Laser focusing device and laser focusing method for coal flow of conveying belt

Abstract

The present disclosure provides a kind of laser focusing device and laser focusing method for conveying belt coal flow, it is related to coal quality detection technical field, comprising: first drive mechanism, it is arranged on support mechanism, for driving linear transmission mechanism to drive focusing lens group to carry out coarse adjustment along the direction of optical axis;Second drive mechanism, its output end is connected with focusing lens group transmission, for driving focusing lens group to carry out fine adjustment along the direction of optical axis;Sensor component, including distance sensor and image sensor being arranged on support mechanism, distance sensor is used to measure the distance of coal flow surface to focusing lens group, and image sensor is used to acquire coal flow surface image;Data acquisition module is electrically connected with sensor component;Data processing module is used to generate the control signal of first drive mechanism and second drive mechanism according to the data collected by data acquisition module.The present disclosure can realize automatic focusing by setting two-stage drive mechanism for coarse adjustment and fine adjustment respectively, combined with multi-sensor data fusion.

Description

Technical Field

[0001] This disclosure relates to the field of coal quality testing technology, and in particular to a laser focusing device and laser focusing method for coal flow in a conveyor belt. Background Technology

[0002] In the field of laser-induced breakdown spectroscopy (LIBS) coal quality testing, traditional methods require pretreatment of coal samples, such as cutting, grinding, and pressing, to maintain a smooth coal flow surface for easy laser focusing. This process is cumbersome, damages the sample structure, and introduces human error. Furthermore, the surface of the coal flow transported by a conveyor belt exhibits dynamic undulations, which traditional methods cannot adapt to, resulting in insufficient focusing accuracy and response lag. Therefore, direct online and accurate detection of coal flow on a conveyor belt is not possible. Summary of the Invention

[0003] To overcome the problems existing in related technologies, this disclosure provides a laser focusing device and laser focusing method for coal flow in a conveyor belt.

[0004] According to a first aspect of the present disclosure, a laser focusing device for a coal flow conveyor belt is provided, comprising: Supporting institutions; A linear transmission mechanism is mounted on the support mechanism; A focusing lens assembly, located at the moving end of the linear transmission mechanism, is used to focus the laser emitted by the laser emitting module onto the surface of the coal flow on the conveyor belt. The first driving mechanism is provided on the support mechanism, and its output end is connected to the linear transmission mechanism for driving the linear transmission mechanism to coarsely adjust the focusing lens group along the optical axis. The second driving mechanism is located at the moving end of the linear transmission mechanism, and its output end is connected to the focusing lens group for driving the focusing lens group to make fine adjustments along the optical axis. The sensor assembly includes a distance sensor and an image sensor mounted on the support mechanism. The distance sensor is used to measure the distance from the coal flow surface to the focusing lens group, and the image sensor is used to acquire images of the coal flow surface. The data acquisition module is electrically connected to the sensor assembly and is used to acquire distance data fed back by the distance sensor, image data fed back by the image sensor, and speed data of the coal flow on the conveyor belt. The data processing module is electrically connected to the data acquisition module, the first drive mechanism, and the second drive mechanism, respectively, and is used to generate control signals for the first drive mechanism and the second drive mechanism based on the data acquired by the data acquisition module.

[0005] In some embodiments, the support mechanism includes: a frame and a linear guide rail; The linear guide rail is fixed to the frame and is used to provide linear motion guidance for the linear transmission mechanism; The linear transmission mechanism is a lead screw transmission mechanism, with both ends fixed to the frame via connecting parts. A shock-absorbing component is provided between the connecting parts and the frame.

[0006] In some embodiments, the first driving mechanism is a servo drive motor, whose output shaft is coaxially connected to the lead screw of the lead screw transmission mechanism; The data processing module is used to generate control signals for the servo drive motor based on the distance data and the speed data.

[0007] In some embodiments, the second driving mechanism is a piezoelectric driving element; The data processing module is used to generate a control signal for the piezoelectric drive element based on the coal particle density shown in the image data.

