Mine fire identification and alarm method based on image contour parallel side ratio

Abstract

The application discloses a mine fire identification and alarm method based on an image contour parallel edge ratio, wherein the fire identification method is characterized in that a camera is installed in a roadway, a tunneling working face, a fully-mechanized mining working face, an electromechanical chamber and other fire-prone areas, real-time collection and identification of suspected fire images in a monitoring area are performed, and mine fire identification and alarm are performed by monitoring the irregular shape characteristics of flame combustion. The fire identification and alarm method fully considers the fire combustion image characteristics, is fast, accurate and simple to identify, and can help underground trapped personnel to gain valuable rescue and escape time.

Description

TECHNICAL FIELD

[0001] The present application relates to a mine fire identification and alarm method based on image contour parallel edge ratio, which relates to the fields of digital image processing technology and communication technology. BACKGROUND

[0002] In the coal industry, gas, fire, flood, roof, coal dust and other accidents have plagued the safety production of coal mines. Once a mine fire occurs, if the fire cannot be controlled in time, the scope of the fire will quickly expand, causing a large number of casualties and property losses; further, it may cause an explosion in the high-concentration gas and coal dust area underground as an ignition source, causing secondary trauma to the underground environment. Therefore, it is crucial for coal safety production to quickly identify the fire disaster in the mine, timely alarm, and start the emergency plan and emergency rescue accordingly.

[0003] In the existing mine fire monitoring technology, there are various types of sensor comprehensive monitoring methods, such as temperature, smoke, gas sensors, etc. Although this type of monitoring has the advantages of high reliability and simple operation, it is affected by the complex underground operation scene, the layout and maintenance workload is large, and it is greatly affected by interference sources. The infrared radiation temperature measurement equipment monitoring method can measure the temperature of the fire source, but the temperature measurement accuracy is greatly affected by the underground environmental factors and fire interference sources. The visual feature monitoring method is the current mainstream mine fire monitoring technology. However, the existing monitoring technology adopts many characteristic variables to determine the fire, although the information features contain a lot of information, there are also many unstable factors. Based on the comprehensive determination of fire disaster by multiple cameras and multiple frames of images, the determination time is long, and the false alarm rate and the missed alarm rate are high.

[0004] Therefore, it is necessary to study a new mine fire fast identification method to shorten the determination time and reduce the false alarm rate and the missed alarm rate of the existing monitoring technology for mine fire perception. Early detection of mine fires and timely alarm of fire disasters are important guarantees for timely emergency rescue and saving the lives of people in distress underground. SUMMARY

[0005] The present application aims to provide a mine fire identification and alarm method based on image contour parallel side ratio. Since flame burning has irregular shape, the method fully considers fire burning image features, can quickly identify fire and fire interference source, is accurate and simple, can save more rescue and escape time for people in distress in underground mine, includes installing camera in roadway, tunneling working face, fully mechanized working face and electromechanical chamber where fire is easy to occur to monitor the monitoring area in real time, making parallel sides in the contour of suspected fire area on suspected fire image, and determining whether the fire alarm meets the set conditions according to the length ratio of the parallel sides to the contour base side, the ratio of two adjacent values of the length ratio of the parallel sides to the contour base side, and the absolute value ratio of the difference of two adjacent values of the length ratio of the parallel sides to the contour base side, determining the underground monitoring area fire according to whether the ratio of the number of times of determining fire alarm in the set time to the total number of times of determining meets the set conditions, and immediately sending fire alarm signal to the monitoring terminal when determining that fire occurs in the underground monitoring area;

[0006] The working process of the fire alarm determination includes:

[0007] Step 1: the camera collects the image of the monitoring area in real time, the monitoring image is filtered and denoised, image enhancement and image pixel binarization are performed, when the pixel feature value M1 of a single block area on the image is greater than the set threshold Q, it is determined that the image is a suspected fire image of a single block area; when the pixel feature values M i (i≥2) of multiple unconnected areas on the image are all greater than the set threshold Q, it is determined that the image is a suspected fire image of multiple block areas, and step 2 is executed; if the suspected fire image determination condition is not met, continuous monitoring is performed;

[0008] Step 2: when there is only a single suspected fire area on the suspected fire image, the suspected fire area on the suspected fire image is directly processed for contour edge features; or when there are multiple suspected fire areas on the suspected fire image, the multiple suspected fire areas are segmented and processed for contour edge features, and step 3 is executed;

