A lithium strip bandwidth and thickness online detection system and method

Abstract

The application discloses a lithium strip broadband thick online detection system and method, relates to the technical field of strip thickness online monitoring, and comprises a PLC controller, a profile generation module and four laser ranging sensors. The first laser ranging sensor and the second laser ranging sensor are vertically collinear. The third laser ranging sensor and the fourth laser ranging sensor are vertically collinear. The profile generation module is used for calculating the coordinates of the detection points of the four laser ranging sensors according to the three-dimensional coordinates of the four laser ranging sensors and the distances between the four laser ranging sensors and the lithium strip surface at the same time, and sequentially connecting the four detection points to obtain a profile line. The PLC controller is used for calculating the strip thickness according to the profile line and judging whether the strip thickness meets the requirements. The application has the advantages that the non-contact online monitoring of the strip thickness can be realized through the setting of the four laser ranging sensors and a specific algorithm, the detection precision is high, the application is not sensitive to jitter, the detection speed is fast, and the environmental adaptability is stronger.

Description

Technical Field

[0001] This invention relates to the field of online band thickness monitoring technology, and in particular to an online detection system and method for lithium band width and thickness. Background Technology

[0002] Lithium-ion battery strip is a key material constituting the negative electrode of a lithium-ion primary battery, endowing this type of battery with the core characteristics of high voltage, high energy density, and long lifespan. It plays a crucial role in energy storage and release within the battery, making it an indispensable "main material" in the entire battery system. The width and thickness of the lithium-ion battery strip are critical parameters affecting battery characteristics. The forming process of the lithium-ion battery strip involves extrusion, rolling / pressing, and winding. Continuous online monitoring of the width and thickness of the lithium-ion battery strip after rolling / pressing and before winding is of great significance. In particular, the thickness of the lithium-ion battery strip is a key parameter affecting battery capacity, internal resistance, and voltage performance, directly determining the battery's "electrochemical performance" and "safety."

[0003] Generally, the thickness of the lithium strip is monitored online during the winding process. Currently, there are three main methods for online thickness monitoring: The first method uses collimated laser rangefinders to measure the distances from the upper and lower surfaces of the lithium strip, and then subtracts the measured distances from the distance between the two sensors to calculate the thickness of the lithium strip. The second method is an improvement on the first, also using a through-beam laser thickness measurement method. It measures the thickness of curved surfaces by moving the sensor to scan and calculate the tilt angle. However, this method relies on the sensor's position at different times to calculate the tilt angle and is suitable for measuring 'curved surfaces' with slow shape changes. The third method involves mounting an industrial camera on the side of the lithium strip to acquire images of the side in real time, processing the images, and calculating the thickness of the lithium strip.

[0004] Because lithium strips are both soft and thin, high-frequency, small-amplitude jitter is inevitable during the winding process. All three methods mentioned above have problems. Method one has the problem that the detection point is highly likely to tilt during winding, becoming non-horizontal, and the distance between the two detection points is greater than the actual strip thickness. If the difference exceeds the set allowable threshold, it will trigger an alarm, resulting in low detection accuracy. Method two has the following problems with the high-frequency, irregular random jitter generated during winding: 1) Time lag: The tilt angle calculated based on previous and subsequent moments cannot accurately reflect the instantaneous tilt caused by jitter at the current moment, resulting in limited correction; 2) Complex structure: It requires a precise XY movement platform, which is costly, slow to respond, and cannot meet the real-time requirements of high-speed winding. Method three has the problem that industrial camera lenses have a certain depth of field range, and only objects within this range can be clearly imaged. Lithium strips are very thin (usually around 2mm), and once jitter occurs, it can easily lead to image blurring, inability to extract edges, or even complete displacement outside the depth of field, making it impossible to acquire an image of the lithium strip. Therefore, it is essential to develop an online monitoring system that can accurately detect the thickness of the lithium strip even when it tilts or vibrates. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an online detection system and method for lithium strip bandwidth and thickness, which has high detection accuracy, is not sensitive to vibration, has fast detection speed, and is more adaptable to the environment.

[0006] To address the aforementioned technical problems, this invention provides an online lithium strip width and thickness detection system, comprising a contour generation module and four laser ranging sensors electrically connected to it: a first laser ranging sensor, a second laser ranging sensor, a third laser ranging sensor, and a fourth laser ranging sensor. The contour generation module is electrically connected to a PLC controller. The first and second laser ranging sensors are vertically collinear; the third and fourth laser ranging sensors are also vertically collinear. The contour generation module calculates the coordinates of detection points A, B, C, and D of the four laser ranging sensors based on their three-dimensional coordinates and measured distances from the lithium strip surface at the same time, and then sequentially connects the four detection points A, B, C, and D to obtain a contour line. The PLC controller calculates the strip thickness based on the contour line and compares the calculated thickness with a set value to determine whether the strip thickness meets the requirements.

[0007] Furthermore, the method by which the PLC controller calculates the band thickness based on the contour line includes the following steps: S1. Calculate the angle θ between the upper edge contour line AC and the horizontal plane based on the coordinates of the two detection points A and C; the coordinates of point A are (x1, y1, z1). A The coordinates of point C are (x3, y3, z). C The first and third laser ranging sensors have the same coordinates in the lithium strip width direction, but different coordinates in the direction of lithium strip movement; that is, y 1= y3; x1≠x3; where x represents the direction of lithium strip movement on the horizontal plane, y represents the width direction of the lithium strip on the horizontal plane, and z represents the vertical direction; ;or ; S2. Calculate the band thickness h2 based on the distance h1 between the two detection points A and B and the included angle θ. ; ; in: L 12 The vertical distance between the first laser rangefinder and the second laser rangefinder; L1 is the distance between the first laser rangefinder and monitoring point A on the upper surface of the lithium strip, as measured by the first laser rangefinder. L2 is the distance between the second laser ranging sensor and monitoring point B on the lower surface of the lithium strip.

[0008] Furthermore, the method for calculating the thickness of the band, after step S2, also includes the following steps: S3. Calculate the angle Φ between the upper edge contour line BD and the horizontal plane based on the coordinates of the two detection points B and D; the coordinates of point B are (x2, y2, z2). B The coordinates of point D are (x4, y4, z). D ); ;or ; S4. Calculate the band thickness h4 based on the distance h3 between the two detection points C and D and the included angle Φ. ; ; in: L 34 The vertical distance between the third and fourth laser rangefinder sensors; L3 is the distance between the third laser ranging sensor and the monitoring point C on the upper surface of the lithium strip; L4 is the distance between the fourth laser rangefinder and the monitoring point D on the lower surface of the lithium strip.

[0009] The PLC controller is also used for: Calculate the deviation Δh between h2 and h4. ; Based on the deviation Δh and the preset deviation threshold Δh th The comparison results, and h2 and h4 with the preset band thickness range [h min ,h max The system status is determined by comprehensively considering the relationship between the following conditions: normal status, product out-of-tolerance status, sensor abnormal status, and lithium strip abnormal status. when And both h2 and h4 are in [h min ,h max When the system is within the specified range, it is determined that the system is in a normal state. when And at least one of h2 and h4 is not in [h min ,h max If the thickness is within the specified range, the product is deemed to be out of tolerance. when And both h2 and h4 are in [h min ,h max When the range is within ], it is determined that there is local abnormal deformation in the lithium strip; when And at least one of h2 and h4 is not in [h min ,h max If the laser rangefinder is within the specified range, it is determined that the laser rangefinder is malfunctioning.

[0010] Preset deviation threshold Δh th It can be determined based on the nominal accuracy of the laser rangefinder sensor and the allowable error of the manufacturing process.