[0008] According to a second aspect of the present disclosure, a laser focusing method for a coal flow conveyor is provided, applied to the laser focusing apparatus described in the first aspect, the method comprising: Acquire distance data from the coal flow surface to the focusing lens group, image data of the coal flow surface, and velocity data of the coal flow on the conveyor belt; Based on the distance data and the speed data, a target focal length value is generated; Based on the target focal length value, a first driving signal is generated to control the first driving mechanism; wherein, the first driving mechanism is used to drive the focusing lens group to perform coarse adjustment along the optical axis. Based on the coal flow particle density shown in the image data, the undulation level of the coal flow surface is determined; Based on the undulation level, a second driving signal is generated to control the second driving mechanism and complete the focusing of the coal flow; wherein, the second driving mechanism is used to drive the focusing lens group to make fine adjustments along the optical axis.

[0009] In some embodiments, generating a target focal length value based on the distance data and the velocity data includes: The target focal length value is determined by the following formula: ; in, The target focal length value; These are dynamic weighting coefficients, positively correlated with the velocity data at the current moment; This represents the distance data at the current moment. This is the distance data from the previous moment.

[0010] In some embodiments, the dynamic weighting coefficient is determined by the following formula: ; in, These are dynamic weighting coefficients; The speed data at the current moment; This is the preset baseline speed data; This is the speed sensitivity coefficient.

[0011] In some embodiments, the first driving mechanism is a servo drive motor; generating a first driving signal for controlling the first driving mechanism based on the target focal length value includes: Using the target focal length value as the control target, a first drive signal for controlling the first drive mechanism is generated based on the proportional-integral-derivative control method. In the aforementioned proportional-integral-derivative control method... The proportionality coefficient is ;in, This is the proportionality coefficient; This is the baseline tuning parameter for the proportional coefficient; The conveyor belt speed sensitivity coefficient is related to the proportionality coefficient; The speed data at the current moment; The integral coefficient is ;in, The integral coefficient; These are the baseline tuning parameters for the integral coefficients; The conveyor belt speed sensitivity coefficient is associated with the integral coefficient; The speed data at the current moment; The differential coefficient is ;in, These are the differential coefficients; These are the baseline tuning parameters for the differential coefficients; The conveyor belt speed sensitivity coefficient is associated with the differential coefficient; This represents the speed data at the current moment.

[0012] In some embodiments, determining the undulation level of the coal flow surface based on the coal flow particle density shown in the image data includes: Obtain the number of coal particles along the preset path of the image data; Based on the number of coal particles, determine the density of coal particles along the preset path; The undulation level of the coal flow surface is determined based on the relationship between the coal particle density and at least one undulation level classification threshold; the undulation level is positively correlated with the coal particle density.

[0013] In some embodiments, the second driving mechanism is a piezoelectric driving element; a second driving signal for controlling the second driving mechanism is generated according to the ripple level, including: A frequency parameter matching the fluctuation level is determined, the frequency parameter being used to control the piezoelectric drive element, and the frequency parameter being positively correlated with the fluctuation level; The frequency parameter is used as the second driving signal.

[0014] The laser focusing device disclosed herein, by setting up two-stage drive mechanisms for coarse adjustment and fine adjustment respectively, combined with multi-sensor data fusion, can not only quickly respond to large-range changes in coal flow height through coarse adjustment, but also accurately compensate for focal length deviation caused by micro-undulations on the coal flow surface through fine adjustment. Thus, it can achieve automatic focusing on the coal flow surface on the conveyor belt. It is easy to operate, does not damage the sample structure, and does not introduce human error. Attached Figure Description

[0015] Figure 1 This is a front view of a laser focusing device for a conveyor belt coal flow according to an embodiment of the present disclosure.

[0016] Figure 2 A side view of a laser focusing device for a coal flow conveyor belt is shown in an embodiment of this disclosure.

[0017] Figure 3 This diagram illustrates a flow chart of a laser focusing method for a coal flow in a conveyor belt, according to an embodiment of the present disclosure. Detailed Implementation

[0018] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0019] The following will describe the exemplary implementation method in detail with reference to the accompanying drawings and embodiments.

