CN111813167B - Flight speed and trajectory combined optimization method and system - Google Patents
Flight speed and trajectory combined optimization method and system Download PDFInfo
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Abstract
The invention discloses a combined optimization method and a system of flight speed and trajectory, wherein the method comprises the following steps: determining the optimal number of flying turns, the optimal flying radius and the optimal flying speed of the unmanned aerial vehicle in the mode 1, and calculating the number of received information bits and the difference value of the unmanned aerial vehicle in the mode 1; judging whether the difference is greater than the precision; if so, enabling the unmanned aerial vehicle to calculate the number of received information bits in the mode 1 to be equal to the number of the information bits received by the unmanned aerial vehicle in the mode 1, and re-determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 1; otherwise, determining the optimal flight time of the unmanned aerial vehicle in the mode 1, the optimal flight time of the unmanned aerial vehicle in the mode 3, the optimal flight speed and the optimal flight time of the unmanned aerial vehicle in the mode 2; and controlling the unmanned aerial vehicle to fly according to the optimal flight parameters. The invention jointly adjusts the flight speed and the flight track of the unmanned aerial vehicle relay node according to the bit number of the information to be transmitted by the source node and the distance between the source node and the destination node.
Description
Technical Field
The invention relates to the technical field of unmanned aerial vehicle control, in particular to a flight speed and trajectory combined optimization method and system.
Background
In recent years, unmanned aerial vehicle cooperative communication technology has become a hot spot of research in the field of wireless communication. Compared with the traditional ground communication, the unmanned aerial vehicle cooperative communication is easy to realize distribution as required, so that higher cost benefit is achieved; the unmanned aerial vehicle has high mobility, so that the unmanned aerial vehicle is more flexible and rapid to deploy; unmanned aerial vehicle is mostly the line of sight link with the channel link of ground terminal, can provide better channel environment. Therefore, the unmanned aerial vehicle will play an extremely important role in the future wireless communication field, and its application mainly includes: (1) as a temporary base station; (2) as a mobile relay; (3) the method is used for the Internet of things.
At present, a great deal of literature researches optimization problems of information capacity and spectral efficiency of an unmanned aerial vehicle relay cooperative communication system when the unmanned aerial vehicle is used as a mobile relay. Meanwhile, drones have limited onboard energy, so the energy-saving problem is considered as an important research direction for communication of the drones. A large amount of documents consider the energy efficiency problem of the unmanned aerial vehicle relay cooperative communication system under the condition of a straight track or a circular track. However, when the drone is flying in a straight trajectory, the communication system will have an upper limit on the throughput of information, which means that a straight trajectory is not suitable for the case of large data transfers; when the drone flies on a circular track, if the distance between the source node and the destination node is long, the information throughput of the system will be poor.
Disclosure of Invention
Based on the above, the invention aims to provide a method and a system for jointly optimizing flight speed and flight trajectory, so as to realize the joint adjustment of the flight speed and the flight trajectory of the relay node of the unmanned aerial vehicle and the minimization of the total flight energy consumption of the unmanned aerial vehicle.
In order to achieve the above object, the present invention provides a method for jointly optimizing flight speed and trajectory, the method comprising:
step S1: initializing, wherein the bit number of information received by the unmanned aerial vehicle in the mode 1 is equal to the bit number of information to be sent, and the precision is given;
step S2: determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 3;
step S3: determining the optimal number of flying turns of the unmanned aerial vehicle in the mode 1;
step S4: determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 1 according to the number of information bits and the optimal number of flight turns received by the unmanned aerial vehicle in the mode 1 by adopting a one-dimensional search algorithm;
step S5: determining the number of information bits received by the unmanned aerial vehicle in the mode 1;
step S6: calculating the number of received information bits calculated by the unmanned aerial vehicle in the mode 1The difference value between the information bit number received by the unmanned aerial vehicle in the mode 1;
step S7: judging whether the difference is greater than the precision; if the difference is greater than the precision, the number of information bits received by the unmanned aerial vehicle in the mode 1 is equal to the number of information bits calculated and received by the unmanned aerial vehicle in the mode 1, and the step S4 is skipped; if the difference is less than or equal to the precision, performing step S8;
step S8: determining the optimal flight time of the unmanned aerial vehicle in the mode 1, the optimal flight time of the unmanned aerial vehicle in the mode 3, the optimal flight speed and the optimal flight time of the unmanned aerial vehicle in the mode 2; outputting optimal flight parameters so as to control the unmanned aerial vehicle to fly according to the optimal flight parameters; the optimal flight parameters include: the optimal flight radius, the optimal flight speed, the optimal flight duration and the optimal number of flight turns of the unmanned aerial vehicle in the mode 1, the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 3, and the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 2.
