Method for solving edge effect problem and realizing obstacle avoidance in numerical control system by using double capacitors, readable storage medium and control equipment thereof

Abstract

This invention relates to a method for solving edge effect problems and achieving obstacle avoidance in a CNC system using dual capacitors, belonging to the field of laser cutting technology. The invention adds a sensing metal ring with a detection range larger than the nozzle capacitance to the laser cutting head, forming a dual-capacitor structure with the nozzle capacitance. The capacitance value of the sensing metal ring is collected in real time and its change is calculated. Trend judgment triggers the detection of peaks or troughs in the capacitance change curve. When a peak characteristic representing proximity to the edge of the material is detected, height compensation is activated in advance to prevent abnormal downward movement of the cutting head. When a trough characteristic representing proximity to an obstacle is detected, the cutting head is controlled to rise in advance to avoid the obstacle. This invention solves both the edge effect problem and the early obstacle avoidance problem in the laser cutting process with a simple and economical hardware configuration, and has the advantages of wide detection range, timely response, strong anti-interference ability, and wide applicability.

Description

Technical Field

[0001] This invention relates to the field of CNC laser cutting technology, specifically to a method for solving edge effect problems and achieving obstacle avoidance in a CNC system using dual capacitors, a computer-readable storage medium, and its control device. Background Technology

[0002] The laser cutting industry currently mainly uses capacitance detection (capacitance between the nozzle and the plate) to achieve stable control of the distance between the laser beam focus and the plate surface. When the nozzle is too close to the edge of the plate, the nozzle capacitance is affected by the edge effect, causing the cutting head to move downward and affecting the processing technology. During the cutting process, in order to prevent machine tool damage, obstacle detection is required around the nozzle to assist in obstacle avoidance.

[0003] Existing technology CN108637469A proposes a vision-based edge detection scheme. This scheme uses a camera mounted at a 45° angle to the side of the machine tool, covering most of the sheet metal. After capturing images, a series of image processing steps are employed, including grayscale conversion, grayscale range compression, edge detection, and histogram peak analysis for coarse edge localization. Then, straight line fitting is used to precisely locate the four sides of the sheet metal, and finally, the rotation center and angle are calculated. This technology focuses on determining the placement and installation angle of the sheet metal on the machine tool through visual scanning, but it struggles to identify the position of the cutting head relative to the sheet metal and cannot address the issue of the nozzle being affected by edges.

[0004] Existing technology CN119609417A proposes a scheme that uses a point laser sensor to replace capacitive detection. This method controls the sensor to move along a preset trajectory and collects height data in real time. Edge points are quickly located using a height difference threshold, and then a geometric algorithm is used to calculate the vertices and rotation angles of the material to correct the processed shape. This technology solves the problems of slow speed, low accuracy, and easy damage to the cutting head caused by capacitive edge detection. However, this technology has difficulty determining the relative position of the nozzle to the edge of the processed material and cannot detect the nozzle's exit edge.

[0005] The existing technology CN121050353A proposes a scheme for bidirectional scanning of pipe edges using a point laser sensor. This scheme automatically calculates and compensates for the zero-point position offset of the cutting head using geometric algorithms, solving the problem of insufficient cutting contour accuracy caused by pipe clamping deviations and bending. However, this edge detection scheme can only detect the edge position after the nozzle has moved beyond the edge of the plate. It cannot detect the position where the nozzle begins to be affected by the edge before the nozzle moves beyond the plate, or even before it approaches the edge of the plate.

[0006] The existing technology CN212094858U proposes an obstacle avoidance method based on capacitance detection. It constructs an obstacle avoidance system using a layered shielding structure to reduce electromagnetic interference between the nozzle and the sensing ring. A capacitance detection circuit monitors the capacitance change of the sensing ring in real time. When an obstacle is detected approaching and the capacitance change reaches a threshold, obstacle avoidance is initiated. However, its sensing ring uses side detection, which is difficult to effectively detect when the follower height is low and the obstacle height is also low.

[0007] The existing technology CN215766949U proposes a method for obstacle avoidance detection using ultrasonic ranging principles. This method involves arranging an ultrasonic position and height detection matrix module around the nozzle to accurately measure the height between the nozzle and the machining surface. If an abnormal height is detected, obstacle avoidance is initiated. However, the ultrasonic device must be installed around the nozzle, and to prevent interference, the device is installed at a very low height, resulting in a small detection range. This makes it difficult to take early measures to avoid obstacles, and it is only suitable for braking obstacle avoidance.

[0008] Current edge detection methods primarily utilize capacitance sensing, line laser scanning, and visual recognition to determine the position of the sheet metal. These methods are mainly used to identify the overall placement and tilt angle of the sheet metal relative to the machine tool, and edge positions can only be detected when the nozzle center moves away from the top surface of the sheet metal, causing a sudden change in detection volume. Therefore, a method is needed that can detect the relative position of the nozzle center on the sheet metal in real time during the cutting process and identify the nozzle before it approaches the edge.