[0020] Figure 1 This illustration shows a front view of a laser focusing device for a conveyor belt coal flow according to an embodiment of the present disclosure. Figure 2 A side view of a laser focusing device for a conveyor belt coal flow is shown in an embodiment of this disclosure. Figure 1 and Figure 2 As shown, the laser focusing device for coal flow in a conveyor belt provided in this embodiment includes: a support mechanism 100, a linear transmission mechanism 200, a focusing lens group 300, a first drive mechanism 400, a second drive mechanism 500, a sensor assembly 600, a data acquisition module 700, and a data processing module 800.

[0021] The linear transmission mechanism 200 is fixedly mounted on the support mechanism 100, and the support mechanism 100 enables stable bearing and positioning.

[0022] The focusing lens group 300 is located at the moving end of the linear transmission mechanism 200 and is used to focus the laser emitted by the laser emitting module onto the surface of the coal flow on the conveyor belt. The linear transmission mechanism 200 drives it to move along the optical axis to adjust the focusing position.

[0023] The first drive mechanism 400 is fixedly mounted on the support mechanism 100, and its output end is connected to the linear transmission mechanism 200 for driving the linear transmission mechanism 200 to coarsely adjust the focusing lens group 300 along the optical axis, thereby achieving a wide range of rapid adjustment of the focusing position.

[0024] The second drive mechanism 500 is located at the moving end of the linear transmission mechanism 200, and its output end is connected to the focusing lens group 300 for transmission. It is used to drive the focusing lens group 300 to make fine adjustments along the optical axis to achieve high-precision small-range compensation of the focusing position.

[0025] The sensor assembly 600 includes a distance sensor 601 and an image sensor 602 mounted on the support mechanism 100. The distance sensor 601 is used to measure the distance from the coal flow surface to the focusing lens group 300, and the image sensor 602 is used to acquire images of the coal flow surface, providing a basis for detection data for focus adjustment.

[0026] The data acquisition module 700 is electrically connected to the sensor assembly 600 and is used to acquire distance data fed back by the distance sensor 601, image data fed back by the image sensor 602, and speed data of coal flow on the conveyor belt, so as to realize the synchronous acquisition of multi-source detection data.

[0027] The data processing module 800 is electrically connected to the data acquisition module 700, the first drive mechanism 400, and the second drive mechanism 500, respectively. It is used to generate control signals for the first drive mechanism 400 and the second drive mechanism 500 based on the data acquired by the data acquisition module 700, so as to realize the automated closed-loop control of the focusing process.

[0028] Next, we will provide a detailed introduction to each mechanism / module involved in the laser focusing device.

[0029] For example, the support mechanism 100 includes a frame 101 and a linear guide rail 102; the linear guide rail 102 is fixed on the frame 101 and is used to provide linear motion guidance for the linear transmission mechanism 200; the linear transmission mechanism 200 is a lead screw transmission mechanism, and its two ends are fixed on the frame 101 through connecting members, and a shock-absorbing member is provided between the connecting member and the frame 101.

[0030] Specifically, the frame 101, serving as the load-bearing skeleton of the entire device, has reinforcing ribs welded to its key parts to enhance structural rigidity. The linear guide rail 102 is bolted into a pre-set T-slot in the frame 101. The guide rail surface is coated with lubricating oil to ensure smooth movement. Conductive foam is filled between the contact surfaces of the frame 101 and the guide rail to prevent static electricity from interfering with the detection signal and to help absorb mechanical vibrations during equipment operation, ensuring the smooth movement of the focusing lens group 300. The two ends of the lead screw drive mechanism are fixed to the frame 101 via flange-type connectors. Shock-absorbing rubber pads are installed between the connectors and the frame 101 to effectively absorb mechanical vibrations and improve focusing accuracy. The lead screw drive mechanism, in conjunction with the linear guide rail 102, converts rotary motion into linear motion, and its moving end can reciprocate linearly along the optical axis. For example, the moving end of the lead screw drive mechanism can have a movement range of ±15mm to accommodate fluctuations in the surface height of the coal flow on the conveyor belt.

