阅读说明：本技术 一种无人机通信技术结合无线能量传输的联合优化方法 (Unmanned aerial vehicle communication technology and wireless energy transmission combined optimization method ) 是由 黄高飞 赵讯 叶炜 赵赛 唐冬 于 2021-07-13 设计创作，主要内容包括：本发明涉及一种无人机通信技术结合无线能量传输的联合优化方法,包括步骤：S1、建立无人机与地面传感器无线能量传输和数据传输模型,联合优化无线能量传输区间、数据传输区间、无人机速度、无人机在无线能量传输区间工作的时间和无人机在数据传输区间工作的时间,进而最小化无人机总的飞行时间；S2、求解无人机对一个地面传感器的最小飞行时间；S3、扩展无人机对所有地面传感器的解。本发明通过无人机飞行速度的优化,能量传输和数据收集两个阶段的时间优化,对无人机飞行时间进行优化,使其在满足无人机与地面传感器通信要求的同时,减少无人机的飞行时间,能够节省无人机的飞行能耗,提升无人机作为飞行基站进行辅助通信的应用价值。(The invention relates to a joint optimization method combining unmanned aerial vehicle communication technology and wireless energy transmission, which comprises the following steps: s1, establishing a wireless energy transmission and data transmission model of the unmanned aerial vehicle and the ground sensor, and jointly optimizing a wireless energy transmission interval, a data transmission interval, the speed of the unmanned aerial vehicle, the working time of the unmanned aerial vehicle in the wireless energy transmission interval and the working time of the unmanned aerial vehicle in the data transmission interval so as to minimize the total flight time of the unmanned aerial vehicle; s2, solving the minimum flight time of the unmanned aerial vehicle to a ground sensor; and S3, expanding the solution of the unmanned aerial vehicle to all the ground sensors. According to the invention, the flight time of the unmanned aerial vehicle is optimized through the optimization of the flight speed of the unmanned aerial vehicle and the time optimization of two stages of energy transmission and data collection, so that the flight time of the unmanned aerial vehicle is reduced while the communication requirement of the unmanned aerial vehicle and a ground sensor is met, the flight energy consumption of the unmanned aerial vehicle can be saved, and the application value of the unmanned aerial vehicle as a flight base station for auxiliary communication is improved.)

1. A joint optimization method combining unmanned aerial vehicle communication technology and wireless energy transmission is characterized by comprising the following steps:

s1, jointly optimizing a wireless energy transmission interval, a data transmission interval, the speed of the unmanned aerial vehicle, the working time of the unmanned aerial vehicle in the wireless energy transmission interval and the working time of the unmanned aerial vehicle in the data transmission interval by establishing a wireless energy transmission and data transmission model of the unmanned aerial vehicle and the ground sensor, and further minimizing the total flight time of the unmanned aerial vehicle;

s2, solving the minimum flight time of the unmanned aerial vehicle to a ground sensor;

and S3, expanding the solutions of the unmanned aerial vehicle to all the ground sensors by using the solution of the unmanned aerial vehicle to the minimum flight time of one ground sensor.

2. The joint optimization method for unmanned aerial vehicle communication technology and wireless energy transmission according to claim 1, wherein the specific steps of step S1 are as follows:

s11, arranging a plurality of sensors on the ground, and collecting data by using the unmanned aerial vehicle to fly over the N sensors; if the arranged sensors are positioned on a line, the serial number is S₁S₂...S_nH is the fixed height of the unmanned plane, W is the bandwidth, beta₀The radio frequency transmission power of the unmanned aerial vehicle to the sensor is fixed to be P for the reference channel ratio⁽¹⁾And the transmitting power is fixed to P when the sensor transmits data to the unmanned aerial vehicle⁽²⁾The channel model adopts an LOS ground-air channel model; if the set sensor is two-dimensional and has a given access sequence, converting the set sensor into an equivalent model of a line model, and taking [ S [ [ S ]_n,S_n+1]Midpoint j of interval_nAs y_nAnd x_n+1As the end of the sensor interval and the start of the next sensor interval;