[0009] Current obstacle avoidance methods mainly rely on capacitance detection and ultrasonic ranging, which have narrow detection ranges and are susceptible to many interference factors. Therefore, it is necessary to design a stable obstacle detection method with a larger detection range. Summary of the Invention

[0010] This invention aims to provide a method for solving edge effect problems and achieving obstacle avoidance in CNC systems using dual capacitors, to address the following technical problems: Part 1 Current Issue: 1.1 Edge Effect Problem Laser processing involves focusing a high-power-density laser beam onto the surface of a sheet material, heating it to a molten state, and then removing waste material with high-speed air blowing to achieve cutting. The power is highest at the laser beam focal point, and its distance from the sheet surface directly affects the cutting power. Therefore, maintaining a constant focal distance from the sheet is crucial and directly impacts the final cutting effect.

[0011] Current control methods generally employ capacitance detection-assisted control, with the process as follows: Figure 1 As shown, in a laser processing scenario, the nozzle and the surface of the material form a capacitor. The capacitance relationship is as follows: in, This represents the capacitance detection area. The distance between the two plates of the capacitor. It is related to the medium; Currently, most frequency detection methods use LC oscillation circuits, and the frequency value obtained from frequency measurement represents the follower capacitance. The measured frequency value is: Substituting the capacitor formula into the frequency measurement formula, we get: Subsequent capacitance values ​​will all be based on this frequency measurement value. This indicates that, clearly, during laser processing, the capacitance value is positively correlated with the nozzle-to-plate distance and negatively correlated with the capacitance detection area.

[0012] In typical cutting scenarios, and One-to-one correspondence, therefore it can be used The value represents Involved in control. However, when cutting near the edge of the sheet material, The relative reduction in the central area of ​​the plate causes a change in the correspondence between f and d, resulting in the failure of capacitor height measurement.

[0013] At this point, the closer to the edge, the smaller S becomes, and the larger f becomes. This causes the spacing d detected by the servo system to be larger, and the control system lowers the cutting head, making the height of the cutting head lower when cutting the edge of the board than when it is at the center of the board. This further reduces the distance between the focal point and the board, thus disrupting the original process.

[0014] Most existing edge detection technologies are designed for edge finding, and lack means to deal with edge effect problems.

[0015] 1.2 Obstacle Avoidance Problem Traditional obstacle detection methods mostly employ capacitive sensing on the side of the nozzle for obstacle avoidance, or add simple ranging sensors near the nozzle to achieve obstacle avoidance. These traditional methods either have a narrow detection range or are limited to a single obstacle avoidance scenario. Some emerging methods also suffer from stability and cost issues, resulting in excessively high costs.

[0016] Part 2 Problem Solving: 1.1 Improve edge processing to solve edge following problem The first objective of this method is to detect the nozzle approaching the edge before the cutting head height is abnormally lowered due to the influence of the edge, by adding a capacitive detection sensor with a larger detection range than the nozzle, thus forming a dual-capacitor structure with the nozzle. This allows for the activation of height compensation to correct the height in advance.

[0017] 1.2 Detect obstacles in advance and raise the obstacle avoidance mechanism. The second objective of this method is to use a capacitive sensing sensor with a larger detection range and a higher installation height than the nozzle to detect obstacles before the nozzle senses them, allowing the sensor to lift up and pass over obstacles in advance. Increasing the installation height solves the problems of traditional obstacle avoidance methods, such as difficulty in overcoming tall obstacles and detecting hollow obstacles.

[0018] To achieve the above objectives, the CNC system of the present invention utilizes dual capacitors to solve the edge effect problem and achieve obstacle avoidance as follows: The method for solving edge effect problems and achieving obstacle avoidance in this CNC system using dual capacitors is characterized by the following steps: (1) A first capacitive sensor and a second capacitive sensor are provided on the laser cutting head. The first capacitive sensor is a sensing nozzle used to detect the distance between itself and the plate. The second capacitive sensor is a sensing metal ring that is coaxially mounted with the sensing nozzle and has a detection range greater than that of the sensing nozzle. (2) Collect the capacitance value of the second capacitance sensor in real time and calculate the capacitance change in the current period; (3) Filter the capacitance change and determine whether to trigger peak detection or trough detection based on the capacitance change trend of multiple consecutive cycles. (4) If peak detection is triggered, check whether the capacitance change curve meets the preset peak shape characteristics within the preset backtracking window. If so, determine that the cutting head is approaching the edge of the board and perform height compensation control to prevent the cutting head from moving down. (5) If the trough detection is triggered, the capacitance change curve is checked within the backtracking window to see if it meets the preset trough shape characteristics. If so, it is determined that the cutting head is approaching the obstacle and the upward obstacle avoidance control is executed.