[0011] Furthermore, it also includes an image processing module and a first image acquisition module electrically connected to it and mounted above the lithium strip; a fifth laser sensor is also disposed above the lithium strip; the first image acquisition module is used to acquire images of the upper surface of the lithium strip in real time; the image processing module is used to perform image processing on the received images of the upper surface of the lithium strip; the PLC controller is also used to identify the edge contour of the upper surface image, then calculate the bandwidth w based on the edge contour, calculate the tilt angle of the lithium strip in the width direction, and correct the bandwidth w to obtain wo. real When w real In the preset [w min ,w max Within the specified range, the bandwidth is determined to meet the requirements; if it exceeds the range, the bandwidth is determined to not meet the requirements. The coordinates of the installation position of the fifth laser sensor are (x5, y5, z5); the coordinates of the monitoring point E on the upper surface of the lithium strip by the fifth laser sensor are (x5, y5, z5). EThe x-coordinate x5 of the fifth laser sensor is the same as the x-coordinate x1 of the first laser ranging sensor, and its y-coordinate y5 is different from the y-coordinate y1 of the first laser ranging sensor, i.e., x1 = x5. y 1≠y 5； ; Where L5 is the distance between the fifth laser sensor and the monitoring point E as measured by the fifth laser sensor; The bandwidth w is corrected to obtain the corrected bandwidth w. real The method is as follows: ; Where Ψ is the tilt angle of the lithium strip in the width direction; .

[0012] Furthermore, the PLC controller is also used to determine the instantaneous jitter amplitude A and instantaneous jitter frequency f of the lithium strip based on the data of the contour line within the sampling time window Δt. peak ; and based on A and the preset threshold [A min A max Based on the comparison results, the control mode is dynamically selected: When A≦A min At that time, the first image acquisition module uses a fixed exposure time and a fixed acquisition time; When A min A A max At the same time, the exposure time and trigger acquisition time of the first image acquisition module are dynamically adjusted; When A>A max If this occurs, the measurement will be paused and an alarm will be issued.

[0013] Furthermore, the specific calculation method for the instantaneous jitter amplitude A is as follows: S1.1 The PLC controller first calculates the z-coordinate of the center point M of points A and C based on the z-coordinates of points A and C at the same time. M =(Z A +Z C ) / 2; S1.2 Record Z within a time window Δt (e.g., containing 10-20 sampling periods). M The difference between the maximum and minimum values ​​ΔZ M The instantaneous jitter amplitude A within the current time window Δt is: A1=ΔZ M / 2; The instantaneous jitter frequency fpeak is calculated by performing spectral analysis on the time series data of the Z-axis coordinate of point M. S3.1 Constructing the time series: The PLC controller uses a fixed sampling frequency f S (e.g., 100Hz) Receive data from the contour generation module; for each sampling time t i Record the Z coordinate of the corresponding center point M. M (t i This forms a discrete-time signal Z. M [n]; S3.2, Spectrum Analysis: The PLC controller analyzes the Z-axis at N consecutive time points. M Perform a discrete Fourier transform on [n] to obtain the spectrum Z of the Z-coordinate signal at the center M of the lithium band. M (f); S3.3 Calculate the amplitude of each frequency component |Z M (f)∣ reflects the vibration intensity of each frequency component; S3.4 Extracting the dominant frequency: Search for the maximum value in the amplitude spectrum; the corresponding frequency is the instantaneous jitter frequency f of the lithium band within the current time window. peak .

[0014] Furthermore, the method for dynamically adjusting the trigger acquisition time is as follows: S4.1, Phase Detection: For Z M [n] is smoothed to obtain Z M-smooth [n]; Then, based on the peak detection algorithm, the positions of the peaks and troughs are found; S4.2 Inflection Point Detection and Recording: Based on Z M-smooth [n] Detect inflection points and record the Z-coordinate and inflection point type for each inflection point; S4.3 Real-time jitter period calculation: The time interval between two consecutive peaks or two consecutive troughs is the real-time jitter period T. jitter ; S4.4 Phase Judgment and Next Inflection Point Prediction: Suppose that a phase is detected in the past time period t current The adjacent inflection point is t. last , If t current ≠t last , then t next_exterme =t last +T jitter / 2; If t current =t last , then t next_exterme =t currentt +T jitter / 2; Where: t next_exterme This represents the time when the next inflection point will arrive. t curren Represents the current time; T jitter Represents the real-time jitter period; S4.5 The PLC controller sends a command with a preset delay to the first image acquisition module to ensure that the first image acquisition module acquires the image at the exact moment the next inflection point arrives.

[0015] Furthermore, the smoothing methods include exponentially weighted moving average, moving average, and median filtering.

[0016] Furthermore, the smoothing method for the exponentially weighted moving average is as follows: ; ; Among them: Z M-smooth [n] represents the current smoothed output value; Z M [n] represents the current original measurement value; η is the smoothing factor; fc is the cutoff frequency of the smoothing filter; fc can be set to fc = λ * fpeak, where λ is a constant greater than 1, such as λ = 1.3; or it can be set manually. Through preliminary experimental calibration, the jitter energy of the lithium strip during normal winding is mainly concentrated in the 5~20Hz frequency band. To ensure that the true jitter signal is preserved while effectively suppressing high-frequency noise, the cutoff frequency fc = 25Hz is set.

[0017] Furthermore, the method for dynamically adjusting the exposure time of the first image acquisition module is as follows: by adjusting Z... M [n] Perform analysis and calculate the instantaneous vertical velocity V(t) of the center point M on the upper surface. i Then, based on the calculated V(t) i The exposure time T is calculated. exp ; Among them, the instantaneous vertical velocity V(t) of the center point M on the upper surface i The calculation method for ) is as follows: ; Wherein, V(t) i (t) represents the current time. i The instantaneous vertical velocity of the center point M on the upper surface; Z M (t i (t) represents the current time. i The Z-coordinate of the center point M on the upper surface; Z M (t i-1 ) represents the previous time t i-1 The Z-coordinate of the center point M on the upper surface; f s The system sampling frequency, i.e., the number of times the laser sensor collects data per second, is controlled by the PLC controller via a synchronous trigger signal at a fixed frequency f. s Simultaneously trigger four laser rangefinders to perform measurements, and acquire measurement data from all sensors within the same communication cycle; Based on the calculated V(t) i The exposure time T is calculated. exp The method is as follows: ; J(t i )=α∣V(t i )∣+β∣ I will (t i) |; I will (t i )=( i (t i )- i (t i-1 )) / Δt; in: T min-hw Minimum exposure time; T max This is the maximum exposure time allowed by the system; for example, 10 ms, determined by camera performance and frame rate, while also taking into account the lighting capability to ensure that the image is neither saturated nor underexposed. K is a pre-calibrated constant that needs to be determined through calibration. The unit is mm·ms or mm·s to ensure dimensional consistency. e To prevent small positive numbers with a denominator of zero, and to prevent the denominator from being zero when the speed is zero, we can take 0.001; V(t i The instantaneous vertical velocity is (mm / s or mm / ms), and must be a positive number; I will (t i ) represents the rate of change of the angle θ between the upper edge contour line AC and the horizontal plane at the current moment, which can be obtained by the difference of θ over time; i (t i )and i (t i-1 ) are the angles between the upper edge contour line AC calculated at the current time and the previous time and the horizontal plane, respectively, and Δt is the sampling period, Δt=1 / fs; α , β The conversion factor is determined experimentally.

[0018] When the sensor installation distance L12 or L34 changes slightly due to thermal expansion and contraction, it will cause a fixed, small deviation Δh between h2 and h4. Furthermore, a calibration module is included; the PLC controller is also used to record the sequence of deviation Δh for R consecutive sampling periods and calculate its moving average. If the moving average stabilizes within a preset non-zero range (e.g., 0.01-0.02 mm), it is determined that the system needs calibration. 12 and L 34 The value, the calibration module for L 12 and L 34 Perform calibration as follows: S51. Place the standard part stably, so that it is located between the first laser rangefinder and the second laser rangefinder, and between the third laser rangefinder and the fourth laser rangefinder; the upper and lower surfaces of the standard part are both horizontal. S52. Turn on the first laser rangefinder, the second laser rangefinder, the third laser rangefinder, and the fourth laser rangefinder. The first laser rangefinder measures the distance L5 between itself and the upper surface of the standard part; the second laser rangefinder measures the distance L6 between itself and the lower surface of the standard part; the third laser rangefinder measures the distance L7 between itself and the upper surface of the standard part; and the fourth laser rangefinder measures the distance L8 between itself and the lower surface of the standard part. S53, The calibration module calculates L based on L5, L6, L7, L8, and the distance L9 between the upper and lower surfaces of the standard part. 12 and L 34 The value; ; .