s12, dividing the transmission interval of the unmanned aerial vehicle into two parts; time for flight of unmanned aerial vehicle to transmit energy to Nth sensorFor the first part of each transmission interval, inIn the method, the unmanned aerial vehicle transmits energy to a sensor; [ x ] of_n,z_n]A range interval for the drone to transmit energy to the sensor, and within the range interval, the drone is at a fixed speedThe flight or unmanned plane hovers at a certain point to transmit energy and then at the maximum speed v_maxFlying away; time for collecting data of Nth sensor by unmanned aerial vehicle flightFor a second part of each transmission interval, inIn, the sensors transmit data to the drone using the collected energy, [ z_n,y_n]Range interval for sensor to transmit data to drone, in [ z ]_n,y_n]In, unmanned plane is with fixed speedFlying; optimization of v_n1,v_n2,x_n,y_n,z_n,I.e. the speed v of the drone in the energy harvesting phase, respectively_n1Speed v of the data collection phase_n2Unmanned aerial vehicle transmission energy interval [ x ]_n,z_n]And a collected data interval [ z ]_n,y_n]Time spent by the drone transmitting energyAnd the time spent by the drone collecting the dataTo optimize the minimum flight time of the drone.

3. The joint optimization method for unmanned aerial vehicle communication technology and wireless energy transmission according to claim 2, wherein the step S12 is implemented as follows:

s121, in the range interval [ x ] of the first part of unmanned aerial vehicle for transmitting energy to the sensor_n,z_n]In, use radio frequency wireless transmission to charge for the user in the downlink through unmanned aerial vehicle, the sensor collects the energy, it is fixed as P to establish unmanned aerial vehicle to the radio frequency transmitting power of sensor⁽¹⁾Then the power of the energy collected by the sensor is:

wherein the content of the first and second substances,the time for the drone to transmit energy to the sensor in each transmission interval; eta is wireless energy transmission efficiency, is a constant, and is 0<η<1；h_nChannel gain of the nth unmanned aerial vehicle transmission energy interval; x is the number of_nThe starting point of the nth unmanned aerial vehicle transmission energy interval; s_nIs the position of the Nth sensor;

the total energy obtained by the sensor is then:

wherein the content of the first and second substances,the time for the drone to transmit energy to the sensor in each transmission interval;

s122, in the range interval [ z ] of the second part of sensors for transmitting data to the unmanned aerial vehicle_n,y_n]Internal, sensingThe device utilizes the energy collected in the first part wireless energy transmission to transmit data to the unmanned aerial vehicle, and the transmitting power is fixed as P when the sensor transmits data to the unmanned aerial vehicle⁽²⁾Then the rate at which the sensor uploads data is:

wherein α is a path loss exponent; z is a radical of_nThe nth sensor transmits data to the starting point of the range interval of the unmanned aerial vehicle;

s123, minimizing the total flight time of the unmanned aerial vehicle, wherein the specific formula is as follows:

wherein the content of the first and second substances,

wherein the content of the first and second substances,transmitting data for the unmanned aerial vehicle during flight; i is_hData is transmitted for the unmanned aerial vehicle when hovering.

4. The joint optimization method for the unmanned aerial vehicle communication technology and the wireless energy transmission according to claim 3, wherein the sensor transmits data to the unmanned aerial vehicle in step S122, and the following constraints are satisfied:

s1221, in the range interval [ z ] of the second part of sensors for transmitting data to the unmanned aerial vehicle_n,y_n]In the inner, the sensor needs to upload more than B_nData of bits:

wherein n is the number of iterations; b is_nThe data volume to be uploaded for the Nth sensor;

s1222, each sensor transmits power without energy consumption exceeding the energy carried by itself, and the sensor uses fixed transmitting power P⁽²⁾To transmit data, then