[0019] Preferably, step (2) calculates the capacitance change of the second capacitive sensor in the current period in the following manner: Let the current sampling time be The corresponding capacitance value According to the cutting speed Determine the difference interval The change in capacitance at the current moment for: Preferably, step (3) utilizes an ascending counter. and the down counter To determine whether peak detection or trough detection is triggered, the specific steps are as follows: Compare the capacitance change in the previous period The change in capacitance during the current period Differences between them: When the capacitance change in the previous cycle The capacitance change greater than the current period At that time, the rising counter will be... Reset to zero and reset the descending counter. Add one; When the capacitance change in the previous cycle Capacitance change less than the current period At that time, the descending counter will be... Reset to zero and reset the rising counter. Add one; When the capacitance change in the previous cycle Equal to the change in capacitance during the current period At that time, the rising counter and the down counter All are 0; When the descending counter The value is greater than the preset trend threshold. At that time, peak detection is triggered; When the rising counter The value is greater than the preset trend threshold. At that time, trough detection is triggered.

[0020] Preferably, step (4) detects whether the capacitance change curve meets the preset peak shape characteristics in the following manner: Find the maximum value within the backtracking window. and its corresponding index position; Calculate the maximum value. The difference between the first and last elements within the backtracking window; If both differences are greater than or equal to the preset minimum height difference And the maximum value mentioned Greater than the preset minimum peak threshold If so, it is determined that the initial peak shape is satisfied.

[0021] Preferably, step (5) detects whether the capacitance change curve meets the preset trough shape characteristics in the following manner: Find the minimum value within the backtracking window. and its corresponding index position; Calculate the minimum value. The difference between the first and last elements within the backtracking window; If both of the aforementioned differences are less than or equal to a negative preset minimum height difference And the minimum value Less than the preset minimum peak threshold If so, it is determined that the initial trough pattern is met.

[0022] Preferably, after determining that the initial peak or trough shape is met, a width verification step is also included: With the stated maximum value or minimum value Centered on the index position, a real-time detection radius k is extended to the left and right sides to form a detection interval; Determine whether all capacitance changes within the detection interval are greater than (for peaks) or less than (for troughs) a preset capacitance width threshold. ; Gradually increase the real-time detection radius k and iterate until k is greater than the preset minimum detection radius threshold. If all detection intervals meet the conditions during this process, then a valid peak or trough is finally confirmed to have been detected.

[0023] Preferably, the sensing metal ring is assembled in the cylindrical connector of the cutting head, located above the sensing nozzle fixing ring, with its bottom surface parallel to the end face of the sensing nozzle, for forming capacitance with the surface of the plate.

[0024] Preferably, the capacitance signal of the second capacitance sensor is amplified by a signal amplifier and then transmitted to the controller for processing.

[0025] The main feature of this computer-readable storage medium is that it stores a computer program thereon, which can be executed by a processor to implement the steps of the method for solving edge effect problems and achieving obstacle avoidance using dual capacitors in the above-described CNC system.

[0026] The main feature of this laser cutting head obstacle avoidance and follow-up control device is that the device includes: The sensing nozzle serves as the first capacitive sensor. The sensing metal ring is coaxially mounted in the cutting head connector above the sensing nozzle, serving as a second capacitive sensor. A capacitance detection circuit is used to collect the capacitance values ​​of the sensing nozzle and the sensing metal ring. The controller is used to execute the method of using dual capacitors to solve the edge effect problem and achieve obstacle avoidance in the CNC system as described above, and to control the cutting head to perform height compensation or upward obstacle avoidance actions based on the detection results.

[0027] The method for solving edge effect problems and achieving obstacle avoidance using dual capacitors in the CNC system of this invention, along with the computer-readable storage medium and its control device, have the following significant advantages compared to existing technologies: 1. A simple hardware configuration can solve two pain points, making it economical and cost-effective;

[0028] 2. The method can be implemented using common hardware and software, with low environmental requirements and wide applicability. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the capacitance detection process in the prior art.

[0030] Figure 2 This is an oblique upward view of the sensing metal ring connector of the present invention.

[0031] Figure 3 This is a front half-sectional view of the induction metal ring connector of the present invention.

[0032] Figure 4 This is a top view of the induction metal ring connector of the present invention.

[0033] Figure 5 This is a hardware structure connection diagram of the present invention.

[0034] Figure 6 This is a schematic diagram of the division of the plate area in this invention.

[0035] Figure 7 This is a graph showing the capacitance value and its change when the cutting head approaches the edge of the plate, according to the present invention.

[0036] Figure 8 This is a graph showing the capacitance value of the sensing metal ring and its change when the cutting head approaches an obstacle, according to the present invention.

[0037] Figures 9(a), 9(b), and 9(c) are respectively logical flowcharts of the peak and / or trough detection in each cycle of the present invention.

