A fall detection system and method in nursing monitoring

Abstract

The present invention discloses a fall detection method and system for nursing monitoring. The fall detection system comprises an infrared light-emitting unit array, an infrared sensor, an alarm unit, a monitoring server, and a communication unit. The infrared light-emitting unit array comprises a plurality of light-emitting units arranged in a spherical structure in a longitude-latitude array. The infrared light-emitting unit array is configured to operate alternately in a stroboscopic manner, emitting detection light toward respective detection angles. One or more infrared sensors are configured to receive diffuse light emitted and reflected by the currently operating light-emitting unit, calculate the time interval between the two, and determine the distance to obstacles in that direction.

Description

Technical Field

[0001] The present invention relates to data signal processing, and in particular to a fall detection system in nursing monitoring. Background Art

[0002] With the development of an aging society, the number of elderly people requiring care is increasing rapidly, while the labor force is declining significantly. In order to better utilize technological products to provide better monitoring for the elderly, especially those living alone, many technology companies have produced an increasing number of wearable devices.

[0003] For elderly people living alone, wearable devices are somewhat inconvenient, as they cannot be worn 24 / 7. To address this, cloud-based video monitoring devices have been designed. These devices are often installed in public areas like living rooms. However, because video monitoring devices can easily leak user privacy, users are reluctant to install them in more private areas like bedrooms and bathrooms, which has led to certain obstacles in the application and promotion of video monitoring devices.

[0004] It's worth noting that the most common places for elderly people to have accidents are often unmonitored areas like bathrooms, washrooms, and bedrooms. Furthermore, elderly people often suffer from osteoporosis, making them more susceptible to fractures when they fall, particularly those of the hip, wrist, and spine. Furthermore, falls can cause cardiac arrest, which is particularly dangerous in elderly people with a history of heart disease. Even if a fall doesn't directly lead to a heart attack, the stress and panic that follows the fall can trigger a heart attack. Most elderly people die due to being unable to rescue themselves after a fall, and developing cardiovascular and cerebrovascular complications that delay help. Therefore, contactless fall detection is crucial for elderly people living alone. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes a fall detection system that can detect when a user falls without the need to capture video of the target population or wear a device, thereby eliminating users' concerns about privacy leaks.

[0006] The technical solutions of the present invention are as follows:

[0007] In one aspect, the present invention provides a fall detection system for nursing monitoring, comprising: an infrared light emitting unit array, an infrared sensor, and a monitoring server.

[0008] The infrared light emitting unit array includes a plurality of light emitting units arranged in a spherical structure in a longitude and latitude manner. The infrared light emitting unit array is used to work alternately in a stroboscopic manner and emit detection light toward respective detection angles.

[0009] The infrared sensor is used to receive the diffuse light emitted by the currently working light-emitting unit and reflected back, calculate the time interval between the two, and determine the distance to the obstacle in that direction;

[0010] The monitoring server is used to control the strobe of the infrared light emitting unit array and perform detection based on the obtained signal. The specific detection process is as follows:

[0011] Before use, after completing one or more cycles of flashing, the obtained distance measurement array data is sent to the monitoring server. The monitoring server forms an initial distance point distribution matrix M0 of the target area based on the current sequencing array. When in use, the strobing process of the infrared light emitting unit array is repeated to measure the distance point distribution matrix M1 of the target area at that moment. The measured distance point distribution matrix M1 of the target area at that moment is compared point by point with the initial distance point distribution matrix M0 to determine whether there are distance distribution points in the distance point distribution matrix whose change amplitude exceeds the threshold;

[0012] If there is a distance distribution point whose change amplitude exceeds the threshold, the changed distribution point is determined as an active distribution point;