Optionally, the method further comprises:
and calculating the minimum total flight energy consumption according to the optimal flight parameters.
Optionally, the minimum total flight energy consumption is calculated according to the optimal flight parameters, and a specific formula is as follows:
wherein E represents minimum total energy consumption for flight, g represents gravitational acceleration, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2Representing the power of the received noise, beta0Which represents the channel power per unit distance,andrespectively represents the optimal flight radius, the optimal flight speed and the optimal flight of the unmanned plane in the mode 1The length of the line is the length of the line,andrespectively represent the optimal flying speed and the optimal flying time of the unmanned aerial vehicle flying in the mode 2, andrespectively representing the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 3.
Optionally, determining an optimal flight radius and an optimal flight speed of the unmanned aerial vehicle in the mode 3 specifically includes:
according toDetermining the optimal flying speed of the unmanned aerial vehicle in the mode 3; wherein the content of the first and second substances,represents the optimal flying speed of the unmanned plane in the mode 3, g represents the gravity acceleration, r2Representing a second radius of flight, vminAnd vmaxRespectively representing the minimum and maximum speed of flight of the drone, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Representing the wingspan efficiency, W representing the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2Representing the power of the received noise, beta0Represents the channel power per unit distance;
substituting the optimal flying speed of the unmanned aerial vehicle in the mode 3 into a flying energy consumption optimization formula of the unmanned aerial vehicle in the mode 3 by adopting a one-dimensional search algorithm to obtain the optimal flying radius of the unmanned aerial vehicle in the mode 3; the flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 3 is as follows:
vmin≤v3≤vmax,0<r2<L,T3≥0;
wherein the content of the first and second substances,indicating the optimal flight radius in drone mode 3,indicating the optimal flying speed of the drone in mode 3,representing the number of information bits received by the destination node in mode 3, g representing the acceleration of gravity, PRRepresenting the signal transmission power of the relay node of the unmanned aerial vehicle, L representing the horizontal distance between the source node S and the destination node D, v3And T3Respectively representing the flight speed and duration of the unmanned aerial vehicle in mode 3, r2Denotes the second radius of flight, H denotes the altitude of flight, vminAnd vmaxRespectively representing the minimum and maximum speed of flight of the drone, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Representing the wingspan efficiency, W representing the overall weight of the drone, ARTo indicate nobodyAspect ratio, gamma, of the airfoil0=β0/σ2,σ2Representing the power of the received noise, beta0Representing the channel power per unit distance.
Optionally, the optimal number of turns of the unmanned aerial vehicle in mode 1 is determined, and a specific formula is as follows:
wherein the content of the first and second substances,represents the optimal number of turns of the drone in mode 1,andrespectively representing the flight time, the flight speed and the flight radius of the unmanned plane in the mode 1 under the condition that the flight number n is a non-integer number of turns.