[0038] Figure 10 This is a flowchart illustrating the single-cycle control process of this invention.

[0039] Figure 11 This is a graph showing the detection results of the present invention in actual testing.

[0040] Figure Labels 1. Sensor nozzle 2. Nozzle retaining ring 3. Metal ring to fix the inner ring 4. Induction metal ring 5. Metal ring to fix the outer ring 6 Laser cutting head 7. Screw head 8 RF cables Detailed Implementation

[0041] To more clearly describe the technical content of the present invention, the following description is provided in conjunction with specific embodiments.

[0042] Before describing the embodiments of the present invention in detail, it should be noted that, in the following, the terms “comprising,” “including,” or any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0043] The CNC system of this technical solution utilizes dual capacitors to solve the edge effect problem and achieve obstacle avoidance. Its detection is mainly divided into two scenarios: the first is when the nozzle approaches the edge, the change curve of the metal ring shows a peak, and the peak is detected to determine whether it is necessary to stop the cutting head from moving down; the other is when the nozzle approaches the obstacle, the change curve of the metal ring shows a trough, and the trough is detected to determine whether it is necessary to raise the head to avoid the obstacle.

[0044] This method determines whether peak / trough detection is triggered by trend detection, and detects the shape of peaks / troughs by window backtracking, thereby eliminating noise interference.

[0045] The implementation principle of this technical solution will be explained in detail below: Part 1: Methodology and Principles 1.1 Dual-capacitor design principle like Figure 2 As shown, the capacitance detection range of this method is expanded by assembling a metal ring with a larger outer radius in the cylindrical connector of the cutting head above the original nozzle fixing ring 2. A new capacitor is formed by the bottom surface of the metal ring and the surface of the plate. Because the outer circle of the metal ring and the edge circle of the nozzle are coaxial and move synchronously, the future movement state of the nozzle can be determined by judging the capacitance state of the metal ring.

[0046] 1.2 Principles of Edge Problem Solving As the nozzle approaches the edge, a larger metal ring generates edge sensing before the nozzle reaches the edge. It senses that the nozzle is about to go off the edge and activates height compensation when it detects that the nozzle is going off the edge, preventing the cutting head from moving down abnormally.

[0047] 1.3 Principles of Obstacle Avoidance Problem Solving When the nozzle approaches an obstacle, the bottom surface detection of the metal ring will detect the obstacle earlier than the edge detection of the nozzle. When detecting tall or hollow obstacles, the installation height of the metal ring is much higher than the nozzle, which can cover the height of most obstacles. At the same time, the bottom surface detection of the metal ring can cover the upper surface of the obstacle, solving the problem that the nozzle could not detect hollow obstacles.

[0048] Part 2: Hardware Structure The hardware structure of this invention adopts the following... Figure 5 The connection diagram shown can be used to select appropriate hardware for assembly based on the processing environment.

[0049] A conductive metal ring is used as a capacitance sensor, and the capacitance signal is amplified by a signal amplifier to compensate for transmission losses over long paths. The amplified signal is transmitted to the controller, which processes the collected data and controls the Z-axis based on the detection results to achieve height compensation and obstacle avoidance. Simultaneously, relevant process data is uploaded to the host computer.

[0050] Part 3: Data Processing and Feature Representation 3.1 Calculate the change in the metal ring collection At any given time, the capacitance of the metal ring is The change is calculated using the difference, and the fixed difference value is used. By cutting speed Confirmed, unit .

[0051] in, Indicates rounding up. Change in the copper ring at time t The calculation method is as follows: The change in the capacitance of the metal ring in each cycle is represented by the difference in the metal ring through calculation of the difference in each cycle.

[0052] 3.2 Filtering Process Update the filter window with the change in metal ring capacitance for the current period. Window width is Mean filtering is applied to the change in this period: Update the filtered value to the backtracking detection window. Window width is .

[0053] 3.3 Features near the edge 3.3.1 Reasons for the generation of features Near the edge, the metal ring capacitance rises before the nozzle capacitance. When the nozzle begins to be affected by the edge and the cutting head begins to lower, it will offset part of the rise in metal ring capacitance, causing its capacitance growth trend to slow down and the metal capacitance change curve to show a peak.

[0054] 3.3.2 Principle of Panel Area Division As the device approaches the edge, the capacitance of the metal ring remains constant at a distance from the edge; however, as the device gets closer to the edge, the capacitance begins to increase significantly with decreasing distance from the edge. The nozzle exhibits the same behavior, but due to the significant difference in detection radius, the distance from the edge at which the nozzle capacitance begins to be affected by the edge is much smaller than that of the metal ring. Both devices have a critical distance from the edge; when the distance is greater than this distance, the capacitance is unaffected; when the distance is less than this distance, the capacitance is affected.

