Laser range finder strong light avoidance system and detection algorithm based on main echo combination detection

Abstract

This invention relates to the field of laser ranging technology, and in particular to a strong light avoidance system and detection algorithm for a laser rangefinder based on main echo merging detection. In the strong light avoidance system, a laser emitting unit emits probe photons and simultaneously outputs a main wave electrical signal; a photoelectric detection unit receives the reflected probe photons and converts them into echo electrical signals; a signal recording unit records the generation time and pulse width of the main wave electrical signal and the echo electrical signal, and transmits this data to a time calculation unit; the time calculation unit calculates the time difference between the two signals and the total pulse width of the merged pulse, and transmits this data to a control unit; the control unit calculates the echo energy based on the echo electrical signal, compares the total pulse width of the merged pulse and the echo energy with preset thresholds, and controls a protection execution unit to perform shutdown, current limiting, or light-shielding protection operations on the photoelectric detection unit. In this way, strong light can be detected immediately at the initial stage of strong light interference, improving detection response speed and accuracy, achieving graded protection, and preventing damage to the photoelectric detection unit.

Description

Technical Field

[0001] This invention relates to the field of laser ranging technology, and in particular to a laser rangefinder avoidance system and detection algorithm based on main echo merging detection. Background Technology

[0002] Laser rangefinders, with their non-contact and high-precision measurement advantages, are widely used in various ranging scenarios such as autonomous driving, drone navigation, industrial surveying, and aerospace telemetry and control. The core component of a laser rangefinder is the photodetector. Photodetectors are highly sensitive devices, exhibiting extremely high sensitivity to strong light, requiring specific strong light protection to prevent damage. For example, InGaAs detectors are sensitive to light exceeding 10W / cm². 2 Under continuous exposure, it will be permanently damaged and unable to continue to perform normal ranging functions.

[0003] The core of existing laser rangefinders lies in signal transmission and reception, as well as subsequent time measurement. A laser emitting unit emits probe photons, which are then received by a photoelectric detection unit after reflection from the object being measured. The photoelectric detection unit converts these photons into an echo signal, and the control unit calculates the distance by combining the time difference between the main wave signal and the echo signal. The proper functioning of the photoelectric detector is fundamental to the entire ranging process; if the photoelectric detector is damaged by strong light, the entire laser rangefinder system will completely lose its ranging capability.

[0004] In actual ranging operations, the intensity of strong light exhibits a significant attenuation pattern with varying ranging distance, meaning the intensity decreases quadratically with distance. This makes it difficult to quantitatively determine the target's strong light intensity at different ranging distances, hindering the provision of accurate data to support the protection requirements of photoelectric detectors and making it difficult to achieve tiered protection. Furthermore, in scenarios involving moving targets, laser rangefinder systems need to track the target in real time and complete continuous ranging. Current technologies lack efficient strong light detection mechanisms, making it difficult to quickly capture dynamic changes in strong light and trigger protective actions in a timely manner.

[0005] Specifically, existing technologies do not incorporate the characteristics of the main wave and echo signals of the laser rangefinder itself for detection. They cannot utilize the correlation between the main wave electrical signal and the echo electrical signal to achieve rapid identification of strong light. Consequently, the laser rangefinder system cannot promptly control the protection execution unit to shut down, limit current, or shield the photoelectric detection unit. This not only easily leads to damage to the photoelectric detector due to strong light exposure, but also causes problems such as distance measurement interruption and inaccurate distance measurement results, seriously affecting the stable and reliable operation of the laser rangefinder system.

[0006] Therefore, it is imperative for those skilled in the art to solve the aforementioned problems. Summary of the Invention

[0007] The purpose of this invention is to provide a laser rangefinder strong light avoidance system based on main echo merging detection, which aims to solve the problems in existing designs where it is difficult to quantify strong light from targets, strong light detection is lagging in mobile target scenarios, and the system does not combine the characteristics of the main echo signal to achieve rapid identification, thus failing to protect the photodetector in a timely manner and affecting the stable operation of the system.

