Subway platform screen door safety detection method and system based on laser ranging

Abstract

The invention discloses a subway shielding door safety detection system based on laser ranging and a human body detection method, and the system employs an infrared laser ranging sensor which is disposed at the top between a shielding door and a vehicle door, projects an infrared laser beam from top to bottom, and forms a light spot on the surface of a target. The distance information between the light spot and the detector is obtained in real time, intelligent judgment is carried out, whether a target appears or not is recognized, and an alarm is given immediately after the target is found. The detection system can directly output an alarm signal, and further processing of an upper computer is avoided. The optical-mechanical-electrical integration technology is adopted, the size is small, the occupied space is small, and installation, debugging and maintenance are all very convenient. Based on a mature laser triangulation ranging technology and a laser displacement sensor product technology, the method has the advantages of low cost and less investment. A serial bus is adopted for multi-point cascade connection, one cable can be connected with all detection systems, the hardware cost is extremely low, and distributed networking is very simple.

Description

Technical Field

[0001] The invention relates to a subway screen door safety detection method, in particular to a subway screen door safety detection system based on laser ranging and a passenger safety detection method. Background Art

[0002] Shield doors refer to glass curtain walls that surround the railway platform and the space for trains to get on and off. Shield doors are devices installed on the edge of the subway platform near the track to separate the platform area from the track area. When the train arrives, the electric door on the glass curtain wall is opened for passengers to get on and off the train. The main purpose of setting up shield doors is to prevent accidents caused by people falling on the track, reduce the operating energy consumption of the station's air conditioning and ventilation system, and reduce the impact of train running noise and piston wind on the station, providing passengers with a safe and comfortable waiting environment, avoiding delays in operations due to platform accidents, improving the service level of rail transit, and creating necessary conditions for the realization of unmanned driving in the rail transit system.

[0003] The function of the shield door is to ensure safety. Usually, electric / magnetic devices are installed on trains. Only when the train stops accurately at the designated position of the platform will the sensor be activated through electromagnetic induction and the shield door can be opened. If the train has not arrived or has already started to leave, the shield door will automatically lock, forcibly preventing passengers from intentionally or unintentionally entering the track to avoid danger. However, when passengers are playing with their mobile phones while getting on and off the subway, they are caught by the shield door, causing personal injury and the vehicle cannot start. Some passengers break in when the door is about to close, and they are stuck in the gap between the shield door and the train. The driver is unaware of the danger, and the passengers are injured after the train departs. Children with thin bodies or suitcases are small in size, and the shield door will automatically close without detection, causing accidents.

[0004] The number of subway passengers is large, especially during rush hour. Although the operator has increased the frequency of departure, the number of trains that can be operated is still limited due to the safe interval of train operation. Therefore, the subway is sometimes very crowded (this is particularly prominent in the Shanghai subway), or the number of passengers exceeds the design. In this case, the safety factor of some facilities will be greatly reduced.

[0005] Therefore, effective protective devices are installed in the existing platform screen door system. Through certain detection devices, an invisible defense wall is formed in the narrow gap between the door and the platform screen door to sense the existence of this "sandwich" danger, prevent the train from starting and notify the staff to deal with it. This has become the top priority in subway safety work and is imperative! At present, the main methods of platform screen door safety detection used in subway systems are as follows: (1) Laser beam detection method: a pair of laser emitting and receiving devices are installed on the left and right sides between the shield door and the car door, and an alarm is triggered when an obstruction occurs. Advantages: stable performance, resistant to strong light interference; Disadvantages: occupies a lot of ground space, laser sweeping poses a safety hazard; the system is complex and requires a large investment.

[0006] (2) Lidar method: The detector is installed on the top of the shielding door and uses TOF ranging scanning technology to effectively detect and identify dynamic obstacles. Advantages: small size, low power consumption; high detection frequency, no blind spots; all-solid-state design, high stability. Disadvantages: high cost and large investment.

[0007] (3) Infrared detection method: Install infrared light emitting and receiving equipment on the inside of the shielding door, and immediately alarm when infrared heat radiation targets appear. Advantages: stable performance, resistant to lighting interference. Disadvantages: occupies more ground space; weak resistance to heat source interference; complex system and high investment.

