CN110337066B - Indoor personnel activity identification method based on channel state information and man-machine interaction system - Google Patents
Indoor personnel activity identification method based on channel state information and man-machine interaction system Download PDFInfo
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Abstract
The invention belongs to the technical field of wireless communication, and discloses an indoor personnel activity identification method and a man-machine interaction system based on channel state information; preprocessing the collected CSI data to extract environment change information including correlation coefficients and variances; sensing the surrounding environment by using a decision tree, monitoring the activity of the personnel, continuously collecting CSI data if the activity of the personnel is not detected, keeping the activity monitoring state, and triggering an activity feature extraction module if the activity of the personnel is not detected; carrying out extreme value removing processing and low-pass filtering processing on the acquired CSI data in the module; and then carrying out activity matching and recognition of the heaviest personnel activity by using a dynamic time programming algorithm based on principal component analysis. According to the invention, the indoor personnel activity monitoring and activity recognition are combined, and the indoor personnel activity recognition is carried out through PCA-DTW, so that the step of offline acquisition data training in the prior art is omitted, and the system performance and the recognition rate are improved.
Description
Technical Field
The invention belongs to the technical field of wireless communication, and particularly relates to an indoor personnel activity identification method based on channel state information and a man-machine interaction system.
Background
Currently, the closest prior art: e-eyes and WiFinger, and WiGest and CARM.
The prior art has the defects that: e-eyes and WiFinger can not effectively adapt to different environments or need to correct system parameters in different environments, the transportability is poor, and the identification efficiency is reduced. This is because E-eyes and WiFinger lack matching models that can quantitatively correlate CSI statistics with indoor human activity; WiGest and CARM are very sensitive to the effects of environmental noise and indoor channel variations when performing activity recognition. This is because they require capturing small changes in activity to be able to perform the matching of actions, but the captured CSI data also contains noise components. When the noise component is large or the channel changes, the activity recognition effect is poor and the recognition rate is low.
The scheme solves the defects that: 1. a matching model which quantitatively associates the CSI statistical characteristics with the indoor personnel activities is established, the method can be effectively suitable for different environments, set parameters do not need to be changed, and the activity recognition efficiency is improved. 2. The anti-interference capability of the system to environmental noise and indoor channel change is improved, and the anti-interference capability comprises extreme value processing, low-pass filtering and the like, so that the activity recognition rate is improved.
Currently, the closest prior art: in recent years, with the rapid development of wireless communication technology and the great popularization of WiFi devices, passive indoor activity recognition has attracted extensive attention in many fields such as human-computer interaction, security monitoring, old people care, emergency rescue, and the like, and has become a research hotspot in the technical field of wireless communication. The existing technologies applied to indoor personnel Identification are mainly based on computer vision, infrared and Radio Frequency Identification (RFID), and these methods can achieve expected effects, but have certain application defects. They can only work in a single scenario or require special sensor equipment and are costly. If widely deployed WiFi infrastructure can be utilized, not only can the cost be saved and the use be facilitated, but also the wide application can be realized. This approach does not require the deployment of a specific sensor network nor does it require special equipment to be worn by the personnel in the room. In a conventional sensor network, a large number of sensor nodes are deployed in a specific area, and the sensor nodes are responsible for sensing signals and transmitting collected signals through a special channel. The method not only consumes a great deal of manpower to deploy the equipment, but also consumes a great deal of labor and needs long-term maintenance, so that the method is not suitable for wide deployment. Conventional indoor personnel activity identification techniques do not meet the high efficiency, low cost and increasing demand. Due to the rapid development of wireless communication technology, WiFi networks are widely available, and indoor activity identification using WiFi networks has become a research hotspot.
At present, a physical quantity characteristic commonly used by a passive human body recognition system designed by using a WIFI Signal and irrelevant to equipment is Received Signal Strength (RSSI), which is convenient to obtain, but the RSSI is the superposition of Signal strengths of a plurality of paths and is greatly influenced by other noises in the environment. For example, the technology utilizes the abnormal fluctuation of the RSSI to capture the environmental change to realize human body identification, and has the defect of unreliable identification result when performing activity identification, because the activity identification needs to detect the environmental characteristic change situation in real time, and the RSSI comes from a Media Access Control (MAC) layer, which is the superposition of the signal intensity of multiple paths, and the influence of multipath and noise in an indoor environment can cause the RSSI accuracy to be seriously interfered, thereby having strong randomness and dynamic property. Channel State Information (CSI) is finer-grained physical layer Information, and Channel Information of multiple Orthogonal Frequency Division Multiplexing (OFDM) subcarriers can be measured simultaneously, so that more accurate detection can be provided for wireless environment sensing, and applications developed by using CSI, such as gesture detection, activity recognition, indoor positioning, security monitoring, and the like, are increasing. These applications are helpful for child and geriatric care, smart home, and security monitoring. The CSI may provide a channel frequency response, including amplitude and phase, for each subcarrier. By studying some of the unique features exhibited in CSI, the basic activities of a person, even gestures and typed keys, can be identified.
