A method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared light.

Abstract

This invention discloses a method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared light, belonging to the field of underground coal mine detection technology. This method generates a PWM-modulated signal through a main control unit, driving the infrared transmitter to output scattered infrared light. The infrared receiver matches the received signal and outputs the status. The main control unit continuously samples to form a sampling sequence, combining jitter reduction processing and a dual-threshold judgment mechanism to distinguish between occupancy establishment and occupancy removal states. Simultaneously, an offset warning function is set, ultimately linking with audio-visual equipment to output a prompt. This invention utilizes PWM modulation to resist underground stray light and electrical interference, and scattered infrared light to adapt to scenarios of partial occupancy and equipment offset, effectively improving the accuracy and stability of determining the occupancy of a mine car passing chamber.

Description

Technical Field

[0001] This application relates to the field of underground safety detection and intelligent early warning technology in coal mines, specifically to a method for determining the occupancy of a mine car passing chamber based on PWM modulated scattering infrared. Background Technology

[0002] During underground coal mining operations, the narrow spaces in the tunnels and the frequent movement of various mining transport vehicles and personnel make the passing chambers crucial for ensuring the safe passage and avoidance of vehicles. To prevent vehicles from accidentally entering and occupying these chambers, causing collisions, and to prevent personnel from accidentally entering dangerous areas, it is necessary to continuously monitor the occupancy status of the passing chambers and guide passage through warning devices.

[0003] Currently, the industry's solutions for detecting obstructions in passageways and chambers are mainly divided into three categories: infrared beam detection, laser beam detection, and ordinary continuity-based photoelectric detection. These traditional detection solutions can achieve basic obstruction detection under normal indoor and surface conditions. However, the underground environment of coal mines is unique, with a large amount of roadway lighting, reflected light, and stray light scattered by dust. At the same time, underground electrical equipment is densely packed, resulting in severe electromagnetic interference and electrical noise. The application of traditional detection technologies in underground fields has revealed many shortcomings: There is a lot of light from underground lights, reflected light, stray light, and electrical interference, which can easily affect the receiver's stable identification of valid signals. If the occlusion status is judged based on a single reception result, it is easy to cause false alarms or false alarms due to dust, shaking or instantaneous disturbances. In the scenario of passing vehicles in the tunnel, edge occlusion, partial occlusion and short-term swaying occlusion often occur when vehicles pass by. Simple binary judgment is difficult to balance sensitivity and stability. Traditional centralized beam receivers are prone to unstable reception even in unobstructed conditions after the installation position shifts, which is detrimental to long-term operation in mines.

[0004] Therefore, existing mine access chamber detection technologies have weak anti-interference capabilities, poor stability, and insufficient adaptability, failing to meet the high-precision and high-reliability occupancy determination requirements in complex underground environments. A new method is needed to solve these problems. Summary of the Invention

[0005] To overcome the above-mentioned shortcomings, the purpose of this application is to provide a method for determining the occupancy of a mine car passage based on PWM modulated scattering infrared, so as to solve the problems in the prior art, such as misjudgment caused by underground environmental interference, unstable detection results, inability to balance sensitivity and stability, and failure to trigger alarms when state changes occur.

[0006] To achieve the above objectives, this application adopts the following technical solution: This application provides a method for determining the occupancy of a mine car passing chamber based on PWM modulated scattered infrared light, including the following steps: The main control unit outputs a PWM modulation signal of a set frequency to drive the infrared transmitter to emit modulated and scattered infrared light outward. The infrared receiver receives the modulated and scattered infrared light and outputs a valid reception status signal. The main control unit continuously collects the received valid state signals at a fixed sampling period to form a continuous sampling sequence; The main control unit performs validity statistics and de-jitter processing based on the continuous sampling sequence, and at the same time completes occlusion state recognition based on the dual threshold judgment rule; The main control unit determines the occupancy status of the meeting chamber based on the occupancy status recognition result, and at the same time, it activates the audio-visual prompt device to perform the corresponding linkage operation.

[0007] Furthermore, the main control unit completes the occlusion state recognition based on the dual threshold determination rule, specifically including: When the reception abnormality reaches a first set number of times or a first set duration, the blockage is determined to be established. When the number of consecutive valid reception states reaches the second preset number or the second preset duration, the blockage is determined to be lifted. The second set number of times is greater than the first set number of times, and the second set duration is greater than the first set duration, in order to avoid the system recovering too early due to slight shaking, rear obstruction or dust disturbance when the vehicle has just left the detection area.

