A planar laser-enhanced small falling object monitoring method and system

Abstract

The present invention belongs to the field of machine vision technology, and specifically relates to a planar laser enhanced fine dropped object monitoring method and system, the method comprising: step (1) arranging event cameras and planar lasers; step (2) plane calibration of the planar laser projection area; step (3) detecting fine dropped object events with event cameras, and generating dropped object drop trajectories by detecting with event cameras; step (4) enhancing fine dropped object events with planar lasers, and generating dropped object bright spot event signals and dropped object dark spot event signals by using event cameras; step (5) determining whether it is a dropped object drop event based on the bright spot event signals and the dark spot event signals. The present invention utilizes event cameras to perform real-time monitoring of fine dropped objects, and cooperates with planar lasers and their projections to perform secondary judgments on fine dropped object events, thereby improving the accuracy of fine dropped object event detection and reducing the false alarm rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of machine vision, and in particular relates to a planar laser-enhanced small falling object monitoring method and system. Background Art

[0002] Radioactive containment is an important goal of nuclear safety in nuclear power plants. Small debris falling into the reactor pool and then following the process medium into the primary circuit of the nuclear power plant will cause damage to the fuel assembly, steam generator, and main pump. Severe cases will lead to uncontrolled release of radioactive substances.

[0003] Existing methods for detecting small dropped objects usually include computer vision solutions of traditional cameras / camcorders and laser / infrared grating solutions.

[0004] Traditional cameras require a certain exposure time, have a low refresh rate when detecting small dropped objects, and require strong auxiliary lighting, so they cannot capture small targets moving at high speeds. In the use environment of nuclear power plants, due to the high height of the plant building, dropped objects may move at extremely high speeds when approaching the ground. At the same time, the lighting sources in the nuclear power plant area have strict layout specifications, making it difficult to add additional auxiliary lighting around the defense area.

[0005] The existing laser / infrared grating detection scheme uses multiple sets of linear lasers or infrared sensors to aim at corresponding receivers, and detects dropped objects by measuring the principle of light being blocked. However, in the existing laser / infrared grating detection scheme, the receiver can only sense point-shaped light sources and has a low refresh rate. There is a large deployment interval between gratings, so small dropped objects can easily pass through the gratings without blocking them, or the blocking time is too short to be sensed by the sensor, resulting in missed detection.

[0006] In summary, the existing dropped object detection technology solutions are difficult to work effectively for small objects moving quickly under challenging lighting conditions. Therefore, it is urgent to develop a small dropped object monitoring method that can overcome the above-mentioned defects in the existing methods. Summary of the invention

[0007] The purpose of the present invention is to provide a planar laser enhanced small dropped object monitoring method and system, which uses an event camera to perform real-time monitoring of small dropped objects, and cooperates with a planar laser and its projection to make a secondary judgment on small dropped object events, thereby improving the accuracy of small dropped object event detection and reducing the false alarm rate.

[0008] The technical solution to achieve the purpose of the present invention is:

[0009] A planar laser-enhanced small falling object monitoring method, the method comprising:

[0010] Step (1) deploying event cameras and planar lasers;

[0011] Step (2) plane calibration of the plane laser projection area;

[0012] Step (3) the event camera detects small falling object events, and generates the falling object trajectory by using the event camera detection;

[0013] Step (4) Planar laser enhances small falling object events, and uses an event camera to generate falling object bright spot event signals and falling object dark spot event signals;

[0014] Step (5) determines whether it is a falling object event based on the bright spot event signal and the dark spot event signal.

[0015] The step (1) is specifically as follows:

[0016] An event camera and a plane laser are arranged in the monitoring area. The event camera maps a monitoring area in the monitoring area, and the plane laser projects a laser area in the monitoring area.

[0017] The event camera and the planar laser are arranged on the same side of the monitoring area, at the same vertical height, and staggered by a certain distance in the horizontal plane;

[0018] The plane laser projection area falls within the monitoring area, and the monitoring area covers the plane laser projection area in the longitudinal angle.

[0019] The step (2) is specifically as follows:

[0020] The planar laser projects a planar laser projection area in the monitoring area. According to the brightness change caused by turning the planar laser on or off, the linear range of the planar laser projection area is obtained in the projection area to complete the plane calibration of the planar laser projection area.

