Galvanometer beating motion compensation method of material sorting device based on LIBS (Laser-induced Breakdown Spectroscopy)

Abstract

The invention belongs to the technical field of laser-induced breakdown spectroscopy (LIBS) online sorting, and provides a galvanometer striking motion compensation method of a material sorting device based on an LIBS technology. The external trigger signal sequentially controls the imaging module and the galvanometer to act, the camera obtains a multi-target initial position at a set moment through the hardware external trigger signal, and the computer combines the speed of the conveyor belt, the initial position of the galvanometer and target point distribution to determine the target position of the galvanometer based on the consistency constraint of the galvanometer moving time and the material advancing time. Dynamically calculating actual striking coordinates of each target and generating a task sequence; before striking, the galvanometer is preset at the material leaving end to wait for a hardware trigger signal. According to the method, through accurate striking time and position compensation, the problem of coordinate offset caused by multi-target time sequence, image-striking delay and conveyor belt displacement is effectively solved, and the accuracy of plasma spectrum acquisition is remarkably improved. The ablation stability and the spectrum repeatability can be further improved in combination with strategies such as synchronous following.

Description

Technical Field

[0001] This invention relates to the field of laser-induced breakdown spectroscopy (LIBS) online detection and sorting technology, specifically to a galvanometer impact motion compensation method for a LIBS-based material sorting device, belonging to industrial automation detection and sorting control. Background Technology

[0002] With the increasing demand for sustainable development, material recycling and efficient sorting play a crucial role in resource reuse. Currently, in the recycling of scrap aluminum, copper, magnesium, stainless steel, and other metals, laser-induced breakdown spectroscopy (LIBS) technology has become one of the main solutions in the field of online material sorting due to its characteristics of speed, non-destructive nature, and wide elemental detection range. Common LIBS sorting devices typically consist of a high-speed conveyor belt, a laser emission system, a galvanometer scanning system, a spectral acquisition system, and a sorting execution mechanism. By performing laser impact and plasma spectral analysis on metal samples on the conveyor belt, automated sorting of different metal categories is achieved.

[0003] However, in existing LIBS material sorting devices, the following problems exist during the galvanometer impact process:

[0004] 1. Image-impact delay leads to coordinate deviation: In traditional methods, there is a calculation and scheduling delay between imaging and laser impact. The high-speed operation of the conveyor belt (common speed of 1.5~2.5 m / s) will cause the target position to drift significantly, resulting in impact coordinate error, reducing spectral stability and sorting accuracy.

[0005] 2. Complex multi-target scheduling: Multiple targets may be detected in a single frame of image. Existing technologies typically employ a fixed order for sequential striking, without considering the coupling relationship between the galvanometer movement time and the material travel time, which can easily lead to the target "missing the optimal striking window".

[0006] 3. Sample displacement during the impact process: In high-speed sorting, when the galvanometer performs multi-pulse laser ablation, the sample moves continuously with the conveyor belt within the ablation time window, causing the laser to form an uncontrolled line ablation trajectory on the sample surface, resulting in laser energy dispersion and a decrease in plasma signal intensity. Especially under complex surface conditions such as paint, oxide layer, and contaminants, it is impossible to obtain a stable and effective bulk spectrum.

[0007] 4. Limitations of Existing "Flying Marking" Technology: "Flying marking" technology already exists in the fields of laser processing and laser cleaning. It uses a galvanometer to compensate for conveyor belt motion, enabling continuous graphic marking of a single task on a low-speed conveyor belt. However, this technology is not suitable for LIBS sorting scenarios:

[0008] LIBS testing requires pulse dwell and ablation on the target surface, rather than simple continuous mapping;

[0009] The sorting process requires rapid switching between multiple targets, and each switching requires compensation for the displacement of the conveyor belt.

[0010] Under high-speed conveyor belt conditions, the "flying marking" of single-task compensation cannot solve the problems of multi-task scheduling and time consistency.

[0011] Therefore, relying solely on existing "flying marking" technology is insufficient to meet the high-precision compensation and multi-target task coordination requirements of LIBS sorting.