[0008] Furthermore, the main control unit includes an STM32 microcontroller, which outputs a PWM waveform of a set frequency to the infrared emission drive circuit. The infrared emitting end includes one or more infrared light-emitting diodes and a scattering optical unit; The infrared LED emits light under the drive of the PWM modulation signal. After being diffused by the scattering optical unit, it forms a wide infrared detection area covering the passage area of ​​the passing tunnel. The PWM modulation signal is used to enable the receiver to identify infrared signals of a specific frequency in order to suppress the interference of ambient stray light.

[0009] Furthermore, the infrared emitting end adopts a pulsed modulation light emission method, and the duration of each emitted pulse train is controlled by the timing drive unit; The transmitted pulse is a nanosecond or microsecond pulse window. The infrared receiver performs signal detection within a time window synchronized with the transmitter to improve the ability to identify target signals, while reducing energy consumption and interference accumulation caused by continuous light emission.

[0010] Furthermore, after receiving the light signal, the infrared receiver sequentially filters, amplifies, and shapes the signal to output a standardized valid reception status signal. After the main control unit reads the valid reception status signal, it counts the number of times the valid signal appears within the continuous sampling window. Based on the comparison between the number of occurrences and the threshold, it determines whether the current reception status is valid or abnormal, and thus forms a continuous sampling sequence.

[0011] Furthermore, the de-jitter processing includes: Ignore isolated single or small number of outlier sampling points in a continuous sampling sequence; To prevent false alarms caused by non-vehicle entities briefly crossing the detection area, a trigger delay is set for the detection of obstruction. To prevent frequent status changes when the vehicle's rear or attached cargo has just left the obstruction area, a recovery delay is set. When the received signal strength remains low for an extended period but still exhibits periodic responses, it is identified as an offset warning state, prompting maintenance personnel to adjust the position of the transmitter or receiver.

[0012] Furthermore, it also includes an offset warning operation, which includes: When the signal strength of the infrared receiver remains at a low level for an extended period, but periodic PWM modulation response can still be detected, it is determined that there is an installation position misalignment between the infrared transmitter and receiver, and an early warning is output to remind maintenance personnel to adjust the equipment position.

[0013] Furthermore, the process by which the linked audio-visual prompting device performs the corresponding prompting operation includes: When it is determined that there is no obstruction and the chamber is not occupied, the green light will be turned on and a passage permission prompt will be output; When the chamber is determined to be obstructed or occupied, a red light will illuminate and a voice broadcast will be activated, displaying a "Do Not Enter" message.

[0014] Furthermore, when the obstruction continues for more than the third set time, the system outputs a continuous occupancy prompt and uploads the chamber occupancy status data to the mine's centralized maintenance platform.

[0015] Furthermore, the system is equipped with a parameter storage unit for storing operating parameters such as voice start / stop, voice volume, prompt content, and light flashing rhythm. These parameters can be customized according to the needs of the mine site. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: With its strong anti-interference capability, the PWM modulated signal can filter out stray light and electrical interference in the well, solving the problem of misjudgment caused by interference in traditional technology, and can also perform stable detection in the harsh environment of the well.

[0016] With better scene adaptability, the diffused infrared can cover the entire passage area, solving the problem of missed detection due to partial or edge occlusion. At the same time, the offset warning function solves the problem of device failure after device offset, reducing the difficulty of operation and maintenance.

[0017] Balancing sensitivity and stability, the dual-threshold de-jitter mechanism can quickly identify vehicle entry, ensuring response speed, while avoiding state jumps when vehicles leave, thus ensuring stability and solving the problem that traditional technologies cannot achieve both.

[0018] Stable linkage output, the judgment result is filtered through multiple layers, and there will be no frequent jumps. It can stably drive the sound and light equipment, and there will be no situation where the light flashes back and forth or the voice plays back and forth.

[0019] Low energy consumption: Pulsed light emission reduces energy consumption, making it suitable for long-term operation downhole and extending the equipment's lifespan.

[0020] Intelligent operation and maintenance, including offset early warning and remote reporting, makes equipment operation and maintenance more intelligent and improves the level of intelligence in the mine. Attached Figure Description

[0021] The accompanying drawings are provided to illustrate the technical solutions of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of this disclosure and do not constitute a limitation on the technical solutions of this disclosure. The shapes and sizes of the components in the drawings do not reflect actual proportions and are only intended to illustrate the content of this application.