[0031] For example, the first drive mechanism 400 is a servo drive motor, whose output shaft is coaxially connected to the lead screw of the lead screw transmission mechanism; the data processing module 800 is used to generate control signals for the servo drive motor based on distance data and speed data.

[0032] Specifically, the servo drive motor is fixed to the top of the frame 101 via a rigid flange. Epoxy resin is injected into the mounting holes of the flange, significantly improving the structure's vibration resistance. A thermally conductive silicone gasket is installed between the motor housing and the frame 101, balancing heat dissipation and structural stability. The servo drive motor receives control signals generated by the data processing module 800, converting rotational motion into linear motion via a lead screw transmission mechanism. This drives the focusing lens group 300 to perform millimeter-level coarse adjustments along the optical axis, rapidly responding to large changes in coal flow height and suppressing focusing lag errors caused by sudden changes in coal flow velocity.

[0033] For example, the second drive mechanism 500 is a piezoelectric drive element; the data processing module 800 is used to generate a control signal for the piezoelectric drive element based on the coal flow particle density shown in the image data.

[0034] Specifically, the piezoelectric drive element can be a piezoelectric ceramic motor, which is connected to the focusing lens group 300 through a fine wire adjustment structure within a matching 90-degree bend 900. This allows the focusing lens group 300 to be finely adjusted along the optical axis at the nanometer level, with a response time down to the millisecond level and an adjustment accuracy controlled within ±50 nanometers. The piezoelectric ceramic motor receives a control signal generated by the data processing module 800 based on the coal flow particle density and adjusts the drive frequency according to the undulations of the coal flow surface. This real-time compensation for focal length deviations caused by microscopic undulations on the coal flow surface ensures focusing accuracy.

[0035] When energized, the piezoelectric ceramic motor generates a horizontal nanometer-level linear micro-displacement based on the inverse piezoelectric effect, pulling / pushing a transmission filament fixed at its output end. The filament is redirected by a guide at the 90° bend of the 90° tube, seamlessly converting the horizontal micro-displacement into a vertical pulling / pushing force. This, in turn, drives the moving mirror of the focusing lens group 300 to perform synchronous, high-precision displacement along the optical axis, ultimately achieving nanometer-level fine-tuning of the focusing position and accurately compensating for focal length deviations caused by microscopic undulations on the coal flow surface.

[0036] For example, the focusing lens group 300 can focus the pulsed laser emitted by the laser emitting module into a high-energy-density laser spot. The laser emitting module can be fixed to the top of the frame 101 by a stainless steel clamp. A flexible shock-absorbing pad is attached to the inside of the clamp to reduce the impact of equipment operation vibration on the stability of laser emission. The laser emission direction is along the optical axis from top to bottom toward the surface of the coal flow in the conveyor belt.

[0037] For example, the distance sensor 601 can be a laser rangefinder sensor, mounted on the frame 101 via an independent adjustment platform 1000. The adjustment platform 1000 is locked in the reserved hole in the frame 101 by a locking screw, allowing for flexible adjustment of the installation position. The distance sensor 601 uses laser triangulation to measure the distance from the coal flow surface to the focusing lens group 300 in real time at a high frequency of 1kHz, with a measurement range covering 0.5m to 3m, adapting to the detection needs of different working conditions. The image sensor 602 can be an industrial camera, attached to the side of the linear guide rail 102 via a magnetic quick-release bracket for easy on-site disassembly and maintenance. The distance sensor 601 and the image sensor 602 are housed in different stainless steel tubes, with their acquisition ends facing the coal flow, thus synchronously acquiring corresponding detection data.

[0038] For example, the data acquisition module 700 can be installed in a separate sealed chamber, capable of simultaneously acquiring laser-induced spectral signals, image data, and data feedback from various sensors, and ensuring the time synchronization of multi-source data. The data processing module 800 can be an embedded microcontroller, mounted on the reinforcing ribs of the frame 101 via guide rails.