[0012] To address the aforementioned issues, existing LIBS sorting solutions often rely on reducing conveyor belt speed or the number of multi-target tasks to improve accuracy. However, this significantly reduces system processing capacity and sorting efficiency, making it difficult to meet the demands of large-scale, high-speed industrial sorting. Therefore, a novel galvanometer impact motion compensation method is urgently needed to achieve high-precision dynamic compensation for multiple targets under high-speed operating conditions, and to provide assurance for subsequent spectral acquisition and sorting control. Summary of the Invention

[0013] The purpose of this invention is to achieve high-precision dynamic compensation for multiple targets under high-speed conveyor belt conditions based on external trigger timing control and motion compensation algorithms, so as to ensure that the galvanometer accurately hits the target within a predetermined time, thereby improving the spectral signal quality and sorting accuracy. On this basis, it can optionally support synchronous tracking to further optimize spectral line stability and system throughput.

[0014] The technical solution adopted in this invention is: a galvanometer impact motion compensation method for a LIBS-based material sorting device. During laser sorting, the following steps are performed to achieve motion compensation, thereby correcting the ablation spot position coordinates and optimizing the ablation trajectory, including the following steps:

[0015] During the laser sorting process, an industrial vision camera is triggered to capture images of multiple target samples that are randomly placed on a conveyor belt with disordered positions and irregular spacing. The original positions of the target samples are located using the visual images, and the ablation sequence of the multiple target samples is planned.

[0016] Combining the process timing of each sample impact by the galvanometer and the synchronous constraints of the conveyor belt, calculate the first... Dynamic ablation spot position of each target sample ;

[0017] Based on the constraint of consistency between the galvanometer movement time and the material travel time, dynamic compensation is performed on the impact time, and the compensation is calculated for the [missing information]. The optical spot correction coordinates of the target sample at the moment of galvanometer impact ;

[0018] The laser spot is controlled to follow the target sample along a preset ablation trajectory within the ablation time to perform impact ablation. The preset ablation trajectory parameters include: the initial position of the ablation laser spot during this movement. Length of ablation trajectory The ablation method is either a unidirectional single-pass ablation method or a reciprocating multi-pulse stacked ablation method using smaller line segments.

[0019] Based on the preset scheduling and priority strategy of galvanometer impact tasks, the ablation task queue with the sample is dynamically optimized to complete motion-compensated ablation in an orderly manner.

[0020] The method of visually locating the original position of the target sample and planning the ablation sequence of multiple target samples includes:

[0021] The industrial vision camera is triggered by a timing signal, causing it to move at any time. Multiple target samples were randomly placed on a conveyor belt, with disordered positions and varying spacing. Images;

[0022] Identify individual target samples in an image using machine vision methods. The original position is used to obtain the position set { }, and serve as the original impact coordinates of the galvanometer on each target sample, while simultaneously recording the corresponding timestamp information; where the set { } target sample The order in which the particles enter the field of view of the industrial vision camera is determined, and also serves as the order in which the galvanometer strikes and ablates them.

[0023] The process timing of each sample impact by the galvanometer and the synchronous constraint of the conveyor belt are combined to calculate the first... Dynamic impact position of each target sample include:

[0024] The sequence of each sample impact by the galvanometer is divided into a jump-movement sequence and an impact-ablation sequence.

[0025] Define the ablation time for each target sample. galvanometer from the first The target sample jumps to the first... The jump time for each target sample is ;

[0026] When the galvanometer begins to strike the first The first goal is to end the galvanometer reading. The moment of ablation of the target is approaching the first... The moment the target moves;

[0027] And because of the galvanometer before impact The mirror movement time and ablation time generated by the target are as follows, while the conveyor belt moves at a speed V. Therefore, the first... The dynamic position of the target sample is not the initial impact position. The position where the galvanometer strikes is defined as follows: ;

[0028] but =Original striking position + × (before) Cumulative galvanometer movement time for each target With cumulative ablation time (and); that is:

[0029]

[0030] The constraint based on the consistency between the galvanometer movement time and the material travel time is used to calculate the first... The target's deviation coordinates at the moment of galvanometer impact It is solved according to the following formula Complete the initial strike coordinates Dynamic compensation;

[0031]

[0032] in This represents the functional relationship between the distance the galvanometer moves and time. This is the time it takes for the galvanometer to move. For the first The coordinates of the target at the moment of impact with the galvanometer. For the first The position coordinates of the target at the moment of impact with the galvanometer.

