Ring splitting and mobile charging vehicle scheduling method and system for wireless rechargeable sensor network

Abstract

The present invention discloses a ring division and mobile charging vehicle scheduling method and system for a wireless rechargeable sensor network. The method comprises the following steps: first, the wireless rechargeable sensor network is initially divided into rings based on the attribute information of the wireless rechargeable sensor network, the attribute information of each sensing node, and the attribute information of the mobile charging vehicle; if the task load of the mobile charging vehicle is uneven in the initial ring division result, a secondary ring division is performed; secondly, the base station dispatches the mobile charging vehicle serving each ring to start the first round of energy replenishment tasks, then obtains the energy consumption rate of the sensing node in each ring and calculates the charging request threshold of each ring; then, the base station dispatches the mobile charging vehicle serving each ring to perform periodic charging starting from the second charging round. The present invention can maintain the periodic changes in the energy of the sensing node, prevent its death, and enable the network to operate stably and sustainably.

Description

Technical Field

[0001] The present invention belongs to the field of wireless rechargeable sensor networks, and in particular relates to a ring division and mobile charging vehicle scheduling method and system for wireless rechargeable sensor networks. Background Art

[0002] Wireless sensor networks (WSNs) are networks composed of wireless sensor nodes deployed in space. These nodes are interconnected via wireless communications and are used to monitor, collect, and transmit information about the environment. They play a vital role in a variety of fields, including environmental monitoring and military reconnaissance. Wireless rechargeable sensor networks (WRSNs) are a special type of wireless sensor network in which sensor nodes have rechargeable batteries, allowing them to recover energy after consumption. Because wireless rechargeable sensor nodes typically use energy-limited sources such as batteries, extending their lifespan has been a research hotspot.

[0003] In this field, wireless charging vehicles are often used to recharge the energy of sensing nodes. When one wireless charging vehicle cannot bear the charging task of all sensing nodes, multiple wireless charging vehicles are often used to charge the sensing nodes. However, many existing technologies limit the shape of the network area served and cannot adapt to more general network areas. In addition, many technologies distribute tasks to mobile charging vehicles unevenly, which results in some mobile charging vehicles having too many or too few tasks. If the task load is too large, the mobile charging vehicle cannot serve all the sensing nodes in its charging queue within one cycle, making some sensing nodes unable to be replenished in time, resulting in the death of the sensing nodes; if the task load is too small, the mobile charging vehicle will be idle for too long, resources will be idle, and resource utilization will be reduced.

[0004] Therefore, how to adapt to network areas with more general shapes, how to balance the task allocation of mobile charging vehicles and plan suitable charging paths, reduce the mortality rate of sensing nodes, and improve energy utilization have become the focus of current research.

[0005] There is an urgent need for a new ring-splitting and mobile charging vehicle scheduling method and system for wireless rechargeable sensor networks. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this paper proposes a method and system for ring segmentation and mobile charging vehicle scheduling for wireless rechargeable sensor networks. Based on the network's attributes, the attributes of each sensing node, and the attributes of the mobile charging vehicles, the wireless rechargeable sensor network is initially segmented into rings. Based on the final segmentation results, the base station performs scheduling services.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The present invention provides a ring-splitting and mobile charging vehicle scheduling method for a wireless rechargeable sensor network, comprising:

[0009] First, the wireless rechargeable sensor network is initially divided into rings based on the attribute information of the wireless rechargeable sensor network, the attribute information of each sensing node, and the attribute information of the mobile charging vehicle.

[0010] Secondly, if the task load of mobile charging vehicles is unbalanced in the initial ring division result, a secondary ring division is performed. Otherwise, the initial ring division result is used to obtain the final ring division result.

[0011] Thirdly, based on the final ring division results, the base station dispatches mobile charging vehicles serving each ring to start the first round of energy replenishment tasks;

[0012] Finally, the base station obtains the energy consumption rate of each ring's sensing node, calculates the charging request threshold of each ring, and schedules the mobile charging vehicles serving each ring to perform periodic charging starting from the second charging round.

[0013] Furthermore, the attribute information of the wireless rechargeable sensor network includes:

[0014] A wireless rechargeable sensor network with no obstacles and any shape. The base station (BS) is located at the center of the wireless rechargeable sensor network and has the ability to broadcast to the entire network. The range of the entire wireless rechargeable sensor network is defined as S max , whose area is recorded as A max ;

[0015] Divide the network into rings from the inside out, and denote the i-th ring as L i , the maximum number of rings is recorded as m, 1≤i≤m; the area enclosed by the outer boundary of the i-th ring is called S i , S i The area is recorded as A i , each S i The shapes are similar to S max Similar, and the center position is the same, and let S m =S max ;

[0016] Furthermore, the attribute information of each sensing node includes:

[0017] N homogeneous sensing nodes are randomly and evenly deployed in the network, denoted as s. The sensing nodes have sensing, communication, and computing capabilities, and their locations are known. They are also equipped with wireless charging coils based on magnetic coupling resonance to receive wireless energy supply from mobile charging vehicles. The maximum battery capacity of all sensing nodes is E0, and they are all fully charged at the beginning. The number of sensing nodes in the i-th ring is denoted as N i ;

[0018] Furthermore, the attribute information of the mobile charging vehicle includes:

[0019] Each ring layer is assigned a mobile charging vehicle that has the ability to transmit wireless energy and wireless data using magnetic coupling resonance and can know its own location coordinates at any time;

[0020] E MC Represents the maximum amount of electricity that a mobile charging vehicle can carry, E M (i) represents the energy consumed by the mobile charging vehicle to charge all the sensing nodes in the i-th ring for one round, E C (i) represents the energy consumed by a mobile charging vehicle to charge all sensor nodes in the i-th ring.

[0021] Furthermore, the initial ring division of the wireless rechargeable sensor network includes:

[0022] S101, initialize i=1, m=1, flag=0, where flag is a Boolean value that determines whether the current ring splitting scheme requires "secondary ring splitting". Flag=0 indicates that "secondary ring splitting" is not required, and flag=1 indicates that "secondary ring splitting" is required;

[0023] S102, determine N i , then calculate the minimum "can cover greater than or equal to N i The ring of sensing nodes is L i If the number of sensing nodes in the network that have not yet been divided into the ring is less than N i , let L m =S max -S i-1 , and let m=i,N m is the number of sensing nodes that have not yet been divided into the ring, calculate E M (m) and E C (m), the initial sub-ring is completed, and the process goes to S201, otherwise, the process continues to S103;

[0024] S103, L i The area is expanded by 5% and the value is stored in the temporary variable L temp In, if L temp The outer boundary of L exceeds the network boundary. m=S max -S i-1 , and let m=i,N m is the number of sensing nodes that have not yet been divided into the ring, calculate E M (m) and E C (m), the initial ring is completed, go to S201, otherwise calculate E M (i) and E C (i), and continue to execute S104; expanding the area by 5% each time is based on a comprehensive consideration of calculation accuracy and time overhead. If an expansion ratio greater than 5% is selected, the area expanded each time is too large, the calculation accuracy is reduced, and the implementation result of the method is poor; if an expansion ratio less than 5% is selected, the area expanded each time is too small, and more calculations are required, which increases the time overhead of the method. Considering the above, 5% is selected as the ratio of each area expansion.

[0025] S104, if E is satisfied M (i)+E C (i)≤E MC , then L i Update to temporary variable L temp The value of , go to S103, otherwise update N i For this time L i The number of covered sensing nodes is determined, and S105 is continued to be executed;

[0026] S105, if i is equal to m-1 and flag is equal to 1, then let L m =S max -S i-1 , and let N m is the number of sensing nodes that have not yet been divided into the ring, the ring division is ended, and the final ring division result is obtained. Otherwise, i=i+1, and go to S102.

[0027] Furthermore, considering the outermost ring m ring L m There may be fewer sensing nodes to serve, which may cause an imbalance in the workload of mobile charging vehicles in each ring. Therefore, after initially determining each ring, it is determined whether to perform "secondary ring division". If the workload of mobile charging vehicles in the initial ring division result is uneven, then a secondary ring division is performed. Otherwise, the initial ring division result is used to obtain the final ring division result, including:

[0028] In step S201, let ω represent the ratio of the energy consumed by charging the sensing nodes in the mth ring and the energy consumed by the mobile charging vehicle to the maximum amount of power that the mobile charging vehicle can carry. The expression for ω is:

[0029]

[0030] In step S202, if ω≥60%, the ring split ends; if ω<60%, set flag=1 and perform a second ring split to balance the energy consumption of each ring. Let μ be the percentage of energy consumption of the mobile charging vehicle after balance, and the expression of μ is:

[0031]

[0032] S203, let i=1, E MC =μ×E MC , go to S102.

[0033] Furthermore, N i The value of is given by the following formula:

[0034]

[0035] Among them, e is the energy consumed by the mobile charging vehicle moving 1 meter, d max1 (s,BS) is the maximum Euclidean distance between the sensing node and the base station in the network, d max2 (s,BS) is the second largest Euclidean distance between the sensing node and the base station in the network, d max It is the maximum value of the Euclidean distance between any two sensor nodes in the network.

[0036] The above N i The formula for the value of is solved by the following inequality:

[0037] e×(d max1 (s,BS)+d max2 (s,BS))+e×d max ×(N i -1)+N i ×E0≤E MC

[0038] The meaning of this inequality is to assume an extreme case, that is, the first sensing node and the last sensing node of a periodic service are the farthest and second farthest from the base station respectively, and the path length between the sensing nodes is set to the maximum distance between any two sensing nodes in the network. Each sensing node is fully charged. Since the number of sensing nodes is an integer, it is rounded down. The N calculated to meet this inequality is i Minimum, must be able to meet the subsequent energy constraints.

