Millimeter wave radar and camera fused fall detection device and detection method thereof
Technical Field
The invention belongs to the technical field of digital signal processor application, and particularly relates to a millimeter wave radar and camera fused fall detection device and a detection method thereof.
Background
Fall detection is divided into two modes, namely contact detection and non-contact detection. The contact detection generally adopts to wear wearable equipment, judges the state of tumbleing through acceleration sensor motion characteristic, and the shortcoming of contact equipment is that need wear relevant equipment and just can detect, needs regularly to charge, and is poor to users' ease of use such as old man. The non-contact detection mainly judges the falling state through modes of electromagnetic waves, optical sensors and the like and a related algorithm, has the advantages of no need of wearing equipment, no binding feeling and suitability for monitoring falling of people in a specific area.
One of the more popular schemes at present is that a visible light image sensor is used for analyzing the movement posture of a person through collecting regional pictures and a machine learning algorithm, so that whether the person falls or not can be judged. The method has the advantages that the method has high accuracy by using a deep learning algorithm and a visualization function, and the fallen scene pictures and videos can be pushed to the application programs of the relatives' mobile phones.
The disadvantage is that the visible light image sensor is relatively easily influenced by the ambient light. The imaging effect is poor in a weak light environment, so that the personnel detection rate is low, and the corresponding falling recognition rate is low. Even in a dark environment, it is completely inoperable.
By adopting the infrared image sensor, the defects of the visible light sensor can be overcome, but the infrared light imaging effect is poor, and the recognition rate is lower than that of visible light. More importantly, the infrared image sensor is usually very high in price and low in practical value.
In addition, the millimeter wave radar sensor can detect the Doppler displacement of a human body, and the falling state of the person can be judged by detecting the position change of the human body in the vertical direction. Its advantages are low cost and high effect on normal operation in no light. However, the millimeter wave radar sensor scheme has the defects of high technical difficulty and incapability of directly observing the field condition.
Disclosure of Invention
Aiming at the technical problems, the invention provides a millimeter wave radar and camera fused fall detection device and a detection method thereof, which solve the problems that the visible light sensor is low in recognition rate in a weak light environment and cannot work in a no light environment; the problems of poor imaging effect, low recognition rate, high cost and the like of an infrared image sensor are solved; the defects that visual checking cannot be performed by adopting a millimeter wave radar and the like are overcome.
The specific technical scheme is as follows:
a millimeter wave radar and camera integrated fall detection device comprises a fall detection sensor, an application server and a mobile terminal monitoring module;
the fall detection sensor collects physiological signs, and the application server is responsible for providing access service for the fall detection sensor and pushing the field situation and sign information of a fall event to the mobile terminal monitoring module in real time.
The fall detection sensor comprises a visible light image unit, a millimeter wave radar unit, a machine learning inference unit and a communication unit;
the visible light image unit and the millimeter wave radar unit are respectively connected with the machine learning inference unit, and the machine learning inference unit is connected with the communication unit.
Preferably, the visible light imaging unit is an integrated SOC chip. Or may be a discrete chip.
Furthermore, the visible light image unit comprises a visible light image sensor and an image signal processing module, and is responsible for visible light image acquisition and preprocessing;
the visible light image sensor comprises an optical lens, a visible light image sensor and a sensor controller;
and the image signal processing module is responsible for image signal preprocessing.
Preferably, the millimeter wave radar unit is an integrated SOC chip. And a radio frequency front-end chip and a digital back-end chip which are separated can be adopted, so that the cost is reduced.
Furthermore, the millimeter wave radar unit comprises a millimeter wave sensor and a digital signal processing unit, and completes the functions of millimeter wave modulation, demodulation, IQ signal processing and sign signal calculation.
The millimeter wave sensor comprises a millimeter wave antenna, a radio frequency processing front end and a digital-to-analog signal conversion module.
The digital signal processing unit comprises a digital signal preprocessing module and a physical sign monitoring module.
The machine learning inference unit comprises a processor for machine learning inference and is mainly responsible for posture detection and falling fusion detection of personnel.
The communication unit is a communication module for accessing a network.
In addition, as an optimal design, the detection device reserves a Flash memory chip and an SD card slot for storing key frame compressed pictures in a certain period, and adopts a cyclic replacement mode according to time when the storage space is full.