[0033] The length of the ablation trajectory is calculated as follows: For the first... The target is when the galvanometer is in the dynamic compensation position. During the ablation process at the point, during the ablation time Inside, the optical path of the galvanometer is changed to control the ablation spot along the conveyor belt direction at the conveyor belt speed. Follow the ablation trajectory length. Set as This is used to ensure that laser ablation occurs at the same point on the target even when the target is in motion.

[0034] The initial position of the ablation spot during this movement The calculation is as follows: If the galvanometer controls the light spot to follow the ablation time, then for the th... The target, the initial position of the ablation spot controlled by the galvanometer during this movement. For the first The coordinates of the light spot at the moment the galvanometer strikes the target sample. With the length of the ablation trajectory The sum of:

[0035]

[0036] At this time, during the galvanometer jump time period The coordinates satisfy:

[0037]

[0038] The reciprocating multi-pulse stacking ablation using smaller line segments is as follows: if the galvanometer controls the ablation spot to follow within the ablation time, the galvanometer spot following speed is dynamically adjusted according to the specific situation, so that the ablation line segment is shorter or longer than under strict compensation, in order to achieve N ≥ 2 point-to-point or near-point multi-pulse stacking on the sample surface.

[0039] Where the conveyor belt speed Update in real time when fluctuations exceed the threshold. With constraint equations And dynamically adjust the timing of the strikes.

[0040] The strike task scheduling strategy adopts a joint cost function with the objective of minimizing the total travel time, and automatically discards or postpones unreachable targets. The unreachable targets include, but are not limited to, target samples that exceed the range of a single frame image.

[0041] A galvanometer impact motion compensation system for a LIBS-based material sorting device includes a front-end sensor and a back-end host computer.

[0042] The front-end sensor includes an industrial vision camera, a galvanometer optical path, and a laser-induced breakdown spectroscopy (LIBS) device. The industrial vision camera acquires images of the target sample within its field of view. The galvanometer serves as the optical path propagation medium for the LIBS device. The LIBS device is used to strike the target sample with a laser to generate plasma on its surface and to collect the spectral data of the plasma.

[0043] The backend host computer includes a control backend and a frontend interface;

[0044] The front-end interface is used for human-computer interaction to collect user-input algorithm parameters, front-end sensor operating parameters and operating instructions, and send them to the control backend. It also provides a visual display of the motion compensation calculation process and results, as well as the results of real-time online correction compensation and ablation trajectory. The algorithm parameters include, but are not limited to, machine vision image processing methods and parameters, calculation formulas and specific formula parameter values.

[0045] The control backend is equipped with a memory and a processor. The memory stores the program, and the processor converts the working parameters and instructions of the front-end sensor into hardware timing command signals and outputs them to the front-end sensor to ensure nanosecond / microsecond level synchronization accuracy. It also loads the program to execute the above method steps, calculates the dynamic compensation result according to the algorithm formula, and uses it to dynamically compensate and correct the galvanometer.

[0046] The present invention has the following beneficial effects and advantages:

[0047] 1. High-precision compensation for impact time and position: Based on a dynamic compensation model that ensures consistency between the galvanometer movement time and the material travel time, the target position deviation caused by the image-impact delay is accurately corrected, effectively solving the coordinate drift problem in high-speed sorting scenarios.

[0048] 2. Optimal scheduling of multi-target tasks: When a single frame image contains multiple metal targets, the optimal striking sequence is dynamically generated by combining the galvanometer movement time, conveyor belt speed, and ablation time to avoid targets missing the striking window and improve the efficiency of multi-target processing.