[0008] This invention relates to a laser rangefinder strong light avoidance system based on main echo merging detection, comprising a power supply unit, a control unit, a laser emitting unit, a photoelectric detection unit, a signal recording unit, a time calculation unit, a communication unit, and a protection execution unit; The power supply unit provides power support for the control unit, laser emission unit, photoelectric detection unit, signal recording unit, time calculation unit, communication unit, and protection execution unit; The laser emitting unit is electrically connected to the control unit. It is used to emit detection photons and synchronously output the main wave electrical signal. The photoelectric detection unit is used to receive the detection photons reflected by the object being measured and convert them into echo electrical signals. The signal recording unit is electrically connected to the laser emitting unit, the photoelectric detection unit, and the time calculation unit, respectively. It is used to record the generation time and pulse width of the main wave electrical signal and the generation time and pulse width of the echo electrical signal, and transmit all the recorded data to the time calculation unit. The time calculation unit is electrically connected to the control unit. It is used to calculate the time difference between the main wave electrical signal and the echo electrical signal, as well as the total pulse width of the combined pulse formed by the overlap of the main wave electrical signal and the echo electrical signal, and transmits the calculated time difference and the total pulse width of the combined pulse to the control unit. The protection execution unit is electrically connected to the control unit and the photoelectric detection unit respectively. It is used to receive control commands issued by the control unit and perform shutdown, current limiting or light shielding operations on the photoelectric detection unit according to the control commands. The communication unit is electrically connected to the control unit. It is used to provide feedback on the ranging results and report strong light alarm information to the outside world. It also receives and transmits start ranging command and stop ranging command from the outside to the control unit. The control unit is used to calculate the echo energy based on the echo electrical signal, compare the total pulse width of the merged pulse and the echo energy with preset thresholds respectively, control the protection execution unit to execute the graded protection strategy according to the comparison result, calculate the ranging result according to the time difference transmitted by the time calculation unit, and control the working status of the laser emitting unit, photoelectric detection unit, signal recording unit and time calculation unit according to the external instructions transmitted by the communication unit. The preset thresholds include detector damage thresholds and detector alarm thresholds; and the detector alarm threshold is 30% to 50% of the detector damage threshold.

[0009] As a further improvement to the technical solution disclosed in this invention, the power supply unit includes an input power module and a power conversion module; the input power module and the power conversion module are electrically connected.

[0010] As a further improvement to the technical solution disclosed in this invention, the power conversion module is an isolated power conversion module, used to provide isolated power supply for the control unit, laser emitting unit, photoelectric detection unit, signal recording unit, time calculation unit, communication unit and protection execution unit; the input power module has a built-in surge protection circuit and electromagnetic compatibility filter circuit.

[0011] As a further improvement to the technical solution disclosed in this invention, the photoelectric detection unit includes a photoelectric detection module and a signal conditioning module; the photoelectric detection module and the signal conditioning module are electrically connected; the photoelectric detection module is used to convert the detection photons into echo analog electrical signals; the signal conditioning module is used to amplify, filter and perform analog-to-digital conversion on the echo analog electrical signals, output digital echo electrical signals and transmit them to the signal recording unit.

[0012] As a further improvement to the technical solution disclosed in this invention, the photoelectric detection module is an avalanche photodiode detector; the signal recording unit includes a main wave time recording module and an echo time recording module; the main wave time recording module is electrically connected to the laser emission unit and is used to record the generation time and main wave pulse width of the main wave electrical signal; the echo time recording module is electrically connected to the signal conditioning module and is used to record the generation time and echo pulse width of the digital echo electrical signal.

[0013] As a further improvement to the technical solution disclosed in this invention, the time calculation unit includes a time-to-digital converter chip; the time-to-digital converter chip is used only to perform high-precision time measurement operations.