[0019] Furthermore, it also includes a second image acquisition module electrically connected to the image processing module and installed on the side of the lithium strip; the second image acquisition module is used to acquire images of the side of the lithium strip in real time; the image processing module is also used to perform image processing on the received images of the side of the lithium strip; the PLC controller is also used to perform defect identification based on the processed images of the side of the lithium strip and the upper surface image, and if a defect is identified, it is determined that a surface defect exists. The exposure time and trigger acquisition time of the second image acquisition module are synchronized with those of the first image acquisition module.

[0020] Furthermore, it also includes an audible and visual alarm module, a data storage module, a parameter setting module, and a display module; the audible and visual alarm module is used to issue an audible and visual alarm when the PLC controller determines that the bandwidth or thickness does not meet the requirements, there are surface defects, or calibration is required; the data storage module is used to store abnormal data within a time period T; the display module is used to display the contour line generated by the contour generation module in the current detection state, the images acquired by the first image acquisition module and the second image acquisition module, and the bandwidth w. real The judgment results for band thickness h2, h4, bandwidth, band thickness, and surface defects; the parameter setting module is used to set [h min ,h max ]、[w min ,w max Threshold parameters such as ]

[0021] This invention also provides an online method for detecting the bandwidth and thickness of lithium-ion bandgap, comprising the following steps: S1. Laser ranging: Activate the first, second, third, and fourth laser ranging sensors. The first laser ranging sensor measures the distance L1 between itself and the upper surface of the lithium strip; the second laser ranging sensor measures the distance L2 between itself and the lower surface of the lithium strip; the third laser ranging sensor measures the distance L3 between itself and the upper surface of the lithium strip; and the fourth laser ranging sensor measures the distance L4 between itself and the lower surface of the lithium strip. Then, send L1, L2, L3, and L4 to the contour generation module. S2. The contour generation module calculates the coordinates of detection points A, B, C, and D: the three-dimensional coordinates of the first, second, third, and fourth laser rangefinders are (x1, y1, z1), (x2, y2, z2), (x3, y3, z3), and (x4, y4, z4), respectively; the coordinates of A, B, C, and D are (x1, y1, z4), (x2, y2, z2), (x3, y3, z3), and (x4, y4, z4), respectively. A (x2,y2,z) B (x3,y3,z) C (x4,y4,z) D );in ; ; ; x represents the direction of lithium strip movement on the horizontal plane, y represents the width direction of the lithium strip on the horizontal plane, and z represents the vertical direction; x1=x2; y1=y2; x3=x4; y3=y4; S3. The contour generation module connects four detection points A, B, C, and D in sequence to obtain the contour line; S4, the PLC controller calculates the strip thickness based on the outline: S41. Calculate the angle θ between the upper edge contour line AC and the horizontal plane based on the coordinates of the two detection points A and C. ;or ; S42. Calculate the band thickness h2 based on the distance h1 between the two detection points A and B and the included angle θ. ; ; Where L 12 The vertical distance between the first laser rangefinder and the second laser rangefinder; S43. Calculate the angle Φ between the upper edge contour line BD and the horizontal plane based on the coordinates of the two detection points B and D; the coordinates of point B are (x2, y2, z2). B The coordinates of point D are (x4, y4, z). D ); ;or ; S44. Based on the distance h3 between the two detection points C and D and the included angle Φ, the thickness h4 is calculated. ; ; Where L 34 The vertical distance between the third and fourth laser rangefinder sensors; S5. Comprehensive judgment of system state: Calculate the deviation Δh between h2 and h4. ; Based on the deviation Δh and the preset deviation threshold Δh th The comparison results, and h2 and h4 with the preset band thickness range [h min ,h max Based on the relationship between the system status and the product out-of-tolerance status, the system status includes at least one of the following: normal status, product out-of-tolerance status, sensor abnormal status, and lithium strip abnormal status. S6. Image Acquisition: The first image acquisition module and the second image acquisition module acquire images of the side surface and the top surface of the lithium strip, respectively; S7. Image Processing: The image processing module performs image processing on the received images of the side and top surfaces of the lithium strip. S8. Defect Identification: The PLC controller identifies defects based on the images of the side and top surface of the lithium strip processed by the image processing module. If a defect is identified, it is determined that there is a surface defect, and an alarm is triggered by the audible and visual alarm module. S9. Calculate the jitter amplitude and dynamically select the control mode: The PLC controller determines the instantaneous jitter amplitude A and instantaneous jitter frequency f of the lithium strip based on the data of the contour line within the sampling time window Δt.peak ; and based on A and the preset threshold [A min A max Based on the comparison results, the control mode is dynamically selected: When A≦A min At that time, the first image acquisition module uses a fixed exposure time and a fixed acquisition time; When A min A A max At the same time, the exposure time and trigger acquisition time of the first image acquisition module are dynamically adjusted; When A>A max When this happens, the measurement is paused and an alarm is issued; S10. Bandwidth Detection and Correction: The PLC controller is also used to identify the edge contours of the upper surface image, then calculate the bandwidth w based on the edge contours, calculate the tilt angle of the lithium strip in the width direction, and correct the bandwidth w to obtain wo. real When w real In the preset [w min ,w max Within the specified range, the bandwidth is determined to meet the requirements; if it exceeds the range, the bandwidth is determined to fail to meet the requirements, and an alarm is triggered via the audible and visual alarm module. S11. Online display: The display module displays the contour line generated by the contour generation module under the current detection state, the images acquired by the first image acquisition module and the second image acquisition module, the bandwidth w, band thickness h2, h4 calculated by the PLC controller, and the judgment results of bandwidth, band thickness, and surface defects.

[0022] Furthermore, during initial system installation, sensor replacement, or routine maintenance, L... 12 and L 34 Perform calibration.

[0023] Furthermore, the PLC controller records a sequence of deviations Δh for R consecutive sampling periods. ; and calculate the moving average value of Δh. If the moving average value is stable within a preset non-zero interval, it is determined that the system needs to be calibrated L. 12 and L 34 The value, the calibration module for L 12 and L 34 Perform calibration.

[0024] Furthermore, L 12 and L 34 The calibration method is as follows: S51. Place the standard part stably, so that it is located between the first laser rangefinder and the second laser rangefinder, and between the third laser rangefinder and the fourth laser rangefinder; the upper and lower surfaces of the standard part are both horizontal. S52. Turn on the first laser rangefinder, the second laser rangefinder, the third laser rangefinder, and the fourth laser rangefinder. The first laser rangefinder measures the distance L5 between itself and the upper surface of the standard part; the second laser rangefinder measures the distance L6 between itself and the lower surface of the standard part; the third laser rangefinder measures the distance L7 between itself and the upper surface of the standard part; and the fourth laser rangefinder measures the distance L8 between itself and the lower surface of the standard part. S53, The calibration module calculates L based on L5, L6, L7, L8, and the distance L9 between the upper and lower surfaces of the standard part. 12 and L 34 The value; ; .

[0025] Beneficial effects of this invention: This application utilizes two sets of fixed-position through-beam laser sensors to simultaneously sample different spatial positions of the lithium strip. This allows for precise capture of the instantaneous complex posture of the lithium strip caused by high-frequency jitter and accurate calculation of its true thickness at that instant. Compared to traditional methods that rely on historical data to calculate the tilt angle, this instantaneous spatial sampling method offers a fundamental advantage in compensating for high-frequency jitter.

[0026] This invention enables online monitoring of lithium strip thickness and bandwidth during the winding process, which is of great significance for lithium strip production. Compared with vision-based detection methods, it has the following significant advantages: High detection accuracy: Laser sensors use a direct measurement method, achieving micron-level accuracy; while visual measurement is an indirect measurement, and its accuracy is affected by calibration, lens distortion, and algorithm stability. This invention uses four fixedly installed laser sensors, eliminating the need for moving parts and ensuring long-term stability of measurement accuracy from a hardware perspective.