[0039] Furthermore, E M The expression of (i) is:

[0040] E M (i) = e × l i

[0041] Among them, l iis the length of the shortest Hamiltonian circuit that includes all sensor nodes in the i-th ring. In this method, a Hamiltonian circuit refers to a path that starts from the base station, passes through all sensor nodes in the current ring once and only once, and then returns to the base station;

[0042] E C The expression of (i) is:

[0043]

[0044] Among them, η is the ratio of “energy received by the sensing node” to “total energy of the sensing node”, and ε is the energy receiving efficiency of the sensing node during wireless charging.

[0045] Furthermore, based on the final ring division results, the base station dispatches mobile charging vehicles serving each ring to begin the first round of energy replenishment tasks, including:

[0046] Define the charging stop threshold δ: When the battery charge of any sensing node reaches or exceeds δ, the mobile charging vehicle will stop charging the sensing node and leave to charge the next sensing node. δ is called the charging stop threshold;

[0047] A fully charged sensing node is deployed in the network and starts working and consuming energy. The time at this time is recorded as 0. The base station monitors all sensing nodes. When the first sensing node with a power drop to 70% × E0 appears in the i-th ring, the mobile charging vehicle of the i-th ring starts from the base station and drives in a straight line to the sensing node of the i-th ring, which is the sensing node with the highest energy consumption rate. This sensing node is recorded as s i If there are multiple sensing nodes with the highest energy consumption rate, the nearest sensing node is selected and recorded as s i ;

[0048] s i As the first sensing node served by the mobile charging vehicle starting from the base station, the shortest Hamiltonian circuit is constructed to traverse all sensing nodes in a clockwise order. If the power of any sensing node s has dropped to δ or below, the sensing node is charged to δ. Otherwise, the sensing node is not charged. After traversing all the sensing nodes, the mobile charging vehicle returns to the base station.

[0049] Furthermore, the base station obtains the energy consumption rate of the sensing node of each ring, calculates the charging request threshold of each ring, and schedules the mobile charging vehicle serving each ring to perform periodic charging starting from the second charging round, including:

[0050] Define the charging request threshold θ of the i-th ring i :When the energy consumption rate of the sensing node with the highest energy consumption rate in the i-th layer drops to θ i When θ iThis is called the charging request threshold of the i-th ring. i The expression is:

[0051]

[0052] Among them, the sensing node s with the highest energy consumption rate in the i-th layer ring is i The power consumption is recorded as p i , v is the speed of the mobile charging vehicle, P is the power of the mobile charging vehicle to charge the sensing node, p ij is the energy consumption rate of the jth sensing node in the i-th ring, arranged in the charging order, where 1≤j≤N i ;

[0053] The base station calculates the charging request threshold θ for each ring i ,θ i Only needs to be calculated once, starting from the second charging round, when s i Energy reduced to θ i When , the sensing node sends a charging request, the mobile charging vehicle starts from the base station and traverses the sensing nodes in the ring in a clockwise order, charging each sensing node to δ. After the traversal is completed, the mobile charging vehicle returns to the base station, replaces the battery and waits for the next charging request. When no charging request is received, the mobile charging vehicle rests at the base station.

[0054] θ i The expression is derived from the following process: as long as the sensing node with the highest energy consumption rate in each ring can survive after one cycle of charging and still be charged in the next cycle, then all the sensing nodes in the entire ring can survive, and the cycles of all sensing nodes in the entire ring are the same. The cycle of the i-th layer ring is denoted as T i , expressing

[0055]

[0056] In addition, the time consumed by the mobile charging vehicle serving this ring is The total time to charge the sensing node is If the mobile charging vehicle arrives at the base station to replace the battery and immediately enters the next charging round, then

[0057]

[0058] express Combined, solve for θ i The expression is:

[0059]

[0060] Considering that according to the above formula, there may be θ iIn a larger case, that is, if the mobile charging vehicle arrives at the base station to replace the battery and leaves immediately, s i There may be more energy and the energy utilization rate is low. Therefore, in order to improve the energy utilization rate, the following adjustments are made: i Compare with 30%×E0 and select the smaller one as the charging request threshold θ i The selection of 30% × E0 for comparison is based on a comprehensive consideration of estimating unexpected situations and improving energy utilization. If a smaller energy value is selected, the remaining energy of the sensing node may not be enough to cope with the unexpected situation, and the sensing node may not be able to wait for the arrival of the mobile charging vehicle, resulting in the death of the sensing node. If a larger energy value is selected, the sensing node may request charging due to the remaining energy, which will increase the number of mobile charging vehicle services and reduce energy utilization.