[0055] Based on the critical distance of the metal ring, the critical line of the metal ring and the critical line of the nozzle can be drawn parallel to the edge on the surface of the plate. The critical line is parallel to the affected edge, and the distance between each point on the critical line and the edge is the critical distance.

[0056] like Figure 6 As shown, by using the critical line to divide the board into regions, the entire surface of the board can be divided into three parts: The first part consists of the edge of the plate and the nozzle critical line. In this area, the capacitance of the nozzle and the capacitance of the metal ring are both affected by the edge, and the cutting height here is abnormal. This area is the area that this method needs to detect in advance.

[0057] The second part consists of the nozzle critical line and the metal ring critical line. In this region, only the capacitance of the metal ring is affected by the edge, while the nozzle capacitance is unaffected.

[0058] The third part is the region enclosed by the critical line of the metal ring. In this region, neither is affected by the edge, and the capacitance of either remains unchanged.

[0059] The feature appears when the nozzle center crosses the nozzle critical line.

[0060] 3.3.3 Characteristic Manifestations Near the edge, the capacitance of the metal ring increases with the increase of the outgoing distance; the change in capacitance of the metal ring first increases and then decreases with the increase of the outgoing distance, exhibiting a peak characteristic, such as... Figure 7 As shown.

[0061] 3.4 Characteristics of proximity to obstacles 3.4.1 Reasons for the generation of features When approaching an obstacle, the obstacle is positioned above the plate, effectively reducing the height *d* of the metal ring from the plate. Since the capacitance *f* is positively correlated with *d*, the capacitance of the metal ring decreases significantly at this point. As the obstacle fully enters the detection range of the metal ring, the change in the ring's height decreases, and the rate of decrease in capacitance slows. This causes the decrease in the metal ring's capacitance to stop, creating a trough.

[0062] 3.4.2 Characteristic Manifestations As the metal ring approaches an obstacle, its capacitance decreases with increasing travel distance. The change in capacitance initially decreases and then increases with increasing travel distance, exhibiting a trough-like characteristic. Figure 8 As shown.

[0063] Part 4: Peak and trough detection methods Peaks and troughs are detected periodically, and the specific detection logic is shown in Figures 9(a), 9(b), and 9(c).

[0064] 4.1 Trend Judgment: Peak and Trough Feature Detection Triggered 4.1.1 Determine whether peak / trough detection is triggered based on the trend, using an ascending counter. and the down counter To determine the trend. The capacitance difference value of the previous cycle is... Difference between this period and the current period Compare the sizes and update the counter status.

[0065] , , , 4.1.2 In the backtracking detection window When the buffer is full, use the threshold. Determine the timer status to decide whether to trigger the main peak / trough detection of the backtracking window.

[0066] Initiate the backtracking window to detect the main trough. Set as ; The trough detection condition was not triggered. Initiate the backtracking window to detect the main peak. Set as ; The peak detection condition was not triggered.

[0067] 4.2 Peak and trough feature detection 4.2.1 Traverse the elements of the current backtracking window. Detect target. This is used to determine the purpose of this call.

[0068] Calculate the backtracking interval Internal extreme values and and its corresponding position index and : 4.2.2 Quickly determine the shape of the extreme values The peak features are sufficiently distinct, and the height variation meets the requirements.

[0069] Other issues include insufficient peak characteristics and unmet height variation requirements, leading to exit from the detection process.

[0070] The trough features are sufficiently obvious, and the height variation meets the conditions.

[0071] Other issues include insufficient trough characteristics and unmet height variation requirements, leading to exit from the detection process.

[0072] 4.2.3 For extreme values, a threshold is used for judgment, and the threshold is set to... The peak features are sufficiently obvious, and the peak values ​​are sufficiently prominent; The peak characteristics are not obvious enough, so the detection program is terminated. The trough features are sufficiently obvious, and the trough values ​​are sufficiently low; The trough features are not obvious enough, so the detection process is terminated.

[0073] 4.2.4 Perform width detection for peaks and troughs. Detection radius threshold for width detection The capacitance threshold is ,in: The height factor for width detection is set to 0.6~0.8.

[0074] Take the real-time detection radius as k, initialize it to 1, and then judge the numerical distribution on the left and right sides of the extreme value.

[0075] Enter the following loop for judgment: When the detection radius is k, the detection range of the peak All values ​​within are greater than the threshold. Detection radius The test passed and modifications were made. Then proceed to the next iteration.

[0076] The detection fails when the detection radius is k. The upper width of the peak does not meet the requirements. The main peak detection fails this time, and the current call is terminated.

[0077] When the detection radius is k, the detection range of the trough All values ​​within are less than the threshold. Detection radius The test passed and modifications were made. Then proceed to the next iteration.

[0078] The detection fails when the detection radius is k, because the bottom width of the trough does not meet the requirements. The main trough detection fails this time, and the current call is terminated.