[0008] Therefore, the existing technical means cannot achieve the role of safety detection and passenger protection well, and a new means with less space occupation, low cost and low investment, and easy installation and maintenance is urgently needed. Summary of the invention

[0009] The invention aims at the defects and shortcomings of the current subway field, such as the lack of safety detection means for platform shield doors, large space occupation, high cost and large investment, and proposes a subway platform shield door safety detection system and a human body detection method based on laser ranging. The infrared laser ranging sensor is placed on the top between the platform shield door and the car door, and an infrared laser beam is projected from top to bottom to form a laser spot on the target surface. The distance information between the spot and the detector is obtained in real time, and intelligent judgment is performed to identify whether a target appears, and an alarm is immediately issued after the target is found. The detection system can directly output an alarm signal, eliminating the need for further processing by the host computer, and is fast, accurate, stable and reliable. The detection system adopts optomechanical integration technology, has a small size, occupies less space, and is very convenient to install, debug and maintain. The detection system is based on mature laser triangulation ranging technology and laser displacement sensor product technology, so it has the advantages of low cost and low investment. The detection system adopts a serial bus for multi-point cascading, and one cable can connect all detection systems, which is very convenient for forming safety detection of the entire station, with extremely low hardware cost and very simple distributed networking.

[0010] The present invention is achieved through the following technical solutions: The present invention provides a subway screen door safety detection system based on laser ranging, the detection system comprises: a laser, a focusing lens, a window sheet, a filter, an imaging lens, a photoelectric device, a measurement and control circuit, an alarm indicator light, a communication socket, a housing and a setting button, wherein: The laser is a semiconductor laser, which is placed in the center of the detection system and emits laser forward to achieve non-sensing detection of passengers. The power of the laser is based on the requirement of distance measurement. The focusing mirror is placed inside the detection system and at the front end of the laser, and converges and appropriately expands the divergent beam of the laser to form a divergent beam with a certain shape and size at the human body detection distance, and the size is equivalent to the width of the human body, so as to achieve stable and reliable detection of human targets; The window piece is a high-transmittance lens made of optical materials, located on the housing of the detection system, at the front end of the central position, and at the front end of the focusing lens. On the one hand, it realizes the low-loss passage of the laser beam, and on the other hand, it realizes the functions of sealing, dustproof, waterproof, etc. There are two filters, which are located on the housing of the detection system and on the left and right sides of the front window. The filter is an optical narrow-band filter, whose central wavelength is consistent with the wavelength of the laser, so that the spot signal can pass through. The bandwidth of the filter is as narrow as possible, which can effectively filter out the interference of ambient light and improve the reliability and stability of detection. There are two imaging mirrors, which are located on the left and right sides of the detection system and behind the filter. The imaging mirror is a low-aberration optical lens, which can be a single lens or a multi-lens lens to ensure the imaging quality. There are two photoelectric devices, which are located on the left and right sides of the detection system and behind the imaging mirror. The photoelectric device is an industrial-grade linear array photoelectric conversion device, which can detect the position of the light spot and thus detect the target distance. The measurement and control circuit is located at the end of the detection system. It is a high-performance integrated circuit that can receive the output signals from the two photoelectric devices, convert them into corresponding data and process the data, and finally get the conclusion whether the target exists; when the distance of the target appears within the range of the dangerous area, an alarm signal will be generated; The communication socket is a waterproof aviation communication socket, which is located at the rear end of the housing of the detection system. On the one hand, it provides power to the detection system, and on the other hand, it outputs the signal of the detection result to the shielding door control system for controlling the opening and closing of the shielding door. The alarm indicator light is a multifunctional LED color-changing alarm indicator light, which is installed at the front end of the detection system housing. When the detection system is not connected to power, the alarm indicator light does not show anything; when the detection system is powered on and no target is detected, the alarm indicator light is green, indicating that everything is normal; when the detection system is powered on and a target is detected, the alarm indicator light is red, realizing a light alarm; The housing is an integrated housing, in which all components of the detection system are built, and is made of lightweight metal material to reduce deadweight and facilitate installation; The setting button is a self-resetting button, which is installed at the front end of the housing of the detection system and is used to set the threshold of the safety range to facilitate debugging and operation.

[0011] The working process of the subway screen door safety detection system of the present invention is as follows: a laser beam emitted by a laser is focused and expanded by a focusing mirror, and then a divergent light beam is projected from top to bottom through a window sheet, and a light spot is formed on the surface of the track foundation of the train. After the light spot passes through the left and right filters, it is imaged by the left and right imaging mirrors onto the imaging surfaces of the left and right photoelectric devices. The left and right photoelectric devices output corresponding electrical signals respectively, and send them to the measurement and control circuit for data processing to obtain the distance value between the light spot and the detection system. When a passenger on the platform passes through the screen door and appears at a position between the screen door and the train door, the distance value between the light spot irradiated on the passenger's body and the detection system will be reduced exponentially, thereby generating a signal that the passenger is in danger. At this time, the detection system will light up the alarm indicator light to form a light alarm prompt. At the same time, this signal is uploaded to the subway screen door control system through the communication socket to timely control the closing or opening of the screen door to ensure the personal safety of the passengers.