[0027] Insensitive to jitter: The instantaneous spatial sampling method of this invention acquires the coordinates of different positions of the lithium strip at the same time, directly calculating the true thickness under the current posture, without relying on historical data to calculate the tilt angle. Therefore, even if the lithium strip experiences high-frequency random jitter, as long as it does not move out of the sensor's range, accurate measurement is possible. In contrast, traditional vision solutions are extremely sensitive to jitter and are prone to measurement failure due to defocusing or blurring.

[0028] High detection speed: The response time of the laser sensor is in the microsecond range, and with the synchronous triggering of the PLC, high-frequency detection in the kHz range can be achieved. In contrast, traditional vision measurement is limited by the speed of image acquisition, transmission and processing, and the detection frequency is usually low, making it difficult to meet the real-time requirements of high-speed winding.

[0029] Greater environmental adaptability: Laser sensors, based on the principle of active ranging, are unaffected by changes in ambient light and are insensitive to the reflective properties of lithium strip surfaces, making them suitable for complex industrial environments. In contrast, traditional vision solutions have stringent requirements for lighting systems, and changes in lighting or surface reflections can easily lead to measurement failures. Attached Figure Description

[0030] Figure 1 This is a simplified system framework diagram for an embodiment; Figure 2 This is a diagram showing the arrangement of the four laser ranging sensors in the embodiment; Figure 3 This is a simplified diagram of the contour lines generated in the embodiment; Figure 4 This is a schematic diagram illustrating the principle of the calibration process; Figure 5 This is a partial view of the laser sensor arrangement in an embodiment.

[0031] In the diagram, 1-first laser rangefinder, 2-second laser rangefinder, 3-third laser rangefinder, 4-fourth laser rangefinder, and 5-standard component. Detailed Implementation

[0032] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] Example 1 An online detection system for lithium-ion bandwidth and thickness, such as Figure 1-2As shown, the system includes a contour generation module and four laser ranging sensors electrically connected to it: a first laser ranging sensor 1, a second laser ranging sensor 2, a third laser ranging sensor 3, and a fourth laser ranging sensor 4. The contour generation module is electrically connected to a PLC controller. The first laser ranging sensor 1 and the second laser ranging sensor 2 are vertically collinear; the third laser ranging sensor 3 and the fourth laser ranging sensor 4 are vertically collinear. The contour generation module is used to calculate the coordinates of detection points A, B, C, and D of the four laser ranging sensors based on their three-dimensional coordinates and measured distances from the lithium strip surface at the same time. The module then connects these four detection points A, B, C, and D sequentially to obtain a contour line. The PLC controller is used to calculate the strip thickness based on the contour line and compare the calculated thickness with a set value to determine whether the thickness meets the requirements.

[0034] Specifically, the PLC controller is based on the contour line (e.g. Figure 3 The method for calculating the band thickness (as shown) includes the following steps: S1. Calculate the angle θ between the upper edge contour line AC and the horizontal plane based on the coordinates of the two detection points A and C; the coordinates of point A are (x1, y1, z1). A The coordinates of point C are (x3, y3, z). C The first laser ranging sensor 1 and the third laser ranging sensor 3 have the same coordinates in the lithium strip width direction, but different coordinates in the direction of lithium strip movement; that is, y 1= y3; x1≠x3; where x represents the direction of lithium strip movement on the horizontal plane, y represents the width direction of the lithium strip on the horizontal plane, and z represents the vertical direction; ;or ; S2. Calculate the band thickness h2 based on the distance h1 between the two detection points A and B and the included angle θ. ; ; in: L 12 The vertical distance between the first laser rangefinder 1 and the second laser rangefinder 2; L1 is the distance between the first laser rangefinder 1 and the monitoring point A on the upper surface of the lithium strip, as measured by the first laser rangefinder 1. L2 is the distance between the second laser rangefinder 2 and the monitoring point B on the lower surface of the lithium strip, as measured by the second laser rangefinder 2.

[0035] Furthermore, the method for calculating the thickness of the band, after step S2, also includes the following steps: S3. Calculate the angle Φ between the upper edge contour line BD and the horizontal plane based on the coordinates of the two detection points B and D; the coordinates of point B are (x2, y2, z2). B The coordinates of point D are (x4, y4, z). D ); ;or ; S4. Calculate the band thickness h4 based on the distance h3 between the two detection points C and D and the included angle Φ. ; ; in: L 34 The vertical distance between the third laser rangefinder 3 and the fourth laser rangefinder 4; L3 is the distance between the third laser rangefinder 3 and the monitoring point C on the upper surface of the lithium strip, as measured by the third laser rangefinder 3. L4 is the distance between the fourth laser rangefinder 4 and the monitoring point D on the lower surface of the lithium strip, as measured by the fourth laser rangefinder 4.

[0036] In another embodiment, the PLC controller is further configured to: Calculate the deviation Δh between h2 and h4. ; Based on the deviation Δh and the preset deviation threshold Δh th The comparison results, and h2 and h4 with the preset band thickness range [h min ,h max The system status is determined by comprehensively considering the relationship between the following conditions: normal status, product out-of-tolerance status, sensor abnormal status, and lithium strip abnormal status. when And both h2 and h4 are in [h min ,h max When the system is within the specified range, it is determined that the system is in a normal state. when And at least one of h2 and h4 is not in [h min ,h max If the thickness is within the specified range, the product is deemed to be out of tolerance. when And both h2 and h4 are in [h min ,h max When the range is within ], it is determined that there is local abnormal deformation in the lithium strip; when And at least one of h2 and h4 is not in [h min ,h max If the laser rangefinder is within the specified range, it is determined that the laser rangefinder is malfunctioning.

[0037] Preset deviation threshold Δhth The accuracy can be determined based on the nominal accuracy of the laser rangefinder sensor and the allowable thickness fluctuation in the manufacturing process. For example, if the accuracy of the laser rangefinder sensor is ±0.01mm and the allowable thickness fluctuation in the manufacturing process is ±0.02mm, then Δh can be set. th =0.03mm, ensuring that Δh will not exceed this threshold under normal operating conditions.

[0038] In another embodiment, the system further includes an image processing module and a first image acquisition module electrically connected thereto and mounted above the lithium strip; a fifth laser sensor is also disposed above the lithium strip; the first image acquisition module is used to acquire images of the upper surface of the lithium strip in real time; the image processing module is used to perform image processing on the received images of the upper surface of the lithium strip; the PLC controller is also used to identify the edge contour of the upper surface image, then calculate the bandwidth w based on the edge contour, calculate the tilt angle of the lithium strip in the width direction, and correct the bandwidth w to obtain wo. real When w real In the preset [w min ,w max Within the specified range, the bandwidth is determined to meet the requirements; if it exceeds the range, the bandwidth is determined to not meet the requirements. The coordinates of the installation position of the fifth laser sensor are (x5, y5, z5); the coordinates of the monitoring point E on the upper surface of the lithium strip by the fifth laser sensor are (x5, y5, z5). E )(like Figure 5 As shown); the x-coordinate x5 of the fifth laser sensor is the same as the x-coordinate x1 of the first laser ranging sensor 1, and its y-coordinate y5 is different from the y-coordinate y1 of the first laser ranging sensor 1, that is, x1=x5, and y 1≠y 5； ; Where L5 is the distance between the fifth laser sensor and the monitoring point E as measured by the fifth laser sensor; The bandwidth w is corrected to obtain the corrected bandwidth w. real The method is as follows: ; Where Ψ is the tilt angle of the lithium strip in the width direction; .

[0039] The contour data measured by the laser sensor is not only used for its own thickness calculation, but also the tilt angle of the calculated bandwidth direction is used to correct the visual bandwidth measurement value. This allows the bandwidth measurement to maintain extremely high accuracy even when the lithium strip undergoes complex spatial twisting, achieving laser-vision data fusion, an effect that cannot be achieved by solutions that rely solely on vision or solely on laser.