[0014] Furthermore, this invention also discloses a strong light avoidance detection algorithm for laser rangefinders based on main echo merging detection, applied to a strong light avoidance system for laser rangefinders based on main echo merging detection, comprising the following steps: S1. When the system is powered on, the control unit continuously checks whether it receives an externally sent start ranging command through the communication unit; if it does not receive it, it continues to check; if it receives it, it executes S2. S2. The control unit controls the laser emitting unit to emit a detection laser and simultaneously outputs the main wave electrical signal; S3. The signal recording unit acquires and records the generation time and pulse width of the main wave electrical signal, and transmits the recorded data to the time calculation unit. S4. The photoelectric detection unit receives the detection laser reflected by the object being measured, converts it into an echo electrical signal, and transmits it to the signal recording unit. S5. The signal recording unit acquires and records the generation time and pulse width of the echo electrical signal, and transmits the recorded data to the time calculation unit. S6. The time calculation unit calculates the time difference between the main wave electrical signal and the echo electrical signal, as well as the total pulse width of the combined pulse formed by the overlap of the main and echo signals, based on the recorded data, and transmits the time difference and the total pulse width of the combined pulse to the control unit. S7. The control unit calculates the echo energy based on the echo electrical signal and adopts the main echo merging detection method, using the total pulse width of the merged pulse and the echo energy as dual criteria for strong light detection. S8. The control unit determines whether the total pulse width of the combined pulse or the echo energy is greater than the detector damage threshold. If yes, execute S9; otherwise, execute S10. S9. The control unit controls the protection execution unit to perform protection operations on the photoelectric detection unit, reports strong light alarm information to the outside world through the communication unit, terminates the current ranging and executes S13. S10. The control unit determines whether the total pulse width of the combined pulse or the echo energy is greater than the detector alarm threshold. If yes, S11 is executed; otherwise, S12 is executed. S11. The control unit reports the strong light alarm information to the outside world through the communication unit, and then executes S12; S12. The control unit calculates the ranging result based on the time difference and feeds back the ranging result to the outside world through the communication unit; S13. The control unit detects whether it has received an externally sent stop ranging command through the communication unit; if it has not received it, it returns to S2 to continue ranging; if it has received it, it terminates the overall ranging process.

[0015] As a further improvement to the technical solution disclosed in this invention, in S7, the strong light detection is based on a dual-criteria logic: combining the judgment of abnormal total pulse width and the judgment of abnormal echo energy; if either the total pulse width or the echo energy meets the corresponding threshold condition, it is determined that strong light has been detected.

[0016] As a further improvement to the technical solution disclosed in this invention, the abnormal judgment of the total pulse width of the combined pulse is as follows: the control unit compares the total pulse width of the combined pulse with the preset normal ranging main wave pulse width threshold. If it is greater than the threshold, the pulse width is determined to be abnormal. The abnormal echo energy is determined by the control unit comparing the calculated echo energy with the preset normal ranging echo energy threshold. If the threshold is greater than the threshold, the energy is determined to be abnormal.

[0017] Regarding the topic of laser rangefinder strong light avoidance system based on main echo merging detection, it can achieve at least the following beneficial technical effects in practical applications, specifically: 1) The pulse width information of the main wave electrical signal and the echo electrical signal is collected by the signal recording unit. The total pulse width of the combined pulse formed by the overlap of the main wave electrical signal and the echo electrical signal is calculated by the time calculation unit. Combined with the echo energy, a two-dimensional strong light detection basis is formed. In this way, strong light can be determined in real time in the early stage of strong light interference by abnormal changes in the combined pulse width of the main wave electrical signal and the echo electrical signal. This effectively improves the response speed and accuracy of strong light detection and reserves sufficient time window for subsequent protective operations of the photoelectric detection unit. 2) Based on a tiered protection strategy, and with the strategy matching the detector damage threshold and alarm threshold of the photodetector, tiered execution of strong light warning and photodetector protection can be achieved. When strong light is detected approaching the detector damage threshold of the photodetector, the control unit immediately controls the protection execution unit to perform shutdown, current limiting, or light-shielding protection operations on the photodetector unit, effectively preventing permanent damage to the photodetector unit due to oversaturation of strong light. Furthermore, the control unit synchronously reports strong light alarm information through the communication unit, ensuring the laser rangefinder can operate continuously and stably in strong light environments.