[0013] Determine whether the number of active distribution points exceeds a threshold. If so, project the active distribution points into three-dimensional space: divide the points along the main axis of each light-emitting unit according to fixed-length intervals, and then divide the quadrangular pyramid area corresponding to each light-emitting unit into multiple spatial areas with two arc-shaped end faces and four quadrangular pyramid structures on the side faces. For each measured distance result, obtain an active area spatial distribution map. In three-dimensional space, divide the jump area spatial distribution map into connected domains;

[0014] Cut the divided connected area from one end at the inflection point of the connected area, and determine whether the cut connected area contains at least one area with a size of 4-100dm 2 The first active space area between 2 and more dimensions in 1-8dm 2 a second active spatial region between the first active spatial region;

[0015] If the obtained connected area includes one first active spatial area and two or more second active spatial areas, it is determined that the target user appears in the target spatial area;

[0016] Calculate the center or center of gravity of the first active spatial area and the second active spatial area respectively, repeat the above steps, and determine the change in the center of the first active spatial area and the second active spatial area for any two adjacent periods. When the first active spatial area and the second active spatial area meet the predetermined conditions, it is determined that the monitored target has fallen.

[0017] Furthermore, with the center of the spherical structure as the base point, the infrared light coverage range faced by the spherical structure is divided radially along the radial direction and spherically along the intersection of the spherical surface and the luminous direction, thereby realizing spatial division and dividing it into multiple tetrahedral segmentation areas.

[0018] Furthermore, for any light-emitting unit, a quasi-quadrangular pyramid structure centered on a ray emitted from the center of the arc structure and coinciding with the light-emitting direction of the light-emitting unit, and surrounded by a longitudinal cutting surface that bisects two adjacent light-emitting units laterally and a latitudinal cutting surface that bisects the two adjacent light-emitting units longitudinally is determined as the corresponding control area of ​​the LED light-emitting unit. For this control area, multiple spherical surfaces with the center of the circle corresponding to the arrangement of the light-emitting unit array as the center and a radius of multiples of a fixed interval are used for cutting to form multiple quadrangular structure areas with spherical end faces.

[0019] Furthermore, during the monitoring process, the monitoring server increases the detection frequency for the active distribution points and the detection points in the neighborhood of the active distribution points.

[0020] Furthermore, when it is detected that the area of ​​at least the second active space region satisfies the above conditions, the center of gravity positions of the first active space region and the second active space region are continuously calculated in different periods, and whether a fall occurs is determined according to the following conditions:

[0021]

[0022] Wherein, H is the installation height of the infrared light emitting unit array, is the distance measurement value corresponding to the spatial cell where the center of gravity of the second active spatial area is located, is the distance measurement value corresponding to the spatial cell where the center of gravity of the first active spatial area is located, The time duration of the connected region corresponding to the active distribution point relative to the initial distance point distribution matrix. α is the vertical angle between two adjacent infrared light-emitting units or the planes on which they lie. The horizontal and vertical angles between the infrared units can be the same or different.

[0023] Preferably, the device further comprises an alarm unit and a communication unit, wherein the communication unit is used to send the detected fall information to the user's guardian or medical institution, and the alarm unit is used to send an alarm signal locally.

[0024] In another aspect, the present invention provides a method for fall detection using the fall detection system, the method comprising:

[0025] An array of infrared light-emitting units in an arc-shaped structure is used to emit detection light in an alternating manner, wherein the plurality of light-emitting units arranged in an array form a spherical structure and are arranged in a longitude and latitude manner. The infrared light-emitting unit array is used to operate alternately in a stroboscopic manner, emitting detection light toward respective detection angles;

[0026] Receive the diffuse light emitted by the currently working light-emitting unit and reflected back, calculate the time interval between the two, and determine the distance to the obstacle in that direction;

[0027] Control the infrared light emitting unit array to periodically flash and perform detection based on the obtained signal.