Currently, CSI-based indoor activity recognition techniques have been proposed in large numbers. Some functions are like E-eyes and WiFinger. The E-eye performs activity recognition by using the amplitude characteristics extracted by the CSI and a related matching algorithm (including Dynamic Time Warping (DTW) and bulldozer Distance (EMD)), and compares the amplitude characteristics with the related characteristics of known activities. WiFinger is a lightweight algorithm for gesture behavior recognition using Discrete Wavelet Transform (DWT) and DTW algorithms. Therefore, WiFinger can recognize gestures by detecting unique features exhibited in CSI. Although E-eyes and wifi finger can guarantee a certain recognition accuracy, they are limited by the lack of a model that can quantitatively correlate CSI statistics and indoor human activities. Still other indoor human activity recognition, such as WiGest and CARM, model the propagation of WiFi signals in physical space under indoor human activity. WiGest utilizes the effect of hand motion on wireless signals to recognize gestures. CARM uses quantitative correlation as an analysis mechanism and identifies it by activity matching. Their main advantage is that they both establish a quantitative correspondence between CSI statistics and indoor human activity. Unfortunately, they are also very sensitive to indoor environmental noise and variations.
In summary, the problems of the prior art are as follows: the existing indoor personnel activity recognition technology lacks a matching model capable of quantitatively correlating CSI statistical characteristics with indoor personnel activities, so that a system cannot be well adapted to different environments, or parameters need to be reset when the system is transplanted to different environments, namely, the environment adaptability is poor; the method is very sensitive to the influence of environment random noise and indoor channel variation, so that the activity recognition effect is poor and the recognition rate is low.
The difficulty of solving the technical problems is as follows: how to effectively utilize the statistical characteristics of the CSI data to establish a matching model and how to solve the influence of identifying process environmental noise and indoor channel variation.
The significance of solving the technical problems is as follows: the indoor personnel identification has very important significance for production and life, and can be widely applied to places such as families, markets, hospitals and the like. The technical problem is solved, and the passive indoor personnel activity recognition can meet the requirements of low cost and high precision.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides an indoor personnel activity identification method based on channel state information and a man-machine interaction system.
The invention is realized in such a way that the indoor personnel activity identification method based on the channel state information preprocesses the collected CSI data to extract the environment change information including the correlation coefficient and the variance; then, sensing the surrounding environment by using a decision tree to monitor the activities of the personnel; secondly, if no personnel activity is detected, continuously collecting CSI data and keeping the activity monitoring state, otherwise triggering an activity feature extraction module, and carrying out extreme value removal processing and low-pass filtering processing on the collected CSI data in the activity feature extraction module; and then carrying out activity matching and recognition of the heaviest personnel activity by using a dynamic time programming algorithm based on principal component analysis.
Further, the indoor personnel activity identification method based on the channel state information specifically comprises the following steps:
the method comprises the steps that firstly, Channel State Information (CSI) is collected through existing WiFi equipment;
secondly, preprocessing the collected CSI data, and respectively extracting correlation coefficients and variances among subcarriers;
thirdly, constructing a decision tree based on the correlation coefficient and the variance, monitoring personnel activities by using the decision tree, triggering an indoor personnel activity identification module when monitoring the indoor personnel activities, and carrying out the fourth step, otherwise, continuously collecting CSI data and keeping monitoring of the personnel activities;
fourthly, further processing the collected CSI original data to obtain activity characteristic information, firstly removing extreme values in the CSI data by using an extreme value detection algorithm based on K-means clustering, and then removing environmental noise and high-frequency components in the CSI data by using a low-pass filter;
fifthly, extracting activity principal component information through a dynamic time programming matching algorithm based on principal component analysis, and then performing activity matching;
and sixthly, identifying the indoor personnel activities, then ending the activity identification process, entering the next personnel activity identification state, and returning to the first step.
Further, the step one of acquiring channel state information CSI through the existing WiFi device specifically includes:
at time t, acquiring channel state information H of the l-th link between the transmitting terminal TX and the receiving terminal TR, including subcarrier information of multiple groups of links:
wherein [ ·]TDenotes transposition, NsubIs the number of OFDM subcarriers, g represents all the links, h (i) can be expressed as:
H(i)=||H(i)||ej∠H(i);
wherein h (i) is channel state information of the ith subcarrier, | h (i) and ═ h (i) represent amplitude and phase information, respectively;
selecting one of the links fromThe acquisition of continuous unprocessed CSI is started and then passed through a sliding window of length m, denoted as:
wherein the content of the first and second substances,is a number NsubXm matrix, t is the start index of the sliding window;
Further, the step of preprocessing the collected CSI data to extract environment change information, that is, to extract correlation coefficients and variances between subcarriers, specifically includes:
(1) preprocessing original CSI data;
1) calculating the variance of the CSI subcarriers;
the variance of each subcarrier over the sliding window constitutes NsubA x 1 vector, expressed as;
wherein the content of the first and second substances,viis the variance of the ith subcarrier, and Var (-) is the variance symbol;
secondly, measuring the average variance of all subcarriers;
V=Var(Vw);
wherein V represents the degree of channel fluctuation;
2) calculating correlation coefficients among the CSI subcarriers;
for NsubSub-carriers, measuring the correlation coefficient as follows;
where ρ isi,jRepresenting the correlation coefficient between the ith subcarrier and the jth subcarrier, wherein Corr (-) is a correlation symbol;
repeating the above calculation to obtain a group of correlation coefficients, performing extreme point detection through the least median square, and screening out incorrect correlation coefficients, wherein the definition of the objective function is as follows:
wherein:
ρi,j={ρi,j,i<j∈[1,Nsub]};
Γ=Nsub(Nsub-1)/2;
where min (-) and med (-) are min and median operations, respectively, ri,jIs the remainder of the process,is the least mean square estimate, and Γ is ρi,jThe number of (2);
(2) outlier detection was as follows:
after incorrect correlation coefficients are determined, they are filtered out and the remaining coefficients are then averaged as a final estimate of a set of correlation coefficients:
where ρ and I (ρ)i,j) Respectively is the final phaseAnd finally obtaining a correlation coefficient rho for identifying the indoor personnel activities by using the correlation coefficient and the outlier index.