[0018] Regarding the strong light avoidance detection algorithm for laser rangefinders based on main echo merging detection, steps S1 to S5 realize the accurate acquisition and data transmission of start command reception, detection laser emission, main wave electrical signal and echo electrical signal, providing comprehensive and reliable basic data support for subsequent strong light detection and ranging calculation, ensuring the accuracy of detection and calculation; step S6 completes the calculation of time difference and total pulse width of merged pulse through time calculation unit, providing core data basis for dual-criteria strong light detection in step S7; steps S7 to S11 construct a graded strong light response mechanism, combining detector damage threshold and detector alarm threshold to realize the linkage of strong light warning and protection operation; steps S12 to S13 complete the ranging result feedback and process closed-loop control, realizing continuous ranging and flexible start and stop in the scenario of changing mobile targets, ensuring the stable and efficient operation of the strong light avoidance system of laser rangefinder based on main echo merging detection. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the laser rangefinder strong light avoidance system based on main echo merging detection disclosed in this invention. Figure 2 This is a schematic diagram of the TDC signal counting of the laser rangefinder strong light avoidance system based on main echo merging detection disclosed in this invention. Figure 3 This is a flowchart illustrating the strong light avoidance detection algorithm for laser rangefinders based on main echo merging detection disclosed in this invention.

[0021] 1-Power supply unit; 11-Input power module; 12-Power conversion module; 2-Control unit; 3-Laser emission unit; 4-Photoelectric detection unit; 5-Signal recording unit; 51-Main wave time recording module; 52-Echo time recording module; 6-Time calculation unit; 7-Communication unit; 8-Protection execution unit. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments. Figure 1 The diagram shows the structural composition of the laser rangefinder strong light avoidance system based on main echo merging detection disclosed in this invention. It can be seen that the power supply unit 1 provides power support to the control unit 2, laser emission unit 3, photoelectric detection unit 4, signal recording unit 5, time calculation unit 6, communication unit 7, and protection execution unit 8. The laser emission unit 3, photoelectric detection unit 4, signal recording unit 5, time calculation unit 6, communication unit 7, and protection execution unit 8 are all electrically connected to the control unit 2. In practical applications, after receiving external commands through the communication unit 7, the control unit 2 controls the laser emitting unit 3 to emit detection photons and simultaneously output the main wave electrical signal; the photoelectric detection unit 4 receives the detection photons reflected by the object being measured, converts them into echo electrical signals, and transmits them to the signal recording unit 5; the signal recording unit 5 completes the acquisition and recording of key parameters of the main wave electrical signal and echo electrical signal, and transmits the recorded data to the time calculation unit 6 for calculation; the time calculation unit 6 feeds back the calculation results to the control unit 2, which then completes the distance measurement result calculation and strong light detection, and controls the protection execution unit 8 to perform protection operations on the photoelectric detection unit 4 based on the strong light detection results. At the same time, the control unit 2 realizes the distance measurement result feedback, strong light alarm information reporting, and external command reception through the communication unit 7, forming a complete closed-loop working logic.

[0023] It is known that during the operation of a laser rangefinder strong light avoidance system based on main echo merging detection, batch and continuous laser ranging operations can be achieved. Furthermore, it can rely on the main wave and echo signal characteristics of the laser rangefinder itself to complete rapid and accurate detection of strong light, simultaneously performing graded protection operations on the photoelectric detection unit 4. For example... Figure 2 , Figure 3As shown, the laser rangefinder strong light avoidance system based on main echo merging detection uses the total pulse width of the main echo merging pulse and the echo energy as dual criteria to carry out strong light detection, and sets matching graded protection thresholds. It can realize the instantaneous determination of strong light in the early stage of strong light interference, and at the same time provide accurate data support for the protection requirements of the photoelectric detection unit 4. It adapts to the strong light dynamic detection requirements in the scenario of changing mobile targets, and ensures the stable operation of the laser rangefinder strong light avoidance system based on main echo merging detection in complex ranging scenarios.