The invention also provides a combined optimization system of flight speed and trajectory, comprising:
the initialization module is used for initializing, so that the bit number of the information received by the unmanned aerial vehicle in the mode 1 is equal to the bit number of the information to be sent, and the precision is given;
the first determining module is used for determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 3;
the second determining module is used for determining the optimal number of flying turns of the unmanned aerial vehicle in the mode 1;
the third determining module is used for determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 1 according to the number of information bits and the optimal number of flight turns received by the unmanned aerial vehicle in the mode 1 by adopting a one-dimensional search algorithm;
the information bit number determining module is used for determining the number of the information bits which are calculated and received by the unmanned aerial vehicle in the mode 1;
a difference determination module for calculating the bit number of the information received by the UAV in the mode 1The difference value between the information bit number received by the unmanned aerial vehicle in the mode 1;
the judging module is used for judging whether the difference value is greater than the precision; if the difference is greater than the precision, enabling the number of information bits received by the unmanned aerial vehicle in the mode 1 to be equal to the number of information bits calculated and received by the unmanned aerial vehicle in the mode 1, and jumping to a third determining module; if the difference is less than or equal to the precision, executing an output control module;
the output control module is used for determining the optimal flight time of the unmanned aerial vehicle in the mode 1, the optimal flight time of the unmanned aerial vehicle in the mode 3, the optimal flight speed and the optimal flight time of the unmanned aerial vehicle in the mode 2; outputting optimal flight parameters so as to control the unmanned aerial vehicle to fly according to the optimal flight parameters; the optimal flight parameters include: the optimal flight radius, the optimal flight speed, the optimal flight duration and the optimal number of flight turns of the unmanned aerial vehicle in the mode 1, the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 3, and the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 2.
Optionally, the system further comprises:
and the minimum total flight energy consumption determining module is used for calculating the minimum total flight energy consumption according to the optimal flight parameters.
Optionally, the minimum total flight energy consumption is calculated according to the optimal flight parameters, and a specific formula is as follows:
wherein E is the minimum total energy consumption for flight, g is the acceleration of gravity, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2For receiving the power of the noise, beta0Is the channel power per unit distance,andrespectively the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 1,andrespectively the optimal flying speed and the optimal flying time of the unmanned aerial vehicle flying in the mode 2,andrespectively, the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle flying in the mode 3.
Optionally, the first determining module specifically includes:
a first determination unit for determining based on
Determining the optimal flying speed of the unmanned aerial vehicle in the mode 3; wherein the content of the first and second substances,to representOptimal flight speed of the unmanned plane in mode 3, g represents gravitational acceleration, r2Representing a second radius of flight, vminAnd vmaxRespectively representing the minimum and maximum speed of flight of the drone, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Representing the wingspan efficiency, W representing the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2Representing the power of the received noise, beta0Represents the channel power per unit distance;
the second determining unit is used for substituting the optimal flight speed of the unmanned aerial vehicle in the mode 3 into a flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 3 by adopting a one-dimensional search algorithm to obtain the optimal flight radius of the unmanned aerial vehicle in the mode 3; the flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 3 is as follows:
vmin≤v3≤vmax,0<r2<L,T3≥0;
wherein the content of the first and second substances,indicating the optimal flight radius in drone mode 3,indicating the optimal flying speed of the drone in mode 3,indicating that the destination node is in mode 3The number of bits of information received, g representing the acceleration of gravity, PRRepresenting the signal transmission power of the relay node of the unmanned aerial vehicle, L representing the horizontal distance between the source node S and the destination node D, v3And T3Respectively representing the flight speed and duration of the unmanned aerial vehicle in mode 3, r2Denotes the second radius of flight, H denotes the altitude of flight, vminAnd vmaxRespectively representing the minimum and maximum speed of flight of the drone, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Representing the wingspan efficiency, W representing the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2Representing the power of the received noise, beta0Is the channel power per unit distance.