Further, the third step is to construct a decision tree based on the correlation coefficient and the variance, monitor the activity of the people by using the decision tree, trigger the indoor people activity recognition module after monitoring the activity of the indoor people, and otherwise continue to collect CSI data and maintain the activity monitoring state, and specifically includes:
according to the result of the second step, on the basis of environmental change, namely subcarrier correlation coefficient and variance, constructing a decision tree and monitoring personnel activities by using the decision tree, triggering an indoor personnel activity identification module after monitoring the indoor personnel activities, and otherwise, continuously collecting CSI data and keeping an activity monitoring state;
indoor human activity monitoring with correlation coefficients and variances is expressed as:
further, the fourth step is to further process the collected CSI raw data to obtain activity characteristic information, remove extreme values in the CSI data by using an extreme value detection algorithm based on K-means clustering, and remove environmental noise and high-frequency components in the CSI data by using a low-pass filter;
(1) the K-means clustering method is very sensitive to abnormal values, finds strongly related data point groups, and detects the abnormality to find data points which are not strongly related to other data points; the extreme point processing of the original CSI data comprises the following steps;
1) the data was subjected to a normalization operation, expressed as:
whereinh is the output of the data normalization, Z-score (. cndot.) is the data normalization operationMaking a symbol;
2) randomly selecting k data points from a data set h as an original centroid:
u={u1,u2,...uω...,uk},(ω=1,2,...,k);
3) the maximum number of iterations is set to Ω, and the iterations are from 1 to Ω, as follows:
wherein C isχIs the original cluster;
3.2) Next step, labelingCategory corresponding as minimumAt this time, the cluster is updated, which is expressed as:
3.3) for all data points Cω,ω∈[1,k]Recalculating new centroids:
3.4) if the k centroids buzai2 are changed, entering the step four;
4) the final C cluster outputs are:
C={C1,C2,...,Ck};
5) after clustering, extremum detection in CSI data:
u={u1,u2,...uε...,uk},ε∈[1,k];
C={C1,C2,...Cε...,Ck},ε∈[1,k];
where u is the final cluster centroid and C is the corresponding cluster:
5.2) after the extreme value detection algorithm based on the K-means clustering is processed, obtaining:
where EVD (-) is an extremum detecting opcode;
(2) the low-pass filter eliminates random environmental noise and high-frequency components caused by any non-human activities; meanwhile, the special statistical characteristics caused by the human activities in the CSI data are reserved, and the statistical characteristics are obtained through a low-pass filter:
where LPF (-) is the low pass filter operator.
Further, the fifth step of extracting activity features, namely activity principal component information, by a dynamic time programming matching algorithm based on principal component analysis, and then performing activity matching specifically comprises:
(1) the step of extracting the active principal component information in the CSI data is as follows;
1) collecting filtered CSI, i.e.Will be provided withDividing into data blocks containing 2 second intervals, arranging the data blocks of g links in rows to form a matrix
2) Correlation estimation, calculating a correlation matrix with dimension m × m:
3) and (3) feature decomposition, namely performing feature decomposition on the correlation matrix, and calculating a feature vector:
whereinυiIs a feature vector, sigma is the number of principal components to be obtained, deceigen (·) is a feature decomposition operation symbol;
4) and (3) reconstructing an activity signal, wherein the main components are constructed as follows:
whereinAndare respectively the τ -th eigenvector and the τ -th component, PiIs a principal component matrix;
(2) according to the characteristics of indoor personnel activities, carrying out similarity measurement on two activity characteristics, namely unknown activities and activity characteristics in a known database by adopting dynamic time warping; the specific algorithm is as follows:
1) given two activity characteristics, an unknown PiA is knownThen find a function of the point-to-point distance:
2) finding the correspondence between the points:
wherein:
then, considering ψ (w), the solution for the cumulative distance between two active features is as follows:
3) the final DTW estimate is to find the optimum ψ (w) that minimizes the cumulative distance:
further, step six carries out indoor personnel's activity discernment, after personnel's activity discernment, ends this identification process, enters next personnel's activity discernment state, will return to step one promptly and specifically include:
by computing the unknown activity features and the activity features in the pre-constructed database, the process of human activity recognition is as follows:
where argmin (·) is the minimum operator symbol and κ represents the category of human activity. Only whenWhen the minimum is taken, the activity of the person is correctly identified.