[0024] In practical applications, thanks to the innovative design concept of main echo merging detection, the total pulse width of the merged pulse and the echo energy are combined to form a two-dimensional basis for strong light detection, which effectively improves the response speed and judgment accuracy of strong light detection. It can effectively identify the strong light before it causes irreversible damage to the photoelectric detection unit 4, leaving sufficient time window for subsequent protective operations. Furthermore, it can also provide accurate and quantitative data support for the protection of the photoelectric detection unit 4, realize targeted and graded protection of the photoelectric detection unit 4, ensure continuous and stable ranging of the laser rangefinder in mobile target scenarios, and make the strong light detection and protection operation of the laser rangefinder strong light avoidance system based on main echo merging detection more scientific and accurate.

[0025] Furthermore, the laser rangefinder's strong light avoidance system based on main echo merging detection is equipped with a graded protection strategy. The control unit 2 can flexibly control the protection execution unit 8 to perform shutdown, current limiting, or light-shielding protection operations on the photoelectric detection unit 4 according to the strong light detection results. Moreover, the protection execution unit 8 and the communication unit 7 form a collaborative working mechanism. While the protection execution unit 8 performs the protection operation, the communication unit 7 simultaneously reports strong light alarm information to the outside world, which can effectively prevent the photoelectric detection unit 4 from being permanently damaged by strong light oversaturation irradiation, and at the same time ensure the continuous operation of the ranging work to the maximum extent in non-damaging strong light environments.

[0026] like Figure 1 As shown, the power supply unit 1 mainly consists of several parts, including an input power module 11 and a power conversion module 12. The input power module 11 and the power conversion module 12 are electrically connected. The power conversion module 12 is an isolated power conversion module, specifically designed to provide isolated power to the control unit 2, laser emitting unit 3, photoelectric detection unit 4, signal recording unit 5, time calculation unit 6, communication unit 7, and protection execution unit 8, effectively avoiding power interference between the units and ensuring their independent and stable operation.

[0027] Furthermore, the input power module 11 has a built-in surge protection circuit and electromagnetic compatibility filter circuit, which can effectively improve the anti-interference capability and power supply stability of the power supply unit 1, providing continuous and reliable power supply for the normal operation of the entire laser rangefinder avoidance system based on main echo merging detection. From the power supply perspective, it lays the foundation for the stable operation of the control unit 2, laser emitting unit 3, photoelectric detection unit 4, signal recording unit 5, time calculation unit 6, communication unit 7, and protection execution unit 8.

[0028] It is particularly important to emphasize that the photoelectric detection unit 4, as the core highly sensitive component of the laser rangefinder, is fundamental to the entire laser ranging process. This invention features a targeted structural optimization design for the photoelectric detection unit 4, which mainly consists of a photoelectric detection module and a signal conditioning module. The photoelectric detection module and the signal conditioning module are electrically connected. The photoelectric detection module is specifically used to convert the detected photons into echo analog electrical signals. The photoelectric detection module is preferably an avalanche photodiode detector, possessing high-sensitivity detection characteristics, enabling accurate capture of the detected photons reflected by the measured object. The signal conditioning module is specifically used to amplify, filter, and perform analog-to-digital conversion on the echo analog electrical signals, transmitting the processed digital echo electrical signals to the signal recording unit 5. Through professional conditioning and optimization of the echo analog electrical signals, the accuracy of the electrical signals is effectively improved, providing reliable and accurate data for signal recording in the signal recording unit 5 and data calculation in the time calculation unit 6, ensuring the accuracy of the signal acquisition stage of the entire laser rangefinder's strong light avoidance system based on main echo merging detection.

[0029] Correspondingly, the signal recording unit 5 includes a main wave time recording module 51 and an echo time recording module 52. The main wave time recording module 51 is electrically connected to the laser emitting unit 3 and is specifically used to record the generation time and pulse width of the main wave electrical signal. The echo time recording module 52 is electrically connected to the signal conditioning module and is specifically used to record the generation time and pulse width of the digital echo electrical signal. The modular dedicated recording design of the main wave time recording module 51 and the echo time recording module 52 realizes the accurate acquisition and classified transmission of the parameters of the main wave electrical signal and the echo electrical signal, ensuring the accuracy and orderliness of the signal recording by the signal recording unit 5 from the source.