[0061] Therefore, θ i The expression is updated to:

[0062]

[0063] According to another aspect of the present invention, a ring-splitting and mobile charging vehicle dispatching system for a wireless rechargeable sensor network is provided, the system comprising:

[0064] The first module is used to initially divide the wireless rechargeable sensor network into rings according to the attribute information of the wireless rechargeable sensor network, the attribute information of each sensing node, and the attribute information of the mobile charging vehicle;

[0065] The second module is used to perform secondary ring division if the task load of mobile charging vehicles is unbalanced in the initial ring division result. Otherwise, the initial ring division result is used to obtain the final ring division result.

[0066] In the third module, based on the final ring division results, the base station dispatches mobile charging vehicles serving each ring to start the first round of energy replenishment tasks;

[0067] In the fourth module, the base station obtains the energy consumption rate of each ring sensing node, calculates the charging request threshold of each ring, and schedules the mobile charging vehicles serving each ring to perform periodic charging starting from the second charging round.

[0068] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the steps of the ring division and mobile charging vehicle scheduling method for a wireless rechargeable sensor network of the present invention are implemented.

[0069] According to another aspect of the present invention, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the method for ring segmentation and mobile charging vehicle scheduling for a wireless rechargeable sensor network of the present invention are implemented.

[0070] Compared with the existing technology, the beneficial effects achieved by the present invention are: the present invention can maintain the periodic changes in the energy of the sensing nodes, avoid the death of the sensing nodes, and enable the network to operate persistently and stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0072] Figure 1 It is a flow chart of the network ring splitting method of the present invention;

[0073] Figure 2 This is a diagram of an un-ringed wireless rechargeable sensor network in Example 1 of the present invention;

[0074] Figure 3 This is a diagram of the wireless rechargeable sensor network of the initial sub-ring in Example 1 of the present invention;

[0075] Figure 4 This is a wireless rechargeable sensor network diagram of the final sub-ring in Example 1 of the present invention;

[0076] Figure 5 This is a schematic diagram of periodic charging in Example 1 of the present invention. DETAILED DESCRIPTION

[0077] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0078] Example 1:

[0079] The present invention provides a ring-splitting and mobile charging vehicle scheduling method for a wireless rechargeable sensor network, comprising:

[0080] First, the wireless rechargeable sensor network is initially divided into rings based on the attribute information of the wireless rechargeable sensor network, the attribute information of each sensing node, and the attribute information of the mobile charging vehicles. Second, if the task load of the mobile charging vehicles is unbalanced in the initial ring division result, a secondary ring division is performed. Otherwise, the initial ring division result is used to obtain the final ring division result.

[0081] Again, based on the final ring division results, the base station dispatches mobile charging vehicles serving each ring to start the first round of energy replenishment tasks; finally, the base station obtains the energy consumption rate of the sensing nodes in each ring, calculates the charging request threshold of each ring, and dispatches the mobile charging vehicles serving each ring to start periodic charging from the second charging round.

[0082] Step A: Based on the attribute information of the wireless rechargeable sensor network, the attribute information of each sensing node and the attribute information of the mobile charging vehicle, the wireless rechargeable sensor network is initially divided into rings; if the task load of the mobile charging vehicle is unbalanced in the initial ring division result, a secondary ring division is performed, otherwise the initial ring division result is used to obtain the final ring division result. Figure 1 The specific implementation process includes:

[0083] A wireless rechargeable sensor network with no obstacles of any shape. The network is initially undivided into rings. Figure 2 The base station (BS) is located in the center of the wireless rechargeable sensor network and has the ability to broadcast to the entire network; the range of the entire wireless rechargeable sensor network is defined as S max , whose area is recorded as A max N (in this embodiment, N = 65) homogeneous sensing nodes, denoted as s, are randomly and evenly deployed in the network. These sensing nodes have sensing, communication, and computing capabilities, and their locations are known. They are also equipped with wireless charging coils based on magnetic coupling resonance to receive wireless energy recharge from mobile charging vehicles. The maximum battery capacity of all sensing nodes is E0, which in this embodiment is 1000 mAH, and they are all initially fully charged.

[0084] Divide the network into rings from the inside out, and denote the i-th ring as L i , the number of sensing nodes in the i-th ring is recorded as N i , the maximum number of rings is recorded as m, 1≤i≤m; the area enclosed by the outer boundary of the i-th ring is called S i , S i The area is recorded as A i , each S i The shapes are similar to S max Similar, and the center position is the same, and let S m =S max ;

[0085] The attribute information of the mobile charging vehicle includes:

[0086] Each ring layer is assigned a mobile charging vehicle that has the ability to transmit wireless energy and wireless data using magnetic coupling resonance and can know its own location coordinates at any time;

[0087] E MC Represents the maximum amount of electricity that a mobile charging vehicle can carry, E M (i) represents the energy consumed by the mobile charging vehicle to charge all the sensing nodes in the i-th ring for one round, E C (i) represents the energy consumed by a mobile charging vehicle to charge all sensor nodes in the i-th ring.