The invention also aims to provide a human-computer interaction control system applying the indoor human activity identification method based on the channel state information.
Another object of the present invention is to provide an intelligent home control system using the method for identifying indoor human activities based on channel state information.
In summary, the advantages and positive effects of the invention are: the invention solves the problems that the existing indoor personnel activity identification technology is easily influenced by environmental noise and channel change and the statistical characteristics of CSI data are effectively utilized. The implementation scheme is as follows: collecting CSI data by using WiFi equipment; and preprocessing the CSI data, and extracting environment change information, namely subcarrier correlation coefficients and variances. Sensing the environment of a target area by using a decision tree through environment change information, monitoring personnel activities, triggering a personnel activity feature extraction module if the human activities are monitored, and continuing to collect CSI data and keeping an activity monitoring state if the human activities are monitored; if the activity exists in the target area, performing data processing on the collected original CSI data to obtain activity characteristic information, namely principal component information, firstly removing extreme values in the data by using an extreme value detection algorithm based on K-means clustering, and then removing environmental noise and high-frequency components in the data by using a low-pass filter; and (3) performing activity feature extraction and personnel activity matching by using a Principal Component Analysis based on Dynamic Time programming matching algorithm (PCA-DTW). And identifying the indoor personnel activities, finishing the identification process after identifying the personnel activities, and entering the next personnel activity identification state.
The invention overcomes the defect of low reliability of the recognition result in the prior art and improves the activity recognition precision. Because the invention adopts the environment change information and the indoor personnel activity monitoring method based on the decision tree, the invention can sense the indoor environment and monitor the activity change of the indoor personnel, thereby avoiding the system from missing the activity.
The invention carries out extreme value elimination and low-pass filtering in the CSI data processing stage, screens and de-noizes the CSI data, overcomes the defects of low detection accuracy and poor reliability caused by data original errors, and improves the identification rate.
According to the invention, the indoor personnel activity monitoring and activity recognition are combined, and the indoor personnel activity recognition is carried out through PCA-DTW, so that the step of offline acquisition data training in the prior art is omitted, and the system performance and the recognition rate are improved.
The following table shows the comparison of the present invention with the prior art
Method | Activity monitoring | Extremum processing | Filtering process | Principal component analysis | Matching |
WiAR | Is provided with | Is provided with | Is provided with | Is provided with | Is provided with |
E-eyes | Is free of | Is free of | Is provided with | Is free of | Is provided with |
WiFinger | Is free of | Is free of | Is provided with | Is free of | Is provided with |
Drawings
Fig. 1 is a flowchart of an indoor human activity identification method based on channel state information according to an embodiment of the present invention.
Fig. 2 is a flowchart of an implementation of the method for identifying indoor human activities based on channel state information according to an embodiment of the present invention.
Fig. 3 is a sub-flow diagram of an active feature database construction module provided by an embodiment of the present invention.
Fig. 4 is a sub-flowchart of an indoor environment change information extraction module according to an embodiment of the present invention.
FIG. 5 is a sub-flow diagram of an activity monitoring module provided by an embodiment of the present invention.
Fig. 6 is a sub-flow diagram of an activity feature extraction module provided by an embodiment of the present invention.
Fig. 7 is a sub-flow diagram of an activity recognition module provided by an embodiment of the present invention.
Fig. 8 is a comparison graph of simulation results of two existing indoor human activity recognition methods according to the embodiment of the present invention.
Fig. 9 is a comparison diagram for simulating whether to recognize human activities based on principal component analysis when the experimental environment is unchanged according to the embodiment of the present invention.
Fig. 10 is a diagram illustrating collected raw CSI data according to an embodiment of the present invention.
Fig. 11 is a schematic diagram of CSI data after K-means extremum detection according to an embodiment of the present invention.
Fig. 12 is a schematic diagram of CSI data processed by a low-pass filter according to an embodiment of the present invention.
Fig. 13 is a schematic diagram of the finally collected principal component information provided by the embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention effectively utilizes the characteristics of environmental noise, channel change and CSI data statistics to overcome the defect of low reliability of the recognition result in the prior art and improve the activity recognition precision. In particular to an indoor personnel activity identification method based on channel state information, which can be used for man-machine interaction, smart families, nursing of old people and emergency recourse.
The following detailed description of the principles of the invention is provided in connection with the accompanying drawings.
