T will be adjusted. adj Set to 3 times the echo pulse width, that is, when the echo pulse width is 10ns, adjust the threshold T. adj Set to 30ns.

[0122] For multi-level gain or other complex situations, more refined adjustment strategies can be designed.

[0123] Example 2

[0124] Please refer to Figure 4 This embodiment 2 provides an adaptive segmented gain multi-wavelength laser ranging system, including:

[0125] The laser emitting unit is used to emit laser pulses from a multi-wavelength laser via an emitting optical system under the control of a trigger signal; the triggering methods include synchronous emission, equally spaced emission, and coded emission.

[0126] The echo receiving unit is used to generate echoes when laser pulses are reflected by the target, and the receiving system enables the detectors to receive the echoes of each wavelength separately.

[0127] The signal conversion and processing unit is used to convert echoes of different wavelengths into electrical signals via a segmented gain module, and then generate digital signals via a high-speed analog-to-digital converter. The control processing module processes the digital signals and calculates information including ranging values ​​and echo intensity according to design requirements.

[0128] The gain adjustment unit is used to solve the problem of simultaneously detecting weak signals at long distances and strong signals at close range through adaptive segmented gain settings: within the close range, a low amplification gain circuit is used to suppress the echo intensity of the close-range signal; outside the close range, a high amplification gain circuit is switched to improve the detection capability of weak signals at long distances; at the same time, the number of gain segments is further increased according to the needs of the measurement range to form a stepped gain; and the segmented regions are adaptively adjusted based on echo ranging values, etc., to avoid signal distortion.

[0129] The control processing unit is used to control the processing module to communicate and transmit the processed data with the host computer.

[0130] Example 3

[0131] This embodiment 3 also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, can implement any step of an adaptive segmented gain multi-wavelength laser ranging method.

[0132] The computer-readable storage medium may include various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0133] For a description of the computer-readable storage medium provided in this application, please refer to the above method embodiments; further details will not be repeated here.

[0134] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for multi-wavelength laser ranging with adaptive segment gain, characterized in that, Comprise: S1. Multi-wavelength laser under the control of trigger signal, through the emission optical system emits laser pulse; Trigger mode includes synchronous emission, equal interval emission and coded emission; S2. Laser pulse is reflected by the target to form echo, and each wavelength echo is received by the detector by the receiving system; S3. Different wavelength echoes are converted into electrical signals by the segmented gain module, and then digital signals are generated by high-speed analog-digital conversion, and the digital signals are processed by the control processing module, and information including ranging value and echo intensity is calculated according to the design requirement; S4. The simultaneous detection problem of weak signals at long distance and strong signals at short distance is solved by adaptive segmented gain setting: in the short distance range, low amplification gain circuit is used to suppress the echo intensity of short distance signals; Outside the short distance range, switch to high amplification gain circuit to improve the detection ability of weak signals at long distance; According to the measurement range, further increase the number of gain partitions to form a step gain; At the same time, according to the echo ranging value, the segmented area is adaptively adjusted to avoid signal distortion; S5. The control processing module communicates and transmits the processed data with the host computer; The specific method of S4 is: Let the echo ranging value obtained by the last laser trigger be ; Let the time interval between the echo and the intersection location be The range value from the echo and the intersection location distance by the speed of light converted, namely: ， The adjustment threshold is set as , the lower limit of the adjustment range of the junction is , the upper limit of the adjustment range of the junction is , the distance between the junction of the adjusted gain of the first gear and the adjusted gain of the first gear is ; judging the size relationship of and the relative position to the interface adjustment range; When And At the lower end of the proximity range, i.e. Adjust the junction to the distance corresponding to the upper end of the range: ， When And Approaching the upper range limit, i.e. Adjust the junction to the distance corresponding to the upper range limit: ， When , the junction position remains unchanged, i.e.: ， When the interface position is adjusted to the upper limit or the lower limit of the allowable adjustment range, the interface position can be readjusted to the lower limit, the upper limit, the initial position, or any echo-free position : If or then .

2. The method according to claim 1, wherein, The scene distribution adaptation of S1 is: Synchronous emission mode is used for simultaneous detection of different media; The purpose of equal interval emission mode is to ensure the uniformity of laser trigger interval, so as to ensure the uniformity of measurement point cloud, which is convenient for subsequent point cloud processing; The coded emission mode can further expand the range of distance measurement without ambiguity and the anti-interference ability of other laser radars. By encoding the trigger interval of different wavelength lasers, and according to the relative position relationship between the ranging values of different wavelength receiving echoes, it is judged that the echo matches the first laser trigger, which breaks through the range limitation of single pulse distance measurement ambiguity, or judges whether the echo belongs to the laser pulse echo of the system, avoiding the interference of other laser measurement systems. 3.The method of claim 1, wherein, The receiving system in S2 adopts the method of light splitting and narrowband filtering to make different wavelength echoes received by the detector, avoiding the mutual interference of different wavelength laser pulses.

4. The method of claim 1, wherein, The setting method of gain partition in S4 is: The ranging range of the system is designed as , the total number of gain gears is , the first gear gain and the first gear gain are set as : ， wherein and are the maximum and minimum values of the distance at the junction, corresponding to the upper and lower limits of the range of adjustment of the junction.