[0049] 3. Equivalent residence control of laser spot: By using a synchronous following strategy, the laser continuously compensates for the movement of the conveyor belt during the ablation process, achieving equivalent residence of the laser spot on the sample surface, significantly improving the spectral signal-to-noise ratio and repeatability, while also having the ability to remove surface paint, oxide layer and contaminants.

[0050] 4. Significantly improved system sorting accuracy and throughput: This invention can maintain stable spectral quality and accurate classification accuracy even under high-speed conveyor belt conditions (≥2 m / s), significantly improving sorting efficiency compared to traditional methods, and is suitable for large-scale industrial online material sorting scenarios. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the overall structure of the material LIBS online sorting device of the present invention.

[0052] Figure 2 This is a flowchart of the multi-target dynamic compensation coordinate calculation of the present invention.

[0053] Figure 3 This is a schematic diagram of the synchronous tracking compensation principle of the galvanometer in this invention. Detailed Implementation

[0054] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0056] This invention proposes a method for galvanometer impact motion compensation and synchronous tracking in a material sorting device based on LIBS technology, comprising the following steps:

[0057] (1) Externally triggered imaging and initial localization

[0058] The imaging module is triggered by an external hardware timing signal to acquire the original position set {Aᵢ} and timestamp of multiple target samples on the conveyor belt at time t0. This external trigger signal simultaneously controls the laser, galvanometer, and camera, ensuring that imaging, calculation, and laser impact are strictly synchronized in time, avoiding random delays caused by soft triggering.

[0059] (2) Calculation of dynamic compensation coordinates

[0060] For each target sample, its compensation coordinates are calculated in real time before the galvanometer strikes it. The specific method is as follows:

[0061] Initial position of the galvanometer during this movement The final ablation location of the previous target Plus ablation compensation distance , where V is the conveyor belt speed and T is the single ablation time;

[0062] Dynamically update the initial position of the target = Original position + V × (the sum of the cumulative mirror movement time and the cumulative ablation time for the first i−1 targets);

[0063] Based on the constraint that the galvanometer movement time and the material travel time are consistent, the compensation coordinates are solved. Make it satisfy the following relation:

[0064]

[0065] Where f(x) is the function relating the mirror's movement time to the distance, and tᵢ is the mirror's movement time for this time.

[0066] This dynamic compensation algorithm ensures that even under the combined effects of multi-target scheduling, high-speed conveyor belt movement, and hardware delays, the galvanometer can still reach the precise striking point at the optimal time.

[0067] (3) Synchronous follow-up compensation

[0068] Within the time window T of multi-pulse laser ablation, for the case where the sample moves continuously with the conveyor belt, the controller sends a synchronous tracking scan trajectory along the direction of the conveyor belt to the galvanometer:

[0069] When using strict compensation mode, the synchronous tracking speed is set to u=V, so that the laser spot is equivalently stationed at the same point in the sample reference frame.

[0070] The galvanometer speed u can also be flexibly adjusted according to the sorting strategy, making the ablation trajectory shorter or slightly longer than that of strict compensation. To balance spectral quality and laser energy distribution;

[0071] Through this synchronous tracking method, the laser acts on the same micro-region multiple times within the ablation window, achieving multi-pulse simultaneous excitation and significantly improving the intensity and repeatability of spectral signals.

[0072] (4) Spectral acquisition and sorting discrimination

[0073] Under synchronous multi-pulse excitation, plasma spectral lines are collected and input into a classification model to complete real-time discrimination of various metals such as aluminum, copper, magnesium, and stainless steel. Based on the results, the jet nozzle is driven to achieve high-speed sorting control.

[0074] Specifically, the scheme is described below with reference to the attached diagram.