[0022] Figure 1 This is a schematic diagram of the overall process of the method of the present invention.

[0023] Figure 2 This is a schematic diagram of the PWM modulation and reception identification timing of the present invention.

[0024] Figure 3 This is a schematic diagram of the dual threshold determination method of the present invention.

[0025] Figure 4 This is a schematic diagram of the jitter removal and offset warning functions of the present invention.

[0026] Figure 5 This is a schematic diagram of the sound and light alarm linkage of the present invention. Detailed Implementation

[0027] The above-described solution will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. The implementation conditions used in the embodiments may be further adjusted according to the conditions of specific manufacturers, and the implementation conditions not specified are generally those in routine experiments.

[0028] Unless otherwise defined, the technical or scientific terms used in the embodiments of this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. In this document, "electrical connection" includes the situation where constituent elements are connected together by an element having some electrical function. There is no particular limitation on the "electrically functioning element," as long as it enables the transmission and reception of electrical signals between the connected constituent elements. An "electrically functioning element" can be, for example, an electrode or wiring, a switching element such as a transistor, or other functional elements such as a resistor, inductor, or capacitor. "Up," "down," "left," and "right" are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0029] In this application, the terms "upper," "lower," "inner," "middle," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0030] Example One embodiment of this application provides a method for determining the occupancy of a mine car passing chamber based on PWM modulated scattered infrared light, such as... Figure 1-5 As shown, it includes the following steps: S1. The main control unit outputs a PWM modulation signal of a set frequency to drive the infrared transmitter to emit modulated and scattered infrared light outward. S2. The infrared receiver receives the modulated and scattered infrared light and outputs a valid reception status signal. S3. The main control unit continuously collects the received valid state signals at a fixed sampling period to form a continuous sampling sequence. S4. The main control unit performs validity statistics and de-jitter processing based on the continuous sampling sequence, and at the same time, the main control unit completes occlusion state recognition based on the dual threshold judgment rule. S5. The main control unit determines the occupancy status of the meeting chamber based on the occupancy status recognition result, and at the same time, it links the audio-visual prompt device to perform the corresponding linkage operation.

[0031] This solution is divided into six core components: PWM modulation infrared transmission, infrared signal reception and recognition, continuous sampling and sequence generation, jitter removal and dual threshold occlusion judgment, offset warning, and sound and light linkage prompts. Specifically, the details of each step are as follows: PWM Modulated Scattering Infrared Emission Circuit The main control unit, including an STM32 microcontroller, generates a PWM (Pulse Width Modulation) signal at a set frequency. The modulated signal has a fixed frequency characteristic and is output to the infrared emission drive circuit. The drive circuit then controls the infrared LED at the infrared emitter to emit light. The infrared light emitted by the LED is diffused by the scattering optical unit and diffuser, unlike the traditional narrow beam. This application produces scattered infrared light, forming a wide detection area that covers the entire passage area of ​​the vehicle passage chamber. Whether it is the edge of the vehicle or a partial obstruction, it can be detected without any missed detection.

[0032] Using PWM modulation, the emitted infrared light has a fixed frequency. Natural light, tunnel lights, dust reflections, and electrical interference in the mine do not have this fixed frequency. Therefore, the receiver can only identify signals of this specific frequency, filtering out all stray interference at the source and solving the problem of interference in the underground environment.

[0033] The transmitter can also use a pulsed light emission method, which emits narrow pulses at the nanosecond or microsecond level at regular intervals instead of continuous light emission. The receiver also performs detection within the synchronous time window to further filter asynchronous interference. This also reduces the energy consumption of the LED, reduces heat generation, and extends the life of the device, making it suitable for 24-hour uninterrupted operation in mines.

[0034] Infrared signal receiving and identification stage The infrared receiver collects light signals in space in real time. First, it filters the signal to remove stray light with mismatched spectra. Then, it amplifies the weak effective signal after filtering. Because the scattered infrared light signal is relatively weak, it is shaped after amplification to convert the analog signal into a standard digital signal. Finally, it outputs the effective reception status signal.