[0040] In another embodiment, the PLC controller is further configured to determine the instantaneous jitter amplitude A and instantaneous jitter frequency f of the lithium strip based on the data of the contour line within the sampling time window Δt. peak ; and based on A and the preset threshold [A min A max Based on the comparison results, the control mode is dynamically selected: When A≦A min At that time, the first image acquisition module uses a fixed exposure time and a fixed acquisition time; When A min A A max At the same time, the exposure time and trigger acquisition time of the first image acquisition module are dynamically adjusted; When A>A max If this occurs, the measurement will be paused and an alarm will be issued.

[0041] Specifically, the calculation method for the instantaneous jitter amplitude A is as follows: S1.1 The PLC controller first calculates the z-coordinate of the center point M of points A and C based on the z-coordinates of points A and C at the same time. M =(Z A +Z C ) / 2; S1.2 Record Z within a time window Δt (e.g., containing 10-20 sampling periods). M The difference between the maximum and minimum values ​​ΔZ M The instantaneous jitter amplitude A within the current time window Δt is: A1=ΔZ M / 2; Specifically, the instantaneous jitter frequency fpeak is calculated by performing spectral analysis on the time series data of the Z-axis coordinate of point M: S3.1 Constructing the time series: The PLC controller uses a fixed sampling frequency f S (e.g., 100Hz) Receive data from the contour generation module; for each sampling time t i Record the Z coordinate of the corresponding center point M. M (t i This forms a discrete-time signal Z. M [n]; S3.2, Spectrum Analysis: The PLC controller analyzes the Z-axis at N consecutive time points. M[n] Perform a Discrete Fourier Transform (where the value of N is determined by the desired frequency resolution Δf, Δf = fs / N, usually N is an integer power of 2, for example N=1024); obtain the spectrum Z of the Z coordinate signal of the lithium strip center M. M (f); S3.3 Calculate the amplitude of each frequency component |Z M (f)∣ reflects the vibration intensity of each frequency component; S3.4 Extracting the dominant frequency: Search for the maximum value in the amplitude spectrum; the corresponding frequency is the instantaneous jitter frequency f of the lithium band within the current time window. peak .

[0042] Specifically, the method for dynamically adjusting the trigger acquisition time is as follows: S4.1, Phase Detection: For Z M [n] is smoothed to obtain Z M-smooth [n]; Then, based on the peak detection algorithm, the positions of the peaks and troughs are found; the peaks and troughs correspond to the moments when the lithium strip speed is the lowest and the direction of motion is about to change; S4.2 Inflection Point Detection and Recording: Based on Z M-smooth [n] Detect inflection points and record the Z-coordinate and inflection point type for each inflection point; S4.3 Real-time jitter period calculation: The time interval between two consecutive peaks or two consecutive troughs is the real-time jitter period T. jitter ; S4.4 Phase Judgment and Next Inflection Point Prediction: Suppose that a phase is detected in the past time period t current The adjacent inflection point is t. last , If t current ≠t last , then t next_exterme =t last +T jitter / 2; If t current =t last , then t next_exterme =t currentt +T jitter / 2; Where: t next_exterme This represents the time when the next inflection point will arrive. t curren Represents the current time; T jitter Represents the real-time jitter period; S4.5 The PLC controller sends a command with a preset delay to the first image acquisition module to ensure that the first image acquisition module acquires the image at the exact moment the next inflection point arrives.

[0043] By employing the two dynamic adjustment strategies of trigger acquisition time and exposure time, the success rate of image acquisition by industrial cameras under high-speed shaking conditions of lithium strips can be significantly improved. An intelligent collaborative system guided by a laser sensor and optimized for the working state of the vision sensor has been established, overcoming the inherent problem of traditional vision solutions being "sensitive to shaking".

[0044] Specifically, the smoothing methods include exponentially weighted moving average, moving average, median filtering, etc.

[0045] In this embodiment, an exponentially weighted moving average method is used for smoothing. The specific method is as follows: ; ; Among them: Z M-smooth [n] represents the current smoothed output value; Z M [n] represents the current original measurement value; η is the smoothing factor; fc is the cutoff frequency of the smoothing filter; fc can be set to fc = λ * fpeak, where λ is a constant greater than 1, such as λ = 1.3; or it can be set manually. Through preliminary experimental calibration, the jitter energy of the lithium strip during normal winding is mainly concentrated in the 5~20Hz frequency band. To ensure that the true jitter signal is preserved while effectively suppressing high-frequency noise, the cutoff frequency fc = 25Hz is set.

[0046] The above-mentioned smoothing method links the smoothing factor η with the physical parameters fc and fs, giving the parameters physical meaning. This ensures that the smoothing process can effectively filter out measurement noise while truly preserving the jitter characteristics of the lithium strip, providing a reliable data foundation for subsequent instantaneous velocity calculation and inflection point prediction.

[0047] Specifically, the method for dynamically adjusting the exposure time of the first image acquisition module is as follows: by adjusting the Z... M [n] Perform analysis and calculate the instantaneous vertical velocity V(t) of the center point M on the upper surface. i Then, based on the calculated V(t) i The exposure time T is calculated. exp ; Specifically, the instantaneous vertical velocity V(t) of the center point M on the upper surface i The calculation method for ) is as follows: ; Wherein, V(t) i (t) represents the current time. i The instantaneous vertical velocity of the center point M on the upper surface; Z M (t i (t) represents the current time. i The Z-coordinate of the center point M on the upper surface; Z M (t i-1 ) represents the previous time t i-1 The Z-coordinate of the center point M on the upper surface; f s The system sampling frequency, i.e., the number of times the laser sensor collects data per second, is controlled by the PLC controller via a synchronous trigger signal at a fixed frequency f. s Simultaneously trigger four laser rangefinders to perform measurements, and acquire measurement data from all sensors within the same communication cycle; Specifically, based on the calculated V(t) i The exposure time T is calculated. exp The method is as follows: ; J(t i )=α∣V(t i )∣+β∣ I will (t i) |; in: T min-hw Minimum exposure time; T max This is the maximum exposure time allowed by the system; for example, 10 ms, determined by camera performance and frame rate, while also taking into account the lighting capability to ensure that the image is neither saturated nor underexposed. K is a pre-calibrated constant that needs to be determined through calibration. The unit is mm·ms or mm·s to ensure dimensional consistency. e To prevent small positive numbers with a denominator of zero, and to prevent the denominator from being zero when the speed is zero, we can take 0.001; V(t i The instantaneous vertical velocity is (mm / s or mm / ms), and must be a positive number; I will (t i ) represents the rate of change of the angle θ between the upper edge contour line AC and the horizontal plane at the current moment, which can be obtained by the difference of θ over time; I will (t i )=( i (t i )- i (t i-1 )) / Δt; i (t i )and i (t i-1 ) are the angles between the upper edge contour line AC calculated at the current time and the previous time and the horizontal plane, respectively, and Δt is the sampling period, Δt=1 / fs; α , β The conversion factor is determined experimentally (e.g.: α =1, β =0.2, to make the dimensions of the two consistent).

[0048] When the sensor mounting distance L12 or L34 changes slightly due to thermal expansion and contraction, it will cause a fixed, small deviation Δh between h2 and h4. Therefore, it also includes a method for measuring L 12 and L 34 The calibration module is used for calibration. It is used during initial system installation, sensor replacement, or routine maintenance. 12 and L 34 Perform calibration.

[0049] In another embodiment, the PLC controller is further configured to record a sequence of deviations Δh over R consecutive sampling periods. ; and calculate the sliding average value of Δh. If the sliding average value is stable within a preset non-zero range (e.g., 0.01-0.02 mm), it is determined that the system needs to be calibrated. 12 and L 34 The value is used to calibrate L. 12 and L 34 Perform calibration.

[0050] Specifically, L 12 and L 34 The numerical calibration method is as follows (e.g. Figure 4 (as shown) S51. Place the standard part stably, so that it is located between the first laser rangefinder 1 and the second laser rangefinder 2, and between the third laser rangefinder 3 and the fourth laser rangefinder 4; the upper and lower surfaces of the standard part 5 are both horizontal. S52. Activate the first laser rangefinder 1, the second laser rangefinder 2, the third laser rangefinder 3, and the fourth laser rangefinder 4. The first laser rangefinder 1 measures the distance L5 between itself and the upper surface of the standard part; the second laser rangefinder 2 measures the distance L6 between itself and the lower surface of the standard part; the third laser rangefinder 3 measures the distance L7 between itself and the upper surface of the standard part; and the fourth laser rangefinder 4 measures the distance L8 between itself and the lower surface of the standard part. S53, The calibration module calculates L based on L5, L6, L7, L8, and the distance L9 between the upper and lower surfaces of the standard part. 12 and L34 The value; ; .