[0021] The step (3) is specifically as follows:

[0022] The event camera collects scattered light signals from dropped objects, processes the scattered light signals, generates dropped object event signals, performs feature extraction processing based on the dropped object event signals, calculates the pixel quantity of event displacement, performs curve fitting on events at multiple positions generated by the same object, and obtains the dropped object trajectory.

[0023] The step (4) is specifically as follows:

[0024] When a dropped object passes through the laser area projected by the plane laser, the laser scattered by the dropped object enhances the brightness of the dropped object in the laser area projected by the plane laser, produces a bright spot, and generates a bright spot signal; the dropped object blocks the plane laser, reduces the brightness of the projection area in the laser area, produces a dark spot, and generates a dark spot signal;

[0025] The event camera collects the bright spot signal of the falling object, and processes the bright spot signal of the falling object to generate the bright spot event signal of the falling object; the event camera collects the dark spot signal of the falling object, and processes the dark spot signal of the falling object to generate the dark spot event signal of the falling object.

[0026] The step (5) includes: determining whether it is a falling object event based on the bright spot event signal and the dark spot event signal, the time interval between the bright spot event signal and the dark spot event signal, and the position of the bright spot event signal and the dark spot event signal; or determining whether it is a falling object event based on the falling object trajectory generated in the step, the bright spot event signal and the dark spot event signal, and the time interval between the bright spot event signal and the dark spot event signal.

[0027] In the step (5), when the bright spot event signal and the dark spot event signal appear simultaneously, or the time interval between the bright spot event signal and the dark spot event signal is within the threshold range, and the positions of the bright spot signal and the dark spot signal are within the linear range determined by the plane calibration of the plane laser projection area in step (2), it is determined to be a real falling object event, and an alarm message is generated;

[0028] When the bright spot is in the falling trajectory of the object, and the bright spot event signal and the dark spot event signal appear at the same time, and the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range, it is determined to be a real falling object event and an alarm message is generated;

[0029] When the bright spot event signal and the dark spot event signal do not appear at the same time, or the time interval between the bright spot event signal and the dark spot event signal is greater than the threshold range, it is determined to be a non-falling object falling event.

[0030] The method further comprises: step (6) issuing an alarm for a small dropped object falling event: after the alarm information is generated, an alarm signal is generated and an alarm for a small dropped object falling event is issued.

[0031] A planar laser enhanced fine falling object monitoring system, the system comprising: an event camera, a planar laser, an event recognition module, a trajectory fitting module, a plane fitting module, and an event fitting module;

[0032] The event camera, the event recognition module, and the trajectory fitting module are connected in sequence; the event camera collects scattered light signals of dropped objects and transmits the scattered light signals to the event recognition module; the event recognition module receives and processes the scattered light signals to generate dropped object event signals, and transmits the dropped object event signals to the trajectory fitting module;

[0033] The event camera and the event recognition module are connected with the plane fitting module; the event camera collects the bright spot signal of the dropped object and transmits the bright spot signal of the dropped object to the event recognition module; the event recognition module receives the bright spot signal of the dropped object and processes the bright spot signal of the dropped object to generate the bright spot event signal of the dropped object, and transmits the bright spot event signal of the dropped object to the plane fitting module; the event camera collects the dark spot signal of the dropped object and transmits the dark spot signal of the dropped object to the event recognition module; the event recognition module receives the dark spot signal of the dropped object and processes the dark spot signal of the dropped object to generate the dark spot event signal of the dropped object, and transmits the dark spot event signal of the dropped object to the plane fitting module;

[0034] The trajectory fitting module is connected to the event fitting module; the trajectory fitting module collects the falling object event signal generated by the event recognition module, obtains the falling object trajectory according to the falling object event signal, and transmits the falling object trajectory to the event fitting module;

[0035] The plane fitting module is connected to the event fitting module; the plane fitting module collects the linear range of the plane laser projection area fitted by the event recognition module, and transmits the linear range data of the plane laser projection area to the event fitting module;

[0036] The event fitting module is connected to the alarm module; the event fitting module collects the falling object trajectory obtained by the trajectory fitting module and the linear range of the plane laser projection area fitted by the plane fitting module, and when the bright spot event signal and the dark spot event signal appear at the same time, and the bright spot event signal of the falling object and the dark spot event signal of the falling object are within the linear range of the plane laser projection area, it is determined to be a real falling object falling event; or, when the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range, and the bright spot event signal of the falling object and the dark spot event signal of the falling object are within the linear range of the plane laser projection area, it is determined to be a real falling object falling event; or, when the bright spot event signal and the dark spot event signal appear at the same time, and are in the same plane laser projection plane, and the bright spot event signal is on the falling object falling trajectory, it is determined to be a real falling object falling event; or, when the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range, and are in the same plane laser projection plane, and the bright spot event signal is on the falling object falling trajectory, it is determined to be a real falling object falling event.