[0035] The main control unit reads this status signal according to a fixed sampling period, records the result of each sampling, and forms a continuous sampling sequence. During this sampling process, it also counts the number of valid signals in a sampling window. If the number reaches the threshold, it means that the current reception state is valid, that is, there is no obstruction and the infrared light is received normally. If the number is lower than the threshold, it means that the reception state is abnormal, that is, there is obstruction and the infrared light is blocked.

[0036] By employing a continuous sampling method, the error of a single sampling is effectively avoided, thus improving the reliability of the results.

[0037] Shake removal and dual-threshold occlusion detection process The de-jitter process iterates through the continuous sampling sequence, ignoring isolated, single, or small numbers of outlier sampling points, as these are transient disturbances caused by dust or shaking, rather than actual occlusions; then, a double-threshold judgment rule is applied. When an abnormal status is received, if it reaches the first set number of times consecutively or lasts for the first set duration, an obstruction is determined, meaning that a vehicle has entered the chamber and the chamber is occupied. At the same time, there is a trigger delay. Even if the number of times is reached, there is still a short wait to prevent false alarms caused by non-vehicle objects, such as birds or people passing by briefly.

[0038] When the obstruction is cleared, the threshold should be higher. This means that valid alerts must be received consecutively for a greater number of times or for a longer duration to determine if the obstruction is cleared. This is because when the vehicle leaves, its rear or any attached cargo may briefly obstruct the light path, and dust kicked up by the vehicle can also temporarily block the light. If the threshold is too low, the alarm may be cleared prematurely, only to be triggered again by the rear obstruction, leading to frequent state transitions and affecting alarm stability. Therefore, setting a higher clearing threshold avoids this problem and makes state transitions more stable.

[0039] Meanwhile, a continuous sampling and verification mechanism is adopted, which collects and compares the received results multiple times within a detection cycle. Only when the results are consistent across multiple tests will the occlusion or recovery status be determined, further reducing the probability of misjudgment caused by dust and vibration.

[0040] Deviation warning link Traditional beam-transmitting equipment loses its effective signal when its installation position shifts. The system then misinterprets this as obstruction, triggering a continuous alarm. In reality, the equipment has shifted, leading users to mistakenly believe the chamber is occupied, thus affecting usability. This invention, however, features a shift warning function. It analyzes the characteristics of the received signal in real time. If the signal strength remains consistently low, periodic PWM pulses can still be detected. This indicates that the transmitter is still emitting light normally; only the optical path has shifted, causing signal attenuation. At this point, the installation position is determined to have shifted, and a warning is issued to alert maintenance personnel to adjust the equipment's position. This allows for early detection and maintenance, preventing complete equipment failure.

[0041] Sound and light linkage prompts The judgment result directly triggers the audio-visual prompting equipment to alert personnel on site. When the judgment indicates an unobstructed state, meaning the chamber is not occupied, a green light illuminates, informing vehicles and personnel on site that they can pass normally and the chamber is empty.

[0042] When the chamber is determined to be obstructed, indicating that it is occupied, a red light will illuminate, and a voice announcement will be made saying "The chamber is occupied, entry is prohibited" to warn vehicles and personnel outside not to enter and to avoid collisions.

[0043] If this occupancy status continues for more than the third set time, such as 5 minutes, it is determined to be a long-term occupancy. At this time, this status is uploaded to the mine's centralized maintenance platform so that managers can remotely know about the situation and make scheduling.

[0044] In addition, the system also has a parameter storage unit that saves parameters such as voice start / stop, volume, prompt content, and the flashing rhythm of lights. Users can customize these parameters according to their own mine conditions.

[0045] The working principle of this invention is to filter out underground interference at the signal level through PWM modulation, expand the detection range through scattered infrared light, filter out instantaneous disturbances at the software level through continuous sampling, jitter reduction, and dual threshold algorithms to ensure stable judgment, improve the operation and maintenance capabilities of the equipment through offset warning, and finally, link with audible and visual equipment to realize on-site warning, forming a complete closed loop for underground chamber occupancy detection.

[0046] The above embodiments are only for illustrating the technical concept and features of this application, and are intended to enable those skilled in the art to understand the content of this application and implement it accordingly. They should not be used to limit the scope of protection of this application. All equivalent changes or modifications made in accordance with the spirit and essence of this application should be included within the scope of protection of this application.