As shown in fig. 1, the indoor human activity identification method based on channel state information according to an embodiment of the present invention includes the following steps:
s101: acquiring Channel State Information (CSI) through existing WiFi equipment;
s102: preprocessing the collected CSI data, and respectively extracting correlation coefficients and variances among subcarriers;
s103: constructing a decision tree based on the correlation coefficient and the variance, monitoring personnel activities by using the decision tree, triggering an indoor personnel activity identification module after monitoring the indoor personnel activities, and carrying out S104, otherwise, continuously collecting CSI data and keeping monitoring of the personnel activities;
s104: further processing the collected CSI original data to obtain activity characteristic information, firstly removing extreme values in the CSI data by using an extreme value detection algorithm based on K-means clustering, and then removing environmental noise and high-frequency components in the CSI data by using a low-pass filter;
s105: extracting active Principal Component information by a Principal Component Analysis based on Dynamic Time programming matching algorithm (PCA-DTW), and then performing active matching;
s106: and identifying the indoor personnel activities, then ending the activity identification process, entering the next personnel activity identification state, and returning to the S101.
The application of the principles of the present invention will now be described in further detail with reference to the accompanying drawings.
As shown in fig. 2, the method for identifying indoor personnel activities based on channel state information provided by the embodiment of the present invention specifically includes the following steps:
step one, acquiring Channel State Information (CSI) through existing WiFi equipment, and specifically comprising the following steps:
at time t, acquiring channel state information H of the l-th link between the transmitting terminal TX and the receiving terminal TR, including subcarrier information of multiple groups of links:
wherein [ ·]TDenotes transposition, NsubIs the number of OFDM subcarriers, g represents all the links, h (i) can be expressed as:
H(i)=||H(i)||ej∠H(i);
where h (i) is channel state information of the ith subcarrier, | h (i) and ═ h (i) represent amplitude and phase information, respectively.
Typically, one of the links is selected fromThe acquisition of continuous unprocessed CSI is started and then passes through a sliding window of length m, which can be expressed as:
wherein the content of the first and second substances,is a number NsubXm matrix, t is the start index of the sliding window.
Step two, preprocessing the collected CSI data, and extracting environment change information, that is, extracting correlation coefficients and variances between subcarriers, as shown in fig. 4, specifically including:
(1) preprocessing original CSI data;
1a) calculating the variance of the CSI subcarriers;
the variance of each subcarrier over the sliding window constitutes NsubA x 1 vector, which can be expressed as;
wherein the content of the first and second substances,viis the variance of the ith subcarrier, and Var (-) is the variance symbol.
Secondly, the average variance of all subcarriers can be conveniently measured;
V=Var(Vw);
where V represents the degree of channel fluctuation. Thus, when a person moves in the target area, it is more likely to become larger.
1b) Calculating correlation coefficients among the CSI subcarriers;
in particular, for NsubSub-carriers, measuring the correlation coefficient as follows;
where ρ isi,jRepresents the correlation coefficient between the ith subcarrier and the jth subcarrier, and Corr (-) is the correlation symbol.
A group of correlation coefficients can be obtained by repeating the calculation, and then the incorrect correlation coefficients can be screened out by carrying out extreme point detection through the least mean square. Specifically, the objective function is defined as:
wherein:
ρi,j={ρi,j,i<j∈[1,Nsub]};
Γ=Nsub(Nsub-1)/2;
where min (-) and med (-) are min and median operations, respectively, ri,jIs the remainder of the process,is the least mean square estimate, and Γ is ρi,jThe number of (2).
(2) Outlier detection was as follows:
after incorrect correlation coefficients are determined, they can be filtered out and the remaining coefficients averaged as a final estimate of a set of correlation coefficients:
where ρ and I (ρ)i,j) And finally obtaining a correlation coefficient rho which can be used for indoor personnel activity identification.
Step three, constructing a decision tree based on the correlation coefficient and the variance, monitoring the personnel activities by using the decision tree, triggering an indoor personnel activity recognition module after monitoring the indoor personnel activities, and if not, continuously collecting CSI data and keeping an activity monitoring state, as shown in FIG. 5, specifically comprising:
and according to the result of the second step, on the basis of environmental change, namely subcarrier correlation coefficient and variance, constructing a decision tree and monitoring personnel activities by using the decision tree, triggering an indoor personnel activity identification module after monitoring the indoor personnel activities, and otherwise, continuously collecting CSI data and keeping an activity monitoring state.
Indoor human activity monitoring using correlation coefficients and variances can be expressed as:
step four, further processing the collected CSI original data to obtain activity characteristic information, namely principal component information, firstly removing extreme values in the CSI data by using an extreme value detection algorithm based on K-means clustering, and then removing environmental noise and high-frequency components in the CSI data by using a low-pass filter; the method specifically comprises the following steps:
the collected CSI original data are further processed to obtain activity characteristic information, an extreme value detection algorithm based on K-means clustering is used for removing an extreme value in the CSI data, and then a low-pass filter is used for removing environmental noise and high-frequency components in the CSI data.
(1) K-means is a classical clustering method that is very sensitive to outliers and can be used to find groups of data points that are strongly correlated, while anomaly detection is used to find data points that are not strongly correlated with other data points. Therefore, K-means is very suitable for the detection of abnormal values. The extreme point processing of the original CSI data includes the following five steps.