[0039] For example, the moving parts and fixed circuits in the laser focusing device transmit signals through a flexible circuit board, which can adapt to positional changes caused by mechanical displacement. Furthermore, the key sensors and circuit components of the laser focusing device are all housed in a sealed housing, avoiding equipment failure caused by on-site coal dust contamination.

[0040] Please refer to the following. Figure 3 , Figure 3This diagram illustrates a flow chart of a laser focusing method for a coal flow conveyor belt according to an embodiment of the present disclosure. The method is applied to the laser focusing apparatus of the above embodiment and includes the following steps S301 to S305.

[0041] S301 acquires distance data from the coal flow surface to the focusing lens group, image data of the coal flow surface, and speed data of the coal flow on the conveyor belt.

[0042] For example, sensor components and data acquisition modules can be combined to achieve synchronous acquisition and timestamp alignment of the three types of data, ensuring the temporal consistency of the data.

[0043] The distance data is acquired in real time by a laser rangefinder using laser triangulation, with a sampling frequency of no less than 1 kHz, and is used to characterize the absolute distance between the coal flow surface and the lens group. Image data is acquired in real time by an industrial camera, with the frame rate matched to the distance sampling frequency, and is used to characterize the microscopic morphology of the coal flow surface. The coal flow velocity data is obtained from the encoder or velocity detection unit of the coal flow conveyor, and is used to characterize the motion state of the coal flow, addressing the focusing lag problem of the moving coal flow.

[0044] S302 generates target focal length values ​​based on distance and velocity data.

[0045] For example, the target focal length value refers to the target position parameter along the optical axis of the focusing lens group when the laser is precisely focused on the surface of the coal flow; it can also be understood as the coarse adjustment target during laser focusing. This embodiment can combine the absolute distance and velocity of the coal flow to generate a target focal length value adapted to dynamic working conditions. By introducing velocity data, the position change of the coal flow during the delay time between data acquisition and focusing execution can be predicted, compensating for the focusing stroke in advance and solving the lag problem of traditional static focusing on moving coal flows.

[0046] S303, based on the target focal length value, generates a first drive signal for controlling the first drive mechanism.

[0047] The first driving mechanism is used to drive the focusing lens group to make coarse adjustments along the optical axis.

[0048] For example, during the coarse adjustment process, the target focal length value can be used as the control target to generate a corresponding drive signal for the first drive mechanism, driving the focusing lens group to complete a large-range, rapid displacement at the millimeter level. The first drive mechanism is a servo drive motor, equipped with a lead screw transmission mechanism that enables millimeter-level stroke adjustment, allowing for rapid response to changes in coal flow height, quickly approaching the target focusing position, and suppressing hysteresis errors caused by sudden changes in coal flow velocity. The first drive signal is a pulse control signal for the servo motor, which can precisely control the motor's rotation direction, number of rotations, and speed, thereby precisely controlling the displacement of the lens group.

[0049] S304, based on the coal flow particle density shown in the image data, determine the undulation level of the coal flow surface.

[0050] In some embodiments, the degree of microscopic undulation on the surface of the coal flow can be characterized by the coal flow particle density. Specifically, the coal flow particle density is positively correlated with the degree of undulation on the coal flow surface; the higher the particle density, the denser the protrusions and depressions on the coal flow surface, the more severe the microscopic undulation, and the higher the compensation accuracy and response frequency required for focusing. By using graded and quantified undulation levels, the microscopic morphology of the coal flow surface can be transformed into executable control parameters, complementing the problem of microscopic morphology defocusing that cannot be covered by coarse adjustment.

[0051] S305 generates a second drive signal to control the second drive mechanism based on the fluctuation level, thereby completing the coking of the coal flow.

[0052] The second driving mechanism is used to drive the focusing lens group to make fine adjustments along the optical axis.