The detection method of the fall detection device with the integration of the millimeter wave radar and the camera comprises the following steps:
the millimeter wave thunder unit collects radio frequency signals and calculates parameters of a human body:
vertical displacement mm _ dy
Horizontal displacement mm _ dx
Vertical displacement speed mm _ dvy
The horizontal direction displacement speed mm _ dvx,
respiratory induced thoracic displacement mm _ db
Respiratory rate mm _ br
Heart rate mm _ hr
(2) Acquiring by a visible light image unit:
height img _ dp of human body gravity center
Arm force gravity center height img _ dh
Height of center of gravity img _ dl of leg
Detecting the orientation img _ theta of the human body
Calculating the heart rate img _ br according to the blood flow change of the human face;
(3) taking the parameters collected in (1) and (2) as fall detection input, and recording as a vector X ═ mm _ dy, mm _ dx, mm _ dvy, mm _ dvx, mm _ db, mm _ br, mm _ hr, img _ dp, img _ dh, img _ theta, img _ dl and img _ br); the problem of detecting falling is converted into a two-classification problem to be processed.
Calculating corresponding output of an X input model Y { -F (X), wherein F is a classifier model learned through historical data, the value range of Y is { -1, 1}, the detected fall is represented as 1, and the undetected fall is represented as-1; calculating an intermediate value of the X input model Y ═ F (X), and normalizing to obtain a falling probability P;
the invention adopts a machine learning fusion algorithm, and the realization method is as follows:
step 1, detecting physical signs of an experimenter when falling by using a falling detection sensor and sending the physical signs to an acquisition computer; the system is distributed in the light environment of strong light, weak light and no light, the acquisition sensor acquires a parameter X, the real falling state is recorded, the falling state is recorded as 1, and the non-falling state is recorded as-1;
step 2, repeating the step 1, and collecting experimental data as a training, verifying and testing data set;
dividing data into training set, verification set and test set according to a certain proportion
The binary classification algorithm is adopted as a model, and the model is not limited to a logistic regression model, a support vector machine model, a random gradient descent model, a perception machine model, a neural network model and the like, the binary model is trained by using training set data, the training effect is verified by using verification set data, and the actual effect of the model is observed by using test set data;
step 3, adjusting the parameters of the hyper-parameter optimization model;
and 4, transplanting the trained model to a falling detection machine learning inference unit to serve as a falling decision model.
The invention provides a millimeter wave radar and camera fused fall detection device and a detection method thereof, compared with the prior art, the device has the following beneficial effects:
(1) the millimeter wave radar and camera integrated falling detection device and the detection method thereof provided by the invention can be used for self-adaptively judging the falling state by ambient light.
(2) The device and the method for detecting the falling of the integrated millimeter wave radar and camera provided by the invention can work normally under weak light and no light.
(3) The millimeter wave radar and camera integrated falling detection device and the detection method thereof provided by the invention can detect physiological signs such as respiration and heart rate when people do not fall down or fall down.
(4) The millimeter wave radar and camera integrated falling detection device and the detection method thereof provided by the invention can push pictures and physiological signs to the relative mobile phone when falling.
(5) The millimeter wave radar and camera integrated fall detection device and the detection method thereof provided by the invention can be used for viewing pictures, videos and physiological sign information of specified equipment through an application program or a client with an authentication function on mobile equipment such as a mobile phone.
(6) The device and the method for detecting the falling of the device with the integration of the millimeter wave radar and the camera can automatically dial a set calling phone, such as a family phone or an emergency phone such as 120 and the like, when the device finds that the falling occurs after the setting.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic structural view of the present invention;
fig. 2 is a schematic view of the usage state of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the embodiments of the present invention, it should be further noted that, unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may include, for example, a fixed connection, a detachable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The millimeter wave radar and camera fused fall detection device provided by the invention combines the defects and cost consideration of the prior art, and adopts a scheme of combining a visible light image sensor and a millimeter wave radar sensor (not limited to 24GHz and 77GHz) as a fall detection sensor.
The system comprises a fall detection sensor, an application server program and a monitoring application program, wherein the fall detection sensor, the application server program and the monitoring application program form a complete millimeter wave radar and camera fusion fall detection device, the fall detection sensor acquires physiological signs, and the application server program is responsible for providing access service for the fall detection sensor and pushing the scene situation and sign information of a fall event to the monitoring application program in real time.
The specific structural schematic diagram is shown in fig. 1.
Specifically, the fall detection sensor is composed of a visible light image unit, a millimeter wave radar unit, a machine learning inference unit and a communication unit.
The visible light image unit and the millimeter wave radar unit are respectively connected with the machine learning inference unit, and the machine learning inference unit is connected with the communication unit;
wherein the visible light image unit may be an integrated SOC chip. The visible light image unit comprises a visible light image sensor and an image signal processing module and is responsible for visible light image acquisition and preprocessing. The visible light image sensor includes an optical lens, a visible light image sensor, and a sensor controller. The image signal processing module is responsible for image signal preprocessing.