[0037] The system also includes an alarm module, and the event fitting module is connected to the alarm module; when the event fitting module determines that it is a real falling object event, an alarm message is generated and the alarm message is transmitted to the alarm module; the alarm module receives the alarm message, generates an alarm signal, and issues an alarm.

[0038] The beneficial technical effects of the present invention are:

[0039] 1. The present invention provides a planar laser-enhanced method for monitoring small dropped objects. The event camera generates a "dropped object event" signal based on the change in pixel brightness. In a weak light environment, the detection efficiency and the missed reporting rate are high, which effectively overcomes the problem that traditional optical sensors need to accumulate exposure for imaging, and require a longer shutter time in a weak light environment, resulting in a lower refresh rate (frame rate), which reduces the ability to detect small targets that fall quickly.

[0040] 2. The present invention provides a planar laser-enhanced method for monitoring small dropped objects. The method uses an event camera to collect scattered light from small dropped objects, uses a planar laser to enhance the light scattering and projection of small dropped objects in the monitoring area, and combines the dropped object trajectory, the planar laser bright spot event signal, and the dark spot event signal for judgment: the event camera works independently pixel by pixel, has microsecond time accuracy, and responds to changes in light to achieve detection of high-speed moving targets; the planar laser auxiliary light source uses a Powell lens to form a continuous and uniform laser plane. When small dropped objects pass through the laser plane, their brightness increases due to laser irradiation, forming a primary change signal; at the same time, the laser strip spot in the distance disappears or darkens locally due to the obstruction of the light beam, forming a second brightness change signal; the event camera's extremely high response speed and sensitivity to changes can be used to capture these two types of change signals, thereby achieving detection of small dropped objects in challenging environments, improving the detection efficiency of small drops, and reducing the missed alarm rate and false alarm rate.

[0041] 3. In the planar laser-enhanced small dropped object monitoring system provided by the present invention, since the laser energy is concentrated and has good directivity, it can be set up away from dangerous defense areas, which provides convenience for the deployment of defenses; at the same time, only a small power (usually within 5W) is required to achieve the effect of auxiliary detection, reducing energy consumption and power supply requirements.

[0042] 4. The present invention provides a planar laser-enhanced method for monitoring small falling objects. Based on an event camera, it can detect moving targets (such as bullets) at a speed of hundreds of meters per second, and can detect high-speed small target falling objects that burst or break off, avoiding the limitation of the frame rate of traditional cameras. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A block diagram of a planar laser-enhanced small falling object monitoring system provided by the present invention;

[0044] Figure 2 It is a longitudinal layout diagram of a nuclear power plant reactor pool drop monitoring system in an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of event fitting of a nuclear power plant reactor pool drop monitoring system according to an embodiment of the present invention;

[0046] Figure 4 This is a schematic diagram of the principle of collecting scattered light signals of falling objects by an event camera in an embodiment of the present invention.

[0047] In the figure:

[0048] 110- event camera; 120- plane laser; 111- monitoring area; 121- laser area; 130- event recognition module; 131- trajectory fitting module; 132- plane fitting module; 140- event fitting module; 150- alarm module;

[0049] 300-monitoring area; 122-plane laser projection area; 800-dropped object; 810-dropped object trajectory; 820-bright spot; 830-dark spot. DETAILED DESCRIPTION

[0050] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0051] The present invention provides a planar laser-enhanced small falling object monitoring method, which specifically includes the following steps:

[0052] Step (1) Deploy event camera and planar laser

[0053] like Figure 2 As shown, an event camera 110 and a planar laser 120 are arranged in a monitoring area (such as a reactor pool of a nuclear power plant), the event camera 110 maps a monitoring area 111 in the monitoring area 300 , and the planar laser 120 projects a laser area 121 in the monitoring area 300 .

[0054] The event camera 110 and the planar laser 120 are arranged on the same side of the monitoring area (e.g., the top of the reactor pool) and at the same vertical height ( Figure 2 The figure only shows the device position, not the height difference between the event camera and the plane laser, which are offset by a certain distance in the horizontal plane.