Optionally, the optimal number of turns of the unmanned aerial vehicle in mode 1 is determined, and a specific formula is as follows:
wherein the content of the first and second substances,represents the optimal number of turns of the drone in mode 1,andrespectively representing the flight time, the flight speed and the flight radius of the unmanned plane in the mode 1 under the condition that the flight number n is a non-integer number of turns.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
according to the method and the device, the flight speed and the flight track of the relay node of the unmanned aerial vehicle are jointly adjusted according to the bit number of the information to be transmitted by the source node and the distance between the source node and the destination node, and the minimization of the total flight energy consumption of the unmanned aerial vehicle is realized under the condition that the information to be transmitted by the source node can be completely transmitted to the destination node.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a method for joint optimization of airspeed and trajectory in accordance with an embodiment of the present invention;
FIG. 2 is a schematic view of an embodiment of the invention illustrating the flight of an unmanned aerial vehicle;
FIG. 3 is a schematic view of a flight trajectory of an unmanned aerial vehicle according to an embodiment of the invention;
fig. 4 is a schematic diagram illustrating comparison of total flight energy consumption of the unmanned aerial vehicle according to the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a flight speed and track combined optimization method and system, so as to realize the combined adjustment of the flight speed and the flight track of a relay node of an unmanned aerial vehicle and the minimization of the total flight energy consumption of the unmanned aerial vehicle.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
For an unmanned aerial vehicle full-duplex relay node cooperative communication system, a source node S transmits information to a destination node D through an unmanned aerial vehicle relay node R, the unmanned aerial vehicle flies at a fixed flying height H, the flying height H is the minimum height required by the unmanned aerial vehicle to avoid the terrain or buildings, and the source node S and the destination node D are assumed to have horizontal coordinates q respectivelyS=[0,0]TAnd q isD=[L,0]TWhere L is the horizontal distance between the source node S and the destination node D.
In the whole information transmission process, the unmanned aerial vehicle needs to assist the source node S to transmit information to be transmitted with Q bits to the destination node D, so that the flight trajectory of the unmanned aerial vehicle is divided into three different modes, which are respectively:
mode 1: the unmanned plane takes (0,0, H) as the circle center, r1The first flight radius is the flight radius, the circular track flight is carried out in the air of the flight height H, and the flight speed and the flight duration in the mode 1 are respectively v1And T1。
Mode 2: unmanned plane (r)10, H) is the starting point, (L-r)20, H) as an end point, and the flying speed and the flying duration in the mode 2 are respectively v2And T2。
Mode 3: the unmanned plane takes (L,0, H) as the circle center, r2For a second flight radius, performing circular track flight in the air at the flight height H, wherein the flight speed and the flight duration in the mode 3 are v3And T3。
Suppose the initial position of the relay node of the unmanned aerial vehicle is (r)10, H), the unmanned aerial vehicle relay node firstly flies for n circles above a source node according to the circular track of the mode 1, then flies towards a destination node according to the linear track of the mode 2, and finally flies for Q-bit information above the destination node according to the circular track of the mode 3 until the transmission of the Q-bit information is completed, wherein the duration of the three flight modes needs to meet the condition given by the formula (1), and n is the number of flying circles under the unmanned aerial vehicle mode 1;
wherein r is1Is the first flight radius, v1And T1Respectively, the flying speed and the time length of the unmanned aerial vehicle in the mode 1, n is the number of flying turns in the mode 1 of the unmanned aerial vehicle, v2And T2Respectively, the flight speed and duration of the unmanned aerial vehicle in mode 2, r2Is the second flight radius, T3Is the flight duration of the drone in mode 3.
It should be noted that: 1) the cache space of the unmanned aerial vehicle relay node is assumed to be large enough; 2) links among the unmanned aerial vehicle, the source node and the destination node are line-of-sight links; 3) the Doppler effect caused by the movement of the unmanned aerial vehicle can be completely eliminated; 4) the unmanned aerial vehicle full-duplex relay node respectively completes the receiving and sending of information by using different frequency bands; 5) the source node and the destination node cannot communicate directly.