[0088] Restrictions must be met when splitting the ring

[0089] E M (i)+E C (i)≤E MC

[0090] Meeting this restriction ensures that the mobile charging vehicle can traverse all sensing nodes in the ring to charge and return to the base station normally.

[0091] E M The expression of (i) is:

[0092] E M (i) = e × l i

[0093] Wherein, e is the energy consumed by the mobile charging vehicle moving 1 meter. In this embodiment, e=1J / m, l i is the length of the shortest Hamiltonian circuit that includes all sensor nodes in the i-th ring. In this method, a Hamiltonian circuit refers to a path that starts from the base station, passes through all sensor nodes in the current ring once and only once, and then returns to the base station;

[0094] E C The expression of (i) is:

[0095]

[0096] Wherein, η is the ratio of "energy received by the sensing node" to "total energy of the sensing node", and ε is the energy receiving efficiency of the sensing node during wireless charging. In this embodiment, η = 60% and ε = 70%.

[0097] Now proceed to the ring division, the specific steps are as follows:

[0098] A01, initialize i=1, m=1, flag=0, where flag is a Boolean value that determines whether the current ring splitting scheme requires "secondary ring splitting". Flag=0 indicates that "secondary ring splitting" is not required, and flag=1 indicates that "secondary ring splitting" is required;

[0099] A02, determine N i , Among them, d max1 (s,BS) is the maximum Euclidean distance between the sensing node and the base station in the network, d max2 (s,BS) is the second largest Euclidean distance between the sensing node and the base station in the network, d max It is the maximum value of the Euclidean distance between any two sensing nodes in the network. Then calculate the minimum "can cover greater than or equal to N i The ring of sensing nodes is L iIf the number of sensing nodes in the network that have not yet been divided into the ring is less than N i , let L m =S max -S i-1 , and let m=i,N m is the number of sensing nodes that have not yet been divided into the ring, calculate E M (m) and E C (m), the initial sub-loop is completed, go to A06, otherwise continue to execute A03;

[0100] A03, L i The area is expanded by 5% and the value is stored in the temporary variable L temp In, if L temp The outer boundary of L exceeds the network boundary. m =S max -S i-1 , and let m=i,N m is the number of sensing nodes that have not yet been divided into the ring, calculate E M (m) and E C (m), the initial ring is completed, go to A06, otherwise calculate E M (i) and E C (i) and proceed to A04;

[0101] A04, if E is satisfied M (i)+E C (i)≤E MC , then L i Update to temporary variable L temp The value of , go to A03, otherwise update N i For this time L i The number of sensing nodes covered, and then continue to execute A05;

[0102] A05, if i is equal to m-1 and flag is equal to 1, then let L m =S max -S i-1 , and let N m = is the number of sensing nodes that have not been divided into the ring, the ring division is completed, and the final ring division result is obtained. Otherwise, i=i+1, and go to A02. Figure 3 In this embodiment, the initial sub-ring is divided into three layers of rings, and the number of sensing nodes in each ring is: N1=25, N2=27, and N3=13.

[0103] A06, let ω represent the ratio of the energy consumed by charging the sensing nodes in the mth ring and the energy consumed by the mobile charging vehicle to the maximum amount of power that the mobile charging vehicle can carry. The expression of ω is:

[0104]

[0105] A07, if ω ≥ 60%, the ring split ends; if ω < 60%, set flag = 1 and perform a second ring split to balance the energy consumption of each ring. Let μ be the percentage of energy consumption of the mobile charging vehicle after balance, and the expression of μ is:

[0106]

[0107] A08, let i=1, E MC =μ×E MC , transfer to A02.

[0108] The split ring is completed and the final split ring result is obtained. Figure 4 In this embodiment, the number of sensing nodes in each ring of the final sub-ring is: N1=21, N2=22, N3=22.

[0109] Step B: Based on the final ring division results, the base station dispatches mobile charging vehicles to serve each ring and begins the first round of energy replenishment tasks. The base station obtains the energy consumption rate of the sensing nodes in each ring, calculates the charging request threshold for each ring, and dispatches mobile charging vehicles serving each ring to perform periodic charging starting from the second charging round, including:

[0110] B01, define the charging stop threshold δ: when the battery charge of any sensing node reaches or exceeds δ, the mobile charging vehicle will stop charging the sensing node and leave to charge the next sensing node. δ is called the charging stop threshold. In this embodiment, δ = 90% × E0. A fully charged sensing node is deployed in the network, starts working and consumes energy. The time point at this time is recorded as 0. The base station monitors all sensing nodes. When the first sensing node with a battery charge dropped to 70% × E0 appears in the i-th ring, the mobile charging vehicle of the i-th ring starts from the base station and drives in a straight line to the sensing node of the i-th ring, that is, the sensing node with the highest energy consumption rate. This sensing node is recorded as s i If there are multiple sensing nodes with the highest energy consumption rate, the nearest sensing node is selected and recorded as s i ;

[0111] B02, with s i As the first sensing node served by the mobile charging vehicle starting from the base station, the shortest Hamiltonian circuit is constructed to traverse all sensing nodes in a clockwise order. If the power of any sensing node s has dropped to δ or below, the sensing node is charged to δ. Otherwise, the sensing node is not charged. After traversing all the sensing nodes, the mobile charging vehicle returns to the base station.