[0012] The subway screen door safety detection system based on laser ranging is also characterized in that the laser is an infrared laser that emits an infrared laser beam to achieve non-sensing detection of passengers.

[0013] The subway screen door safety detection system based on laser ranging is also characterized in that: the focusing mirror modulates the laser beam into a divergent beam, and the cross-section of the beam is close to a rectangular shape. At the height of the platform ground, the length of the rectangular cross-section of the laser beam is close to the width of the human body, and the width of the rectangular cross-section of the laser beam is close to but less than the distance between the screen door and the train door, so as to minimize the uncertainty of passenger positions and the mutual occlusion problems between multiple human bodies.

[0014] The present invention provides a passenger safety detection method applicable to the above-mentioned subway screen door safety detection system based on laser ranging, which is as follows: (1) The measurement and control circuit controls the laser to project a divergent light beam from top to bottom onto the surface of the train track foundation. At this time, the detection system will obtain the distance value between the light spot and the detection system, which will be used as the limit distance value of the detection system; (2) Take a flat plate target, called the threshold plate, with diffuse reflection characteristics on its surface, no color limit, a length greater than the width of a human body, a width close to but less than the distance between the shielding door and the subway door, and a thickness not exceeding 2 cm. Place this plate between the subway shielding door and the subway door, and its height should be flush with the platform floor. At this time, the laser beam of the detection system will generate a light spot on the surface of the plate, and the detection system will obtain the distance value between the light spot and the detection system. (3) Press the setting button on the front of the detection system, and the detection system's measurement and control circuit automatically records the distance between the light spot and the detection system at this time, and uses it as the threshold of the safety range; at the same time, turn on the alarm indicator of the detection system as a response to the successful setting of the safety range threshold; (4) During the entire operation process from the opening of the shielding door to its complete closure, the detection system continuously and rapidly obtains the distance value between the light spot and the detection system in real time and compares it with the above-mentioned safety range threshold; (5) When a passenger on the platform passes through the platform screen door and appears between the platform screen door and the train door, the distance between the light spot irradiated on the passenger's body and the detection system will be reduced exponentially and will be far less than the above-mentioned safety range threshold, thereby generating an alarm signal indicating that the passenger is in danger; (6) The alarm signal is uploaded to the subway platform screen door control system through the communication socket, and the closing or opening of the platform screen door is controlled in time to ensure the personal safety of passengers; at the same time, the detection system will light up the alarm indicator light to form a light alarm prompt. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the composition of the subway screen door safety detection system of the present invention; Figure 2 It is a schematic diagram of the working principle of the subway screen door safety detection system of the present invention; Figure 3 A schematic diagram of the working principle of the laser beam of the subway screen door safety detection system of the present invention; Figure 4 A schematic diagram of a laser beam cross section of a subway screen door safety detection system of the present invention; Figure 5 A schematic diagram of the passenger detection principle of the subway screen door safety detection system of the present invention; In the figure: 1 is a laser, 2 is a focusing lens, 3 is a window piece, 4 is a passenger, 5 is a filter, 6 is an imaging lens, 7 is a photoelectric device, 8 is a measurement and control circuit, 9 is a communication socket, 10 is an alarm indicator light, 11 is a housing, 12 is a setting button, 13 is a detection system, 14 is a shielding door, 15 is a subway train, 16 is a platform, and 17 is a threshold plate. DETAILED DESCRIPTION