[0028] Before use, after completing one or more cycles of flashing, the obtained distance measurement array data is sent to the monitoring server. The monitoring server forms an initial distance point distribution matrix M0 of the target area based on the current sequencing array. When in use, the strobing process of the infrared light emitting unit array is repeated to measure the distance point distribution matrix M1 of the target area at that moment. The measured distance point distribution matrix M1 of the target area at that moment is compared point by point with the initial distance point distribution matrix M0 to determine whether there are distance distribution points in the distance point distribution matrix whose change amplitude exceeds the threshold;

[0029] If there is a distance distribution point whose change amplitude exceeds the threshold, the changed distribution point is determined as an active distribution point;

[0030] Determine whether the number of active distribution points exceeds a threshold. If so, project the active distribution points into three-dimensional space: divide the points along the main axis of each light-emitting unit according to fixed-length intervals, and then divide the quadrangular pyramid area corresponding to each light-emitting unit into multiple spatial areas with two arc-shaped end faces and four quadrangular pyramid structures on the side faces. For each measured distance result, obtain an active area spatial distribution map. In three-dimensional space, divide the jump area spatial distribution map into connected domains;

[0031] Cut the connected area from one end at the inflection point of the connected area, and determine whether the cut connected area contains at least one element with a size between 4 and 100 dm. 2 The first active space area between 2 and more dimensions in 1-8dm 2 a second active spatial region between the first active spatial region;

[0032] If the obtained connected area includes at least one first active spatial area and two or more second active spatial areas, it is determined that the target user appears in the target spatial area;

[0033] Calculate the center or center of gravity of the first active spatial area and the second active spatial area respectively, repeat the above steps, and determine the change in the center of the first active spatial area and the second active spatial area for any two adjacent periods. When the first active spatial area and the second active spatial area meet the predetermined conditions, it is determined that the monitored target has fallen.

[0034] The communication unit is used to realize the communication connection between the monitoring server and the remote family members or medical staff of the ward. The alarm unit is a local alarm unit, and the user sends out an alarm sound to remind the person that rescue is needed.

[0035] The monitoring server can be a local server directly connected to the infrared camera (including the light emitting and sensing parts), or it can be a remote server.

[0036] Preferably, the light emitting unit is a highly directional light emitting unit, such as a low-intensity LED laser light emitting unit, with a unit irradiation capacity not exceeding 1mJ / m 2 .

[0037] The main reason why many elderly people are reluctant to install video monitoring is that they are worried about privacy issues. They are worried that video images can clearly distinguish the user's exact behavior, which can easily cause the user to feel monitored and uneasy.

[0038] In one implementation, the term "arranged in longitude and latitude" in this invention refers to an arrangement based on geographic longitude and latitude, whereby the planes containing two adjacent rows of infrared light-emitting units in the longitudinal direction are spaced at the same interval α, and the plane containing any row of infrared light-emitting units in the latitudinal direction is spaced at an integer multiple of β or (n + β / 2) from the equatorial plane. That is, the longitudinal direction is a completely arc-shaped distribution, while the latitudinal direction is along a cutting plane parallel to the equator.

[0039] In another implementation, "arranged in longitude and latitude" means that both the longitude and latitude directions are arranged in the form of a circumferential cutting surface passing through the center of the sphere, that is, the latitude directions are also spherically distributed in the form of the longitude directions.

[0040] It should be noted that the term "quasi-tetrahedron" in the present invention refers to the fact that the cell division in the present invention is performed by cutting the sphere using a vertical longitude plane passing through the center of the sphere and a plane parallel to the equator. Therefore, in the portion off-center, the four sides are not symmetrical but rather have some deformation, so it is only treated as an approximation of a tetrahedron. Therefore, it is referred to as a "quasi-tetrahedron" pyramid. The longitude and latitude method here refers to dividing the sphere vertically by planes passing through the vertical center axis (through the center of the sphere) and separated by a certain angle, and dividing the sphere horizontally by planes passing through the equator, with the two dividing planes separated by a certain angle.