[0079] If after each loop ends, If the main peak / trough detection meets the criteria, the program will exit; if Then Increment the value by 1, and in the next loop, the detection radius will be [value missing]. Check if the detection interval meets the requirements. Repeat this process until... The width detection at time k does not meet the conditions.

[0080] Part 5: Subsequent Control Control is implemented based on the detection results of the main peak and trough of this cycle. The control process is as follows: Figure 10 As shown.

[0081] A main peak was detected: The system detects the current height condition of the cutting head. If height compensation is enabled, it maintains the original state; otherwise, it enables height compensation to prevent the cutting head edge from moving downwards.

[0082] A main valley was detected: The system detects the obstacle avoidance status at this time. If it is currently in obstacle avoidance mode, the original status remains unchanged. If it is in an idle state, active obstacle avoidance is activated, and the cutting head is controlled to lift up and pass over the obstacle.

[0083] No main peak or trough detected: Maintain the existing state without imposing any additional controls.

[0084] In practical applications, the implementation of this technical solution includes two parts: first, the installation of the hardware, and second, the deployment of the peak and trough detection algorithm. Further explanation will follow with specific embodiments: Step 1: Assemble the metal ring connector 1.1 Components and their functions in the connector: like Figure 2 As shown, the sensing nozzle 1 is used for emitting light and serves as the first capacitance detection element; the nozzle fixing ring 2 is used to fix the nozzle and the cutting head; the inner metal ring fixing ring 3 is used to assist in fixing the metal ring to the outer metal ring fixing ring 5; the sensing metal ring 4 acts as the second capacitance detection element; the outer metal ring fixing ring 5 serves as a container for the sensing metal ring 4, used for assembling the cutting head and the sensing metal ring 4, and assists in the contact between the screw head 7 and the sensing metal ring 4; the laser cutting head 6 assembles the whole, and all parts are fixed on it; the screw head 7 connects the sensing metal ring 4 and the radio frequency line 8 to transmit the capacitance signal collected by the sensing metal ring 4; the radio frequency line 8 transmits the capacitance signal of the metal ring to a higher layer.

[0085] 1.2 Assembly of the connecting parts: 1.2.1 The screw head 7 connects to the RF cable 8, and the screw head 7 connects to the metal ring to fix the outer ring 5: The upper side of the screw head 7, with its external threads, connects to the RF cable 8 via threads. The lower side of the screw head 7, with its conductive round head, passes through the connection port of the metal ring fixing outer ring 5, and the raceway-shaped outer shell of the screw head 7 is inserted into the raceway-shaped groove of the metal ring fixing outer ring 5. The raceway-shaped center connection port of the metal ring fixing outer ring 5 has two M2 screw holes on both sides. The metal ring fixing outer ring 5 and the screw head 7 are assembled and fixed using screws and washers through these screw holes.

[0086] 1.2.2 The sensing metal ring 4 is installed onto the metal ring fixing outer ring 5: Align the conductive semi-circular groove on the surface of the sensing metal ring 4 with the conductive round head on the screw head 7 and insert it. Install the sensing metal ring 4 into the groove of the outer metal ring fixing ring 5, and use the tight assembly of the inner metal ring fixing ring 3 and the outer metal ring fixing ring 5 to fix the sensing metal ring.

[0087] 1.2.3 Installation of sensor nozzle 1: Install the outer ring 5 of the metal ring fixing ring 4 onto the laser cutting head 6. Align the conductive round head of the induction nozzle 1 with the conductive round head on the laser cutting head 6, and fix the induction nozzle 1 by assembling the nozzle fixing ring 2 and the screws of the laser cutting head 6.

[0088] Step 2: Connect the metal ring detection circuit 2.1 Connect the RF cable 6 of the metal ring connector to the signal amplifier; 2.2 Connect the signal amplifier and control expansion board using a three-core cable; 2.3 Connect the control expansion board and the main control board using a DB9 transmission cable; 2.4 Connect the control board and the host computer using a DB9 cable.

[0089] Step 3: Set up the exercise 3.1 Perform two edge-out and two obstacle avoidance operations respectively, which should correspond to the detection of two troughs and peaks.

[0090] Step 4: Set parameters 4.1 Speed Set as Differential spacing Filter width 4.2 Counter Threshold Minimum height difference of the window Minimum threshold for extreme values 4.3 Backtracking Window Width Width and height threshold factors Detection radius threshold

[0091] Step 5: Enable functions and data collection Step 6: Start processing Step 7: Periodically detect peaks and troughs 7.1 Based on the logic diagram for processing capacitance data per cycle, peaks and troughs are detected. The basic process is as follows: 7.2 Data Processing: Read the capacitance of this cycle →Calculate the difference for this period → Update the current period's difference value into the sliding window. → Obtain the filtered difference value → Update the filtered difference value into the backtracking window. ; 7.3 Trend Detection: Compare the differences in this period Difference from the previous period Size relationship → Update the ascending counters respectively and the down counter State → Compare counter and counter threshold Size relationship → Based on the counter comparison result, determine whether peak detection needs to be triggered → If triggered, proceed with peak detection and update. Otherwise, the current cycle will end.