[0051] In another embodiment, a second image acquisition module, electrically connected to the image processing module and mounted on the side of the lithium strip, is further included. The second image acquisition module is used to acquire images of the side of the lithium strip in real time. The image processing module is also used to perform image processing on the received images of the side of the lithium strip. The PLC controller is also used to perform defect identification based on the processed images of the side of the lithium strip and the upper surface image. If a defect is identified, it is determined that a surface defect exists. The exposure time and trigger acquisition time of the second image acquisition module are synchronized with those of the first image acquisition module.

[0052] In another embodiment, it further includes an audible and visual alarm module, a data storage module, a parameter setting module, and a display module; the audible and visual alarm module is used to issue an audible and visual alarm when the PLC controller determines that the bandwidth or thickness does not meet the requirements, there are surface defects, or calibration is required; the data storage module is used to store abnormal data within a time period T; the display module is used to display the contour line generated by the contour generation module in the current detection state, the images acquired by the first image acquisition module and the second image acquisition module, and the bandwidth w. real The judgment results for band thickness h2, h4, bandwidth, band thickness, and surface defects; the parameter setting module is used to set [h min ,h max ]、[w min ,w max Threshold parameters such as ]

[0053] The three-dimensional coordinates of the first laser rangefinder 1, the second laser rangefinder 2, the third laser rangefinder 3, the fourth laser rangefinder 4, and the fifth laser rangefinder 5 (x1, y1, z1), (x2, y2, z2), (x3, y3, z3), (x4, y4, z4), and (x5, y5, z5), as well as the distance L9 between the upper and lower surfaces of the standard part 5, need to be measured and set in advance. min ,h max ] and [w min ,w max The settings are based on the specifications and allowable error of the lithium strip to be tested. The first laser rangefinder 1, the second laser rangefinder 2, the third laser rangefinder 3, the fourth laser rangefinder 4, the fifth laser rangefinder, and the standard component 5 are all equipped with mounting brackets; the first image acquisition module and the second image acquisition module both include mounting brackets, industrial cameras, and supplementary lighting.

[0054] Example 2 A method for online detection of bandwidth and thickness of lithium-ion bandgap includes the following steps: S1. Laser ranging: Activate the first laser ranging sensor 1, the second laser ranging sensor 2, the third laser ranging sensor 3, and the fourth laser ranging sensor 4. The first laser ranging sensor 1 measures the distance L1 between itself and the upper surface of the lithium strip; the second laser ranging sensor 2 measures the distance L2 between itself and the lower surface of the lithium strip; the third laser ranging sensor 3 measures the distance L3 between itself and the upper surface of the lithium strip; and the fourth laser ranging sensor 4 measures the distance L4 between itself and the lower surface of the lithium strip. Then, send L1, L2, L3, and L4 to the contour generation module. S2. The contour generation module calculates the coordinates of detection points A, B, C, and D: The three-dimensional coordinates of the first laser ranging sensor 1, the second laser ranging sensor 2, the third laser ranging sensor 3, and the fourth laser ranging sensor 4 are (x1, y1, z1), (x2, y2, z2), (x3, y3, z3), and (x4, y4, z4), respectively; the coordinates of A, B, C, and D are (x1, y1, z4), (x2, y2, z2), (x3, y3, z3), and (x4, y4, z4), respectively. A (x2,y2,z) B (x3,y3,z) C (x4,y4,z) D );in ; ; ; x represents the direction of lithium strip movement on the horizontal plane, y represents the width direction of the lithium strip on the horizontal plane, and z represents the vertical direction; x1=x2; y1=y2; x3=x4; y3=y4; S3. The contour generation module connects four detection points A, B, C, and D in sequence to obtain the contour line; S4, the PLC controller calculates the strip thickness based on the outline: S41. Calculate the angle θ between the upper edge contour line AC and the horizontal plane based on the coordinates of the two detection points A and C. ;or ; S42. Calculate the band thickness h2 based on the distance h1 between the two detection points A and B and the included angle θ. ; ; Where L 12 The vertical distance between the first laser rangefinder 1 and the second laser rangefinder 2; S43. Calculate the angle Φ between the upper edge contour line BD and the horizontal plane based on the coordinates of the two detection points B and D; the coordinates of point B are (x2, y2, z2). B The coordinates of point D are (x4, y4, z). D); ;or ; S44. Based on the distance h3 between the two detection points C and D and the included angle Φ, the thickness h4 is calculated. ; ; Where L 34 The vertical distance between the third laser rangefinder 3 and the fourth laser rangefinder 4; S5. Comprehensive judgment of system state: Calculate the deviation Δh between h2 and h4. ; Based on the deviation Δh and the preset deviation threshold Δh th The comparison results, and h2 and h4 with the preset band thickness range [h min ,h max Based on the relationship between the system status and the product out-of-tolerance status, the system status includes at least one of the following: normal status, product out-of-tolerance status, sensor abnormal status, and lithium strip abnormal status. S6. Image Acquisition: The first image acquisition module and the second image acquisition module acquire images of the side surface and the top surface of the lithium strip, respectively; S7. Image Processing: The image processing module performs image processing on the received images of the side and top surfaces of the lithium strip. S8. Defect Identification: The PLC controller identifies defects based on the images of the side and top surface of the lithium strip processed by the image processing module. If a defect is identified, it is determined that there is a surface defect, and an alarm is triggered by the audible and visual alarm module. S9. Calculate the jitter amplitude and dynamically select the control mode: The PLC controller determines the instantaneous jitter amplitude A and instantaneous jitter frequency f of the lithium strip based on the data of the contour line within the sampling time window Δt. peak ; and based on A and the preset threshold [A min A max Based on the comparison results, the control mode is dynamically selected: When A≦A min At that time, the first image acquisition module uses a fixed exposure time and a fixed acquisition time; When A min A A max At the same time, the exposure time and trigger acquisition time of the first image acquisition module are dynamically adjusted; When A>A max When this happens, the measurement is paused and an alarm is issued; S10. Bandwidth Detection and Correction: The PLC controller is also used to identify the edge contours of the upper surface image, then calculate the bandwidth w based on the edge contours, calculate the tilt angle of the lithium strip in the width direction, and correct the bandwidth w to obtain wo. real When w real In the preset [w min ,w max Within the specified range, the bandwidth is determined to meet the requirements; if it exceeds the range, the bandwidth is determined to fail to meet the requirements, and an alarm is triggered via the audible and visual alarm module. S11. Online display: The display module displays the contour line generated by the contour generation module under the current detection state, the images acquired by the first image acquisition module and the second image acquisition module, the bandwidth w, band thickness h2, h4 calculated by the PLC controller, and the judgment results of bandwidth, band thickness, and surface defects.

[0055] During initial system installation, sensor replacement, or routine maintenance, L... 12 and L 34 Perform calibration.

[0056] The PLC controller records a sequence of deviations Δh for R consecutive sampling periods and calculates its moving average. If the moving average stabilizes within a preset non-zero interval, it determines that the system needs calibration L. 12 and L 34 The value, the calibration module for L 12 and L 34 Perform calibration.

[0057] L 12 and L 34 The calibration method is as follows: S51. Place the standard part 5 stably, so that it is located between the first laser rangefinder 1 and the second laser rangefinder 2, and between the third laser rangefinder 3 and the fourth laser rangefinder 4; the upper and lower surfaces of the standard part 5 are both horizontal. S52. Turn on the first laser rangefinder 1, the second laser rangefinder 2, the third laser rangefinder 3, and the fourth laser rangefinder 4. The first laser rangefinder 1 measures the distance L5 between itself and the upper surface of the standard part 5; the second laser rangefinder 2 measures the distance L6 between itself and the lower surface of the standard part 5; the third laser rangefinder 3 measures the distance L7 between itself and the upper surface of the standard part 5; and the fourth laser rangefinder 4 measures the distance L8 between itself and the lower surface of the standard part 5. S53, The calibration module calculates L based on L5, L6, L7, L8, and the distance L9 between the upper and lower surfaces of standard part 5. 12 and L 34 The value; ; .