5. The joint optimization method for unmanned aerial vehicle communication technology and wireless energy transmission according to claim 1, wherein the step S2 is implemented as follows:

s21, converting the total flight time of the unmanned aerial vehicle minimized in the step S1 into the minimum flight time of a single sensor, firstly converting the minimum flight time of a plurality of sensors into the minimum flight time of the single sensor, and setting (S)₀,S₂) For the transmission interval of the sensor, S₁Is the position of the sensor and is provided with S₁The minimum time of flight for a single sensor is obtained by minimizing the total time of flight for the drone as follows:

wherein the content of the first and second substances,

0≤v⁽¹⁾≤v_max

0≤v⁽²⁾≤v_max

S₀≤x≤z≤y≤S₂

wherein v is⁽¹⁾The flight speed of the unmanned aerial vehicle when transmitting energy; v. of⁽²⁾The flight speed of the unmanned aerial vehicle when receiving the data; x is the starting point of the unmanned aerial vehicle transmission energy interval; z is the starting point of a data transmission interval of the sensor; y is the end point of the data transmission interval of the sensor; t is t⁽¹⁾The time consumed by energy transmission when the unmanned aerial vehicle flies; t is t⁽²⁾The time consumed by the sensor for transmitting data when the unmanned aerial vehicle flies is calculated; t is t_h1The time consumed by energy transmission when the unmanned aerial vehicle is suspended; t is t_h2The time consumed by the sensor for transmitting data when the unmanned aerial vehicle is suspended is saved; i is_z≠xThe unmanned aerial vehicle transmits energy in flight as 1; i is_z＝xThe unmanned aerial vehicle transmits energy when hovering as 1; i is_z≠yThe data are transmitted by the unmanned aerial vehicle during flying as 1; i is_z＝yThe data are transmitted when the unmanned plane hovers 1;

s22, by giving a condition that satisfies the constraint S₀≤x≤z≤y≤S₂(x, y) of (a), the optimization of the minimum time of flight of a single sensor is translated into the following optimization:

wherein the content of the first and second substances,

6. the joint optimization method for unmanned aerial vehicle communication technology and wireless energy transmission according to claim 5, wherein the solution of optimizing the minimum flight time of step S22 is performed by the following iterative solution:

s221, give v⁽²⁾、t⁽²⁾Solving for v⁽¹⁾、z、t⁽¹⁾(ii) a The specific optimization process is as follows:

wherein the content of the first and second substances,

0≤v⁽¹⁾≤v_max

wherein the energy is constrained toThe least time spent is calculated:

by integral transformationThe product of this formula is decomposed to yield:

namely:

let E₂＝P⁽²⁾t⁽²⁾Obtaining a new minimum flight time as follows:

wherein the content of the first and second substances,

0≤v⁽¹⁾≤v_max

wherein E is₂The energy required to transmit the data;

solving new minimum flight time, finding a z value meeting the data quantity constraint by using a dichotomy and defining the z value as z_maxIn (x, z)_max) Giving z, judging whether the constraint condition of the speed can be met, and if so, solving v⁽¹⁾，t⁽¹⁾Otherwise, finding the minimum z value in (x, z) by dichotomy, wherein the minimum z value can meet the constraint condition and is the minimum in time;

calculating the time consumed by the unmanned aerial vehicle when hovering to transmit energy to the sensorThe calculation formula is as follows:

calculating the time consumed by the unmanned aerial vehicle when hovering to transmit energy to the sensorThen, the time is compared with the time of the non-hovering state, and the time is taken to be shortWill be provided withThe corresponding z value is substituted into step S222 for iterative solution;

s222, utilizing v acquired in step S221⁽¹⁾、z、t⁽¹⁾Solving for v⁽²⁾、t⁽²⁾：

Wherein the content of the first and second substances,

0≤v⁽²⁾≤v_max

calculating the time consumed by the unmanned aerial vehicle when hovering to collect data from the sensorThe calculation formula is as follows:

by constraint P⁽²⁾t⁽²⁾≤E₁To obtainI.e. v⁽²⁾Having a minimum velocityThe optimization is continued as follows:

wherein the content of the first and second substances,

P⁽²⁾*t⁽²⁾≤E₁

calculate B_maxIntegration of (d) yields:

wherein, B_max(v) If B or more satisfies the condition, then calculateIf the condition is satisfied, use B_max(v) Calculated as B, get the maximum v⁽²⁾The shortest time is obtained;

if it is calculatedWhen the condition of B is satisfied, adopting hovering scheme, and calculating by hovering, if yes, adopting hovering schemeThe energy provided is insufficient;

calculate t⁽²⁾The energy to be collected is determined according to the following equation:

E⁽²⁾＝P⁽²⁾t⁽²⁾ (19)

substituting the value into step S221 for iterative solution, wherein the final judgment condition of the iterative solution isAnd isIf yes, a fixed set of (x, y) solutions is obtained, and multiple sets of (x, y) solutions are listed by using an enumeration method, namely, an optimal solution is obtained.

7. The joint optimization method for unmanned aerial vehicle communication technology combined with wireless energy transmission according to claim 1, wherein step S3 comprises the following steps:

s31, taking [ S_n,S_n+1]Midpoint j of interval_nAs y_nAnd x_n+1As the transmissionThe end of the sensor transmission interval and the beginning of the next sensor transmission interval;

s32, calculating each ground sensor, sequentially obtaining the optimal solution of all the sensors, and obtaining the optimal interval of each sensor as And

s33, judgmentAndand [ S ]_n,S_n+1]Midpoint j of interval_nIs determined by the relationship ofIf it isThen orderRecalculating the optimal solution of the sensor node; judgment ofIf it isThen orderAnd recalculateAnd calculating the optimal solution of the sensor node.

Technical Field

The invention relates to the technical field of unmanned aerial vehicle wireless communication and wireless energy, in particular to a joint optimization method combining unmanned aerial vehicle communication technology and wireless energy transmission.

Background

In recent years, unmanned aerial vehicles have been a popular field, and cargo distribution, real-time video transmission, agricultural plant protection, and the like using unmanned aerial vehicles as carriers have been rapidly developed in the past decade. Because it has characteristics such as mobility is strong, small and the cost is low, will also see unmanned aerial vehicle's shadow in more fields in the future. The unmanned aerial vehicle auxiliary communication system can be applied to the field of the Internet of things, the Internet of things node generally has the characteristics of small transmitting power, incapability of carrying out remote communication and the like, and the unmanned aerial vehicle can serve as a mobile base station or a mobile relay to assist the Internet of things node to complete data transmission service in a shorter time by planning the flight track of the unmanned aerial vehicle.

However, the existing research work focuses on improving the energy efficiency or spectrum efficiency of the sensor node, but ignores the fact that the limited energy of the drone is one of the fundamental bottlenecks of the drone-assisted wireless network. Unmanned aerial vehicle's main energy resource consumption lies in propulsion control system, and unmanned aerial vehicle's energy consumption model is very complicated, under the limited condition of unmanned aerial vehicle maximum speed, reduces flight time and is an effective mode that reduces unmanned aerial vehicle energy loss. However, the existing minimum flight time optimization scheme of the unmanned aerial vehicle does not consider wireless energy transmission, and batteries of the sensors are exhausted quickly, so that network connection is interrupted.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides a combined optimization method combining unmanned aerial vehicle communication technology and wireless energy transmission, and the flight time of the unmanned aerial vehicle is optimized through the optimization of the flight speed of the unmanned aerial vehicle and the time optimization of two stages of energy transmission and data collection, so that the flight time of the unmanned aerial vehicle is reduced while the communication requirements of the unmanned aerial vehicle and a ground sensor are met, the flight energy consumption of the unmanned aerial vehicle can be saved, and the application value of the unmanned aerial vehicle as a flight base station for auxiliary communication is improved.