[0041] The system of the present invention can detect falls without requiring user video capture or wearable wear, eliminating user concerns about privacy breaches while meeting fall detection requirements. This invention pioneers a detection method using an infrared arc array. Using distance signals from the arc array, it performs spatial stereoscopic projection and connected domain segmentation, eliminating interference and obtaining accurate detection information. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The figure is a schematic flow chart of fall detection performed by the fall detection system of the system of the present invention.

[0043] Figure 2 is a schematic block diagram of a detection system of the present invention;

[0044] Figure 3-5 A schematic structural diagram of an infrared light emitting unit array according to the present invention;

[0045] Figure 6 This is a schematic diagram of the area division method of one row of light-emitting units. The angle between any two units is approximately 12 degrees.

[0046] Figure 7 A schematic diagram illustrating the division of control areas for an example cell array;

[0047] Figure 8 Schematic diagram of the spatial basic unit partitioning of an example cell array. DETAILED DESCRIPTION

[0048] The present invention will be described in detail below with reference to the accompanying drawings and embodiments thereof, but the protection scope of the present invention is not limited to the scope of the embodiments described herein.

[0049] Example

[0050] According to one embodiment of the present invention, a fall detection system is provided. The system comprises an infrared LED array 100 (comprising multiple light-emitting units 101), an infrared sensor 102, and a monitoring server. The infrared LED array is controlled by a time-division controller (integrated into the monitoring server). The infrared LED array is arranged in a time-division manner, and the time-division controller controls the infrared sensor, serving as part of the controller for the infrared camera sensor. The infrared sensor performs cyclic detection at a fixed time period. To ensure signal reception, four infrared sensors 102 are used in this embodiment. During detection, the pulse peak of the infrared sensor that first receives the reflected signal is used as the signal reception time.

[0051] The infrared light-emitting unit array comprises a plurality of light-emitting units arranged in a spherical structure in a longitude-latitude array. The planes containing two adjacent rows of infrared light-emitting units in the longitudinal direction are spaced at a constant interval α. In the latitudinal direction, the interval between the plane containing any row of infrared light-emitting units and the equatorial plane is an integer multiple of β. The longitude direction is a perfect arc distribution, while the latitudinal direction is distributed along a cut plane parallel to the equator. The infrared light-emitting unit array is configured to operate alternately in a stroboscopic manner, emitting detection light toward respective detection angles. Preferably, the first angle and the second angle are equal.

[0052] Specifically, for simplicity, an 8x8 LED array is described here. Vertically, the planes containing two adjacent rows of infrared light-emitting units are spaced at a first angle of 12 degrees. Horizontally, the planes containing two adjacent rows of infrared light-emitting units are spaced at a second angle, also 12 degrees. The infrared light-emitting unit array operates in a stroboscope-like manner, emitting detection light at different detection angles. Because the sphere is divided and arranged according to longitude and latitude, using the latitude plane as an example (a horizontal cut), a 12-degree angle between two planes covers an 84-degree vertical angle range. The angles between units near the center (relative to the center O) differ slightly from those at the edges. For calculations, the horizontal and vertical spacing between any two units is approximated to be 12 degrees. Assuming each unit covers 12 degrees, each side of the unit covers a half-angle of 6 degrees. Taking into account the half-angles of the edge units, the array can be considered to cover a 96-degree angular range. To achieve higher longitudes, the number of rows and columns of light-emitting units in the array can be increased. Here we take 8*8 as an example just to simplify the description.

[0053] (1) In the initial stage of use, each LED array flashes at a high frequency and emits detection light alternately, toward its respective detection angle. When the infrared light encounters an obstacle at the detection angle of the array, it is diffusely reflected by the obstacle. The infrared sensor receives the reflected diffuse light and calculates the time interval between the two to determine the distance of the obstacle in that direction, forming an initial distance distribution matrix. The detection is repeated for a certain period of time. When it is determined that the distance distribution matrix remains unchanged, the initial distance distribution matrix M0 in the target space is formed in the target-free state.