[0112] B03, define the charging request threshold θ of the i-th ring i :When the energy consumption rate of the sensing node with the highest energy consumption rate in the i-th layer drops to θ iWhen θ i This is called the charging request threshold of the i-th ring; θ i The expression is:

[0113]

[0114] Among them, the sensing node s with the highest energy consumption rate in the i-th layer ring is i The power consumption is recorded as p i , v is the speed of the mobile charging vehicle, P is the power of the mobile charging vehicle to charge the sensing node. In this embodiment, v = 1m / s, P = 5W, p ij is the energy consumption rate of the jth sensing node in the i-th ring, arranged in the charging order, where 1≤j≤N i ;

[0115] B04, the base station calculates the charging request threshold θ of each ring i ,θ i Only needs to be calculated once, starting from the second charging round, when s i Energy reduced to θ i When , the sensing node sends a charging request, the mobile charging vehicle starts from the base station and traverses the sensing nodes in the ring in a clockwise order, charging each sensing node to δ. After the traversal is completed, the mobile charging vehicle returns to the base station, replaces the battery and waits for the next charging request. When no charging request is received, the mobile charging vehicle rests at the base station. See the schematic diagram of periodic charging for details. Figure 5 , three mobile charging vehicles are performing cycle charging in the three-layer ring.

[0116] This embodiment performs an initial ring division on the wireless rechargeable sensor network based on the attribute information of the wireless rechargeable sensor network, the attribute information of each sensing node, and the attribute information of the mobile charging vehicle. If the task load of the mobile charging vehicle in the initial ring division result is unbalanced, a secondary ring division is performed; otherwise, the initial ring division result is used to obtain a final ring division result. Based on the final ring division result, the base station dispatches the mobile charging vehicles serving each ring to start the first round of energy replenishment tasks. The base station obtains the energy consumption rate of the sensing node in each ring, calculates the charging request threshold of each ring, and dispatches the mobile charging vehicles serving each ring to perform periodic charging starting from the second charging round. The method proposed in the present invention can maintain the periodic changes in the energy of the sensing nodes, avoid the death of the sensing nodes, and enable the network to operate stably and sustainably.

[0117] A ring-splitting and mobile charging vehicle dispatching system for a wireless rechargeable sensor network, the system comprising:

[0118] The first module is used to initially divide the wireless rechargeable sensor network into rings according to the attribute information of the wireless rechargeable sensor network, the attribute information of each sensing node, and the attribute information of the mobile charging vehicle;

[0119] The second module is used to perform secondary ring division if the task load of mobile charging vehicles is unbalanced in the initial ring division result. Otherwise, the initial ring division result is used to obtain the final ring division result.

[0120] In the third module, based on the final ring division results, the base station dispatches mobile charging vehicles serving each ring to start the first round of energy replenishment tasks;

[0121] In the fourth module, the base station obtains the energy consumption rate of each ring sensing node, calculates the charging request threshold of each ring, and schedules the mobile charging vehicles serving each ring to perform periodic charging starting from the second charging round.

[0122] Example 2:

[0123] The computer-readable storage medium of this embodiment stores a computer program, which, when executed by a processor, implements the steps of the method for ring division and mobile charging vehicle scheduling for a wireless rechargeable sensor network of embodiment 1.

[0124] The computer-readable storage medium of this embodiment may be an internal storage unit of the terminal, such as a hard disk or memory of the terminal; the computer-readable storage medium of this embodiment may also be an external storage device of the terminal, such as a plug-in hard disk, a smart memory card, a secure digital card, a flash memory card, etc. equipped on the terminal; further, the computer-readable storage medium may also include both an internal storage unit of the terminal and an external storage device.

[0125] The computer-readable storage medium of this embodiment is used to store computer programs and other programs and data required by the terminal. The computer-readable storage medium can also be used to temporarily store data that has been output or is to be output.

[0126] Example 3:

[0127] The computer device of this embodiment includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the method for ring segmentation and mobile charging vehicle scheduling for a wireless rechargeable sensor network of embodiment 1 are implemented.