[0053] In some embodiments, a drive signal corresponding to the second drive mechanism can be generated based on the level of undulation, and the focusing lens group can be driven to complete nanometer-level high-precision displacement compensation. The second drive mechanism is a piezoelectric drive element (piezoelectric ceramic motor), which can achieve nanometer-level micro-displacement adjustment with a response speed down to the millisecond level, and is used to compensate for focal length deviations caused by microscopic undulations on the coal flow surface.

[0054] By combining coarse and fine-tuning two-stage control, both the response speed over a long stroke and the final focusing accuracy can be guaranteed, achieving real-time and precise focusing of the coal flow on the conveyor belt and providing stable focusing conditions for LIBS coal quality testing.

[0055] In some embodiments, when performing S302 above, the target focal length value can be determined by the following formula: ; in, The target focal length is expressed in mm. These are dynamic weighting coefficients, positively correlated with the velocity data at the current moment; This represents the distance data at the current moment, in mm. This is the distance data from the previous moment, used to reduce measurement errors and noise; the unit is mm.

[0056] This embodiment generates a target focal length value by weighted fusion of distance data from the current moment and the previous moment, which can effectively suppress instantaneous noise and random errors in the laser ranging process and improve the stability of the target focal length value. At the same time, by using dynamic weighting coefficients, it adapts to the focusing requirements under different coal flow velocities, avoiding the inability of a single fixed weight to balance response speed and anti-interference capability.

[0057] For example, dynamic weighting coefficients It can be determined by the following formula: ; in, These are dynamic weighting coefficients; The current velocity data is in m / s. The preset reference speed data is the rated operating speed of the coal conveyor belt, in m / s. This is the speed sensitivity coefficient, with a value ranging from 0 to 1.

[0058] When the coal flow velocity is faster The higher the value, the more the focus adjustment relies on the current ranging data to ensure a faster response time; the slower the coal flow velocity, the more the focus adjustment relies on the current ranging data. The smaller the value, the more the system relies on historical data, suppressing the interference of instantaneous noise and improving focusing stability.

[0059] In some embodiments, the first drive mechanism is a servo drive motor. When executing S303 above, the target focal length value can be used as the control target, and a first drive signal for controlling the first drive mechanism can be generated based on the proportional-integral-derivative control method. In proportional-integral-derivative control... The proportionality coefficient is ;in, This is the proportionality coefficient; This is the baseline tuning parameter for the proportional coefficient; The conveyor belt speed sensitivity coefficient is related to the proportionality coefficient; The speed data at the current moment; The integral coefficient is ;in, The integral coefficient; These are the baseline tuning parameters for the integral coefficients; The conveyor belt speed sensitivity coefficient is associated with the integral coefficient; The speed data at the current moment; The differential coefficient is ;in, These are the differential coefficients; These are the baseline tuning parameters for the differential coefficients; The conveyor belt speed sensitivity coefficient is associated with the differential coefficient; This represents the speed data at the current moment.

[0060] in, , and The calibration can be completed through a conveyor belt calibration experiment. The output of the proportional-integral-derivative control is the vertical coordinate position of the focusing lens group. By dynamically tuning the proportional-integral-derivative parameters, it can adapt to the adjustment requirements under different coal flow velocities and effectively suppress the focusing lag error caused by sudden changes in coal flow velocity.

[0061] For example, in this control process, the proportional-integral-derivative control law of the control system can be expressed as: ; in, The vertical coordinates of the adjustment platform used to mount the laser rangefinder sensor; The target focal length value; Used to indicate time.

[0062] In some embodiments, the above-described S304 can be implemented in the following manner: The number of coal particles along a preset path in the image data is obtained; based on the number of coal particles, the density of coal particles along the preset path is determined; according to the relationship between the coal particle density and at least one undulation level classification threshold, the undulation level of the coal flow surface is determined; the undulation level is positively correlated with the coal particle density.

[0063] For example, the preset path is the vertical centerline of the image data, and the coal particle count can be identified using a machine learning model. By training the machine learning model with a large number of manually labeled coal flow image samples, the number of coal particles on the vertical centerline of the image data can be accurately identified and counted.