[0009] Step 3: the contour base side of the suspected fire area is set, and parallel sides are made in the contour; the length values of the parallel sides and the base side in the contour of the suspected fire area are calculated, further, the length ratio of the parallel sides to the base side is calculated, the ratio of two adjacent values of the length ratio of the parallel sides to the base side is calculated, and the absolute value ratio of the difference of two adjacent values of the length ratio of the parallel sides to the base side is calculated, and step 4 is executed;

[0010] Step 4: when the ratio of two adjacent values of the length ratio of the parallel sides to the base side in the contour of the suspected fire area on the suspected fire image, and the absolute value ratio of the difference of two adjacent values of the length ratio of the parallel sides to the base side meet the set conditions: when the ratio of two adjacent values of the length ratio of the parallel sides to the base side in the contour of the suspected fire area on the suspected fire image, and the absolute value ratio of the difference of two adjacent values of the length ratio of the parallel sides to the base side meet the set conditions:it} represents the ratio of the length of each parallel side to the base side within the outline of the suspected fire area, where k1, k2, k3, and k4 are set thresholds; in the formula, m and n represent the number of suspected fire areas and the number of side length ratios, respectively, and k1, k2, k3, and k4 are obtained by experimental determination or manual setting. Execute step 5; otherwise, return to step 1.

[0011] Step 5: Activate the fire alarm and return to step 1.

[0012] 1. The fire identification method further includes: the base edge of the suspected fire area contour is the line connecting any two adjacent coordinate points on the boundary of the suspected fire area contour.

[0013] 2. The fire identification method further includes: the parallel edge drawn within the outline of the suspected fire area is a straight line drawn within the outline of the suspected fire area according to a certain step distance, parallel to the base edge of the outline, and intersecting the outline boundary at at least two points.

[0014] 3. The fire identification method further includes: the fire determination process in the underground monitoring area includes performing fire alarm determination work cyclically for a duration of T seconds. When the ratio of the number of alarms X of suspected fire images that meet the fire alarm determination conditions to the total number of determinations Y of the images is greater than the set threshold R, that is, X / Y>R, then it is determined that a fire has occurred in the underground monitoring area.

[0015] 4. The fire identification method further includes: in step 3, calculating the side lengths of each parallel edge and the base edge within the outline of the suspected fire area, and calculating the side lengths of each parallel edge and the base edge respectively, wherein the formula for calculating the side length of each parallel edge is: And (r∈(1,n-1),b∈(1,n)), where {(x b1 ,y b1 ),…,(x br ,y br ),…,(x bn ,y bn Let )} be the coordinates of the intersection point of the parallel edge and the contour boundary. The formula for calculating the side length of the base edge is: In the formula {(x ce ,y ce ),(x c(e+1) ,y c(e+1) )} and (e∈(1,n-1),c∈(1,n)) are any two adjacent coordinate points on the outline boundary of the suspected fire area; the ratio of the length of the parallel side to the length of the base side is .

[0016] The mine fire identification and alarm method based on the number of edge corners of the image contour has the following characteristics:

[0017] 1.The fire identification method of the present application fully analyzes the contour features of the fire burning image and the contour features of the underground fire interference source, and makes fire determination based on the length ratio of the parallel sides to the base side in the suspected fire region contour on the suspected fire image, the ratio of the two adjacent values of the length ratio of each parallel side to the base side in the suspected fire region contour, and the absolute value ratio of the difference of the two adjacent values of the length ratio of each parallel side to the base side in the suspected fire region contour, which is more conducive to identifying and eliminating the fire interference source and can reduce the false and missed reports of the fire disaster.

[0018] 2.The method of the present application not only efficiently utilizes the feature information of the fire image, but also has a simple and efficient algorithm structure in the image processing part, and the fire information can be quickly determined from a single frame image, the feature extraction recognition degree is high, the number of variables is small, the identification time of suspected fire is shortened, and more escape time is further obtained for the trapped and affected personnel in the underground mine. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 An implementation scheme diagram of the mine fire identification and alarm method based on the image contour parallel side ratio.

[0020] Figure 2 A structure diagram of a fire monitoring and alarm device.

[0021] Figure 3 A fire alarm process diagram of the mine fire identification and alarm method based on the image contour parallel side ratio.