The invention is realized by adopting the following technical scheme: a joint optimization method combining unmanned aerial vehicle communication technology and wireless energy transmission comprises the following steps:

s1, jointly optimizing a wireless energy transmission interval, a data transmission interval, the speed of the unmanned aerial vehicle, the working time of the unmanned aerial vehicle in the wireless energy transmission interval and the working time of the unmanned aerial vehicle in the data transmission interval by establishing a wireless energy transmission and data transmission model of the unmanned aerial vehicle and the ground sensor, and further minimizing the total flight time of the unmanned aerial vehicle;

s2, solving the minimum flight time of the unmanned aerial vehicle to a ground sensor;

and S3, expanding the solutions of the unmanned aerial vehicle to all the ground sensors by using the solution of the unmanned aerial vehicle to the minimum flight time of one ground sensor.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. according to the invention, aiming at the characteristics of high mobility and sight line transmission of the unmanned aerial vehicle, in the communication between the unmanned aerial vehicle and the ground sensor, the ground sensor collects the radio frequency energy provided by the unmanned aerial vehicle through the radio frequency energy collecting circuit to supply power to the nodes, so that the problem of limited system service life caused by the requirement of battery maintenance on the conventional ground information collecting nodes is solved; simultaneously, according to unmanned aerial vehicle flight speed optimization, the time optimization in energy transmission and data collection two stages optimizes unmanned aerial vehicle flight time, makes it when satisfying unmanned aerial vehicle and ground sensor communication requirement, reduces unmanned aerial vehicle's flight time, can save unmanned aerial vehicle's flight energy consumption, promotes unmanned aerial vehicle and carries out auxiliary communication's using value as the flight basic station.

2. According to the invention, the unmanned aerial vehicle is used as a mobile data center and an energy center to provide wireless energy supply for the ground sensor, the ground sensor sends data to the unmanned aerial vehicle through the collected energy, and compared with a model for collecting ground node data by other unmanned aerial vehicles, the model provides convenient and stable energy supply for the ground sensor through wireless energy transmission by utilizing the unmanned aerial vehicle, so that the problem of short service life of the ground sensor due to limited battery energy can be solved; in addition, in order to achieve the purpose of minimizing the flight time of the unmanned aerial vehicle, a method for optimizing energy transmission and data collection is designed, and an optimization algorithm for performing iterative computation on the energy transmission and data collection stages is derived in the method, so that the flight energy consumption of the unmanned aerial vehicle can be saved, and a green unmanned aerial vehicle data collection system is achieved.

Drawings

FIG. 1 is a flow chart of a method of the present invention;

FIG. 2 is a schematic diagram of data collection by an unmanned aerial vehicle flying over a sensor;

FIG. 3a is a schematic diagram of a sensor distribution in two dimensions with a given access sequence distribution;

FIG. 3b is a schematic diagram of an equivalent model with sensors distributed in two dimensions and with a given access sequence converted to a line model;

FIG. 4 is a flow chart of an algorithm for optimizing minimum time of flight.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.

Examples

As shown in fig. 1, the joint optimization method combining the unmanned aerial vehicle communication technology and the wireless energy transmission in this embodiment is based on a model in which an unmanned aerial vehicle is used as a ground sensor data collection center and a wireless energy transmission model, and mainly includes the following steps:

s1, jointly optimizing a wireless energy transmission interval, a data transmission interval, the speed of the unmanned aerial vehicle, the working time of the unmanned aerial vehicle in the wireless energy transmission interval and the working time of the unmanned aerial vehicle in the data transmission interval by establishing a wireless energy transmission and data transmission model of the unmanned aerial vehicle and the ground sensor, and further minimizing the total flight time of the unmanned aerial vehicle;

s2, solving the minimum flight time of the unmanned aerial vehicle to a ground sensor;

and S3, expanding the solutions of the unmanned aerial vehicle to all the ground sensors by using the solution of the unmanned aerial vehicle to the minimum flight time of one ground sensor.