[0055] The irradiation angle of the planar laser 120 is slightly tilted downward (generally required to be within 0 to -45 degrees) so that the planar laser projection area 122 falls within the monitoring area 300 (for example, within the wall of the reactor water pool).

[0056] The event camera 110 covers the monitoring area 111 required for the monitoring area 300 (e.g., a reactor pool) according to the selected lens. The monitoring area 111 covers the plane laser projection area 122 at a longitudinal angle. The plane laser 120 generates a plane laser projection area 122 within the monitoring area 111 of the event camera 110 .

[0057] Step (2) Plane calibration of the laser projection area

[0058] The plane laser 120 projects a plane laser projection area 122 in the monitoring area 300 (for example, in the wall of the reactor pool). The plane laser projection area 122 should be a linear range, such as Figure 2 As shown, according to the brightness change caused by turning on and off the planar laser, the linear range of the planar laser projection area 122 is obtained in the projection area. The calibration of the position of the planar laser projection area should be done by turning the laser on and off several times after the detection equipment is fixed and working. Since there is a large brightness difference between the presence and absence of the laser beam, the position of the laser beam on the event camera pixel can be obtained by fitting the linear equation according to the pixel position where the event is generated in the sequence of the laser power on and off.

[0059] Step (3) The event camera detects small falling objects and generates the falling object trajectory using the event camera detection

[0060] The event camera 110 collects scattered light signals from dropped objects, processes the scattered light signals, generates dropped object event signals, performs feature extraction processing based on the dropped object event signals, calculates the pixel quantity of event displacement, performs curve fitting on events at multiple positions generated by the same object, and obtains the dropped object trajectory. The process of the event camera 110 collecting scattered light signals from dropped objects and obtaining dropped object event signals is implemented by the event camera's own hardware device. The main principle is that the pixel circuit responds to light that exceeds a threshold. The schematic diagram is shown in FIG. Figure 4 shown.

[0061] After acquiring the event signal data, feature extraction processing is performed, and each feature map matrix and three-channel feature map matrix are calculated by the following formula:

[0062] Average time feature map matrix:

[0063] (1)

[0064] The latest time feature map matrix:

[0065] (2)

[0066] Time variance feature map matrix:

[0067] (3)

[0068] Three-channel feature map matrix:

[0069] T = [ T avg , T rec , T var ] (4)

[0070] Among them, T represents the average time feature map, the latest time feature map, and the time variance feature map. Figure 3 The three-channel feature map matrix of single-channel combinations, Tavg represents the feature map matrix generated based on the average time, represents the average of the event timestamps at position (i, j); T rec Represents the feature map matrix generated based on the latest time, Indicates the maximum value of the event timestamp at position (i, j); T var represents the feature map matrix generated based on time variance, The variance of the timestamp of the event at position (i, j); L ij represents the number of events at pixel position (i, j), t represents the event time, and t avg represents the average event time at position (i, j), ζ ij Represents a collection of timestamps for events at position (i, j).

[0071] According to the obtained feature map matrices and three-channel feature map matrices, the pixel volume of event displacement is calculated. By combining event clustering to distinguish events in different regions, the pixel volume of event displacement in each region and the time information before and after can be used to obtain the speed of movement. The pixel position with a large downward component of the movement speed is a suspicious drop. In the continuous time before and after, if the event movement speed at multiple positions meets the requirement that the downward movement component is continuously increasing and the horizontal position is relatively close, the previous and next positions are regarded as being generated by the same object, and curve fitting is performed to obtain the fitting curve of the motion trajectory.

[0072] Step (4) Planar laser enhances small falling object events and uses event camera to generate falling object bright spot event signal and falling object dark spot event signal

[0073] Planar laser is used to enhance the small falling object event. When the falling object passes through the laser area 121 projected by the plane laser 120, the laser scattered by the falling object enhances the brightness of the falling object in the laser area 121 projected by the plane laser 120, generating a bright spot 820; the falling object blocks the plane laser, reducing the brightness of the projection area in the laser area 121, generating a dark spot 830. Since the event camera 110 and the plane laser 120 are staggered horizontally, the generated bright spot 820 and dark spot 830 are at different positions on the same plane, and the falling object bright spot signal and the falling object dark spot signal collected by the event camera 110 are at different positions on the same plane.