Claims

1. A method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared light, characterized in that: Includes the following steps: The main control unit outputs a PWM modulation signal of a set frequency to drive the infrared transmitter to emit modulated and scattered infrared light outward. The infrared receiver receives the modulated and scattered infrared light and outputs a valid reception status signal. The main control unit continuously collects the received valid state signals at a fixed sampling period to form a continuous sampling sequence; The main control unit performs validity statistics and de-jitter processing based on the continuous sampling sequence, and at the same time completes occlusion state recognition based on the dual threshold judgment rule; The main control unit determines the occupancy status of the meeting chamber based on the occupancy status recognition result, and at the same time, it activates the audio-visual prompt device to perform the corresponding linkage operation.

2. The method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared as described in claim 1, characterized in that: The main control unit completes occlusion state recognition based on the dual threshold determination rule, specifically including: When the reception abnormality reaches a first set number of times or a first set duration, the blockage is determined to be established. When the number of consecutive valid reception states reaches the second preset number or the second preset duration, the blockage is determined to be lifted. The second set number of times is greater than the first set number of times, and the second set duration is greater than the first set duration, in order to avoid the system from recovering too early due to slight shaking, rear obstruction or dust disturbance when the vehicle has just left the detection area.

3. The method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared as described in claim 1, characterized in that: The main control unit includes an STM32 microcontroller, which outputs a PWM waveform of a set frequency to the infrared emission drive circuit. The infrared emitting end includes one or more infrared light-emitting diodes and a scattering optical unit; The infrared LED emits light under the drive of the PWM modulation signal. After being diffused by the scattering optical unit, it forms a wide infrared detection area covering the passage area of ​​the passing tunnel. The PWM modulation signal is used to enable the receiver to identify infrared signals of a specific frequency in order to suppress the interference of ambient stray light.

4. The method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared as described in claim 1, characterized in that: The infrared transmitter adopts a pulsed modulation light emission method, and the duration of each emitted pulse train is controlled by the timing drive unit; The transmitted pulse is a nanosecond or microsecond pulse window. The infrared receiver performs signal detection within a time window synchronized with the transmitter to improve the ability to identify target signals, while reducing energy consumption and interference accumulation caused by continuous light emission.

5. The method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared as described in claim 1, characterized in that: After receiving the light signal, the infrared receiver sequentially filters, amplifies, and shapes the signal to output a standardized valid reception status signal. After the main control unit reads the valid reception status signal, it counts the number of times the valid signal appears within the continuous sampling window. Based on the comparison between the number of occurrences and the threshold, it determines whether the current reception status is valid or abnormal, and thus forms a continuous sampling sequence.

6. The method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared as described in claim 1, characterized in that: The shake reduction process includes: Ignore isolated single or small number of outlier sampling points in a continuous sampling sequence; To prevent false alarms caused by non-vehicle entities briefly crossing the detection area, a trigger delay is set for the detection of obstruction. To prevent frequent status changes when the vehicle's rear or attached cargo has just left the obstruction area, a recovery delay is set. When the received signal strength remains low for an extended period but still exhibits periodic responses, it is identified as an offset warning state, prompting maintenance personnel to adjust the position of the transmitter or receiver.

7. The method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared as described in claim 1, characterized in that: It also includes an offset warning operation, which includes: When the signal strength of the infrared receiver remains at a low level for an extended period, but periodic PWM modulation response can still be detected, it is determined that there is an installation position misalignment between the infrared transmitter and receiver, and an early warning is output to remind maintenance personnel to adjust the equipment position.

8. The method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared as described in claim 1, characterized in that: The process by which the linked audio-visual prompting device performs the corresponding prompting operation includes: When it is determined that there is no obstruction and the chamber is not occupied, the green light will be turned on and a passage permission prompt will be output; When the chamber is determined to be obstructed or occupied, a red light will illuminate and a voice broadcast will be activated, displaying a "Do Not Enter" message.

9. The method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared as described in claim 1, characterized in that: When the obstruction continues for more than the third set time, the system outputs a continuous occupancy prompt and uploads the chamber occupancy status data to the mine's centralized maintenance platform.

10. The method for determining the occupancy of a mine car passing chamber based on PWM-modulated scattered infrared as described in claim 1, characterized in that: The system is equipped with a parameter storage unit for storing operating parameters such as voice start / stop, voice volume, prompt content, and light flashing rhythm. These parameters can be customized according to the needs of the mine site.

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