1) The data is subjected to a normalization operation, which can be expressed as:
whereinh is the output of the data normalization and Z-score (. cndot.) is the data normalization operator.
2) Randomly selecting k data points from a data set h as an original centroid:
u={u1,u2,...uω...,uk},(ω=1,2,...,k);
3) the maximum number of iterations can be set to Ω and the iterations are from1To Ω, as follows:
wherein C isχIs the original cluster.
3.2) Next step, labelingCategory corresponding as minimumThe cluster is updated at this time, which can be expressed as:
3.3) for all data points Cω,ω∈[1,k]Recalculating new centroids:
3.4) if the k centroids buzai2 change, go to step four.
4) Finally, the C cluster outputs are:
C={C1,C2,...,Ck};
5) after clustering, the detection of extrema in the CSI data is as follows:
u={u1,u2,...uε...,uk},ε∈[1,k];
C={C1,C2,...Cε...,Ck},ε∈[1,k];
where u is the final cluster centroid and C is the corresponding cluster:
5.2) after the extreme value detection algorithm based on the K-means clustering is processed, the following can be obtained:
where EVD (-) is an extremum detecting operator.
(2) The purpose of the low-pass filter is to eliminate any random environmental noise and high frequency components caused by non-human activity, considering that human activity usually has a relatively low frequency range. Meanwhile, special statistical characteristics caused by personnel activities in the CSI data can be effectively reserved. After passing through a low-pass filter, the following can be obtained:
where LPF (-) is the low pass filter operator.
Step five, extracting activity characteristic information, namely principal component information, through PCA-DTW, and then performing activity matching, as shown in fig. 6, specifically including:
and extracting activity characteristics, namely activity principal component information, by a dynamic time programming matching algorithm based on principal component analysis, and then performing activity matching.
(1.1) extracting active principal component information in the CSI data as follows;
(1) collecting filtered CSI, i.e.Then, willDividing into data blocks containing 2 second intervals, arranging the data blocks of g links in rows to form a matrix
(2) Correlation estimation, calculating a correlation matrix with dimension m × m:
(3) and (3) feature decomposition, namely performing feature decomposition on the correlation matrix, and calculating a feature vector:
whereinυiIs the eigenvector, σ is the number of principal components to be obtained, and deceigen (·) is the eigen-decomposition operator.
(4) Activity signal reconstruction the main components can be constructed as follows:
whereinAndare respectively the τ -th eigenvector and the τ -th component, PiIs a principal component matrix.
And (1.2) according to the characteristics of indoor personnel activities, performing similarity measurement on two activity characteristics, namely unknown activities and activity characteristics in a known database by adopting dynamic time warping. The specific algorithm is as follows:
(1) given two activity characteristics, an unknown PiA is knownThen find a function of the point-to-point distance:
(2) finding the correspondence between the points:
wherein:
then, considering ψ (w), the solution for the cumulative distance between two active features is as follows:
(3) the final DTW estimate is to find the optimum ψ (w) to minimize the cumulative distance:
step six, identifying indoor personnel activities, finishing the identification process after identifying the personnel activities, and entering the next personnel activity identification state, namely returning to the step one; as further shown in fig. 7, the method specifically includes:
by computing the unknown activity features and the activity features in the pre-constructed database, the process of human activity recognition is as follows:
where argmin (·) is the minimum operator symbol and κ represents the category of human activity. Only whenWhen the minimum is taken, the person activity can be correctly identified.
The application effect of the present invention will be described in detail with reference to the simulation.
Firstly, simulation conditions: the transmitting and receiving end nodes are deployed in an indoor space with a reachable view distance of 10m by 10m, a notebook computer with an Intel5300 wireless network card is arranged as a transmitting end, and the same notebook with the Intel5300 is selected as a receiving end. The CSI collecting tool is an open source drive on a Linux platform, and parameters can be adjusted to collect CSI data after equipment is configured.
Second, simulation content and results
(1) true Positive Rate (TPR): the TPR for activity a is defined as the proportion of class a activities that are correctly identified as activity a.
(2) False Positive Rate (FPR): the FPR for activity A is defined as the proportion of all activities other than A that are misrecognized as A.
The results are shown in FIG. 8. As can be seen from fig. 8, under the same environment, compared with the CSI-based indoor human activity recognition systems E-eyes and WiFinger, the recognition rate of WiFinger activity is 95%, 93%, 94%, and 95%, the recognition rate of E-eyes activity is 98%, 97%, 95%, and 97%, and the recognition rate of invention activity is 100%, 98%, and 100%. Therefore, compared with the former two methods, the method has higher correct identification rate.
As can be seen from fig. 9, when the indoor human activity recognition is performed based on PCA, the recognition rate is 100%, 98%, 100%, otherwise the recognition rate is 87%, 75%, 72%, 82%. The performance based on PCA is better, and the recognition rate is higher.
The effect of the present invention will be described in detail with reference to experiments.