[0074] The event camera responds to changes in illumination. When an object passes through a planar laser beam, the reflection of the laser by the object itself increases, generating a bright spot signal. At the same time, due to the object blocking the laser beam (the previously reflected laser is the planar laser beam that would have irradiated the far wall), the continuous laser beam irradiated on the distant plane has a reduced brightness at the blocked position, forming a dark spot signal.

[0075] Step (5) Determine whether it is a falling object event based on the bright spot event signal and the dark spot event signal.

[0076] Determine whether it is a falling object event based on the bright spot event signal and the dark spot event signal, the time interval between the bright spot event signal and the dark spot event signal, and the position of the bright spot event signal and the dark spot event signal; or determine whether it is a falling object event based on the falling object trajectory generated in step (3), the bright spot event signal and the dark spot event signal, and the time interval between the bright spot event signal and the dark spot event signal.

[0077] Step (5.1) determines whether it is a falling object event based on the bright spot event signal and the dark spot event signal, as well as the positions of the bright spot event signal and the dark spot event signal.

[0078] When the bright spot signal and the dark spot signal appear in pairs or the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range (for example, the time interval is within 0.5 milliseconds), and the positions of the bright spot signal and the dark spot signal are within the strip range determined by the plane calibration of the plane laser projection area in step (2), it can be confirmed that an object has passed through the laser plane (which can be understood as when the bright spot signal at the uncertain position and the dark spot signal at the determined position appear at the pixel position along a line of the laser beam at the same time), it is determined to be a real falling object event and an alarm message is generated.

[0079] Step (5.2) determines whether it is a falling object falling event based on the falling object falling trajectory generated in step (3), the bright spot event signal and the dark spot event signal, and the time interval between occurrences.

[0080] When the bright spot event signal and the dark spot event signal appear at the same time, or the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range, for example, the time interval is within 0.5 milliseconds, and they are in the same plane laser projection plane, it is determined to be a real falling object falling event. In order to further reduce the false alarm rate, the falling object drop trajectory generated in step (3) is compared with the bright spot. When the bright spot is in the falling object drop trajectory, and the bright spot event signal and the dark spot event signal appear at the same time, and the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range, it is determined to be a real falling object falling event and an alarm message is generated.

[0081] When the bright spot event signal and the dark spot event signal do not appear at the same time, or the time interval between the bright spot event signal and the dark spot event signal is greater than the threshold range, it is judged as a non-falling object falling event, and only the suspicious data is stored for subsequent manual query, without generating a falling event judgment and alarm information.

[0082] Step (6) Sending a small falling object drop event alarm

[0083] After the alarm information is generated, an alarm signal is generated to issue an alarm for a small falling object event.

[0084] like Figure 1 As shown, a planar laser enhanced small dropped object monitoring system provided by the present invention includes: an event camera 110, a planar laser 120, an event recognition module 130, a trajectory fitting module 131, a plane fitting module 132, an event fitting module 140, and an alarm module 150.

[0085] The event camera 110 projects a monitoring area 111 in the monitoring area, and the planar laser 120 projects a laser area 121 in the monitoring area. The overlapping position of the monitoring area 111 and the laser area 121 covers the entrance of the monitored area.

[0086] The event camera 110, the event recognition module 130, and the trajectory fitting module 131 are connected in sequence. The event camera 110 projects a monitoring area 111 in the monitoring area. When a dropped object passes through the monitoring area 111, the event camera 110 collects scattered light signals of the dropped object and transmits the scattered light signals to the event recognition module 130; the event recognition module 130 receives and processes the scattered light signals, generates a dropped object event signal, and transmits the dropped object event signal to the trajectory fitting module 131.

[0087] The event camera 110 and the event recognition module 130 are connected to the plane fitting module 132. The plane laser 120 projects a laser area 121 in the detection area. When the dropped object passes through the laser area 121, the laser scattered by the dropped object enhances the brightness of the dropped object in the laser area 121, generating a bright spot 820, as shown in FIG. Figure 3 As shown; the event camera 110 collects the falling object bright spot signal and transmits the falling object bright spot signal to the event recognition module 130; the event recognition module 130 receives the falling object bright spot signal and processes the falling object bright spot signal to generate a falling object bright spot event signal, and transmits the falling object bright spot event signal to the plane fitting module 132. At the same time, the falling object blocks the plane laser, reduces the brightness of the projection area in the laser area 121, and generates a dark spot 830, as shown in FIG. Figure 3 As shown; the event camera 110 collects the dropped object dark spot signal and transmits the dropped object dark spot signal to the event recognition module 130; the event recognition module 130 receives the dropped object dark spot signal and processes the dropped object dark spot signal to generate a dropped object dark spot event signal, and transmits the dropped object dark spot event signal to the plane fitting module 132.