[0128] In this embodiment, the processor can be a central processing unit, or other general-purpose processors, digital signal processors, application-specific integrated circuits, off-the-shelf programmable gate arrays or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc. The memory can include read-only memory and random access memory, and provide instructions and data to the processor. A part of the memory can also include non-volatile random access memory. For example, the memory can also store information about the device type.

[0129] Those skilled in the art will appreciate that the disclosed contents of the embodiments may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage and optical storage, etc.) containing computer-usable program code.

[0130] The present invention is described with reference to the flowcharts and / or block diagrams of the methods and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as the combination of the processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions; these computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0131] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0132] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0133] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing related hardware through a computer program. The program can be stored in a computer-readable storage medium, and when executed, the program can include the processes in the above-described method embodiments. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0134] The examples described in the present invention are merely descriptions of the preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should fall within the scope of protection of the present invention.

Claims

1. A method for dispatching rings and mobile charging vehicles for wireless rechargeable sensor networks, characterized in that: include: S1. Based on the attribute information of the wireless rechargeable sensor network, the attribute information of each sensing node and the attribute information of the mobile charging vehicle, the wireless rechargeable sensor network is initially divided into rings; S2. If the initial split results indicate an imbalance in the number of mobile charging vehicles, perform a secondary split. Otherwise, use the initial split results to obtain the final split results. S3. Based on the final ring division results, the base station dispatches mobile charging vehicles to serve each ring, starting the first round of energy replenishment tasks. S4. The base station obtains the energy consumption rate of each ring's sensing node, calculates the charging request threshold for each ring, and schedules the mobile charging vehicles serving each ring to perform periodic charging starting from the second charging round.

2. The method according to claim 1, characterized in that In S1, the attribute information of the wireless rechargeable sensor network includes: A wireless rechargeable sensor network with no obstacles and any shape. The base station is located at the center of the wireless rechargeable sensor network and has the ability to broadcast to the entire network. The range of the entire wireless rechargeable sensor network is defined as S max , whose area is recorded as A max ; Divide the network into rings from the inside out, and denote the i-th ring as L i , the maximum number of rings is recorded as m, 1≤i≤m; the area enclosed by the outer boundary of the i-th ring is called S i , S i The area is recorded as A i , each S i The shapes are similar to S max Similar, and the center position is the same, and let S m =S max ; The attribute information of each sensing node includes: N homogeneous sensing nodes are randomly and evenly deployed in the network, denoted as s. The sensing nodes have sensing, communication and computing capabilities, and their locations are known. They are also equipped with wireless charging coils based on magnetic coupling resonance to receive wireless energy supply from mobile charging vehicles. The maximum battery capacity of all sensing nodes is E0, and they are all fully charged at the beginning. The number of sensing nodes in the i-th ring is denoted as N i ; The attribute information of the mobile charging vehicle includes: Each ring layer is assigned a mobile charging vehicle that has the ability to transmit wireless energy and wireless data using magnetic coupling resonance and can know its own location coordinates at any time; E MC Represents the maximum amount of electricity that a mobile charging vehicle can carry, E M (i) represents the energy consumed by the mobile charging vehicle to charge all the sensing nodes in the i-th ring for one round, E C (i) represents the energy consumed by a mobile charging vehicle to charge all sensor nodes in the i-th ring; E M The expression of (i) is: E M (i)=e×l i Among them, e is the energy consumed by the mobile charging vehicle moving 1 meter, l i is the length of the shortest Hamiltonian circuit that includes all sensor nodes in the i-th ring. A Hamiltonian circuit is a path that starts from the base station, passes through all sensor nodes in the current ring once and only once, and then returns to the base station. E C The expression of (i) is: Where η is the ratio of the energy received by the sensing node to the total energy of the sensing node, and ε is the energy receiving efficiency of the sensing node during wireless charging.

3. The method according to claim 1, characterized in that In S1, the initial ring division of the wireless rechargeable sensor network includes the following steps: S101, initialize i=1, m=1, flag=0, where flag is a Boolean value that determines whether the current ring splitting scheme requires "secondary ring splitting". Flag=0 indicates that "secondary ring splitting" is not required, and flag=1 indicates that "secondary ring splitting" is required. S102, determine N i , then calculate the smallest "can cover greater than or equal to N i The ring of sensing nodes is L i ; If the number of sensing nodes in the network that have not yet been divided into the ring is less than N i , let L m =S max -S i-1 , and let m=i,N m is the number of sensing nodes that have not yet been divided into the ring, calculate E M (m) and E C (m), the initial sub-ring is completed, and the process goes to S201, otherwise, the process continues to S103; N i The value of is given by the following formula: Among them, d max1 (s, BS) is the maximum Euclidean distance between the sensing node and the base station in the network, d max2 (s, BS) is the second largest Euclidean distance between the sensing node and the base station in the network, d max It is the maximum value of the Euclidean distance between any two sensor nodes in the network; S103, L i The area is expanded by 5% and the value is stored in the temporary variable L temp In, if L temp The outer boundary of L exceeds the network boundary. m =S max -S i-1 , and let m=i,N m is the number of sensing nodes that have not yet been divided into the ring, calculate E M (m) and E C (m), the initial ring is completed, go to S201, otherwise calculate E M (i) and E C (i) and continue to execute S104; S104, if E is satisfied M (i)+E C (i)≤E MC , then L i Update to temporary variable L temp The value of , go to S103, otherwise update N i For this time L i The number of covered sensing nodes is determined, and S105 is continued to be executed; S105, if i is equal to m-1 and flag is equal to 1, then let L m =S max -S i-1 , and let N m is the number of sensing nodes that have not yet been divided into the ring, the ring division is ended, and the final ring division result is obtained. Otherwise, i=i+1, and go to S102.