[0022] Figure 4 A fire determination process diagram of the mine fire identification and alarm method based on the image contour parallel side ratio. DETAILED DESCRIPTION

[0023] Figure 1 The implementation scheme example of the mine fire identification and alarm method based on the image contour parallel side ratio, the main components include:

[0024] 1.A storage server (101) is in communication connection with an image acquisition camera (105), responsible for storing and forwarding the real-time video image data of the monitored area provided by the camera; the storage server is in communication connection with a fire monitoring and alarm device (106), responsible for storing and forwarding the fire alarm data provided by the fire monitoring and alarm device; and provides a service for the monitoring terminal (102) to view the on-site monitoring data of the monitored area or to call the historical monitoring image data.

[0025] 2. Monitoring terminal (102) installed on the well for receiving the fire monitoring alarm device (106) alarm signal; responsible for providing well environment monitoring data display service, real-time, historical data and fire alarm data provided by storage server (101) and sound and light alarm function; production management personnel can query the historical data stored in the storage server (101) through the monitoring terminal.

[0026] 3. Core switch (103), core management and switching equipment of mine Ethernet, responsible for the management and data exchange of all devices connected to mine Ethernet, with routing function, connected to the Internet.

[0027] 4. Ring network switch (104), underground switching equipment of mine Ethernet, installed underground, multiple ring network switches connected in ring network mode.

[0028] 5. Camera (105), image acquisition device, installed in underground roadway, coal mining face and tunneling face, responsible for collecting real-time video images of underground roadway and working face where fire is easy to occur; the camera includes visible light camera, far infrared camera, near infrared camera and ultraviolet camera; the camera has network output and analog video output function; the network interface is directly connected to the ring network switch (104), and the real-time collected video image data of the monitoring area is transmitted to the storage server (101); the analog video output port is connected to the fire monitoring alarm device (106).

[0029] 6. Fire monitoring alarm device (106), responsible for receiving and processing monitoring video image data collected by camera (105), built-in graphic image processing software, when the processed suspected fire image meets the set fire alarm condition, sends fire alarm data to storage server (101); and sends fire alarm signal to monitoring terminal (102); with wired and wireless communication function.

[0030] 7. Suspected fire area, suspected ignition point area in the real-time monitoring area of the camera, the image data is monitored and collected by the camera in real time.

[0031] Figure 2 is the structure diagram of the fire monitoring alarm device:

[0032] The main components of the fire monitoring alarm device include: core processor, graphic processor, storage unit, clock unit, power unit, USB interface unit, video image acquisition module, wireless communication unit, network interface unit, SD card interface unit.

[0033] 1. Core processor (201), using Broadcom BCM2837 processor, using ARM Cortex-A53 architecture, 64-bit quad-core 1.2GHz.

[0034] 2. Graphics processor (202), using Dual Core VideoCore IV GPU processor.

[0035] 3. Storage unit (203), using 1GB LPDD2 memory.

[0036] 4. Clock unit (204), using 19.2MHz crystal oscillator.

[0037] 5. Power supply unit (205), using AC / DC module, input 100V-240V AC, output 12V DC, used for device power supply.

[0038] 6. USB interface unit (206), supporting 4 USB interfaces.

[0039] 7. Video image acquisition module (207), converts mode video signal to digital video data, input connected to the analog video output port of the camera (105), transmits digital video data to the core processor (201) through the USB port, supports multi-channel video acquisition.

[0040] 8. Communication module (208), responsible for converting RS485 communication interface to USB communication interface, connecting other data monitoring devices.

[0041] 9. Wireless communication unit (209), supporting 802.11b / g / n protocol, used for wireless communication with monitoring devices supporting wireless communication.

[0042] 10. Network interface unit (210), responsible for accessing mine Ethernet, connecting ring network switch (104).

[0043] 11. SD card unit (211), used for storing system files, library files, monitoring program files, etc., using Linux system management, built-in OpenCV library for video data processing, using not less than 4GB Micro SD card.

[0044] Figure 3 The fire alarm flowchart of the mine fire identification and alarm method based on image contour parallel side ratio, the fire alarm flowchart comprises:

[0045] 1. (301) Set the internal timer time T of the fire monitoring and alarm device to zero and start timing, set the total number of times Y = 0 that the image of the fire alarm judgment condition is executed, set the number of times X = 0 that the suspected fire image meets the fire alarm condition, and execute step (302).