[0064] For example, the grading thresholds for undulation levels can be set to 0.5 particles / cm and 2 particles / cm. The specific grading rules for undulation levels are as follows: if the coal particle density on the vertical center line is less than 0.5 particles / cm, the coal flow surface is judged to be smooth, corresponding to Level 1 undulation level (smooth surface); if the coal particle density on the vertical center line is greater than or equal to 0.5 particles / cm and less than 2 particles / cm, the coal flow surface is judged to be relatively smooth, corresponding to Level 2 undulation level (relatively smooth surface); if the coal particle density on the vertical center line is greater than or equal to 2 particles / cm, the coal flow surface is judged to be uneven, corresponding to Level 3 undulation level (uneven surface).

[0065] In some embodiments, the second driving mechanism is a piezoelectric driving element, and S305 includes: determining a frequency parameter that matches the ripple level, the frequency parameter being used to control the piezoelectric driving element, and the frequency parameter being positively correlated with the ripple level; and using the frequency parameter as a second driving signal.

[0066] For example, the piezoelectric driving element is a piezoelectric ceramic motor, and the frequency parameter is the driving pulse frequency of the piezoelectric ceramic motor, which directly determines the micro-displacement response frequency of the piezoelectric ceramic motor. Specifically, the first-level undulation level (flat surface) can be matched with low-frequency driving parameters, with a frequency of 20Hz; the second-level undulation level (relatively flat surface) can be matched with medium-frequency driving parameters, with a frequency of 20+30×( D -0.5)Hz, where, D The aforementioned coal particle density; the three-level undulation grade (surface unevenness) can be matched with high-frequency drive parameters, with a frequency of 80Hz.

[0067] In other words, the relationship between the frequency parameter and the coal particle density can be expressed by the following piecewise function: ; in, For coal particle density, This is a frequency parameter.

[0068] As can be seen from the above formula, the more severe the surface undulations of the coal flow (the higher the density of coal particles), the higher the matching frequency parameter, so that the response frequency of the piezoelectric ceramic motor can match the undulations of the coal flow surface, adjust the position of the focusing lens group in real time, and offset the focal length error caused by micro-undulations to achieve nanometer-level focusing compensation.

[0069] Through on-site testing and verification at actual coal mine conveyor belts, the technical solution provided in this disclosure can control the focal length tracking error within 80 μm under stable operating conditions with a coal flow velocity of 2 m / s; even under high-speed fluctuating conditions of 4 m / s, the focal length tracking error can be maintained within 220 μm. Compared with traditional mechanical pressing detection methods, this disclosure eliminates the need for coal sample pretreatment, achieves continuous online monitoring of coal flow, avoids frequent shutdowns for calibration, and simultaneously improves the accuracy of coal elemental analysis from 90% to 98%, significantly enhancing production efficiency and detection accuracy.

[0070] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A laser focusing device for coal flow in a conveyor belt, characterized in that, include: Supporting institutions; A linear transmission mechanism is mounted on the support mechanism; A focusing lens assembly, located at the moving end of the linear transmission mechanism, is used to focus the laser emitted by the laser emitting module onto the surface of the coal flow on the conveyor belt. The first driving mechanism is provided on the support mechanism, and its output end is connected to the linear transmission mechanism for driving the linear transmission mechanism to coarsely adjust the focusing lens group along the optical axis. The second driving mechanism is located at the moving end of the linear transmission mechanism, and its output end is connected to the focusing lens group for driving the focusing lens group to make fine adjustments along the optical axis. The sensor assembly includes a distance sensor and an image sensor mounted on the support mechanism. The distance sensor is used to measure the distance from the coal flow surface to the focusing lens group, and the image sensor is used to acquire images of the coal flow surface. The data acquisition module is electrically connected to the sensor assembly and is used to acquire distance data fed back by the distance sensor, image data fed back by the image sensor, and speed data of the coal flow on the conveyor belt. The data processing module is electrically connected to the data acquisition module, the first drive mechanism, and the second drive mechanism, respectively, and is used to generate control signals for the first drive mechanism and the second drive mechanism based on the data acquired by the data acquisition module.