[0058] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. An online detection system for lithium strip width and thickness, characterized in that: The system includes a contour generation module and four laser ranging sensors (1, 2, 3, and 4) electrically connected to it. The contour generation module is electrically connected to a PLC controller. The first laser ranging sensor (1) and the second laser ranging sensor (2) are vertically collinear. The third laser ranging sensor (3) and the fourth laser ranging sensor (4) are vertically collinear. The contour generation module is used to calculate the coordinates of detection points A, B, C, and D of the four laser ranging sensors based on the three-dimensional coordinates of the first laser ranging sensor (1), the second laser ranging sensor (2), the third laser ranging sensor (3), and the fourth laser ranging sensor (4) at the same time and the measured distance between them and the lithium strip surface. The module then connects the four detection points A, B, C, and D in sequence to obtain the contour line. The PLC controller is used to calculate the strip thickness based on the contour line and compare the calculated strip thickness with the set value to determine whether the strip thickness meets the requirements.

2. The lithium strip width and thickness online detection system according to claim 1, characterized in that: The method for the PLC controller to calculate the band thickness based on the contour line includes the following steps: S1. Calculate the angle θ between the upper edge contour line AC and the horizontal plane based on the coordinates of the two detection points A and C; the coordinates of point A are (x1, y1, z1). A The coordinates of point C are (x3, y3, z). C The first laser ranging sensor (1) and the third laser ranging sensor (3) have the same coordinates in the direction of lithium strip width, but different coordinates in the direction of lithium strip movement; that is, y 1= y3; x1≠x3; where x represents the direction of lithium strip movement on the horizontal plane, y represents the width direction of the lithium strip on the horizontal plane, and z represents the vertical direction; ； or ; S2. Calculate the band thickness h2 based on the distance h1 between the two detection points A and B and the included angle θ. ； ； in: L 12 The vertical distance between the first laser rangefinder (1) and the second laser rangefinder (2); L1 is the distance between the first laser ranging sensor (1) and the monitoring point A on the upper surface of the lithium strip; L2 is the distance between the second laser ranging sensor (2) and the monitoring point B on the lower surface of the lithium strip.

3. The lithium strip width and thickness online detection system according to claim 2, characterized in that: The method for calculating the thickness of the band, after step S2, further includes the following steps: S3. Calculate the angle Φ between the upper edge contour line BD and the horizontal plane based on the coordinates of the two detection points B and D; the coordinates of point B are (x2, y2, z2). B The coordinates of point D are (x4, y4, z). D ); ； or ; S4. Calculate the band thickness h4 based on the distance h3 between the two detection points C and D and the included angle Φ. ； ； in: L 34 The vertical distance between the third laser rangefinder (3) and the fourth laser rangefinder (4); L3 is the distance between the third laser ranging sensor (3) and the monitoring point C on the upper surface of the lithium strip; L4 is the distance between the fourth laser ranging sensor (4) and the monitoring point D on the lower surface of the lithium strip; The PLC controller is also used for: Calculate the deviation Δh between h2 and h4. ; Based on the deviation Δh and the preset deviation threshold Δh th The comparison results, and h2 and h4 with the preset band thickness range [h min ,h max The system status is determined by comprehensively considering the relationship between the following conditions: normal status, product out-of-tolerance status, sensor abnormal status, and lithium strip abnormal status. when And both h2 and h4 are in [h min ,h max When the system is within the specified range, it is determined that the system is in a normal state. when And at least one of h2 and h4 is not in [h min ,h max If the thickness is within the specified range, the product is deemed to be out of tolerance. when And both h2 and h4 are in [h min ,h max When the range is within ], it is determined that there is local abnormal deformation in the lithium strip; when And at least one of h2 and h4 is not in [h min ,h max If the laser rangefinder is within the specified range, it is determined that the laser rangefinder is malfunctioning.

4. The lithium strip width and thickness online detection system according to claim 1, characterized in that: It also includes an image processing module and a first image acquisition module electrically connected to it and mounted above the lithium strip; a fifth laser sensor is also disposed above the lithium strip; the first image acquisition module is used to acquire images of the upper surface of the lithium strip in real time; the image processing module is used to perform image processing on the received images of the upper surface of the lithium strip; the PLC controller is also used to identify the edge contour of the upper surface image, then calculate the bandwidth w based on the edge contour, calculate the tilt angle of the lithium strip in the width direction, and correct the bandwidth w to obtain wo. real When w real In the preset [w min ,w max Within the specified range, the bandwidth is determined to meet the requirements; if it exceeds the range, the bandwidth is determined to not meet the requirements. The coordinates of the installation position of the fifth laser sensor are (x5, y5, z5); the coordinates of the monitoring point E on the upper surface of the lithium strip by the fifth laser sensor are (x5, y5, z5). E The x-coordinate x5 of the fifth laser sensor is the same as the x-coordinate x1 of the first laser ranging sensor (1), and its y-coordinate y5 is different from the y-coordinate y1 of the first laser ranging sensor (1), i.e., x1 = x5. y 1≠y 5； ； Where L5 is the distance between the fifth laser sensor and the monitoring point E as measured by the fifth laser sensor; The bandwidth w is corrected to obtain the corrected bandwidth w. real The method is as follows: ； Where Ψ is the tilt angle of the lithium strip in the width direction; 。 5. The lithium strip width and thickness online detection system according to claim 1, characterized in that: The PLC controller is also used to determine the instantaneous jitter amplitude A and instantaneous jitter frequency f of the lithium strip based on the data of the contour line within the sampling time window Δt. peak ; and based on A and the preset threshold [A min A max Based on the comparison results, the control mode is dynamically selected: When A≦A min At that time, the first image acquisition module uses a fixed exposure time and a fixed acquisition time; When A min A A max At the same time, the exposure time and trigger acquisition time of the first image acquisition module are dynamically adjusted; When A>A max If this occurs, the measurement will be paused and an alarm will be issued.

6. The lithium strip width and thickness online detection system according to claim 5, characterized in that: The specific calculation method for the instantaneous jitter amplitude A is as follows: S1.1 The PLC controller first calculates the z-coordinate of the center point M of points A and C based on the z-coordinates of points A and C at the same time. M =(Z A +Z C ) / 2; S1.2 Record Z within a time window Δt. M The difference between the maximum and minimum values ​​ΔZ M The instantaneous jitter amplitude A within the current time window Δt is: A1=ΔZ M / 2; The instantaneous jitter frequency fpeak is calculated by performing spectral analysis on the time series data of the Z-axis coordinate of point M. S3.1 Constructing the time series: The PLC controller uses a fixed sampling frequency f S Receive data from the contour generation module; for each sampling time t i Record the Z coordinate of the corresponding center point M. M (t i This forms a discrete-time signal Z. M [n]; S3.2, Spectrum Analysis: The PLC controller analyzes the Z-axis at N consecutive time points. M Perform a discrete Fourier transform on [n] to obtain the spectrum Z of the Z-coordinate signal at the center M of the lithium band. M (f); S3.3 Calculate the amplitude of each frequency component |Z M (f)∣ reflects the vibration intensity of each frequency component; S3.4 Extracting the dominant frequency: Search for the maximum value in the amplitude spectrum; the corresponding frequency is the instantaneous jitter frequency f of the lithium band within the current time window. peak .