[0046] 2. (302) Further set the total number of times Y = Y + 1 that the image of the fire alarm judgment condition is executed, and the judgment number is accumulated by one every time the fire alarm judgment condition is executed, and execute step (303).

[0047] 3. (303) The fire monitoring and alarm device processes the image and makes a fire alarm judgment on the suspected fire image, and when the set fire alarm judgment condition is met, step (304) is executed, otherwise step (302) is returned.

[0048] 4. (304) The number of fire alarm times is accumulated by one every time the suspected fire image meets the fire alarm judgment condition, that is, X = X + 1, and a fire warning is sent to the monitoring terminal, and step (305) is executed.

[0049] 5. (305) The workflow of the fire alarm judgment is executed in a set time, and it is judged whether the timer time value T is greater than the set time threshold t, when the time value T > t, step (306) is executed, otherwise step (302) is returned.

[0050] 6. (306) Further judge whether the ratio of the number of fire image alarms X that meet the fire alarm judgment condition to the total number of times Y that the image of the fire alarm judgment condition is executed is greater than the set threshold R, when X / Y > R, step (307) is executed, otherwise step (301) is returned.

[0051] 7. (307) The fire monitoring and alarm device sends a fire alarm signal to the storage server (101) and the monitoring terminal (102).

[0052] Figure 4 The fire determination process of the mine fire identification and alarm method based on the parallel side ratio of the image contour includes:

[0053] 1. (401) The camera is installed in the underground roadway, the tunneling working face, the fully mechanized working face, and the electromechanical chamber, and real-time image of the monitoring area is collected and uploaded to the fire monitoring and alarm device for image recognition processing, and further step (402) is executed.

[0054] 2. (402) The fire monitoring alarm device pre-processes the monitoring image, which has been image denoised, image enhanced and image pixel binarized, and when there is a single block area pixel brightness characteristic value M1>Q on the image, the image is a suspected fire image of a single block area; when there are multiple non-connected area pixel brightness characteristic values on the image, the image is a suspected fire image of multiple block areas; further execute step (403), otherwise return to execute step (401).

[0055] 3. (403) Further determine whether there are multiple suspected fire areas on the suspected fire image, when there are no multiple suspected fire areas on the suspected fire image, it is determined that there is only a single suspected fire area, execute step (404), otherwise execute step (407).

[0056] 4. (404) According to the determination of step (403), there is only a single suspected fire area on the suspected fire image, directly perform contour edge feature processing on the suspected fire area on the suspected fire image, and further calculate the contour base edge of the suspected fire area: extract any two adjacent coordinate points {(x ce ,y ce ),(x c(e+1) ,y c(e+1) )} on the contour, calculate the edge length of the base edge by the formula , and execute step (405).

[0057] 5. (405) According to the reference edge of the contour base edge, calculate the parallel edges intersecting the contour boundary and parallel to the base edge according to a certain step distance H based on the calculation formula , wherein y ib is the straight line equation of the bth parallel edge according to the base edge, k ic is the straight line slope of the base edge, C ib is the step distance of the bth parallel edge, b is the number of parallel edges, and C1 is the constant of the straight line equation; further calculate the edge length value of each parallel edge according to the calculation formula , wherein {(x b1 ,y b1 ),…,(x br ,y br ),…,(x bn ,y bn )} are the intersection coordinates of the parallel edge and the contour boundary, and execute step (408).

[0058] 6. (406) According to the determination of step (403), when there are multiple suspected fire areas on the suspected fire image, perform image segmentation and block processing on the suspected fire areas on the suspected fire image, and execute step (407).

[0059] 7. (407) Calculate the suspected fire area, the suspected fire area contour base edge and the length of the edge, and each parallel edge intersecting the contour boundary and parallel to the base edge and the length of the edge, according to the formula of steps (404) and (405), and execute step (408).

[0060] 8. (408) Further calculate the length of each parallel edge and the length of the base edge according to the formula Calculate the length ratio of each parallel edge and the base edge According to the formula (i∈(1,m),t∈(1,n-1)) Calculate the ratio of two adjacent values of the length ratio of each parallel edge and the base edge; according to the formula (i∈(1,m),t∈(1,n-2)) Calculate the absolute value ratio of the difference of two adjacent values of the length ratio of each parallel edge and the base edge, and execute step (409).

[0061] 9. (409) When the fire monitoring and alarm device monitors the suspected fire area contour on the suspected fire image, and the ratio of the length ratio of each parallel edge and the base edge of the two adjacent values meets the set condition: Execute step (410), otherwise return to step (401).