[0016] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0017] The present invention is achieved through the following technical solutions: The present invention provides a subway screen door safety detection system based on laser ranging, the detection system comprises: a laser 1, a focusing lens 2, a window sheet 3, a filter 5, an imaging lens 6, a photoelectric device 7, a measurement and control circuit 8, an alarm indicator light 9, a communication socket 10, a housing 11 and a setting button 12, such as Figure 1 As shown, where: The laser 1 is a semiconductor laser, which is placed in the central position inside the detection system and emits laser forward to achieve non-sensing detection of passengers. The power of the laser 1 is based on the distance measurement requirements, and is generally 5mW~10mW. The focusing lens 2 is placed inside the detection system and at the front end of the laser 1, and converges and appropriately expands the divergent light beam of the laser 1 to form a divergent light beam with a certain shape and size at the human body detection distance, such as a rectangular cross-sectional shape; the size is equivalent to the width of the human body, such as the length of the cross-sectional rectangle is equivalent to the width of the human body, so as to achieve stable and reliable detection of human targets; The window piece 3 is a high-transmittance lens made of optical materials, and the transmittance is generally required to be not less than 85%; the window piece 3 is located on the housing 11 of the detection system, at the front end of the central position, and at the front end of the focusing lens 2, so as to achieve low-loss passage of the laser beam on the one hand, and to achieve sealing, dustproof, waterproof and other functions on the other hand, and the protection rating is not less than IP54; There are two filters 5, 5a and 5b, which are respectively located on the housing 11 of the detection system and on the left and right sides of the front window 3; the filter 5 is an optical narrow-band filter, the center wavelength of which is consistent with the wavelength of the laser 1, so that the spot signal can pass; the bandwidth of the filter 5 is as narrow as possible, generally not exceeding 20nm, which can effectively filter out the interference of ambient light and improve the reliability and stability of detection; There are two imaging mirrors 6, 6a and 6b, which are respectively located on the left and right sides of the detection system and behind the filters 5a and 5b; the imaging mirror 6 is a low-aberration optical lens, which can be a single lens, such as a single aspherical lens, or a multi-lens lens, such as a combination of multiple plano-convex lenses, so as to ensure the imaging quality; There are two photoelectric devices 7, 7a and 7b, which are located on the left and right sides of the detection system and behind the imaging mirrors 6a and 6b respectively; the photoelectric device 7 is an industrial-grade linear array photoelectric conversion device, such as a one-dimensional PSD, a linear array CMOS, a linear array CCD, etc., which can detect the position of the light spot, thereby detecting the target distance; The measurement and control circuit 8 is located at the end of the detection system. It is a high-performance integrated circuit, such as a circuit system with ARM, FPGA, CPLD, and DSP as the core. It can receive the output signals from the two photoelectric devices 7a and 7b, convert them into corresponding data and process the data, and finally get the conclusion whether the target exists; when the distance of the target appears within the dangerous area, an alarm signal will be generated; The communication socket 9 is a waterproof aviation communication socket, which is located at the rear end of the housing 11 of the detection system. On the one hand, it provides power to the detection system, and on the other hand, it outputs the signal of the detection result to the control system of the shielding door 14, which is used to control the opening and closing of the shielding door 14. The alarm indicator light 10 is a multifunctional LED color-changing alarm indicator light, which is installed at the front end of the housing 11 of the detection system. When the detection system is not connected to power, the alarm indicator light 10 does not show anything; when the detection system is powered on and no target is detected, the alarm indicator light 10 is displayed in green, indicating that everything is normal; when the detection system is powered on and a target is detected, the alarm indicator light 10 is displayed in red, realizing a light alarm; The housing 11 is an integrated housing in which all components of the detection system are built, and is made of a light metal material, such as an aluminum alloy, to reduce its own weight and facilitate installation; The setting button 12 is a self-resetting button, which is installed at the front end of the housing 11 of the detection system and is used to set the threshold of the safety range to facilitate debugging and operation.

[0018] The working process of the subway screen door safety detection system of the present invention is as follows: a beam of laser light emitted by the laser 1 is focused and expanded by the focusing lens 2, and then a divergent light beam is projected from top to bottom through the window 3, and a light spot is formed on the track foundation surface of the train 15. After the light spot passes through the left and right filters 5a and 5b, it is imaged by the left and right imaging mirrors 6a and 6b to the imaging surfaces of the left and right photoelectric devices 7a and 7b respectively. The left and right photoelectric devices 7a and 7b respectively output corresponding electrical signals, and send them to the measurement and control circuit 8 for data processing to obtain the distance value H between the light spot and the detection system. When the passenger 4 on the platform 16 passes through the screen door 14 and appears at the position between the screen door 14 and the door of the train 15, the distance value between the light spot irradiated on the body of the passenger 4 and the detection system 13 will be reduced exponentially, thereby generating a signal that the passenger is in danger. At this time, the detection system 13 will light up the alarm indicator 10 to form a light alarm prompt. At the same time, the signal is uploaded to the control system of the subway platform screen door 14 through the communication socket 12, and the closing or opening of the platform screen door 14 is controlled in time to ensure the personal safety of the passengers 4.