2. The apparatus according to claim 1, characterized in that, The support mechanism includes: a frame and a linear guide rail; The linear guide rail is fixed to the frame and is used to provide linear motion guidance for the linear transmission mechanism; The linear transmission mechanism is a lead screw transmission mechanism, with both ends fixed to the frame via connecting parts. A shock-absorbing component is provided between the connecting parts and the frame.

3. The apparatus according to claim 2, characterized in that, The first driving mechanism is a servo drive motor, whose output shaft is coaxially connected to the lead screw of the lead screw transmission mechanism; The data processing module is used to generate control signals for the servo drive motor based on the distance data and the speed data.

4. The apparatus according to claim 1, characterized in that, The second driving mechanism is a piezoelectric driving element; The data processing module is used to generate a control signal for the piezoelectric drive element based on the coal particle density shown in the image data.

5. A laser focusing method for coal flow in a conveyor belt, characterized in that, The method, applied to the laser focusing apparatus according to any one of claims 1 to 4, comprises: Acquire distance data from the coal flow surface to the focusing lens group, image data of the coal flow surface, and velocity data of the coal flow on the conveyor belt; Based on the distance data and the speed data, a target focal length value is generated; Based on the target focal length value, a first driving signal is generated to control the first driving mechanism; wherein, the first driving mechanism is used to drive the focusing lens group to perform coarse adjustment along the optical axis. Based on the coal flow particle density shown in the image data, the undulation level of the coal flow surface is determined; Based on the undulation level, a second driving signal is generated to control the second driving mechanism and complete the focusing of the coal flow; wherein, the second driving mechanism is used to drive the focusing lens group to make fine adjustments along the optical axis.

6. The method according to claim 5, characterized in that, The step of generating a target focal length value based on the distance data and the velocity data includes: The target focal length value is determined by the following formula: ； in, The target focal length value; These are dynamic weighting coefficients, positively correlated with the velocity data at the current moment; This represents the distance data at the current moment. This is the distance data from the previous moment.

7. The method according to claim 6, characterized in that, The dynamic weighting coefficient is determined by the following formula: ； in, These are dynamic weighting coefficients; The speed data at the current moment; This is the preset baseline speed data; This is the speed sensitivity coefficient.

8. The method according to claim 5, characterized in that, The first driving mechanism is a servo drive motor; the step of generating a first driving signal for controlling the first driving mechanism based on the target focal length value includes: Using the target focal length value as the control target, a first drive signal for controlling the first drive mechanism is generated based on the proportional-integral-derivative control method. In the aforementioned proportional-integral-derivative control method... The proportionality coefficient is ;in, This is the proportionality coefficient; This is the baseline tuning parameter for the proportional coefficient; The conveyor belt speed sensitivity coefficient is related to the proportionality coefficient; The speed data at the current moment; The integral coefficient is ;in, The integral coefficient; These are the baseline tuning parameters for the integral coefficients; The conveyor belt speed sensitivity coefficient is associated with the integral coefficient; The speed data at the current moment; The differential coefficient is ;in, These are the differential coefficients; These are the baseline tuning parameters for the differential coefficients; The conveyor belt speed sensitivity coefficient is associated with the differential coefficient; This represents the speed data at the current moment.

9. The method according to claim 5, characterized in that, The determination of the undulation level of the coal flow surface based on the coal flow particle density shown in the image data includes: Obtain the number of coal particles along the preset path of the image data; Based on the number of coal particles, determine the density of coal particles along the preset path; The undulation level of the coal flow surface is determined based on the relationship between the coal particle density and at least one undulation level classification threshold; the undulation level is positively correlated with the coal particle density.

10. The method according to claim 5 or 9, characterized in that, The second driving mechanism is a piezoelectric driving element; Based on the fluctuation level, a second drive signal for controlling the second drive mechanism is generated, including: A frequency parameter matching the fluctuation level is determined, the frequency parameter being used to control the piezoelectric drive element, and the frequency parameter being positively correlated with the fluctuation level; The frequency parameter is used as the second driving signal.

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