[0054] (2) Then, the detection state is entered. After each LED light array completes a cycle t1 of flashing, the obtained distance measurement array data is sent to the fall detection device. The fall detection device forms a distance point distribution matrix M1 of the target area with a cycle t1 based on the current sequencing array.

[0055] (3) Compare the measured distance point distribution matrix M1 of the target area at that moment with the initial distance point distribution matrix M0 point by point to determine whether there is a distance distribution point in the distance point distribution matrix whose change amplitude exceeds the threshold.

[0056] If there is a distance distribution point whose change amplitude exceeds the threshold, the changed distribution point is determined to be an active distribution point. For the active distribution point and the detection points in the neighborhood of the active distribution point (corresponding LED light source, increasing the light emission frequency), the detection frequency is increased.

[0057] (4) Determine the number of active distribution points. If the number of active distribution points exceeds a threshold, project the active distribution points into a three-dimensional space and divide the active distribution points in the projected three-dimensional space into connected domains. When dividing the connected domains, the connected domains are divided based on the cross-weighted method of distance value and distance distribution area. Taking into account changes in the placement of objects in the target space, the initial distance point distribution matrix M0 is updated at regular intervals, for example, when there are no active points in the target space for a period of time.

[0058] For the connected domain division, specifically, the infrared light coverage area of ​​the arc structure is spatially divided with the center of the arc structure as the base point, and divided into multiple concentric arc division areas, each of which is centered on the main light emitting direction of an LED light emitting unit. Figure 4 As shown in , the area corresponding to the arc surface area 103 centered on each light-emitting unit is set as the control area of ​​the light-emitting unit.

[0059] Taking the above-mentioned setting method of 12-degree interval as an example, since the light emission directions of any two LED light-emitting units are calculated at an interval of 12 degrees, for any light-emitting unit, the area between +6 degrees and -6 degrees (6 degrees in the horizontal and vertical directions) centered on the light emission direction of the light-emitting unit is determined as the corresponding control area of ​​the LED light-emitting unit. That is, it is assumed here that the control range of each light-emitting unit is the light emission direction of the light-emitting unit as the central axis, two rays that form angles of +6 degrees and -6 degrees with the central axis in the vertical plane, and two rays that form angles of +6 degrees and -6 degrees with the central axis in the horizontal plane as the four side boundaries. The control area of ​​the light-emitting unit is defined as follows: Figure 2 shown.

[0060] like Figure 6 The figure shows a schematic diagram of the arrangement of multiple infrared units distributed in the longitudinal direction, where the Cr area represents the control area of ​​one of the infrared distribution units in that direction. Figure 7It indicates that the control area of ​​any infrared unit is divided along its light-emitting direction. The middle dotted line indicates the light-emitting direction of the light-emitting unit. The figure shows that it is divided into two equally spaced parts. In actual use, in order to improve the detection accuracy, it is divided into more basic units.

[0061] Along the main axis of light emission of each light-emitting unit, the quadrangular pyramid area controlled by each light-emitting unit is divided according to fixed length intervals (for example, 1-5 cm), and then the quadrangular pyramid area corresponding to each light-emitting unit is divided into multiple "space basic units". The two end faces of each "space basic unit" are arc surfaces and the four side faces are quadrangular pyramid structures. The arc surfaces of each end face are concentric, and their center is the same as the center of the arc surface where the infrared light-emitting unit array is located. Figure 8 The diagram below shows the structure of a "space basic unit." S1 and S2 represent two arc-shaped end faces, and S3, S4, S5, and S6 represent four side faces.

[0062] For each distance measurement result, that is, for each distance point distribution matrix M i The distribution points in the space are projected into the "spatial basic unit" in each spatial area. i represents the current cycle number. In this embodiment, only the active distribution points are spatially projected, the projection points with unchanged ranging results are filtered out, and the projection points with changed ranging results are retained to obtain the active area spatial distribution map. The active area spatial distribution map is cut and divided into connected domains, and the divided connected areas are cut from one end at the inflection point of the connected areas, and it is determined whether the cut connected areas contain at least one area with a size of 10-100 dm. 2 Preferably, the first active space area is cut with a predetermined radius with the center of gravity of the first active space area as the center to determine whether more than two pieces with a size of 1-8dm can be cut out. 2 The second active space area between.