[0030] It is known that the accuracy of time measurement directly affects the accuracy of the ranging results of a laser rangefinder, and also relates to the accuracy of calculating the total pulse width of the main echo merging pulse, thus having a crucial impact on the determination of strong light detection results. Therefore, as a further optimization of the above technical solution, the time calculation unit 6 includes a time-to-digital converter chip, used solely for performing high-precision time measurement operations. Figure 2The TDC signal counting can assist the time-to-digital converter chip in achieving more accurate time measurement. Through a dedicated chip, high-precision time calculation is achieved, which effectively improves the calculation accuracy of the time difference between the main wave electrical signal and the echo electrical signal, as well as the total pulse width of the merged pulse. This not only ensures the accuracy of the laser rangefinder's ranging results at the core level, but also provides accurate parameter support for the strong light dual-criteria detection of the control unit 2, effectively avoiding protection errors caused by calculation deviations.

[0031] There are various design approaches to the strong light avoidance detection algorithm of laser rangefinders to achieve strong light recognition. However, we recommend an implementation scheme that features fast detection response, high judgment accuracy, and adaptability to continuous ranging scenarios of moving targets. Specifically: Figure 3 The flowchart of the laser rangefinder strong light avoidance detection algorithm based on main echo merging detection disclosed in this invention is shown. This algorithm is specifically applied to the aforementioned laser rangefinder strong light avoidance system based on main echo merging detection, and includes the following steps: S1. When the system is powered on, the control unit 2 continuously detects whether it receives an externally sent start ranging command through the communication unit 7; if it does not receive it, it continues to detect; if it receives it, it executes S2. S2, Control Unit 2 controls Laser Emitting Unit 3 to emit detection laser and synchronously outputs main wave electrical signal; S3, Signal recording unit 5 collects and records the generation time and pulse width of the main wave electrical signal, and transmits the recorded data to time calculation unit 6; S4, the photoelectric detection unit 4 receives the detection laser reflected by the object being measured, converts it into an echo electrical signal and transmits it to the signal recording unit 5; S5, Signal recording unit 5 acquires and records the generation time and echo pulse width of the echo electrical signal, and transmits the recorded data to time calculation unit 6; S6. The time calculation unit 6 calculates the time difference between the main wave electrical signal and the echo electrical signal, as well as the total pulse width of the combined pulse formed by the overlap of the main echo, based on the recorded data, and transmits the time difference and the total pulse width of the combined pulse to the control unit 2. S7, Control Unit 2 calculates the echo energy based on the echo electrical signal, and adopts the main echo merging detection method, using the total pulse width of the merged pulse and the echo energy as dual criteria for strong light detection; S8. Control unit 2 determines whether the total pulse width of the combined pulse or the echo energy is greater than the detector damage threshold. If yes, execute S9; otherwise, execute S10. S9, Control Unit 2 controls Protection Execution Unit 8 to perform protection operation on Photoelectric Detection Unit 4, reports strong light alarm information to the outside world through Communication Unit 7, terminates the current ranging and executes S13; S10. Control unit 2 determines whether the total pulse width of the combined pulse or the echo energy is greater than the detector alarm threshold. If yes, execute S11; otherwise, execute S12. S11, Control unit 2 reports strong light alarm information to the outside world through communication unit 7, and then executes S12; S12, Control Unit 2 calculates the ranging result based on the time difference and feeds back the ranging result to the outside through Communication Unit 7; S13. Control unit 2 detects whether it has received an externally sent stop ranging command through communication unit 7; if it has not received it, it returns to S2 to continue ranging; if it has received it, it terminates the overall ranging process.