[0075] I. System Overall Structure (see...) Figure 1 )

[0076] like Figure 1 As shown, the material LIBS online sorting device of the present invention mainly includes:

[0077] High-speed conveyor belt (1): used to transport material blocks to be sorted. The conveyor belt speed can reach 2m / s, and the speed V is collected in real time by an encoder;

[0078] 3D imaging module (2): preferably a 3D camera or a high-speed camera, which acquires the spatial location {Aᵢ} and timestamp of the target under external hardware triggering;

[0079] Galvanometer scanning module (3): includes a high-speed galvanometer, used to receive the compensation impact coordinate Cᵢ sent by the controller and complete the positioning within a limited time;

[0080] Main controller (4): can be an FPGA / industrial computer, used to realize image processing, dynamic compensation calculation, galvanometer motion planning, synchronous tracking control and spectral analysis and discrimination;

[0081] Sorting actuator (5): preferably a pneumatic nozzle or a mechanical push rod, which blows different metal samples into the corresponding collection container according to the spectral analysis results.

[0082] This structure enables rapid detection, precise impact, and automatic sorting of materials on a high-speed conveyor belt.

[0083] II: Multi-objective dynamic compensation calculation method (see...) Figure 2 )

[0084] like Figure 3 As shown, the present invention achieves multi-objective dynamic compensation through the following steps:

[0085] 1. Initial position of the galvanometer

[0086] The starting point of this galvanometer movement is This refers to the position where the previous target was hit as compensation.

[0087] 2. Dynamically update the initial position

[0088] For the i-th target, its dynamically updated initial position is:

[0089]

[0090] Where Aᵢ is the original position, t k Let T be the mirror movement time for the k-th target, and T be the ablation time of the target.

[0091] 3. Compensation coordinate calculation

[0092] Calculate the compensated impact coordinate Cᵢ based on the time consistency constraint:

[0093]

[0094] Here, f(x) is a function of the mirror's movement time and distance, obtained through calibration.

[0095] 4. Task Scheduling

[0096] The controller generates the final striking sequence based on the galvanometer's reachability and the target time window, employing a joint optimization strategy of "maximizing arrival time margin" and "minimizing total travel time." If a target is unreachable, it is automatically delayed or discarded.

[0097] This method ensures that the galvanometer can accurately and promptly complete the impact under conditions of high-speed conveyor belts and multiple targets.

[0098] 3: Galvanometer Synchronous Tracking Compensation Strategy (see...) Figure 3 )

[0099] For the i-th target, during the ablation process at the dynamically compensated position Cᵢ, the galvanometer can follow the target along the conveyor belt direction at a speed V within the ablation time T. The following length L can be set to L = V×T to ensure that the laser ablation occurs at the same point on the target even when the target is moving. Furthermore, the galvanometer following speed can be dynamically adjusted according to specific circumstances, making the ablation line segment shorter or longer than under strict compensation, thus achieving N ≥ 2 point-to-point or near-point multi-pulse stacking on the sample surface.

[0100] like Figure 3 As shown, this invention proposes three synchronous following modes within the laser ablation time window T:

[0101] 1. No compensation mode

[0102] The galvanometer does not move, but the sample moves with the conveyor belt. The light spot forms an ablation line segment of length V×T on the sample surface, resulting in a low signal-to-noise ratio.

[0103] 2. Strict Compensation Model

[0104] The galvanometer tracking speed is set to u = V, and the scanning trajectory length is L = V×T, so that the laser spot is equivalently stationed at the same point in the sample reference frame, thus obtaining the strongest spectral line signal.

[0105] 3-part compensation model

[0106] The galvanometer tracking speed is set to 0 < u < V, forming a relatively short controllable line segment with a length L = u×T, which can both enhance the signal and take into account the decoating effect on the sample surface.

[0107] Through synchronous tracking compensation, laser pulses are stacked at the same point or near the same point on the sample surface with N ≥ 2, which significantly improves the spectral signal-to-noise ratio and repeatability.

[0108] The present invention also provides a galvanometer impact motion compensation system for a material sorting device based on LIBS technology, including a front-end sensor and a back-end host computer;

[0109] The front-end sensor includes an industrial vision camera, a galvanometer optical path, and a laser-induced breakdown spectroscopy (LIBS) device. The industrial vision camera acquires images of the target sample within its field of view. The galvanometer serves as the optical path propagation medium for the LIBS device. The LIBS device is used to strike the target sample with a laser to generate plasma on its surface and to collect the spectral data of the plasma.