[0063] In another implementation, the connected domain is divided as follows. Each spatial region is numbered in three dimensions: the horizontal coordinate i, the vertical coordinate j, and the depth coordinate k along the ray depth direction corresponding to the cell array. When dividing the connected domain, only the proximity of the cell numbers is considered. Assuming that when a light-emitting unit mn emits light, the depth of the reflected area (the distance from point o) detected is k. The cell corresponding to the distance measurement value of this light-emitting unit at that moment is (i, j, |k / η|+1), where η is the radial spacing between the cell divisions and |k / η| represents rounding. For this cell, if there is a corresponding distance measurement value in (i+ / -1, j, |k / η|+1), (i, j+ / -1, |k / η|+1), (i, j+ / -1, |k / η|+2), or (i, j+ / -1, |k / η|), it is considered connected to it. After determining the connectivity number, the projected area of ​​the spatial region included in the determined connected domain is calculated on the vertical plane.

[0064] If the connected area contains at least one area with a size between 10-100dm 2 If the first active spatial area between the two is found, it is determined that the target user appears in the target spatial area.

[0065] Preferably, after obtaining the connected domain, the connected domain is cut with a predetermined radius (e.g., 3-7 dm) around the center of gravity of the connected domain. The predetermined radius can be determined based on the body shape of the target user, thereby excluding animals that do not match the body shape of the target user.

[0066] If the connected area after cutting contains at least one size between 10-100dm 2 The first active space area between 2 and more dimensions in 1-8dm 2 If the target user is detected in the target spatial area, the luminous frequency and detection frequency of the corresponding luminous units in the active area and the surrounding area of ​​the connected domain are increased. The first active spatial area corresponds to the human torso, and the second active spatial area corresponds to the extended areas such as the limbs and head.

[0067] Because the present invention utilizes an arc-shaped array of light sources for array detection, the projected area (cells in the connected domain) corresponding to the same light-emitting unit varies in size with increasing distance. Therefore, when calculating the connected domain size, a correction is introduced, rather than calculating the connected domain size based on the number of cells. This example describes the device being installed so that the light emission direction of the top row of light-emitting units is generally horizontal. The device is installed on one side or in a corner above the target space, so that its coverage essentially covers the entire target area.

[0068] Assume that in the light-emitting unit array, the number of light-emitting units distributed horizontally is m, the number of rows of light-emitting units distributed vertically is n, the vertical spacing angle between two light-emitting units is α, and the horizontal spacing angle between two light-emitting units is β. Along the light-emitting direction, the space area is divided into units of distance η. For the light-emitting unit in the i-th row and j-th column, the area of ​​the basic unit of the space is calculated based on the distance k: ,

[0069] Since it is used for fall detection, its horizontal component does not contribute to fall detection and needs to be removed. Calculate its component in the vertical plane. .

[0070] For the connected domain obtained, the area of ​​the corresponding connected domain is calculated and approximately equal to

[0071] or represents the set of points in the first active space region, Represents the set of points in the second active space region.

[0072] When it is detected that at least the area of ​​the first active space region meets the above conditions, the center of gravity of the first active space region and the second active space region is continuously calculated in different periods, and whether there is a fall is determined according to the following conditions:

[0073]

[0074] Wherein, H is the installation height of the infrared light emitting unit array, is the distance measurement value corresponding to the spatial cell where the center of gravity of the second active spatial area is located, is the distance measurement value corresponding to the spatial cell where the center of gravity of the first active spatial area is located, Indicates the time that the center of gravity of the connected area corresponding to the active distribution point drops to the threshold relative to the initial distance point distribution matrix and the state lasts.