[0019] The subway screen door safety detection system based on laser ranging is also characterized in that the laser 1 is an infrared laser, such as 780nm, 808nm, 820nm, 830nm, 850nm, etc., which emits an infrared laser beam to achieve non-sensing detection of passengers 4.

[0020] The subway screen door safety detection system based on laser ranging is also characterized in that: the focusing mirror 2 modulates the laser beam into a divergent beam, and the cross section of the beam is close to a rectangular shape, such as Figure 3 and Figure 4 As shown; at the height of the ground of the platform 16, the length of the rectangular cross-section of the laser beam is close to the width of the human body (for example, about 70 cm), and the width of the rectangular cross-section of the laser beam is close to but less than the distance between the shielding door 14 and the door of the train 15 (for example, about 24 cm), so as to minimize the uncertainty of the position of the passenger 4 and the mutual occlusion problem between multiple human bodies.

[0021] The present invention provides a passenger safety detection method applicable to the above-mentioned subway screen door safety detection system based on laser ranging, such as Figure 5 As shown, the body is as follows: (1) The measurement and control circuit 8 controls the laser 1 to project a divergent light beam from top to bottom onto the track foundation surface of the train 15. At this time, the detection system 13 will obtain the distance value between the light spot and the detection system 13, which will be used as the limit distance value H0 of the detection system 13; (2) Take a flat plate target 17, called the threshold plate, whose surface has diffuse reflection characteristics (such as frosted surface), whose color is not limited (white, silver, black, etc.), whose length is greater than the width of the human body (such as more than 80 cm), whose width is close to but less than the distance between the shielding door 14 and the subway door 15 (such as about 20 cm), and whose thickness is preferably no more than 2 cm; place this threshold plate 17 between the shielding door 14 and the subway door, and its height should be flush with the ground of the platform 16; at this time, the laser beam of the detection system 13 will generate a light spot on the surface of the plate 17, and the detection system 13 will obtain the distance value H between the light spot and the detection system 13; (3) Press the setting button 12 on the front end of the detection system 13, and the measurement and control circuit 8 of the detection system 13 automatically records the distance value H between the light spot and the detection system 13 at this time, and uses it as the threshold value H1 of the safety range; at the same time, turn on the alarm indicator 10 of the detection system 13 as a response to the successful setting of the threshold value H1 of the safety range; (4) During the entire operation process from the opening of the shielding door 14 to its complete closing, the detection system 13 continuously and rapidly obtains the distance value H between the light spot and the detection system 13 in real time and compares it with the above-mentioned safety range threshold value H1; (5) When the passenger 4 on the platform 16 passes through the platform door 14 and appears between the platform door 14 and the door of the train 15, the distance value H between the light spot irradiated on the body of the passenger 4 and the detection system 13 will be reduced exponentially and will be much smaller than the above-mentioned safety range threshold value H1, thereby generating an alarm signal indicating that the passenger 4 is in danger; (6) The alarm signal is uploaded to the control system of the platform screen door 14 of the subway 15 through the communication socket 9, and the closing or opening of the platform screen door 14 is controlled in time to ensure the personal safety of the passenger 4; at the same time, the detection system 13 will light up the alarm indicator light 10 to form a light alarm prompt. Compared with the prior art, the present invention has the following beneficial effects: (1) The subway screen door safety detection system proposed in the present invention adopts the laser ranging principle to obtain the distance value between the passenger and the detection system. By comparing it with the safety threshold, it can quickly determine the presence of danger to the passenger. It can not only directly output an alarm signal to avoid further processing by the host computer, but also be fast, accurate, stable and reliable.

[0022] (2) The subway screen door safety detection system proposed in the present invention adopts optomechanical and electrical integration technology, is small in size, occupies little space, and is easy to install, debug and maintain.

[0023] (3) The subway screen door safety detection system proposed in the present invention is based on mature laser triangulation ranging technology and laser displacement sensor product technology, and therefore has the advantages of low cost and low investment.