4. The method according to claim 3, characterized in that S2 specifically includes the following steps: In step S201, let ω represent the ratio of the energy consumed by charging the sensing nodes in the mth ring and the energy consumed by the mobile charging vehicle to the maximum amount of power that the mobile charging vehicle can carry. The expression for ω is: S202, if ω ≥ 60%, the ring splitting ends; if ω < 60%, set flag = 1 and perform secondary ring splitting to balance the energy consumption of each ring; Let μ be the energy consumption percentage of the mobile charging vehicle after equilibrium, and the expression of μ is: S203, let i=1, E MC =μ×E MC , go to S102.

5. The method according to claim 1, wherein S3 specifically includes the following steps: defining a charging stop threshold δ: when the battery charge of any sensing node reaches or exceeds δ, the mobile charging vehicle will stop charging the sensing node and leave to charge the next sensing node. δ is called the charging stop threshold; A fully charged sensing node is deployed in the network and starts working and consuming energy. The time at this time is recorded as 0. The base station monitors all sensing nodes. When the first sensing node with a power drop to 70% × E0 appears in the i-th ring, the mobile charging vehicle of the i-th ring starts from the base station and drives in a straight line to the sensing node of the i-th ring, which is the sensing node with the highest energy consumption rate. This sensing node is recorded as s i If there are multiple sensing nodes with the highest energy consumption rate, the nearest sensing node is selected and recorded as s i ; s i As the first sensing node served by the mobile charging vehicle starting from the base station, the shortest Hamiltonian circuit is constructed to traverse all sensing nodes in a clockwise order. If the power of any sensing node s has dropped to δ or below, the sensing node is charged to δ. Otherwise, the sensing node is not charged. After traversing all the sensing nodes, the mobile charging vehicle returns to the base station.

6. The method according to claim 1, characterized in that S4 specifically includes the following steps: defining the charging request threshold θ of the i-th ring i :When the energy consumption rate of the sensing node with the highest energy consumption rate in the i-th layer drops to θ i When θ i This is called the charging request threshold of the i-th ring; θ i The expression is: Among them, the sensing node s with the highest energy consumption rate in the i-th layer ring is i The power consumption is recorded as p i , v is the speed of the mobile charging vehicle, P is the power of the mobile charging vehicle to charge the sensing node, p ij is the energy consumption rate of the jth sensing node in the i-th ring, arranged in the charging order, where 1≤j≤N i ; The base station calculates the charging request threshold θ for each ring i ,θ i Only needs to be calculated once, starting from the second charging round, when s i Energy reduced to θ i When , the sensing node sends a charging request, the mobile charging vehicle starts from the base station and traverses the sensing nodes in the ring in a clockwise order, charging each sensing node to δ. After the traversal is completed, the mobile charging vehicle returns to the base station, replaces the battery and waits for the next charging request. When no charging request is received, the mobile charging vehicle rests at the base station.

7. A ring-splitting and mobile charging vehicle dispatching system for a wireless rechargeable sensor network, characterized by: The first module is used to initially divide the wireless rechargeable sensor network into rings according to the attribute information of the wireless rechargeable sensor network, the attribute information of each sensing node, and the attribute information of the mobile charging vehicle; The second module is used to perform secondary ring division if the task load of mobile charging vehicles is unbalanced in the initial ring division result. Otherwise, the initial ring division result is used to obtain the final ring division result. In the third module, based on the final ring division results, the base station dispatches mobile charging vehicles to serve each ring and starts the first round of energy replenishment tasks; In the fourth module, the base station obtains the energy consumption rate of each ring sensing node, calculates the charging request threshold of each ring, and dispatches the mobile charging vehicles serving each ring to perform periodic charging starting from the second charging round.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the ring division and mobile charging vehicle scheduling method for a wireless rechargeable sensor network as described in claim 7 are implemented.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the ring division and mobile charging vehicle scheduling method for a wireless rechargeable sensor network as described in claim 7 are implemented.

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