[0032] Depend on Figure 3 As shown in the diagram, the core innovation of the strong light avoidance detection algorithm lies in the dual-criteria strong light detection logic in S7, specifically the combined pulse total pulse width anomaly judgment and echo energy anomaly judgment. If either the combined pulse total pulse width or the echo energy meets the corresponding threshold condition, it is determined that strong light has been detected. Specifically, the combined pulse total pulse width anomaly judgment is as follows: the control unit 2 compares the combined pulse total pulse width with a preset normal ranging main wave pulse width threshold; if it is greater, the pulse width is determined to be abnormal. The echo energy anomaly judgment is as follows: the control unit 2 compares the calculated echo energy with a preset normal ranging echo energy threshold; if it is greater, the energy is determined to be abnormal. Thus, under the premise of achieving rapid strong light detection, the mutual verification of the dual criteria effectively reduces the false positive and false negative rates of strong light detection, ensuring that the protection execution unit 8's protective operation on the photoelectric detection unit 4 is triggered accurately and promptly. This effectively avoids the phenomenon of damage to the photoelectric detection unit 4 or unexplained interruption of ranging operation due to the limitations of single-criteria detection.

[0033] Finally, it should be noted that the above-mentioned preset thresholds include detector damage thresholds and detector alarm thresholds, and the detector alarm threshold is 30% to 50% of the detector damage threshold. This provides a precise and quantitative judgment standard for the graded protection strategy, enabling the control unit 2 to control the communication unit 7 to perform alarm prompts and control the protection execution unit 8 to perform protective operations according to the severity of the strong light. This fundamentally ensures the safety of the photoelectric detection unit 4 while maximizing the normal operation of the laser rangefinder.

[0034] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A laser rangefinder strong light avoidance system based on main echo merging detection, characterized in that, It includes a power supply unit, a control unit, a laser emission unit, a photoelectric detection unit, a signal recording unit, a time calculation unit, a communication unit, and a protection execution unit; The power supply unit provides power support to the control unit, the laser emitting unit, the photoelectric detection unit, the signal recording unit, the time calculation unit, the communication unit, and the protection execution unit. The laser emitting unit is electrically connected to the control unit, and is used to emit detection photons and synchronously output the main wave electrical signal; The photoelectric detection unit is used to receive the detection photons reflected by the object being measured and convert them into echo electrical signals. The signal recording unit is electrically connected to the laser emitting unit, the photoelectric detection unit and the time calculation unit respectively. It is used to record the generation time and pulse width of the main wave electrical signal and the generation time and pulse width of the echo electrical signal, and transmit all the recorded data to the time calculation unit. The time calculation unit is electrically connected to the control unit. It is used to calculate the time difference between the main wave electrical signal and the echo electrical signal, as well as the total pulse width of the combined pulse formed by the overlap of the main wave electrical signal and the echo electrical signal, and transmit the calculated time difference and the total pulse width of the combined pulse to the control unit. The protection execution unit is electrically connected to the control unit and the photoelectric detection unit respectively. It is used to receive control commands issued by the control unit and perform shutdown, current limiting or light shielding operations on the photoelectric detection unit according to the control commands. The communication unit is electrically connected to the control unit. It is used to provide feedback on the ranging results and report strong light alarm information to the outside world. It also receives and transmits start ranging command and stop ranging command from the outside to the control unit. The control unit is used to calculate the echo energy based on the echo electrical signal, compare the total pulse width of the merged pulse and the echo energy with preset thresholds respectively, control the protection execution unit to execute the graded protection strategy according to the comparison result, calculate the ranging result according to the time difference transmitted by the time calculation unit, and control the working status of the laser emitting unit, the photoelectric detection unit, the signal recording unit and the time calculation unit according to the external instructions transmitted by the communication unit. The preset thresholds include detector damage thresholds and detector alarm thresholds; and the detector alarm threshold is 30% to 50% of the detector damage threshold.

2. The laser rangefinder strong light avoidance system based on main echo merging detection according to claim 1, characterized in that, The power supply unit includes an input power module and a power conversion module; the input power module is electrically connected to the power conversion module.

3. The laser rangefinder strong light avoidance system based on main echo merging detection according to claim 2, characterized in that, The power conversion module is an isolated power conversion module, used to provide isolated power supply to the control unit, the laser emitting unit, the photoelectric detection unit, the signal recording unit, the time calculation unit, the communication unit and the protection execution unit; the input power module has a built-in surge protection circuit and an electromagnetic compatibility filter circuit.