In this embodiment, the specific steps of step S1 are as follows:

s11, arranging a plurality of sensors on the ground, and collecting data by using the unmanned aerial vehicle to fly over the N sensors; specifically, as shown in fig. 2, if the sensors are arranged on a line, the number S is set₁S₂...S_nH is the fixed height of the unmanned plane, W is the bandwidth, beta₀The radio frequency transmission power of the unmanned aerial vehicle to the sensor is fixed to be P for the reference channel ratio⁽¹⁾And the transmitting power is fixed to P when the sensor transmits data to the unmanned aerial vehicle⁽²⁾The channel model adopts LOS (line of sight transmission) ground-air channel model; if the sensor is two-dimensional and has a given access order, as shown in FIG. 3a, it is converted to an equivalent model of the line model shown in FIG. 3b, and [ S ] is taken_n,S_n+1]Midpoint j of interval_nAs y_nAnd x_n+1I.e. the end of the interval as the sensor and the start of the next sensor interval.

S12, dividing the transmission interval of the unmanned aerial vehicle into two parts; time for flight of unmanned aerial vehicle to transmit energy to Nth sensorFor the first part of each transmission interval, inIn the method, the unmanned aerial vehicle transmits energy to a sensor; [ x ] of_n,z_n]A range interval for the drone to transmit energy to the sensor, and within the range interval, the drone is at a fixed speedThe flight or unmanned plane hovers at a certain point to transmit energy and then at the maximum speed v_maxFlying away; time for collecting data of Nth sensor by unmanned aerial vehicle flightFor a second part of each transmission interval, inIn, the sensors transmit data to the drone using the collected energy, [ z_n,y_n]Range interval for sensor to transmit data to drone, in [ z ]_n,y_n]In, unmanned plane is with fixed speedFlying; optimization of v_n1,v_n2,x_n,y_n,z_n,I.e. the speed of the drone in the energy harvesting phase respectively_vn1Speed of data collection phase_vn2Unmanned aerial vehicle transmission energy interval [ x ]_n,z_n]And a collected data interval [ z ]_n,y_n]Time spent by the drone transmitting energyAnd the time spent by the drone collecting the dataTo optimize the minimum flight time of the drone.

In this embodiment, the specific implementation process of step S12 is as follows:

s121, in the range interval [ x ] of the first part of unmanned aerial vehicle for transmitting energy to the sensor_n,z_n]In, use radio frequency wireless transmission to charge for the user in the downlink through unmanned aerial vehicle, the sensor collects the energy, it is fixed as P to establish unmanned aerial vehicle to the radio frequency transmitting power of sensor⁽¹⁾Then the power of the energy collected by the sensor is:

wherein the content of the first and second substances,the time for the drone to transmit energy to the sensor in each transmission interval; eta is wireless energy transmission efficiency, is a constant, and is 0<η<1；h_nChannel gain of the nth unmanned aerial vehicle transmission energy interval; x is the number of_nThe starting point of the nth unmanned aerial vehicle transmission energy interval; s_nIs the position of the Nth sensor;

the total energy obtained by the sensor is then:

wherein the content of the first and second substances,the time for the drone to transmit energy to the sensor in each transmission interval.

In this process, the drone is in the interval [ x ]_n,z_n]Give sensor transmission data in, when unmanned aerial vehicle can fly or hover transmission energy, if unmanned aerial vehicle adopts the scheme of hovering, then unmanned aerial vehicle flies to z with maximum speed in advance_nDot or S_nAbove the point, then at z_nDot or S_nThe hover transmit energy is maintained above the point and then flies to the next sensor's transmit interval at maximum velocity.

