To meet the needs of wireless sensor network-based applications, the multisensor data fusion technique, which combines data streams from multiple sensors, must improve accuracy requirements. In recent years, the emergence of multi-application paradigms in wireless sensor networks has enabled sensors to observe their surroundings [7]. Multi-sensor fusion's primary goal is to improve system performance by combining data from all sensors. To provide better spatial and temporal coverage, multiple sensors can be used. Furthermore, using multiple sensors improves estimation accuracy and fault tolerance [26]. To meet the long-term and high-precision requirements, a multi-sensor fusion framework must continuously provide all-time weather parameters [16]. The integrated fusion method is used for isolating measurement failures and fusing state estimates to combine local estimation results obtained from each sensor. Temperature, humidity, and noise are among the physical attributes monitored by the sensors. Additionally, send them at regular intervals. The fixed gateway node receives the transmitted data streams and processes them further. As data transmission speeds up, so does network complexity. When the sensor batteries run out, they cannot be replaced. As a result, it is necessary to increase battery life. Here the influential ADKF-DT multisensor fusion technique is applied as a probable solution to the challenge of earlier identification of forest fires. The proposed framework of the forest fire detection system is depicted in Fig. 1.
The sensors perform data transmission through a wireless medium and are further processed by the proposed technique. Finally, the data is sent to the IoT cloud server which fulfills the objective of communicating early an alert message on the fire threat. The dynamic environmental measurements such as temperature and humidity in real-time are considered input data. The system detects fire and sends an alert message to the station. Depending on the budget, any number of sensors can be used, here the sensors of type Node MCU (ESP8266) interfaced with temperature and humidity sensors, i.e. DHT11. The ADKF-DT-MF algorithm combines and modifies the original scheme of the Decentralized Kalman Filter and Decision Tree algorithms to suit the proposed research objective.
It is necessary to gain knowledge of the observed environment to identify threats. The sensed data must be classified to solve this problem. As a result, the proposed ADKF-DT-MF (Adaptive Decentralized Kalman Filter with Decision Tree for Multisensor Fusion) system is used on a condition-based environment monitoring system to provide valuable real-time data [18]. The data classification technique determines predefined classes providing current event-based situational information in a network of sensor nodes. The predefined types are characterized by the attributes of the sensor output signals. The decision tree classifies the forest weather parameters into maximum and minimum values of temperature, and humidity. The classification with a set of rules interprets and converts into a standard set of values for environment-based situation refinement performing accurate decision making.
The decision-making procedure is employed at the fusion center. Here the large data set is divided into multiple classes, organized into a hierarchical tree structure for efficient classification and decision making. Decision-making shall handle sensor defects, missed out observations/decisions improving the system performance. Once the fire is detected in the perceived area the concerned authorities are communicated regarding the exact location and intensity of the fire which helps to take necessary action. Since sensors exhibit limited energy, the algorithm performs functions such as
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predefining the active sensors and determining the shortest path for information transmission,
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reduces the amount of data sent to the base station,
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sensors that are not active in the path go into sleep mode to save energy.
Algorithm - ADKF-DT-MF (Adaptive Decentralized Kalman Filter with Decision Tree Multisensor Fusion) |
Begin //Wireless Sensor Network Configuration// Declaration n = 100;w = 2*n; h = 2*n; x, y Calculate the node distance//Base Network d = sqrt(xSide^2 + ySide^2); Calculate the distance to previous node xSide = abs(X2-X1); ySide = abs(Y2-Y1); d = sqrt(xSide^2 + ySide^2); Apply ADKF Filter//To remove noise and perform data fusion Calculates cost function for known and unknown variables CostFunction = @(tour) TourLength(tour,model.D); nVar = model.n; //number of unknown variables VarSize = (1 nVar); //unknown variables matrix size Identify the best cost path BestCost = zeros(MaxIt,1); BestCost(it) = BestSol.Cost; Perform Decision Tree Classification accuracy depth = 5; % tree depth noc = 1000; % number of candidates at each tree node Y1 = Y1-1; error = sum(Y1 ~ = Y); accuracy = 1-error/length(Y); Read the Channel ID and Field ID(Temp, Humidity) Display maxTempF//Maximum temperature for the past 24 hours minTempF//Minimum temperature for the past 24 hours avgHumidity = mean(humidity); End |
The coverage function (FC) for a fire hotspot region is expressed in Eq. (1)
The sensing coordinates are x and y, and the time is denoted by t. Eq. (2) expresses the equation for a temperature sensor, while Eq. (3) expresses the equation for a fire event.
$$f(\mathop x\nolimits_{i} ;\mathop \gamma \nolimits_{0} ,\alpha )=\frac{1}{{\sqrt {2\prod \alpha } }}\mathop e\nolimits^{{ - {{(\mathop x\nolimits_{i} - \mathop \gamma \nolimits_{0} )}^2}/2{\alpha ^2}}}$$
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$$f(\mathop x\nolimits_{i} ;\mathop \gamma \nolimits_{F} ,\alpha )=\frac{1}{{\sqrt {2\prod \alpha } }}\mathop e\nolimits^{{ - {{(\mathop x\nolimits_{i} - \mathop \gamma \nolimits_{F} )}^2}/2{\alpha ^2}}}$$
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It is necessary to gain knowledge of the observed environment to identify threats. The amount of energy required for data transmission is determined by the size of the data packet and the distance between the sender and receiver. The global estimation is calculated by the Adaptive Decentralized Kalman Filter at the sink node. The algorithm, which is predefined in terms of parameters and functions, identifies the adjacent and most cost-effective shortest path to the sink node while synthesizing accurate data in information fusion and interpreting a series of continuous-time awareness of climate change.