[0110] The backend host computer includes a control backend and a frontend interface;

[0111] The front-end interface is used for human-computer interaction to collect user-input algorithm parameters, front-end sensor operating parameters and operating instructions, and send them to the control backend. It also provides a visual display of the motion compensation calculation process and results, as well as the results of real-time online correction compensation and ablation trajectory. The algorithm parameters include, but are not limited to, machine vision image processing methods and parameters, calculation formulas and specific formula parameter values.

[0112] The control backend is equipped with a memory and a processor. The memory stores the program, and the processor converts the working parameters and instructions of the front-end sensor into hardware timing command signals and outputs them to the front-end sensor to ensure nanosecond / microsecond level synchronization accuracy. It also loads the program to execute the above method steps, calculates the dynamic compensation result according to the algorithm formula, and uses it to dynamically compensate and correct the galvanometer.

[0113] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for compensating for the impact motion of a galvanometer in a LIBS-based material sorting device, characterized in that, The laser sorting process involves the following steps to achieve motion compensation, thereby correcting the coordinates of the ablation spot and optimizing the ablation trajectory: During the laser sorting process, an industrial vision camera is triggered to capture images of multiple target samples that are randomly placed on a conveyor belt with disordered positions and irregular spacing. The original positions of the target samples are located using the visual images, and the ablation sequence of the multiple target samples is planned. Combining the process timing of each sample impact by the galvanometer and the synchronous constraints of the conveyor belt, calculate the first... Dynamic ablation spot position of each target sample ; Based on the constraint of consistency between the galvanometer movement time and the material travel time, dynamic compensation is performed on the impact time, and the compensation is calculated for the [missing information]. The optical spot correction coordinates of the target sample at the moment of galvanometer impact ; The laser spot is controlled to follow the target sample along a preset ablation trajectory within the ablation time to perform ablation. The preset ablation trajectory parameters include: the initial position of the ablation laser spot during this movement. Length of ablation trajectory The ablation method is either a unidirectional single-pass ablation method or a reciprocating multi-pulse stacked ablation method using smaller line segments. Based on the preset scheduling and priority strategy of galvanometer impact tasks, the ablation task queue with the sample is dynamically optimized to complete motion-compensated ablation in an orderly manner.

2. The method for compensating for galvanometer impact motion in a LIBS-based material sorting device according to claim 1, characterized in that, The method of visually locating the original position of the target sample and planning the ablation sequence of multiple target samples includes: The industrial vision camera is triggered by a timing signal, causing it to move at a specific time. Multiple target samples were randomly placed on a conveyor belt, with disordered positions and varying spacing. Images; Identify individual target samples in an image using machine vision methods. The original position is used to obtain the position set { }, and serve as the original impact coordinates of the galvanometer on each target sample, while simultaneously recording the corresponding timestamp information; where the set { } target sample The order in which the particles enter the field of view of the industrial vision camera is determined, and also serves as the order in which the galvanometer strikes and ablates them.

3. The galvanometer impact motion compensation method for a LIBS-based material sorting device according to claim 1, characterized in that, The process timing of each sample impact by the galvanometer and the synchronous constraint of the conveyor belt are combined to calculate the first... Dynamic impact position of each target sample include: The sequence of each sample impact by the galvanometer is divided into a jump-movement sequence and an impact-ablation sequence. Define the ablation time for each target sample. galvanometer from the first The target sample jumps to the first... The jump time for each target sample is ; When the galvanometer begins to strike the first The first goal is to end the galvanometer reading. The moment of ablation of the target is approaching the first... The moment the target moves; And because of the galvanometer before impact The mirror movement time and ablation time generated by the target are simultaneously measured by the conveyor belt moving at a speed of V. Therefore, the first... The dynamic position of the target sample is not the initial impact position. The position where the galvanometer strikes is defined as follows: ; but =Original striking position + × (before) Cumulative galvanometer movement time for each target With cumulative ablation time (and); that is:

4. The galvanometer impact motion compensation method for a LIBS-based material sorting device according to claim 1, characterized in that, The constraint based on the consistency between the galvanometer movement time and the material travel time is used to calculate the first... The target's deviation coordinates at the moment of galvanometer impact It is solved according to the following formula Complete the initial strike coordinates Dynamic compensation; in This represents the functional relationship between the distance the galvanometer moves and time. This is the time it takes for the galvanometer to move. For the first The coordinates of the target at the moment of impact with the galvanometer. For the first The position coordinates of the target at the moment of impact with the galvanometer.

5. The galvanometer impact motion compensation method for a LIBS-based material sorting device according to claim 1, characterized in that, The length of the ablation trajectory is calculated as follows: For the first... The target is when the galvanometer is in the dynamic compensation position. During the ablation process at the point, during the ablation time Inside, the optical path of the galvanometer is changed to control the ablation spot along the conveyor belt direction at the conveyor belt speed. Follow the ablation trajectory length. Set as This is used to ensure that laser ablation occurs at the same point on the target even when the target is in motion.

6. The galvanometer impact motion compensation method for a LIBS-based material sorting device according to claim 1, characterized in that, The initial position of the ablation spot during this movement The calculation is as follows: If the galvanometer controls the light spot to follow the ablation time, then for the th... The target, the initial position of the ablation spot controlled by the galvanometer during this movement. For the first The coordinates of the light spot at the moment the galvanometer strikes the target sample. With the length of the ablation trajectory The sum of: At this time, during the galvanometer jump time period The coordinates satisfy:

7. The method for compensating for the galvanometer impact motion of a LIBS-based material sorting device according to claim 1, characterized in that, The reciprocating multi-pulse stacking ablation using smaller line segments is as follows: if the galvanometer controls the ablation spot to follow within the ablation time, the galvanometer spot following speed is dynamically adjusted according to the specific situation, so that the ablation line segment is shorter or longer than under strict compensation, in order to achieve N ≥ 2 point-to-point or near-point multi-pulse stacking on the sample surface.

8. The galvanometer impact motion compensation method for a LIBS-based material sorting device according to claim 6, characterized in that, Where the conveyor belt speed Update in real time when fluctuations exceed the threshold. With constraint equations And dynamically adjust the timing of the strikes.

9. The galvanometer impact motion compensation method for a LIBS-based material sorting device according to claim 1, characterized in that, The strike task scheduling strategy adopts a joint cost function with the objective of minimizing the total travel time, and automatically discards or postpones unreachable targets. The unreachable targets include, but are not limited to, target samples that exceed the range of a single frame image.

10. A galvanometer impact motion compensation system for a LIBS-based material sorting device, characterized in that, Includes front-end sensors and back-end host computer; The front-end sensor includes an industrial vision camera, a galvanometer optical path, and a laser-induced breakdown spectroscopy (LIBS) device. The industrial vision camera acquires images of the target sample within its field of view. The galvanometer serves as the optical path propagation medium for the LIBS device. The LIBS device is used to strike the target sample with a laser to generate plasma on its surface and to collect the spectral data of the plasma. The backend host computer includes a control backend and a frontend interface; The front-end interface is used for human-computer interaction to collect user-input algorithm parameters, front-end sensor operating parameters and operating instructions, and send them to the control backend. It also provides a visual display of the motion compensation calculation process and results, as well as the results of real-time online correction compensation and ablation trajectory. The algorithm parameters include, but are not limited to, machine vision image processing methods and parameters, calculation formulas and specific formula parameter values. The control backend is equipped with a memory and a processor. The memory stores the program, and the processor converts the working parameters and instructions of the front-end sensor into hardware timing command signals and outputs them to the front-end sensor to ensure nanosecond / microsecond level synchronization accuracy. It also loads the program to execute the method steps as described in any one of claims 1-9, calculates the dynamic compensation result according to the algorithm formula, and uses it to perform dynamic compensation and correction of the galvanometer.

Images