Wherein, whether unmanned aerial vehicle hovers when energy transmission, withTo judge if x_n＝z_nThen it means that the drone is at z_nPoint hovering over transmitted energy, if x_n≠z_nThat is to sayRepresenting that the unmanned aerial vehicle transmits energy while flying;

s122, transmitting the sensor in the second partRange interval [ z ] for data transmission to unmanned aerial vehicle_n,y_n]In, the sensor utilizes the energy of collecting in the first part wireless energy transmission, and transmission data gives unmanned aerial vehicle, and transmit power is fixed for P when establishing the sensor and sending data to unmanned aerial vehicle⁽²⁾Then the rate at which the sensor uploads data is:

wherein α is a path loss index, generally α is greater than or equal to 2, and the value of this embodiment is α is 2; z is a radical of_nThe nth sensor transmits data to the starting point of the range interval of the unmanned aerial vehicle.

If when flying with unmanned aerial vehicle's minimum speed, when unmanned aerial vehicle flew to next sensor transmission interval, unmanned aerial vehicle still failed to receive the whole data of sensor, then unmanned aerial vehicle will hover in z in advance_nDot or S_nAbove the point, the flight is made to the next sensor transmission interval at maximum speed after the required data has been collected.

Wherein, whether the unmanned aerial vehicle hovers when receiving the data, useTo judge if z is_n＝y_nThen it means that the drone is at z_nDot or S_nHovering over a point to receive data;

s123, minimizing the total flight time of the unmanned aerial vehicle, wherein the specific formula is as follows:

wherein the content of the first and second substances,

wherein the content of the first and second substances,transmitting data for the unmanned aerial vehicle during flight; i is_hData is transmitted for the unmanned aerial vehicle when hovering.

Specifically, in the process of transmitting data to the drone by the sensor in step S122, the following constraint conditions are provided:

s1221, in the range interval [ z ] of the second part of sensors for transmitting data to the unmanned aerial vehicle_n,y_n]In the inner, the sensor must upload more than B_nData of bits:

wherein n is the number of iterations; b is_nThe data volume to be uploaded for the Nth sensor;

s1222, the energy consumed by the emission power of each sensor can not exceed the energy carried by the sensor, and the sensor is set to use the fixed emission power P⁽²⁾To transmit data, then

In this embodiment, the specific implementation process of step S2 is as follows:

s21, converting the total flight time of the unmanned aerial vehicle minimized in the step S1 into the minimum flight time of a single sensor, firstly converting the minimum flight time of a plurality of sensors into the minimum flight time of the single sensor, and setting (S)₀,S₂) For the transmission interval of the sensor, S₁Is the position of the sensor, and assumes S₁The minimum time of flight for a single sensor is obtained by minimizing the total time of flight for the drone as follows:

wherein the content of the first and second substances,

0≤v⁽¹⁾≤v_max

0≤v⁽²⁾≤v_max

S₀≤x≤z≤y≤S₂

wherein v is⁽¹⁾The flight speed of the unmanned aerial vehicle when transmitting energy; v. of⁽²⁾The flight speed of the unmanned aerial vehicle when receiving the data; x is the starting point of the unmanned aerial vehicle transmission energy interval; z is transmissionA starting point of a data transmission interval of the sensor; y is the end point of the data transmission interval of the sensor; t is t⁽¹⁾The time consumed by energy transmission when the unmanned aerial vehicle flies; t is t⁽²⁾The time consumed by the sensor for transmitting data when the unmanned aerial vehicle flies is calculated; t is t_h1The time consumed by energy transmission when the unmanned aerial vehicle is suspended; t is t_h2The time consumed by the sensor for transmitting data when the unmanned aerial vehicle is suspended is saved; i is_z≠xThe unmanned aerial vehicle transmits energy in flight as 1; i is_z＝xThe unmanned aerial vehicle transmits energy when hovering as 1; i is_z≠yThe data are transmitted by the unmanned aerial vehicle during flying as 1; i is_z＝yThe data are transmitted when the unmanned plane hovers 1;

s22, by giving a condition that satisfies the constraint S₀≤x≤z≤y≤S₂(x, y) the above optimization of the minimum time of flight of a single sensor becomes the following optimization:

wherein the content of the first and second substances,

0≤v⁽¹⁾≤v_max

0≤v⁽²⁾≤v_max

as shown in fig. 4, in the present embodiment, the solution of the optimized minimum flight time of step S22 is performed by the following iterative solution:

s221, give v⁽²⁾、t⁽²⁾Solving for v⁽¹⁾、z、t⁽¹⁾(ii) a The specific optimization process is as follows:

wherein the content of the first and second substances,

0≤v⁽¹⁾≤v_max

wherein the energy is constrained toThe least time spent can be calculated by directly waiting for the number:

by integral transformationThe product of this formula is decomposed to yield:

namely:

let E₂＝P⁽²⁾t⁽²⁾Obtaining a new minimum flight time as follows:

wherein the content of the first and second substances,

0≤v⁽¹⁾≤v_max

wherein E is₂The energy required to transmit the data.

Solving new minimum flight time, finding a z value meeting the data quantity constraint by using a dichotomy and defining the z value as z_maxIn (x, z)_max) Giving z, judging whether the constraint condition of the speed can be met, and if so, solving v⁽¹⁾，t⁽¹⁾Otherwise, find the smallest z value in (x, z) with time that can satisfy the constraint condition by dichotomy.

Calculating the time consumed by the unmanned aerial vehicle when hovering to transmit energy to the sensorThe calculation formula is as follows:

calculating the time consumed by the unmanned aerial vehicle when hovering to transmit energy to the sensorThen, the time is compared with the time of the non-hovering state, and the time is taken to be shortWill be provided withThe corresponding z value is substituted into step S222 for iterative solution.

S222, utilizing v acquired in step S221⁽¹⁾、z、t⁽¹⁾Solving for v⁽²⁾、t⁽²⁾：

Wherein the content of the first and second substances,

0≤v⁽²⁾≤v_max

calculating the time consumed by the unmanned aerial vehicle when hovering to collect data from the sensorThe calculation formula is as follows:

by constraint P⁽²⁾t⁽²⁾≤E₁To obtainI.e. v⁽²⁾Having a minimum velocityThe optimization is continued as follows:

wherein the content of the first and second substances,

P⁽²⁾*t⁽²⁾≤E₁

calculate B_maxIntegration of (d) yields:

from the above, B_max(v⁽²⁾) And v⁽²⁾In inverse proportion, that is, as long as B_max(v) If B or more satisfies the condition, it can be foundThen use B directly as long as the condition is satisfied_max(v) B, the maximum v is obtained⁽²⁾Thus obtaining the shortest time.

If it is calculatedIf the condition of B is satisfied, then a hovering scheme is adopted and calculation is performed by hovering, and if the condition is satisfied, the calculation is performed by hoveringThe energy provided is insufficient.

Calculate t⁽²⁾The energy to be collected is determined according to the following equation:

E⁽²⁾＝P⁽²⁾t⁽²⁾ (19)

substituting the value into step S221 for iterative solution, wherein the final judgment condition of the iterative solution is v after the iterative process⁽²⁾、t⁽²⁾Constant, or given v⁽²⁾、t⁽²⁾And v obtained by calculation⁽²⁾、t⁽²⁾The difference being less than an error, i.e.And isIf yes, a fixed set of solutions (x, y) is obtained, and the optimal solution can be obtained by enumerating a plurality of sets of solutions (x, y) by an enumeration method.

In this embodiment, the step S3 includes the following steps:

s31, taking [ S_n,S_n+1]Midpoint j of interval_nAs y_nAnd x_n+1I.e. as the end of the sensor transmission interval and the start of the next sensor transmission interval;

s32, calculating each ground sensor, sequentially obtaining the optimal solution of all the sensors, and obtaining the optimal interval of each sensor as And

s33, judgmentAndand [ S ]_n,S_n+1]Midpoint j of interval_nIs determined by the relationship ofIf it isThen orderRecalculating the optimal solution of the sensor node; judgment ofIf it isThen orderAnd recalculate the optimal solution for the sensor node.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.