Regardless of sensor failure, this approach provides accurate data from predefined paths. The fusion operation is carried out by the fusion centre. The optimal estimation is calculated by the signal level fusion stage, which keeps track of the sensor's estimated state and its uncertainty. The inferred parameters could be inaccurate and uncertain observations. The filter evaluates the incoming evidence recursively, yielding estimates of the state. The system measurement is fed into the filter, and the output is the estimated system state. The filter's dynamic model calculates the time between sensor outputs and sequentially incorporates multiple sensor measurements for data fusion. It also effectively handles uncertainty resulting from the covariance calculated while transmitting noisy sensor data observed within the boundary limits to determine the sensor state.
The proposed filter improves on previous methods because measurements do not need to be inverted, making it suitable for real-time processing. The filter accomplishes this by calculating timeframes between multiple sensor measurements for information fusion. Similarly, the experiment continues to manage uncertainty resulting from the covariance calculated in Eq. (4).
$$\operatorname{cov} =(x1,x2)=E(x1 - \overline {{x1)}} (x2 - \overline {{x2)}}$$
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Where x1 and x2 are independent random variables. The sensor state is determined at this point by the transmission of data within the boundary limits. The system performs observation z using Gaussian noise w as expressed in Eq. (5).
Where x (k) represents the system state vector and w (k) represents the unknown zero mean. The proposed technique's efficiency is also validated by comparing it to the existing ENN technique [23]. Here it develops a decision-making system for situation refinement in a multisensor fusion environment with optimization capabilities. It prevents data estimation delays on the side of the fusion center, helping to incorporate knowledge using a decision tree tool. If any of the sensors fails, the information on the current state is incomplete. Hence optimization here ensures low sensing cost calculating the best path. Tests on simulated data carried out by applying the fuzzy membership optimization function show improvement in the performance of the proposed intelligent control system. Each node in the tree acts as a test case for some attribute and the edge is the possible answer to the test case. The process is recursive and is repeated for every sub-tree. For the classification and regression tree at each level, the root node is considered for attribute selection. The selection of attributes at the root node on each level depends mainly on: Entropy, Information Gain, and Gini index. These criteria calculate the attribute value, the attribute of high value is considered for Information Gain and placed at the root node. The continuous attribute value is calculated using the Gini index. The entropy for a single attribute is mentioned in Eq. (6)
$$\text{E}\left(\text{S}\right)=\sum _{\text{i}=1}^{\text{c}}-{\text{p}}_{\text{i}}{\text{l}\text{o}\text{g}}_{2}{\text{p}}_{\text{i}}$$
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Where S, the current state; \({\text{p}}_{\text{i}}\)the probability of event i of state S; c, the class where i node exists. For multiple attributes, the entropy is as in Eq. (7)\(\)
$$\text{E}\left(\text{S},\text{X}\right)=\sum _{\text{c}=\text{X}}\text{P}\left(\text{c}\right)\text{E}\left(\text{c}\right)$$
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Here X, the selected attribute. Information gain is given in Eq. (8) the statistical property separates the attribute for their target classification. An increase in information gain decreases entropy.
$$\text{I}\text{n}\text{f}\text{o}\text{r}\text{m}\text{a}\text{t}\text{i}\text{o}\text{n} \text{G}\text{a}\text{i}\text{n}\left(\text{S}, \text{X}\right)=\text{E}\text{n}\text{t}\text{r}\text{o}\text{p}\text{y}\left(\text{S}\right)-\text{E}\text{n}\text{t}\text{r}\text{o}\text{p}\text{y} (\text{S},\text{X})$$
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i.e. substituting before, dataset before the split, and subset j after split for k number of subsets the information gain modified as shown in Eq. (9)
$$\text{I}\text{n}\text{f}\text{o}\text{r}\text{m}\text{a}\text{t}\text{i}\text{o}\text{n} \text{G}\text{a}\text{i}\text{n}=\text{E}\text{n}\text{t}\text{r}\text{o}\text{p}\text{y}\left(\text{b}\text{e}\text{f}\text{o}\text{r}\text{e}\right)-\sum _{\text{j}=1}^{\text{k}}\text{E}\text{n}\text{t}\text{r}\text{o}\text{p}\text{y}(\text{j}, \text{a}\text{f}\text{t}\text{e}\text{r})$$
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The cost function corresponds to the Gini index, which evaluates the splits in the dataset favoring large partitions. Whereas information gain favors small partitions with distinct values. The Gini is computed by summing the probability\({\text{p}}_{\text{i}}\) of node i being chosen times the probability as shown in Eq. (10), a mistake in categorizing that node.
$$\sum _{k\ne i}{p}_{k}=1-{p}_{i}$$
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The Gini index reaches a minimum zero value when all cases in the node belong to the same target category. The Gain Ratio is calculated as in Eq. (11)
$$\text{G}\text{a}\text{i}\text{n} \text{R}\text{a}\text{t}\text{i}\text{o}=\frac{\text{I}\text{n}\text{f}\text{o}\text{r}\text{m}\text{a}\text{t}\text{i}\text{o}\text{n} \text{G}\text{a}\text{i}\text{n}}{\text{S}\text{p}\text{l}\text{i}\text{t} \text{I}\text{n}\text{f}\text{o}}$$
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