The method comprises the following steps of establishing a combined optimization formula of the flight speed and the flight track of the unmanned aerial vehicle by taking the minimum total flight energy consumption of the unmanned aerial vehicle as a target, wherein the specific formula is as follows:
constraint conditions are as follows: r is1+r2≤L,r1>0,r2>0 (2b)
vmin≤v1≤vmax,vmin≤v2≤vmax,vmin≤v3≤vmax (2c)
QR(T)≥Q,QD(T)≥Q (2e)
QD(t)≤QR(t),0≤t≤T (2f)
T1+T2+T3=T (2g)
Wherein v isminAnd vmaxMinimum and maximum speed, Q, respectively, of the unmanned aerial vehicle flightR(t) is the total information bit number Q received by the relay node R of the unmanned aerial vehicle at the moment tD(t) is the total number of information bits received by destination node D of UAV at time t, r1Is the first flight radius, v1And T1Respectively, the flight speed and duration of the unmanned aerial vehicle in mode 1, v2And T2Respectively, the flight speed and duration of the unmanned aerial vehicle in mode 2, v3And T3Respectively, the flying speed and the time length of the unmanned aerial vehicle in the mode 3, T is the time length of the whole information transmission process, n is the number of flying turns in the unmanned aerial vehicle mode 1, and r2Is the second flight radius, g is the acceleration of gravity, QR(T) is the total information bit number Q received by the relay node R of the unmanned aerial vehicle at the moment TD(T) is the total number of information bits received by the destination node D of the UAV at time T, Q is the number of information bits to be transmitted,the optimal flight radius of the unmanned plane in the mode 1,For the optimal flying speed of the unmanned plane in the mode 1,For the optimal flight duration of the unmanned plane in mode 1, n*For the optimal number of turns of the drone in mode 1,for the optimum flight radius for the drone to fly in mode 3,for the optimum flying speed of the drone in mode 3,for the optimal flight duration of the drone in mode 3,for the optimum flying speed of the drone in mode 2,and (4) flying the unmanned aerial vehicle in the mode 2 for the optimal flight time.
For the optimization problem (2), namely, the joint optimization problem composed of the formula (2a), the formula (2b), the formula (2c), the formula (2d), the formula (2e), the formula (2f) and the formula (2g), the constraint conditions of the formula (2e) and the formula (2f) are equivalent to the formula (3);
QR(T)≥QD(T)=Q (3)
that is, when solving the problem (2), the constraint equations (2e) and (2f) may be replaced by equation (3).
The channel gains between drone R and source node S, destination node D may be represented as:
wherein h isSR(τ) is the channel gain between the unmanned aerial vehicle relay node R and the source node S, hRD(τ) is the channel gain between the drone relay node R and the destination node D, DSR(τ) is the distance between the unmanned aerial vehicle relay node R and the source node S at τ time, dRD(τ) is the distance between the unmanned aerial vehicle relay node R and the destination node D at the time τ, q (τ) is the horizontal coordinate of the unmanned aerial vehicle relay node at the time τ, and β0Is the channel power per unit distance, L is the horizontal distance between the source node S and the destination node D,h is the flying height.
Under a unit bandwidth, a specific formula of the total information bit number received by the unmanned aerial vehicle relay node R and the destination node D at the time t is as follows:
wherein Q isR(t) is the total information bit number Q received by the relay node R of the unmanned aerial vehicle at the moment tD(t) is the total number of information bits, γ, received by the drone destination node D at time t0=β0/σ2And sigma2For receiving the power of the noise, PSAnd PRRespectively the signal transmitting power of a source node and the signal transmitting power of a relay node of the unmanned aerial vehicle, q (t) is the horizontal coordinate of the relay node of the unmanned aerial vehicle at the moment t, and beta0Is the channel power per unit distance and H is the flying height.
In order to ensure that the information to be transmitted of Q bits can be transmitted in its entirety during the entire information transmission, the condition given by equation (2e) needs to be satisfied.
In addition, the drone relay node can only forward the information that has been received, and therefore the information causality requirement shown in equation (2f) needs to be satisfied.
Because the flight energy consumption of the unmanned aerial vehicle is far higher than the communication energy consumption, the flight energy consumption of the unmanned aerial vehicle is only optimized, and if the unmanned aerial vehicle with fixed wings does circular motion with the speed of v and the radius of r or does linear motion with the speed of v, the power consumption at the moment is [ c ]1+c2/(g2r2)]v3+c2V or c1v3+c2V, wherein the parameter c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]Where ρ represents the air density (in kg/m), CD0Representing zero lift drag systemNumber, S denotes wing area, e0Is the span efficiency, typically between 0.7 and 0.85, W representing the overall weight of the drone, aRRepresenting the aspect ratio of the unmanned wing.