[0092] 7.4 Peak Detection: 7.4.1 Traverse the window to find the maximum and minimum values, and select the maximum and minimum values ​​as the target for detection. Traverse backtrack window Find the maximum and minimum values and →According to Select the corresponding extreme value, and only select the extreme value to participate in the subsequent judgment.

[0093] 7.4.2 Detection of Waveform Features of Peaks and Troughs Find the selected maximum and minimum values ​​for the first and last elements of the backtracking window. and The difference → based on the selected difference and Determine the peak trend based on the size relationship → If the requirements are met, proceed to the next stage; otherwise, the current cycle ends.

[0094] 7.4.3 Peak and trough amplitude detection Compare the selected extreme value with the minimum threshold of the extreme value. The size relationship → If the requirements are met, proceed to the next stage; otherwise, the current cycle ends. 7.4.4 Peak and trough width detection Initialize real-time detection radius →Using the extreme value index Detection and Width detection height threshold The size relationship → If it meets the requirements, proceed to the next stage; otherwise, the current cycle ends. → Compare k and The size relationship → If the condition is met, the peak and trough detection is successful and the current cycle ends; otherwise, the increased value is used. Back to and The step of comparing sizes initiates the next iteration of the loop.

[0095] Step 8: Detect and control the results 8.1 Detection results: Two peaks and troughs were successfully detected, which correspond to the two edge-out movements and obstacle avoidance movements.

[0096] 8.2 Control Results: Control was initiated shortly after the cutting head began to move downwards, preventing the cutting head from moving further downwards and improving the edge cutting process; in obstacle avoidance scenarios, the cutting head began to rise at a considerable distance from the obstacle, adjusting the distance increase and reducing the risk of collision.

[0097] Step 9: Results Display 9.1 During the motion, collect capacitance data and differential value data of the metal ring; 9.2 During the operation, print timer data and filtered data; 9.3 Plot curves and label the actual peaks and valleys and the detected peaks and valleys. Peak and valley detection can detect the existence of peaks and valleys at a very short distance after the true value, and can avoid fluctuation interference and peak and valley interference at the tip.

[0098] Reference Figure 11 Based on the measured data curves, the method of this invention can accurately identify the peaks caused by edge approach and the troughs caused by obstacle approach on the capacitance change curve. The detection point is very close to the starting point of the actual peak / trough, verifying the timeliness of the method. In actual cutting, this method effectively prevents the cutting head from falling during edge cutting and successfully raises it in advance when encountering obstacles, avoiding collision accidents.

[0099] In a preferred embodiment of the present invention, the sensing metal ring 4 is selected as a copper ring in practical applications, but this is not a limitation. It is understood that those skilled in the art can select a metal ring with the same conductivity as the second capacitive sensor according to the actual situation, so as to achieve the same or better technical effects, and such selection should also be within the protection scope of the present invention.

[0100] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0101] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution device.

[0102] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0103] The storage media mentioned above can be read-only memory, disk, or optical disk, etc.

[0104] In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0105] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0106] The present invention employs a method for solving edge effect problems and achieving obstacle avoidance using dual capacitors in the CNC system, a computer-readable storage medium, and its control device. After enabling edge detection, by accurately capturing peak values, the position of the nozzle center near the edge can be accurately detected. By activating height edge compensation at this position, the cutting height is effectively maintained stably. After enabling obstacle detection, by accurately capturing trough values, the nozzle's approach to an obstacle can be predicted in advance. By raising the cutting head in advance to avoid the obstacle, the risk of collision with the cutting head and nozzle abrasion during the cutting process is effectively reduced.

[0107] In this specification, the invention has been described with reference to specific embodiments thereof. However, it will be apparent that various modifications and variations can be made without departing from the spirit and scope of the invention. Therefore, the specification and drawings should be considered illustrative rather than restrictive.

Claims

1. A method for solving edge effect problems and achieving obstacle avoidance in a CNC system using dual capacitors, characterized in that, The method includes the following steps: (1) A first capacitive sensor and a second capacitive sensor are provided on the laser cutting head. The first capacitive sensor is a sensing nozzle used to detect the distance between itself and the plate. The second capacitive sensor is a sensing metal ring that is coaxially mounted with the sensing nozzle and has a detection range greater than that of the sensing nozzle. (2) Collect the capacitance value of the second capacitance sensor in real time and calculate the capacitance change in the current period; (3) Filter the capacitance change and determine whether to trigger peak detection or trough detection based on the capacitance change trend of multiple consecutive cycles. (4) If peak detection is triggered, check whether the capacitance change curve meets the preset peak shape characteristics within the preset backtracking window. If so, determine that the cutting head is approaching the edge of the board and perform height compensation control to prevent the cutting head from moving down. (5) If the trough detection is triggered, the capacitance change curve is checked within the backtracking window to see if it meets the preset trough shape characteristics. If so, it is determined that the cutting head is approaching the obstacle and the upward obstacle avoidance control is executed.