[0024] (4) The subway screen door safety detection system proposed in the present invention adopts a serial bus for multi-point cascading. One cable can connect all detection systems, which is very convenient for forming safety detection of the entire station. The hardware cost is extremely low and the distributed networking is very simple. The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A subway screen door safety detection system based on laser ranging, the detection system comprising: Laser, focusing lens, window, filter, imaging lens, optoelectronic device, measurement and control circuit, alarm indicator light, communication socket, housing and setting button, including: The laser is a semiconductor laser, which is placed in the center of the detection system and emits laser light forward; The focusing mirror is placed inside the detection system and at the front end of the laser, which converges the divergent beam of the laser and expands it appropriately, forming a divergent beam with a certain shape and size at the human body detection distance, and the size is equivalent to the width of the human body; The window piece is a high-transmittance lens made of optical material, which is located on the housing of the detection system, at the center of the front end, and at the front end of the focusing lens; There are two filters, which are located on the housing of the detection system and on the left and right sides of the front window. The filter is an optical narrow-band filter, and its central wavelength is consistent with the wavelength of the laser. There are two imaging mirrors, which are located on the left and right sides of the detection system and behind the filter. The imaging mirror is a low-aberration optical lens, which can be a single lens or a multi-lens lens. There are two photoelectric devices, which are located on the left and right sides of the detection system and behind the imaging mirror. The photoelectric device is an industrial-grade linear array photoelectric conversion device, which can detect the position of the light spot and thus detect the target distance. The measurement and control circuit is located at the end of the detection system, and can receive the output signals from the two photoelectric devices, convert them into corresponding data and process the data, and finally get the conclusion whether the target exists; when the distance of the target appears within the range of the dangerous area, an alarm signal will be generated; The communication socket is a waterproof aviation communication socket, which is located at the rear end of the housing of the detection system. On the one hand, it provides power to the detection system, and on the other hand, it outputs the signal of the detection result to the shielding door control system for controlling the opening and closing of the shielding door. The alarm indicator light is a multifunctional LED color-changing alarm indicator light, which is installed at the front end of the detection system housing. When the detection system is not connected to power, the alarm indicator light does not show anything; when the detection system is powered on and no target is detected, the alarm indicator light is green, indicating that everything is normal; when the detection system is powered on and a target is detected, the alarm indicator light is red, realizing a light alarm; The housing is an integrated housing in which all components of the detection system are built and is made of light metal material; The setting button is a self-resetting button, which is installed at the front end of the housing of the detection system and is used to set the threshold of the safety range.

2. The subway screen door safety detection system based on laser ranging according to claim 1 is also characterized in that: The laser is an infrared laser, which emits an infrared laser beam to realize non-sensing detection of passengers.

3. The subway screen door safety detection system based on laser ranging according to claim 1 is also characterized in that: The focusing mirror modulates the laser beam into a divergent beam, and the beam cross section is close to a rectangular shape. At the height of the platform ground, the length of the rectangular cross section of the laser beam is close to the width of the human body, and the width of the rectangular cross section of the laser beam is close to but less than the distance between the shielding door and the train door.

4. A passenger safety detection method of a subway screen door safety detection system based on laser ranging according to any one of claims 1 to 3, which is as follows: (1) The measurement and control circuit controls the laser to project a divergent light beam from top to bottom onto the surface of the train track foundation. At this time, the detection system will obtain the distance value between the light spot and the detection system, which will be used as the limit distance value of the detection system; (2) Take a flat plate target, called the threshold plate, with diffuse reflection characteristics on its surface, no color limit, a length greater than the width of a human body, a width close to but less than the distance between the shielding door and the subway door, and a thickness not exceeding 2 cm. Place this plate between the subway shielding door and the subway door, and its height should be flush with the platform floor. At this time, the laser beam of the detection system will generate a light spot on the surface of the plate, and the detection system will obtain the distance value between the light spot and the detection system. (3) Press the setting button on the front of the detection system, and the detection system's measurement and control circuit automatically records the distance between the light spot and the detection system at this time, and uses it as the threshold of the safety range; at the same time, turn on the alarm indicator of the detection system as a response to the successful setting of the safety range threshold; (4) During the entire operation process from the opening of the shielding door to its complete closure, the detection system continuously and rapidly obtains the distance value between the light spot and the detection system in real time and compares it with the above-mentioned safety range threshold; (5) When a passenger on the platform passes through the platform screen door and appears between the platform screen door and the train door, the distance between the light spot irradiated on the passenger's body and the detection system will be reduced exponentially and will be far less than the above-mentioned safety range threshold, thereby generating an alarm signal indicating that the passenger is in danger; (6) The alarm signal is uploaded to the subway platform screen door control system through the communication socket, and the closing or opening of the platform screen door is controlled in time to ensure the personal safety of passengers; at the same time, the detection system will light up the alarm indicator light to form a light alarm prompt.

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