7. The lithium strip width and thickness online detection system according to claim 5, characterized in that: The method for dynamically adjusting the trigger acquisition time is as follows: S4.1, Phase Detection: For Z M [n] is smoothed to obtain Z. M-smooth [n]; Then, based on the peak detection algorithm, the positions of the peaks and troughs are found; S4.2 Inflection Point Detection and Recording: Based on Z M-smooth [n] Detect inflection points and record the Z-coordinate and inflection point type for each inflection point; S4.3 Real-time jitter period calculation: The time interval between two consecutive peaks or two consecutive troughs is the real-time jitter period T. jitter ; S4.4 Phase Judgment and Next Inflection Point Prediction: Suppose that a phase is detected in the past time period t current The adjacent inflection point is t. last , If t current ≠t last , then t next_exterme =t last +T jitter / 2; If t current =t last , then t next_exterme =t currentt +T jitter / 2; Where: t next_exterme This indicates the time when the next inflection point will arrive. t curren Represents the current time; T jitter Represents the real-time jitter period; S4.5 The PLC controller sends a command with a preset delay to the first image acquisition module to ensure that the first image acquisition module acquires the image at the exact moment the next inflection point arrives.

8. The lithium strip width and thickness online detection system according to claim 5, characterized in that: The method for dynamically adjusting the exposure time of the first image acquisition module is as follows: by adjusting the Z... M [n] Perform analysis and calculate the instantaneous vertical velocity V(t) of the center point M on the upper surface. i Then, based on the calculated V(t) i The exposure time T is calculated. exp ; Among them, the instantaneous vertical velocity V(t) of the center point M on the upper surface i The calculation method for ) is as follows: ； Wherein, V(t) i (t) represents the current time. i The instantaneous vertical velocity of the center point M on the upper surface; Z M (t i (t) represents the current time. i The Z-coordinate of the center point M on the upper surface; Z M (t i-1 ) represents the previous time t i-1 The Z-coordinate of the center point M on the upper surface; f s This refers to the system sampling frequency, which is the number of times the laser sensor collects data per second. Based on the calculated V(t) i The exposure time T is calculated. exp The method is as follows: ； J(t i )=α∣V(t i )∣+β∣ θ' (t i) ∣; in: T min-hw Minimum exposure time; T max This is the maximum exposure time allowed by the system. K is a pre-calibrated constant; ε is used to prevent positive numbers with a denominator of zero; V(t i () represents the current instantaneous vertical velocity; θ'(t i ) represents the rate of change of the angle θ between the upper edge contour line AC and the horizontal plane at the current moment; α , β This is the conversion factor.

9. The lithium strip width and thickness online detection system according to any one of claims 3-8, characterized in that: It also includes a calibration module; the PLC controller is further used to record a sequence of deviations Δh over R consecutive sampling periods. ; and calculate the moving average value of Δh. If the moving average value stabilizes within a preset non-zero interval, it is determined that the system needs to be calibrated. 12 and L 34 The value, the calibration module for L 12 and L 34 Perform calibration as follows: S51. Place the standard part (5) stably between the first laser rangefinder (1) and the second laser rangefinder (2), and between the third laser rangefinder (3) and the fourth laser rangefinder (4); the upper and lower surfaces of the standard part (5) are both horizontal. S52, turn on the first laser rangefinder (1), the second laser rangefinder (2), the third laser rangefinder (3), and the fourth laser rangefinder (4). The first laser rangefinder (1) measures the distance L5 between itself and the upper surface of the standard part (5); the second laser rangefinder (2) measures the distance L6 between itself and the lower surface of the standard part (5); the third laser rangefinder (3) measures the distance L7 between itself and the upper surface of the standard part (5); and the fourth laser rangefinder (4) measures the distance L8 between itself and the lower surface of the standard part (5). S53, The calibration module calculates L based on L5, L6, L7, L8 and the distance L9 between the upper and lower surfaces of the standard part (5). 12 and L 34 The value; ； 。 10. A method for online detection of lithium strip bandwidth and thickness applied to the online detection system for lithium strip bandwidth and thickness according to any one of claims 1-9, characterized in that: Includes the following steps: S1, Laser ranging: Activate the first laser ranging sensor (1), the second laser ranging sensor (2), the third laser ranging sensor (3), and the fourth laser ranging sensor (4). The first laser ranging sensor (1) measures the distance L1 between itself and the upper surface of the lithium strip; the second laser ranging sensor (2) measures the distance L2 between itself and the lower surface of the lithium strip; the third laser ranging sensor (3) measures the distance L3 between itself and the upper surface of the lithium strip; the fourth laser ranging sensor (4) measures the distance L4 between itself and the lower surface of the lithium strip; and send L1, L2, L3, and L4 to the contour generation module. S2. The contour generation module calculates the coordinates of detection points A, B, C, and D: The three-dimensional coordinates of the first laser ranging sensor (1), the second laser ranging sensor (2), the third laser ranging sensor (3), and the fourth laser ranging sensor (4) are (x1, y1, z1), (x2, y2, z2), (x3, y3, z3), and (x4, y4, z4), respectively; the coordinates of A, B, C, and D are (x1, y1, z4), (x2, y2, z2), (x3, y3, z3), and (x4, y4, z4), respectively. A (x2,y2,z) B (x3,y3,z) C (x4,y4,z) D );in ; ; ; x represents the direction of lithium strip movement on the horizontal plane, y represents the width direction of the lithium strip on the horizontal plane, and z represents the vertical direction; x1=x2; y1=y2; x3=x4; y3=y4; S3. The contour generation module connects four detection points A, B, C, and D in sequence to obtain the contour line; S4, the PLC controller calculates the strip thickness based on the outline: S41. Calculate the angle θ between the upper edge contour line AC and the horizontal plane based on the coordinates of the two detection points A and C. ;or ; S42. Calculate the band thickness h2 based on the distance h1 between the two detection points A and B and the included angle θ. ； ； Where L 12 The vertical distance between the first laser rangefinder (1) and the second laser rangefinder (2); S43. Calculate the angle Φ between the upper edge contour line BD and the horizontal plane based on the coordinates of the two detection points B and D; the coordinates of point B are (x2, y2, z2). B The coordinates of point D are (x4, y4, z). D ); ;or ; S44. Based on the distance h3 between the two detection points C and D and the included angle Φ, the thickness h4 is calculated. ； ； Where L 34 The vertical distance between the third laser rangefinder (3) and the fourth laser rangefinder (4); S5. Comprehensive judgment of system state: Calculate the deviation Δh between h2 and h4. ; Based on the deviation Δh and the preset deviation threshold Δh th The comparison results, and h2 and h4 with the preset band thickness range [h min ,h max Based on the relationship between the system status and the product out-of-tolerance status, the system status includes at least one of the following: normal status, product out-of-tolerance status, sensor abnormal status, and lithium strip abnormal status. S6. Image Acquisition: The first image acquisition module and the second image acquisition module acquire images of the side surface and the top surface of the lithium strip, respectively; S7. Image Processing: The image processing module performs image processing on the received images of the side and top surfaces of the lithium strip. S8. Defect Identification: The PLC controller identifies defects based on the images of the side and top surface of the lithium strip processed by the image processing module. If a defect is identified, it is determined that there is a surface defect, and an alarm is triggered by the audible and visual alarm module. S9. Calculate the jitter amplitude and dynamically select the control mode: The PLC controller determines the instantaneous jitter amplitude A and instantaneous jitter frequency f of the lithium strip based on the data of the contour line within the sampling time window Δt. peak ; and based on A and the preset threshold [A min A max Based on the comparison results, the control mode is dynamically selected: When A≦A min At that time, the first image acquisition module uses a fixed exposure time and a fixed acquisition time; When A min A A max At the same time, the exposure time and trigger acquisition time of the first image acquisition module are dynamically adjusted; When A>A max When this happens, the measurement is paused and an alarm is issued; S10. Bandwidth Detection and Correction: The PLC controller is also used to identify the edge contours of the upper surface image, then calculate the bandwidth w based on the edge contours, calculate the tilt angle of the lithium strip in the width direction, and correct the bandwidth w to obtain wo. real When w real In the preset [w min ,w max Within the specified range, the bandwidth is determined to meet the requirements; if it exceeds the range, the bandwidth is determined to fail to meet the requirements, and an alarm is triggered via the audible and visual alarm module. S11. Online display: The display module displays the contour line generated by the contour generation module under the current detection state, the images acquired by the first image acquisition module and the second image acquisition module, the bandwidth w, band thickness h2, h4 calculated by the PLC controller, and the judgment results of bandwidth, band thickness, and surface defects.

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