[0075] The above judgment conditions include five criteria. Depending on the desired detection sensitivity, different sensitivity requirements can be set. Different sensitivity requirements correspond to the number of conditions that must be met or different combinations of these conditions. For example, the lowest sensitivity requirement is when all the above conditions are met, while the highest sensitivity requirement is when any two or three of the above conditions are met. For example, the second active area determination can be omitted.

[0076] Although the principles of the present invention have been described in detail above in conjunction with the preferred embodiments of the present invention, those skilled in the art should understand that the above embodiments are merely illustrative of the present invention and are not intended to limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Without departing from the spirit and scope of the present invention, any obvious changes such as equivalent transformations and simple substitutions based on the technical solution of the present invention fall within the scope of protection of the present invention.

Claims

1. A fall detection system in nursing monitoring, characterized in that: include: Infrared light emitting unit array, infrared sensor and monitoring server, The infrared light emitting unit array includes a plurality of infrared light emitting units arranged in a spherical structure in a longitude and latitude manner. The infrared light emitting unit array is used to work alternately in a stroboscopic manner and emit detection light toward respective detection angles. The infrared sensor is used to receive the diffuse light emitted by the currently working infrared light-emitting unit and reflected back, calculate the time interval between the two, and determine the distance to the obstacle; The monitoring server is used to control the strobe of the infrared light emitting unit array and perform detection based on the obtained signal. The specific detection process is as follows: Before use, after completing one or more cycles of flashing, the obtained distance measurement array data is sent to the monitoring server. The monitoring server forms an initial distance point distribution matrix M0 of the target area based on the current distance measurement array data. When in use, the stroboscopic process of the infrared light emitting unit array is repeatedly performed to measure the distance point distribution matrix M1 of the target area at the current moment. The measured distance point distribution matrix M1 of the target area is compared point by point with the initial distance point distribution matrix M0 to determine whether there are distance distribution points in the distance point distribution matrix whose change amplitude exceeds the threshold; If there is a distance distribution point whose change amplitude exceeds the threshold, the changed distribution point is determined as an active distribution point; Determine whether the number of active distribution points exceeds a threshold. If so, project the active distribution points into three-dimensional space: divide the points along the main emission axis of each infrared light-emitting unit according to fixed-length intervals, and then divide the quasi-quadrangular area controlled by each infrared light-emitting unit into multiple spatial regions with two arc-shaped end faces and four quasi-quadrangular side faces. For each measured distance result, obtain an active area spatial distribution map. In three-dimensional space, divide the jump area spatial distribution map into connected domains. Cut the connected area from one end at the inflection point of the connected area, and determine whether the cut connected area contains a size between 4-100dm 2 The first active space area between 2 and more dimensions in 1-8dm 2 The second active space area between; If the obtained connected area includes one first active spatial area and two or more second active spatial areas, it is determined that the target user appears in the target spatial area; Calculate the center or center of gravity of the first active spatial area and the second active spatial area respectively, repeat the above steps, and determine the change in the center of gravity of the first active spatial area and the second active spatial area for any two adjacent periods. When the first active spatial area and the second active spatial area meet the predetermined conditions, it is determined that the monitored target has fallen.

2. The fall detection system according to claim 1, wherein: The connected domain is constructed in the following manner: taking the center of the spherical structure as the base point, the infrared light coverage range faced by the spherical structure is radially divided along the radial direction, and spherical division is performed along the sphere around the intersection of the luminous direction and the sphere, thereby realizing spatial division and dividing it into multiple tetrahedral segmentation areas.