5. The method of claim 1, wherein, The equal interval emission mode of multi-wavelength laser in S1 is: For the laser transceiver module of M wavelengths, the trigger frequency of single-wavelength laser is set as Afterwards, the trigger interval between different wavelength lasers is set as ; According to the calculated trigger interval, the laser of different wavelengths is triggered to emit laser pulse in turn; That is, after the first wavelength laser emits, the second wavelength laser is triggered to emit after a certain time interval, and so on, until all M wavelength lasers complete one emission; Then start a new round of emission from the first wavelength laser, and so on, to ensure the uniformity of laser trigger interval; The emitted laser pulses are reflected by the target to form echoes, and the receiving optical system is responsible for collecting these echoes; different wavelengths of echoes are split by the light splitting system, and then received by corresponding detectors and converted into electrical signals, and then digital signals are generated through high-speed analog-to-digital conversion; the control processing module processes these digital signals to calculate information including corresponding ranging values and echo intensities of different wavelengths; Since the laser pulses of different wavelengths are not emitted at the same time in the equal-interval emission mode, the echoes of different wavelengths are not measured for the same target, and therefore, the spectral registration of the same target is achieved through upsampling and interpolation of different wavelength point clouds.

6. The method of claim 5, wherein the adaptive range segmentation is performed by a processor. The method for achieving spectral registration of the same target through upsampling and interpolation of different wavelength point clouds is specifically: Upsampling and interpolation of different wavelength point clouds and spectral registration only need to consider the scanning line direction; Assume the wavelength of the first laser trigger is , then the echo intensity sequence is interpolated M times to obtain the interpolated echo intensity sequence , and the calculation formula is as follows: ， wherein represents the interpolated sequence and the index values of the related intermediate interpolation sequence; the sequence is M-1 zeros are inserted between each pair of values of the sequence, so that the length of the sequence becomes M times the length of the sequence; for the echo intensity sequence before and after interpolation, there is: ， Thus for an echo intensity sequence of M wavelengths emitted at equal intervals, the target spectral information obtained by the Mth laser trigger is: the target spectral information obtained by the Mth laser trigger is: the target spectral information obtained by the Mth laser trigger is: ， In the formula, each parameter represents express Indicates equal intervals of emission In the echo intensity sequence of the i-th wavelength, the i-th During the laser triggering, the vector composed of the interpolated echo intensity values ​​corresponding to each wavelength represents the target spectral information obtained during this triggering. This indicates the interpolation factor, which represents the factor by which the data density of the original echo intensity sequence is increased when interpolating it. This indicates the m-th wavelength used to identify a multi-wavelength system. .

7. The method of claim 1, wherein, The specific method of adaptive segmented gain in S4 is: Parallel resistors with multiple resistance values are arranged in the transimpedance amplification circuit at the back end of the detector, and each parallel resistor is connected in series with a switching device for controlling the connection and disconnection of the resistor in the transimpedance amplification circuit; the switching device is controlled by the control and processing module through high and low levels The equivalent transimpedance of the transimpedance amplification circuit is: ， wherein is the state of the th switch, is the resistance of the th resistor.

8. A multi-wavelength laser ranging system with adaptive segment gain, characterized in that, It comprises: A laser emission unit for emitting laser pulses through an emission optical system under the control of a trigger signal; The trigger mode includes synchronous emission, equal-interval emission, and coded emission; An echo receiving unit for receiving echoes of laser pulses reflected by the target through a receiving system; A signal conversion and processing unit for converting different wavelength echoes into electrical signals through a segmented gain module, and then generating digital signals through high-speed analog-to-digital conversion, and processing digital signals by a control processing module to calculate information including ranging values and echo intensities according to design requirements; A gain adjustment unit for solving the problem of simultaneous detection of weak signals at a long distance and strong signals at a short distance through adaptive segmented gain setting: in the short distance range, a low amplification gain circuit is used to suppress the echo intensity of the short distance signal; outside the short distance range, a high amplification gain circuit is switched to improve the detection capability of weak signals at a long distance; at the same time, according to the needs of the measurement range, the number of gain partitions is further increased to form a step gain; at the same time, the segmented regions are adaptively adjusted according to the echo ranging value and the like to avoid signal distortion; A control processing unit for communicating and transmitting the processed data to an upper computer by the control processing module; The specific method of adaptively adjusting the segmented regions according to the echo ranging value and the like in the gain adjustment unit to avoid signal distortion is: Let the echo ranging value obtained by the last laser trigger be ; Let the time interval between the echo and the intersection location be The distance from the echo ranging value and the intersection location distance by the speed of light is converted, i.e.: ， The adjustment threshold is set as , the lower limit of the adjustment range of the junction is , the upper limit of the adjustment range of the junction is , the distance between the adjusted first The gain and the junction of the first The gain is ; determining the size relationship of and the relative position to the interface adjustment range; When And At the lower end of the proximity range, i.e. Adjust the junction to the distance corresponding to the upper end of the range: ， When And Approaching the upper range limit, i.e. Adjust the junction to the distance corresponding to the upper range limit: ， When , the junction position remains unchanged, i.e.: ， When the interface position is adjusted to the upper limit or the lower limit of the allowable adjustment range, the interface position can be readjusted to the lower limit, the upper limit, the initial position, or any echo-free position : If or then .

9. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to perform the adaptive segmented gain multi-wavelength laser ranging method of any one of claims 1-7.

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