4. The laser rangefinder strong light avoidance system based on main echo merging detection according to claim 1, characterized in that, The photoelectric detection unit includes a photoelectric detection module and a signal conditioning module; the photoelectric detection module is electrically connected to the signal conditioning module; the photoelectric detection module is used to convert the detected photons into echo analog electrical signals; the signal conditioning module is used to amplify, filter and convert the echo analog electrical signals into digital signals, output digital echo electrical signals and transmit them to the signal recording unit.

5. The laser rangefinder strong light avoidance system based on main echo merging detection according to claim 4, characterized in that, The photoelectric detection module is an avalanche photodiode detector; the signal recording unit includes a main wave time recording module and an echo time recording module; the main wave time recording module is electrically connected to the laser emitting unit and is used to record the generation time and main wave pulse width of the main wave electrical signal; the echo time recording module is electrically connected to the signal conditioning module and is used to record the generation time and echo pulse width of the digital echo electrical signal.

6. The laser rangefinder strong light avoidance system based on main echo merging detection according to claim 1, characterized in that, The time calculation unit includes a time-to-digital converter chip; the time-to-digital converter chip is used only to perform high-precision time measurement operations.

7. A laser rangefinder strong light avoidance detection algorithm based on main echo merging detection, applied to the strong light avoidance system of a laser rangefinder based on main echo merging detection as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. When the system is powered on, the control unit continuously detects whether it receives an externally sent start ranging command through the communication unit; if it does not receive it, it continues to detect; if it receives it, it executes S2. S2. The control unit controls the laser emitting unit to emit a detection laser and synchronously outputs the main wave electrical signal; S3. The signal recording unit acquires and records the generation time and pulse width of the main wave electrical signal, and transmits the recorded data to the time calculation unit. S4. The photoelectric detection unit receives the detection laser reflected by the object being measured, converts it into an echo electrical signal, and transmits it to the signal recording unit. S5. The signal recording unit acquires and records the generation time and pulse width of the echo electrical signal, and transmits the recorded data to the time calculation unit. S6. The time calculation unit calculates the time difference between the main wave electrical signal and the echo electrical signal, as well as the total pulse width of the combined pulse formed by the overlap of the main echo, based on the recorded data, and transmits the time difference and the total pulse width of the combined pulse to the control unit. S7. The control unit calculates the echo energy based on the echo electrical signal and adopts the main echo merging detection method, using the total pulse width of the merged pulse and the echo energy as dual criteria for strong light detection. S8. The control unit determines whether the total pulse width of the combined pulse or the echo energy is greater than the detector damage threshold. If so, S9 is executed; otherwise, S10 is executed. S9. The control unit controls the protection execution unit to perform protection operations on the photoelectric detection unit, reports strong light alarm information to the outside world through the communication unit, terminates the current ranging and executes S13. S10. The control unit determines whether the total pulse width of the combined pulse or the echo energy is greater than the detector alarm threshold. If yes, S11 is executed; otherwise, S12 is executed. S11. The control unit reports strong light alarm information to the outside world through the communication unit, and then executes S12; S12. The control unit calculates the ranging result based on the time difference and feeds back the ranging result to the outside through the communication unit. S13. The control unit detects whether it has received an externally sent stop ranging command through the communication unit; if it has not received it, it returns to S2 to continue ranging. If received, the overall ranging process is terminated.

8. The laser rangefinder strong light avoidance detection algorithm based on main echo merging detection according to claim 7, characterized in that, In S7, strong light detection uses a dual-criteria logic: combining the judgment of abnormal total pulse width and the judgment of abnormal echo energy; if either the total pulse width or the echo energy meets the corresponding threshold condition, it is determined that strong light has been detected.

9. The laser rangefinder strong light avoidance detection algorithm based on main echo merging detection according to claim 8, characterized in that, The abnormal determination of the total pulse width of the combined pulse is as follows: the control unit compares the total pulse width of the combined pulse with the preset normal ranging main wave pulse width threshold. If it is greater than the threshold, the pulse width is determined to be abnormal. The abnormal echo energy is determined by the control unit comparing the calculated echo energy with the preset normal ranging echo energy threshold. If the threshold is greater than the threshold, the energy is determined to be abnormal.

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