3. The fall detection system according to claim 2, wherein: For any infrared light-emitting unit, a quasi-quadrangular pyramid structure centered on a ray emitted from the center of the arc structure and coinciding with the light-emitting direction of the infrared light-emitting unit, and surrounded by a longitudinal cutting surface that bisects two adjacent infrared light-emitting units transversely and a latitudinal cutting surface that bisects the two adjacent infrared light-emitting units longitudinally is determined as the corresponding control area of ​​the infrared light-emitting unit. For this control area, multiple spherical surfaces with the center of the circle corresponding to the arrangement of the light-emitting unit array as the center and a radius of multiples of a fixed interval are used for cutting to form multiple quadrangular structure areas with spherical end faces.

4. The fall detection system according to claim 1, wherein: During the monitoring process, the monitoring server increases the detection frequency for the active distribution points and the detection points in the neighborhood of the active distribution points.

5. The fall detection system according to claim 1, wherein: When it is detected that at least the area of ​​the second active space region meets the above conditions, the center of gravity of the first active space region and the second active space region is continuously calculated in different periods, and whether there is a fall is determined according to the following conditions: Wherein, H is the installation height of the infrared light emitting unit array, is the distance measurement value corresponding to the spatial cell where the center of gravity of the second active spatial area is located, is the distance measurement value corresponding to the spatial cell where the center of gravity of the first active spatial area is located, It represents the duration of the connected area state corresponding to the active distribution point relative to the initial distance point distribution matrix, and α is the angle between two adjacent infrared light-emitting units or the planes where the two are located in the vertical direction.

6. The fall detection system according to claim 1, wherein: It also includes an alarm unit and a communication unit. The communication unit is used to send the detected fall information to the user's guardian or medical institution, and the alarm unit is used to send an alarm signal locally.

7. A method for fall detection using the fall detection system according to claim 1, characterized in that: The method comprises: An array of infrared light-emitting units in a spherical structure is used to emit detection light in an alternating manner, wherein the plurality of light-emitting units arranged in an array form have a spherical structure and are arranged in a longitude and latitude manner. The infrared light-emitting unit array is used to operate alternately in a stroboscopic manner, emitting detection light toward respective detection angles; Receive the diffuse light emitted by the currently working infrared light-emitting unit and reflected back, calculate the time interval between the two, and determine the distance to the obstacle in that direction; Control the infrared light emitting unit array to periodically flash and perform detection based on the obtained signal. Before use, after completing one or more cycles of flashing, the obtained distance measurement array data is sent to the monitoring server. The monitoring server forms an initial distance point distribution matrix M0 of the target area based on the current sequencing array. When in use, the strobing process of the infrared light emitting unit array is repeated to measure the distance point distribution matrix M1 of the target area at that moment. The measured distance point distribution matrix M1 of the target area at that moment is compared point by point with the initial distance point distribution matrix M0 to determine whether there are distance distribution points in the distance point distribution matrix whose change amplitude exceeds the threshold; If there is a distance distribution point whose change amplitude exceeds the threshold, the changed distribution point is determined as an active distribution point; Determine whether the number of active distribution points exceeds a threshold. If so, project the active distribution points into three-dimensional space: divide the points along the main axis of each infrared light-emitting unit according to fixed-length intervals, and then divide the quadrangular pyramid area corresponding to each infrared light-emitting unit into multiple spatial regions with two arc-shaped end faces and four quadrangular pyramid structures on the side faces. For each measured distance result, obtain an active area spatial distribution map. In three-dimensional space, divide the jump area spatial distribution map into connected domains; Cut the divided connected area from one end at the inflection point of the connected area, and determine whether the cut connected area contains at least one area with a size of 4-100dm 2 The first active space area between 2 and more dimensions in 1-8dm 2 a second active spatial region between the first active spatial region; If the obtained connected area includes at least one first active spatial area and two or more second active spatial areas, it is determined that the target user appears in the target spatial area; Calculate the center or center of gravity of the first active spatial area and the second active spatial area respectively, repeat the above steps, and determine the change in the center of the first active spatial area and the second active spatial area for any two adjacent periods. When the first active spatial area and the second active spatial area meet the predetermined conditions, it is determined that the monitored target has fallen.

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