[0062] 10. (410) When the fire monitoring and alarm device monitors the suspected fire area contour on the suspected fire image, and the absolute value ratio of the difference of two adjacent values of the length ratio of each parallel edge and the base edge meets the set condition: Execute step (411), otherwise return to step (401).

[0063] 11. (411) The fire monitoring and alarm device sends a fire alarm to the storage server (101) and the monitoring terminal (102).

Claims

1. A mine fire identification and alarm method based on image contour parallel side ratio, characterized in that: The camera is installed in the roadway, the tunneling working face, the fully mechanized working face and the electromechanical chamber to monitor the monitoring area in real time, fire alarm judgment is made according to whether the ratio of two adjacent values of the length ratio of each parallel side to the base side in the suspected fire area profile, the absolute value ratio of the difference of two adjacent values of the length ratio of each parallel side to the base side in the suspected fire area profile meets the set condition, whether the ratio of the number of times of determining the fire alarm in the set time to the total number of times of determining meets the set condition to determine the fire in the underground monitoring area, and a fire alarm signal is immediately sent to the monitoring terminal when it is determined that the fire occurs in the underground monitoring area; The working process of the fire alarm judgment comprises: Step 1: The camera acquires images of the monitored area in real time. After image filtering and noise reduction, image enhancement, and image pixel binarization, the monitored images are used to identify single-area pixel feature values ​​in the image. Greater than the set threshold When the image is determined to be a suspected fire image of a single area; when the image contains multiple disconnected areas of pixel feature values... All are greater than the set threshold. If the image is determined to be a suspected fire image in multiple areas, step 2 is executed; if the suspected fire image determination criteria are not met, monitoring continues. Step 2: when there is only a single suspected fire area on the suspected fire image, the suspected fire area on the suspected fire image is directly processed for contour edge features; or when there are multiple suspected fire areas on the suspected fire image, the multiple suspected fire areas are segmented, the suspected fire areas are processed for contour edge features in blocks, and step 3 is executed; Step 3: a suspected fire area profile base side is set, and parallel sides are made in the profile; the length values of each parallel side and the base side in the suspected fire area profile are calculated, further, the length ratio of each parallel side and the base side is calculated, the ratio of two adjacent values of the length ratio of each parallel side and the base side is calculated, the absolute value ratio of the difference of two adjacent values of the length ratio of each parallel side and the base side is calculated, and step 4 is executed; Step 4: When the ratio of the two adjacent values of the length ratio of each parallel side to the base side in the suspected fire area contour on the suspected fire image, the ratio of the absolute value of the difference of the two adjacent values of the length ratio of each parallel side to the base side satisfies a set condition: wherein is the length ratio of each parallel side to the base side in the suspected fire area contour, is a set threshold value; wherein respectively represent the number of suspected fire areas and the number of length ratios, and wherein is obtained by experiment or artificially set, and Step 5 is performed, otherwise Step 1 is returned to be executed. Step 5: fire alarm is made, and step 1 is returned to be executed.

2. The method for mine fire identification and alarm based on parallel side ratio of image contour according to claim 1, characterized in that: The suspected fire area profile base side is a line between any two adjacent coordinate points on the suspected fire area profile boundary.

3. The method for mine fire identification and alarm based on parallel side ratio of image contour according to claim 1, characterized in that: The parallel sides made in the suspected fire area profile are straight lines parallel to the profile base side made in the suspected fire area profile at a certain step distance and intersecting the profile boundary at least at two points.

4. The method for mine fire identification and alarm based on parallel side ratio of image contour according to claim 1, characterized in that: The downhole monitoring area fire determination process includes, duration performs a fire alarm determination operation every second, and when the number of times of alarm of the suspected fire image satisfying the fire alarm determination condition is greater than the total number of determination times of the image is greater than a set threshold value , that is , it is determined that a fire occurs in the downhole monitoring area.

5. The method for mine fire identification and alarm based on parallel side ratio of image contour according to claim 1, characterized in that: The length of each parallel side and the length of the base are calculated respectively, and the length of each parallel side is calculated by the following formula: , wherein is the coordinate of the intersection point of each parallel side and the contour boundary, and the length of the base is calculated by the following formula: , wherein is any two adjacent coordinate points on the contour boundary of the suspected fire area; and the length ratio of each parallel side to the base is .

Images