[0088] According to the brightness changes caused by turning the planar laser on and off, the linear range data of the planar laser projection area 122 is obtained on the event camera 110, and the linear range data of the planar laser projection area 122 is transmitted to the event recognition module 130. The event recognition module 130 fits the linear range of the planar laser projection area 122 according to the linear range data of the planar laser projection area 122.

[0089] The trajectory fitting module 131 is connected to the event fitting module 140 . The trajectory fitting module 131 collects the falling object event signal generated by the event recognition module 130 , obtains the falling object trajectory according to the falling object event signal, and transmits the falling object trajectory to the event fitting module 140 .

[0090] The plane fitting module 132 is connected to the event fitting module 140 . The plane fitting module 132 collects the linear range of the plane laser projection area 122 fitted by the event recognition module 130 , and transmits the linear range data of the plane laser projection area 122 to the event fitting module 140 .

[0091] The event fitting module 140 is connected to the alarm module 150. The event fitting module 140 collects the falling object trajectory obtained by the trajectory fitting module 131 and the linear range of the plane laser projection area 122 fitted by the plane fitting module 132. When the bright spot event signal and the dark spot event signal appear at the same time, and the bright spot event signal of the dropped object and the dark spot event signal of the dropped object are within the linear range of the planar laser projection area 122, it is determined to be a real dropped object falling event, and an alarm message is generated; or, when the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range, and the bright spot event signal of the dropped object and the dark spot event signal of the dropped object are within the linear range of the planar laser projection area 122, it is determined to be a real dropped object falling event, and an alarm message is generated; or, when the bright spot event signal and the dark spot event signal appear at the same time, and are in the same planar laser projection plane, and the bright spot event signal is on the falling trajectory of the dropped object, it is determined to be a real dropped object falling event, and the event fitting module 140 generates an alarm message; or, when the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range, and are in the same planar laser projection plane, and the bright spot event signal is on the falling trajectory of the dropped object, it is determined to be a real dropped object falling event, and the event fitting module 140 generates an alarm message.

[0092] The event fitting module 140 transmits the alarm information to the alarm module 150; the alarm module 150 receives the alarm information, generates an alarm signal, and issues an alarm.

[0093] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A planar laser-enhanced method for monitoring small falling objects. It is characterized in that The method comprises: Step (1) arranging an event camera and a planar laser; An event camera (110) and a planar laser (120) are arranged in the monitoring area, the event camera (110) maps a monitoring area (111) in the monitoring area (300), and the planar laser (120) projects a laser area (121) in the monitoring area (300); The event camera (110) and the planar laser (120) are arranged on the same side of the monitoring area, at the same vertical height, and staggered by a certain distance on the horizontal plane; The plane laser projection area (122) falls within the monitoring area (300), and the monitoring area (111) covers the plane laser projection area (122) in a longitudinal angle; Step (2) plane calibration of the plane laser projection area; The planar laser (120) projects a planar laser projection area (122) in the monitoring area (300), and according to the brightness change caused by turning the planar laser on and off, the linear range of the planar laser projection area (122) is obtained on the event camera (110), thereby completing the plane calibration of the planar laser projection area; Step (3) the event camera detects small falling object events, and generates the falling object trajectory by using the event camera detection; Step (4) planar laser enhances small falling object events, and uses an event camera to generate falling object bright spot event signals and falling object dark spot event signals; When the dropped object passes through the laser area (121) projected by the planar laser (120), the laser light scattered by the dropped object enhances the brightness of the dropped object in the laser area (121) projected by the planar laser (120), thereby generating a bright spot (820) and a bright spot signal; the dropped object blocks the planar laser light, thereby reducing the brightness of the projected area in the laser area (121), thereby generating a dark spot (830) and a dark spot signal; The event camera (110) collects the bright spot signal of the dropped object, and processes the bright spot signal of the dropped object to generate a bright spot event signal of the dropped object; the event camera (110) collects the dark spot signal of the dropped object, and processes the dark spot signal of the dropped object to generate a dark spot event signal of the dropped object; Step (5) determining whether it is a falling object event according to the bright spot event signal and the dark spot event signal; When the bright spot event signal and the dark spot event signal appear at the same time, or the time interval between the bright spot event signal and the dark spot event signal is within the threshold range, and the positions of the bright spot signal and the dark spot signal are within the linear range determined by the plane calibration of the plane laser projection area in step (2), it is determined to be a real falling object event and an alarm message is generated; When the bright spot is in the falling trajectory of the object, and the bright spot event signal and the dark spot event signal appear at the same time, and the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range, it is determined to be a real falling object event and an alarm message is generated; When the bright spot event signal and the dark spot event signal do not appear at the same time, or the time interval between the bright spot event signal and the dark spot event signal is greater than the threshold range, it is determined to be a non-falling object falling event.