Wherein the millimeter wave radar unit may be an integrated SOC chip. The millimeter wave radar unit comprises a millimeter wave sensor and a digital signal processing unit, and completes functions of millimeter wave modulation, demodulation, IQ signal processing, sign signal calculation and the like. The millimeter wave sensor comprises a millimeter wave antenna, a radio frequency processing front end, a digital-to-analog signal conversion module and the like. The digital signal processing unit comprises modules of digital signal preprocessing, physical sign monitoring and the like.
Preferably, the machine learning inference unit includes an edge processor and a cloud computing platform for machine learning inference, and is not limited to processors of computing architectures such as X86, ARM, DSP, NPU, GPU, and the like, and is mainly responsible for posture detection and fall fusion detection of people.
The communication unit is not limited to Zigbee, bluetooth, WIFI, GSM, WCDMA, LTE, 5G, NB-IOT, etc. and may be used to access the communication module of the network.
Besides, the detection device reserves a Flash memory chip and an SD card slot for storing key frame compressed pictures in a certain period, and adopts a cyclic replacement mode according to time when the storage space is full.
The working state of the millimeter wave radar and camera integrated fall detection device provided by the invention is shown in fig. 2, and the specific flow is as follows:
the millimeter wave thunder unit calculates and collects vertical displacement mm _ dy, horizontal displacement mm _ dx, vertical displacement speed mm _ dvy and horizontal displacement speed mm _ dvx according to the Doppler principle; the phase information is separated and filtered by extracting the phase information in the barrier area and the frequency range, the phase information with the frequency of 0.1-0.6Hz is filtered to calculate the chest displacement mm _ db and the respiratory frequency mm _ br caused by respiration, and the phase information with the frequency of 1.6-4.0Hz is filtered to be used for extracting the heart rate mm _ hr.
The method comprises the steps of obtaining key feature points of a body, arms and legs through a visible light camera posture detection algorithm which is not limited to a machine learning method for extracting features and a neural network, calculating the height of a person, the gravity center of the person, the position of the arms and the position of the legs through a trigonometric relation, and estimating to obtain the height img _ dp of the gravity center of the body, the height img _ dh of the force of the arms and the height img _ dl of the gravity center of the legs.
And detecting the personnel existing in the image through human body target detection, and calculating the orientation img _ theta of the personnel according to the pixel distribution condition.
The heart rate img _ br calculated by the human face blood flow change can be detected through the human face blood flow change caused by the pulse;
the sensor output X is collected and the corresponding fatigue state Y, Y is an instance of Y and the corresponding probability P, P is an instance of P. And training a machine learning fusion algorithm by the acquired data set to obtain a model F.
The machine learning model F trained in advance is transplanted to the reasoning unit, and the newly acquired sensor data is input into the reasoning unit, so that the corresponding falling state and falling probability can be obtained.
Specifically, a machine learning fusion algorithm implementation method is adopted, and the details are as follows:
step 1, detecting physical signs of an experimenter when falling by using a falling detection sensor and sending the physical signs to an acquisition computer; the system is distributed in the light environment of strong light, weak light and no light, the acquisition sensor acquires a parameter X, the real falling state is recorded, the falling state is recorded as 1, and the non-falling state is recorded as-1;
step 2, repeating the step 1, and collecting experimental data as a training, verifying and testing data set;
step 3, dividing the data into a training set, a verification set and a test set according to a certain proportion;
the binary algorithm is adopted as a model, and the model is not limited to a logistic regression model, a support vector machine model, a random gradient descent model, a perception machine model, a neural network model and the like, the network is trained by utilizing training set data, the training effect is verified by utilizing verification set data, and the actual effect of the model is observed by utilizing test set data;
step 4, adjusting the parameters of the hyper-parametric optimization model by methods such as random parameter search, Bayesian optimization and the like;
and 5, transplanting the trained model to a falling detection machine learning inference unit to serve as a falling decision model.
The system outputs a falling state Y, a falling probability P and a sensor acquisition parameter X to be updated to a server in real time; when the falling state is detected, the falling state Y, the falling probability P, the sensor acquisition parameter X and a plurality of scene pictures during falling are uploaded to the server, and push messages are generated and pushed to the monitoring end application program.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is merely exemplary and illustrative of the present invention and various modifications, additions and substitutions may be made by those skilled in the art to the specific embodiments described without departing from the scope of the invention as defined in the following claims.