The system performance is evaluated through a series of experimental simulations, the provided indoor personnel activity recognition is subjected to experimental design and verification, and the experimental result is subjected to detailed analysis. Under the same environment, compared with the indoor human activity recognition systems E-eyes and WiFinger based on CSI, the WiFinger activity recognition rate is 95%, 93%, 94% and 95%, the E-eyes activity recognition rate is 98%, 97%, 95% and 97%, and the E-eyes activity recognition rate is 100%, 98% and 100%. Therefore, compared with the former two methods, the method has higher correct identification rate. When the experimental environment is not changed, simulation is carried out on the basis of the PCA, when indoor personnel activity recognition is carried out on the basis of the PCA, the recognition rate is 100%, 98% and 100%, otherwise, the recognition rate is 87%, 75%, 72% and 82. The performance based on PCA is better, and the recognition rate is higher.
Experimental data
Table 1 sample data collected
Movement of | A | B | C | D |
Number of | 100 | 100 | 100 | 100 |
Motion matching data
WiAR Table 2. action matching Effect of WiAR
WiFinger Table 3. action matching Effect of WiFinger
Movement of | A | B | C | D |
A | 95 | 3 | 2 | 0 |
B | 4 | 93 | 2 | 1 |
|
2 | 3 | 94 | 1 |
|
0 | 2 | 3 | 95 |
E-eyes Table 4. action matching Effect of E-eyes
Movement of | A | B | C | D |
A | 98 | 2 | 0 | 0 |
|
1 | 97 | 2 | 0 |
|
0 | 2 | 97 | 1 |
|
0 | 0 | 1 | 99 |
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (7)
1. The indoor personnel activity identification method based on the channel state information is characterized in that the indoor personnel activity identification method based on the channel state information is used for preprocessing collected CSI data to extract environment change information comprising correlation coefficients and variances; then, sensing the surrounding environment by using a decision tree to monitor the activities of the personnel; secondly, if no personnel activity is detected, continuously collecting CSI data and keeping the activity monitoring state, otherwise triggering an activity feature extraction module, and carrying out extreme value removal processing and low-pass filtering processing on the collected CSI data in the activity feature extraction module; then, performing activity matching and finally achieving personnel activity recognition by using a dynamic time planning algorithm based on principal component analysis;
the indoor personnel activity identification method based on the channel state information specifically comprises the following steps:
the method comprises the steps that firstly, Channel State Information (CSI) is collected through existing WiFi equipment;
secondly, preprocessing the collected CSI data, and respectively calculating correlation coefficients among subcarrier time sequences and variances of corresponding subcarrier time sequences; the method specifically comprises the following steps:
(1) preprocessing original CSI data;
1) calculating the variance of the CSI subcarriers;
the variance of each subcarrier over the sliding window constitutes NsubA x 1 vector, expressed as;
wherein the content of the first and second substances,viis the variance of the ith subcarrier, and Var (-) is the variance symbol;
secondly, measuring the average variance of all subcarriers;
V=Var(Vw);
wherein V represents the degree of channel fluctuation;
2) calculating correlation coefficients among the CSI subcarriers;
for NsubSub-carriers, measuring the correlation coefficient as follows;
where ρ isi,jRepresenting the correlation coefficient between the ith subcarrier and the jth subcarrier, wherein Corr (-) is a correlation symbol;
repeating the above calculation to obtain a group of correlation coefficients, performing extreme point detection through the least median square, and screening out incorrect correlation coefficients, wherein the definition of the objective function is as follows:
wherein:
ρi,j={ρi,j,i<j∈[1,Nsub]};
Γ=Nsub(Nsub-1)/2;
where min (-) and med (-) are min and median operations, respectively, ri,jIs the remainder of the process,is the least mean square estimate, and Γ is ρi,jThe number of (2);
(2) outlier detection was as follows:
after incorrect correlation coefficients are determined, they are filtered out and the remaining coefficients are then averaged as a final estimate of a set of correlation coefficients:
where ρ and I (ρ)i,j) Respectively obtaining a final correlation coefficient and the outlier index, and finally obtaining a correlation coefficient rho for indoor personnel activity identification;
thirdly, constructing a decision tree based on the correlation coefficient and the variance, monitoring personnel activities by using the decision tree, triggering an indoor personnel activity identification module when monitoring the indoor personnel activities, and carrying out the fourth step, otherwise, continuously collecting CSI data and keeping monitoring of the personnel activities;
fourthly, further processing the collected CSI original data to obtain activity characteristic information, firstly removing extreme values in the CSI data by using an extreme value detection algorithm based on K-means clustering, and then removing environmental noise and high-frequency components in the CSI data by using a low-pass filter;
fifthly, extracting activity principal component information through a dynamic time programming matching algorithm based on principal component analysis, and then performing activity matching; the method specifically comprises the following steps:
(1) the step of extracting the active principal component information in the CSI data is as follows;
1) collecting filtered CSI, i.e.Will be provided withDividing into data blocks containing 2 second intervals, arranging the data blocks of g links in rows to form a matrix
2) Correlation estimation, calculating a correlation matrix with dimension m × m:
3) and (3) feature decomposition, namely performing feature decomposition on the correlation matrix, and calculating a feature vector:
whereinυiIs a feature vector, sigma is the number of principal components to be obtained, deceigen (·) is a feature decomposition operation symbol;
4) and (3) reconstructing an activity signal, wherein the main components are constructed as follows:
whereinAndare respectively the τ -th eigenvector and the τ -th component, PiIs a principal component matrix;
(2) according to the characteristics of indoor personnel activities, carrying out similarity measurement on two activity characteristics, namely unknown activities and activity characteristics in a known database by adopting dynamic time warping; the specific algorithm is as follows:
1) given two activity characteristics, an unknown PiA is knownThen find a function of the point-to-point distance:
2) finding the correspondence between the points:
wherein:
then, considering ψ (w), the solution for the cumulative distance between two active features is as follows:
3) the final DTW estimate is to find the optimum ψ (w) that minimizes the cumulative distance:
and sixthly, identifying the indoor personnel activities, then ending the activity identification process, entering the next personnel activity identification state, and returning to the first step.