When the unmanned aerial vehicle flies in the mode 1, compared with the destination node D, the relay node R of the unmanned aerial vehicle is closer to the source node S, the relay node of the unmanned aerial vehicle at the moment is mainly used for receiving information from the source node, similarly, when the unmanned aerial vehicle flies in the mode 3, the relay node of the unmanned aerial vehicle is mainly used for forwarding the information to the destination node, only one channel link with large transmission information amount is considered in the process, and therefore, a flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 1 and the mode 1 is established.
Establishing a flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 1, wherein the specific formula is as follows:
vmin≤v1≤vmax,0<r1<L (8c)
wherein the content of the first and second substances,for the optimal flight radius of the drone in mode 1,for the optimal flying speed of the unmanned plane in the mode 1, r1Is the first flight radius, v1Is the flying speed of the unmanned plane in the mode 1, g is the gravity acceleration, n is the number of flying turns in the unmanned plane mode 1,number of information bits, P, received by the drone in mode 1SIs the signal transmitting power of the source nodeRate, L being the horizontal distance between the source node S and the destination node D, v2For the flight speed of the drone in mode 2, r1Is the first flight radius, H is the flight height, vminAnd vmaxMinimum and maximum speed of flight of the drone, c, respectively1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARRepresenting the aspect ratio of the unmanned wing.
Establishing a flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 3, wherein the specific formula is as follows:
vmin≤v3≤vmax,0<r2<L,T3≥0 (9c)
wherein the content of the first and second substances,the optimum flight radius in mode 3,for the optimal flying speed of the drone in mode 3,the number of information bits received by the destination node in mode 3, g is the acceleration of gravity, PRSignal transmission power of a relay node of the unmanned aerial vehicle, L is a horizontal distance between a source node S and a destination node D, v3And T3Respectively, the flight speed and duration of the unmanned aerial vehicle in mode 3, r2Is the second flight radius, H is the flightHeight, vminAnd vmaxMinimum and maximum speed of flight of the drone, c, respectively1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARRepresenting the aspect ratio of the unmanned wing.
Adopting a one-dimensional search algorithm to determine the bit number of information received by the unmanned aerial vehicle in the mode 1And optimum number of turnsSubstituting the flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 1 to determine the optimal flight radius of the unmanned aerial vehicle in the mode 1And optimum running speed
Because of the optimal number of turns of the drone in mode 1And number of information bitsAll are constant values, the joint optimization problem composed of the formula (8a), the formula (8b) and the formula (8c) directly obtains corresponding optimal solutions through a one-dimensional search algorithmAnd
determining the optimal flight speed in the mode 3, wherein the specific formula is as follows:
wherein the content of the first and second substances,for the optimal flight speed of the unmanned plane in the mode 3, g is the gravity acceleration, r2Is the second radius of flight, vminAnd vmaxMinimum and maximum speed of flight of the drone, c, respectively1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARRepresenting the aspect ratio of the unmanned wing.
Substituting the optimal flight speed of the unmanned aerial vehicle in the mode 3 into the flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 3 by adopting a one-dimensional search algorithm to obtain the optimal flight radius of the unmanned aerial vehicle in the mode 3
Substituting the optimal flying speed and the optimal flying radius in the mode 1 and the optimal flying speed and the optimal flying radius in the mode 3 into a combined optimization formula of the flying speed and the flying track of the unmanned aerial vehicle for simplification, and obtaining a first simplified formula as follows:
constraint conditions are as follows: v. ofmin≤v2≤vmax (11b)
Wherein the content of the first and second substances,for the optimal flight radius of the drone in mode 1,for the optimal flying speed of the drone in mode 1,the optimum flight radius in mode 3,for the optimal flying speed, v, of the unmanned plane in mode 32For the flight speed of the drone in mode 2, T1For the flight duration of unmanned aerial vehicle in mode 1, T2For the flight duration of unmanned aerial vehicle in mode 2, T3The flight duration of the unmanned aerial vehicle in the mode 3 is determined, n is the number of flying turns of the unmanned aerial vehicle above the source node according to the mode 1, g is the gravity acceleration, L is the horizontal distance between the source node S and the destination node D, and c is the horizontal distance between the source node S and the destination node D1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARRepresenting the aspect ratio of the unmanned aerial vehicle wing,andare respectively unmanned aerial vehiclesThe number of information bits received under the mode 1, mode 2 and mode 3 conditions,andthe number of information bits received by the destination node under the conditions of mode 1, mode 2 and mode 3 respectively, Q is the number of information bits to be transmitted, vminAnd vmaxRespectively, the minimum and maximum speeds at which the drone is flying.