2. According to claim 1, a planar laser enhanced small falling object monitoring method, It is characterized in that The step (3) is specifically: The event camera (110) collects scattered light signals of dropped objects, processes the scattered light signals, generates dropped object event signals, performs feature extraction processing based on the dropped object event signals, calculates the pixel quantity of event displacement, performs curve fitting on events generated at multiple positions of the same object, and obtains a dropped object drop trajectory.

3. According to claim 1, a planar laser enhanced small falling object monitoring method, It is characterized in that The method also includes: step (6) issuing an alarm for a small dropped object falling event: after the alarm information is generated, an alarm signal is generated and an alarm for a small dropped object falling event is issued.

4. A planar laser-enhanced small falling object monitoring system, It is characterized in that The system comprises: an event camera (110), a plane laser (120), an event recognition module (130), a trajectory fitting module (131), a plane fitting module (132), and an event fitting module (140); An event camera (110), an event recognition module (130), and a trajectory fitting module (131) are connected in sequence; the event camera (110) collects scattered light signals of dropped objects and transmits the scattered light signals to the event recognition module (130); the event recognition module (130) receives and processes the scattered light signals to generate dropped object event signals, and transmits the dropped object event signals to the trajectory fitting module (131); The event camera (110), the event recognition module (130) and the plane fitting module (132) are connected; the event camera (110) collects the dropped object bright spot signal and transmits the dropped object bright spot signal to the event recognition module (130); the event recognition module (130) receives the dropped object bright spot signal and processes the dropped object bright spot signal to generate a dropped object bright spot event signal, and transmits the dropped object bright spot event signal to the plane fitting module (132); the event camera (110) collects the dropped object dark spot signal and transmits the dropped object dark spot signal to the event recognition module (130); the event recognition module (130) receives the dropped object dark spot signal and processes the dropped object dark spot signal to generate a dropped object dark spot event signal, and transmits the dropped object dark spot event signal to the plane fitting module (132); The trajectory fitting module (131) is connected to the event fitting module (140); the trajectory fitting module (131) collects the falling object event signal generated by the event recognition module (130), obtains the falling object trajectory according to the falling object event signal, and transmits the falling object trajectory to the event fitting module (140); The plane fitting module (132) is connected to the event fitting module (140); the plane fitting module (132) collects the linear range of the plane laser projection area (122) fitted by the event recognition module (130), and transmits the linear range data of the plane laser projection area (122) to the event fitting module (140); The event fitting module (140) is connected to the alarm module (150); the event fitting module (140) collects the falling object trajectory obtained by the trajectory fitting module (131) and the linear range of the plane laser projection area (122) fitted by the plane fitting module (132), and when the bright spot event signal and the dark spot event signal appear at the same time, and the falling object bright spot event signal and the falling object dark spot event signal are within the linear range of the plane laser projection area (122), it is determined to be a real falling object falling event; or when the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range, and the falling object When the bright spot event signal of the object and the dark spot event signal of the dropped object are within the linear range of the planar laser projection area (122), it is determined to be a real dropped object falling event; or, when the bright spot event signal and the dark spot event signal appear at the same time and are in the same planar laser projection plane, and the bright spot event signal is on the falling trajectory of the dropped object, it is determined to be a real dropped object falling event; or, when the time interval between the bright spot event signal and the dark spot event signal is within a smaller threshold range, and they are in the same planar laser projection plane, and the bright spot event signal is on the falling trajectory of the dropped object, it is determined to be a real dropped object falling event.

5. A planar laser enhanced small falling object monitoring system according to claim 4, It is characterized in that The system further comprises an alarm module (150), and the event fitting module (140) is connected to the alarm module (150); when the event fitting module (140) determines that it is a real falling object event, alarm information is generated and transmitted to the alarm module (150); the alarm module (150) receives the alarm information, generates an alarm signal, and issues an alarm.

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