2. The method for identifying indoor human activities based on channel state information according to claim 1, wherein the first step of collecting channel state information CSI through existing WiFi equipment specifically includes:
at time t, acquiring channel state information H of the l-th link between the transmitting terminal TX and the receiving terminal TR, including subcarrier information of multiple groups of links:
wherein [ ·]TDenotes transposition, NsubIs the number of OFDM subcarriers, g represents all the links, h (i) can be expressed as:
H(i)=||H(i)||ej∠H(i);
wherein h (i) is channel state information of the ith subcarrier, | h (i) and ═ h (i) represent amplitude and phase information, respectively;
selecting one of the links fromStart of acquisition of continuous no additionThe processed CSI, then passes through a sliding window of length m, represented as:
wherein the content of the first and second substances,is a number NsubXm matrix, t is the start index of the sliding window;
3. The method for identifying indoor human activities based on channel state information according to claim 1, wherein the third step constructs a decision tree based on the correlation coefficient and the variance, monitors human activities by using the decision tree, triggers an indoor human activity identification module when the indoor human activities are monitored, and otherwise continues to collect CSI data and maintains an activity monitoring state, and specifically comprises:
according to the result of the second step, on the basis of environmental change, namely subcarrier correlation coefficient and variance, constructing a decision tree and monitoring personnel activities by using the decision tree, triggering an indoor personnel activity identification module after monitoring the indoor personnel activities, and otherwise, continuously collecting CSI data and keeping an activity monitoring state;
indoor human activity monitoring with correlation coefficients and variances is expressed as:
4. the method for identifying indoor human activity based on channel state information according to claim 1, wherein the fourth step further processes the collected CSI raw data to obtain activity characteristic information, removes extrema in the CSI data using an extremum detection algorithm based on K-means clustering, and removes environmental noise and high frequency components in the CSI data using a low pass filter;
(1) the K-means clustering method is very sensitive to abnormal values, finds strongly related data point groups, and detects the abnormality to find data points which are not strongly related to other data points; the extreme point processing of the original CSI data comprises the following steps;
1) the data was subjected to a normalization operation, expressed as:
whereinh is the output of the data normalization, Z-score (. cndot.) is the data normalization operator;
2) randomly selecting k data points from a data set h as an original centroid:
u={u1,u2,...uω...,uk},(ω=1,2,...,k);
3) the maximum number of iterations is set to Ω, and the iterations are from 1 to Ω, as follows:
wherein C isχIs the original cluster;
3.2) Next step, labelingCategory corresponding as minimumAt this time, the cluster is updated, which is expressed as:
3.3) for all data points Cω,ω∈[1,k]Recalculating new centroids:
3.4) if the k centroids buzai2 are changed, entering the step four;
4) the final C cluster outputs are:
C={C1,C2,...,Ck};
5) after clustering, extremum detection in CSI data:
u={u1,u2,...uε...,uk},ε∈[1,k];
C={C1,C2,...Cε...,Ck},ε∈[1,k];
where u is the final cluster centroid and C is the corresponding cluster:
5.2) after the extreme value detection algorithm based on the K-means clustering is processed, obtaining:
where EVD (-) is an extremum detecting opcode;
(2) the low-pass filter eliminates random environmental noise and high-frequency components caused by any non-human activities; meanwhile, the special statistical characteristics caused by the human activities in the CSI data are reserved, and the statistical characteristics are obtained through a low-pass filter:
where LPF (-) is the low pass filter operator.
5. The indoor human activity recognition method based on channel state information as claimed in claim 1, wherein the sixth step performs indoor human activity recognition, and after human activity recognition, ends the recognition process this time, and enters the next human activity recognition state, that is, it needs to return to step one to specifically include:
by computing the unknown activity features and the activity features in the pre-constructed database, the process of human activity recognition is as follows:
6. A human-computer interaction control system applying the method for identifying the indoor personnel activities based on the channel state information as claimed in any one of claims 1 to 5.
7. An intelligent home control system applying the method for identifying the activity of people in a room based on channel state information as claimed in any one of claims 1 to 5.
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