2. The method for solving edge effect problems and achieving obstacle avoidance in a CNC system using dual capacitors according to claim 1, characterized in that, Step (2) calculates the capacitance change of the second capacitive sensor in the current period as follows: Let the current sampling time be The corresponding capacitance value According to the cutting speed Determine the difference interval The change in capacitance at the current moment for: 。 3. The method for solving edge effect problems and achieving obstacle avoidance in a CNC system using dual capacitors according to claim 1, characterized in that, Step (3) utilizes an ascending counter. and the down counter To determine whether peak detection or trough detection is triggered, the specific steps are as follows: Compare the capacitance change in the previous period The change in capacitance during the current period Differences between them: When the capacitance change in the previous cycle The capacitance change greater than the current period At that time, the rising counter will be... Reset to zero and reset the descending counter. Add one; When the capacitance change in the previous cycle Capacitance change less than the current period At that time, the descending counter will be... Reset to zero and reset the rising counter. Add one; When the capacitance change in the previous cycle Equal to the change in capacitance during the current period At that time, the rising counter and the down counter All are 0; When the descending counter The value is greater than the preset trend threshold. At that time, peak detection is triggered; When the rising counter The value is greater than the preset trend threshold. At that time, trough detection is triggered.

4. The method for solving edge effect problems and achieving obstacle avoidance in a CNC system using dual capacitors according to claim 1, characterized in that, Step (4) involves detecting whether the capacitance change curve meets the preset peak shape characteristics in the following manner: Find the maximum value within the backtracking window. and its corresponding index position; Calculate the maximum value. The difference between the first and last elements within the backtracking window; If both differences are greater than or equal to the preset minimum height difference And the maximum value mentioned Greater than the preset minimum peak threshold If so, it is determined that the initial peak shape is satisfied.

5. The method for solving edge effect problems and achieving obstacle avoidance in a CNC system using dual capacitors according to claim 1, characterized in that, Step (5) involves detecting whether the capacitance change curve meets the preset trough shape characteristics in the following manner: Find the minimum value within the backtracking window. and its corresponding index position; Calculate the minimum value. The difference between the first and last elements within the backtracking window; If both of the aforementioned differences are less than or equal to a negative preset minimum height difference And the minimum value Less than the preset minimum peak threshold If so, it is determined that the initial trough pattern is met.

6. The method for solving edge effect problems and achieving obstacle avoidance in a CNC system using dual capacitors according to claim 4 or 5, characterized in that, After determining that the initial peak or trough shape is met, a width verification step is also included: With the stated maximum value or minimum value Centered on the index position, a real-time detection radius k is extended to the left and right sides to form a detection interval; Determine whether all capacitance changes within the detection interval are greater than (for peaks) or less than (for troughs) a preset capacitance width threshold. ; Gradually increase the real-time detection radius k and iterate until k is greater than the preset minimum detection radius threshold. If all detection intervals meet the conditions during this process, then a valid peak or trough is finally confirmed to have been detected.

7. The method for solving edge effect problems and achieving obstacle avoidance in a CNC system using dual capacitors according to claim 1, characterized in that, The inductive metal ring is assembled in the cylindrical connector of the cutting head, located above the inductive nozzle fixing ring, with its bottom surface parallel to the end face of the inductive nozzle, for forming capacitance with the surface of the plate.

8. The method for solving edge effect problems and achieving obstacle avoidance in a CNC system using dual capacitors according to claim 1, characterized in that, The capacitance signal of the second capacitance sensor is amplified by a signal amplifier and then transmitted to the controller for processing.

9. A computer-readable storage medium, characterized in that, It stores a computer program that can be executed by a processor to implement the steps of the method for solving edge effect problems and achieving obstacle avoidance using dual capacitors in the CNC system according to any one of claims 1 to 8.

10. A laser cutting head obstacle avoidance and follow-up control device, characterized in that, The device includes: The sensing nozzle serves as the first capacitive sensor. The sensing metal ring is coaxially mounted in the cutting head connector above the sensing nozzle, serving as a second capacitive sensor. A capacitance detection circuit is used to collect the capacitance values ​​of the sensing nozzle and the sensing metal ring. The controller is used to execute the method of using dual capacitors to solve the edge effect problem and achieve obstacle avoidance in the CNC system as described in any one of claims 1 to 8, and to control the cutting head to perform height compensation or upward obstacle avoidance actions based on the detection results.

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