However, due to the existence of the integer n, the problem (11), i.e., the joint optimization problem composed of the equations (11a), (11b), (11c), (11d), and (11e), is difficult to directly solve, and therefore, the value of the number of flying turns n needs to be calculated first. It can be easily found from the problem (11) that the total flight energy consumption of the drone increases after decreasing with increasing n, so that there must be an optimal number of flight turns n to minimize the total flight energy consumption.
Firstly, ignoring the constraint condition that the number of flying turns n of the unmanned aerial vehicle in the mode 1 stage is an integer, simplifying the flight energy consumption optimization formula (formula 8) of the unmanned aerial vehicle in the mode 1, and obtaining the flight energy consumption simplification formula of the unmanned aerial vehicle in the mode 1 as follows:
constraint conditions are as follows: v. ofmin≤v1≤vmax,0<r1<L (12b)
Wherein the content of the first and second substances,andunder the limitation that the number of flying turns n is a non-integer number of turns, the flying speed and the flying radius of the unmanned aerial vehicle under the condition of the mode 1 are determined.
Similar to the solution of sub-problem (9), problem (12), i.e.A joint optimization problem composed of the formula (12a) and the formula (12b), and therefore the flight speed of the unmanned plane in the mode 1 under the condition that the flight number n is a non-integer number of turns limit is determinedCan be expressed as:
wherein the content of the first and second substances,representing the flight speed of the unmanned aerial vehicle in the mode 1 under the limitation that the number of flying turns n is a non-integer number of turns, g is the gravity acceleration, r2Is the second radius of flight, vminAnd vmaxMinimum and maximum speed of flight of the drone, c, respectively1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2For receiving the power of the noise, beta0Is the channel power per unit distance.
Substituting formula (13) into problem (12), and obtaining corresponding flight radius of the unmanned aerial vehicle in mode 1 under the limitation that the number of flight turns n is a non-integer number of turns through a one-dimensional search algorithm
Neglecting the constraint that the number of turns n of the drone in the mode 1 phase is an integer, the problem (11) can be written as:
constraint conditions are as follows: vmin≤v2≤Vmax (14b)
T1≥0,T3≥0 (14c)
Wherein the content of the first and second substances,andthe flying speed of mode 2, the flying time of mode 1 and the flying time of mode 3 under the limitation that the flying turns n are non-integer turns respectively,andis the optimal solution to the problem (12), i.e. the flight speed and the flight radius, T, of the drone in the case of mode 1, with n being a non-integer number of turns constraint1And T3Time of flight, v, of the drone in mode 1 and mode 3, respectively2For the flight speed of the drone in mode 2,andfor the optimal solution of the problem (9), i.e. the optimal flight radius and the optimal flight speed of the drone in mode 3, Q is the number of information bits to be transmitted,andthe number of information bits received by the drone in mode 1 and mode 2 respectively,andthe number of information bits received by the destination node in mode 2 and mode 3, respectively, L is the horizontal distance between the source node S and the destination node D, H is the flight altitude, vminAnd vmaxMinimum and maximum speed of flight of the drone, c, respectively1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARRepresenting the aspect ratio of the unmanned aerial vehicle wing,
the problem (14), namely, the joint optimization problem composed of the formula (14a), the formula (14b), the formula (14c), the formula (14d) and the formula (14e), is a convex optimization problem, the corresponding solution can be obtained by the KKT condition, and the problem (14) corresponds to the limitation of the number of turns when n is a non-integerTime of flight in mode 1Comprises the following steps:
f1=8×21/3a2(a3a5-b1b3)c2/k1-k1/[6×21/3a2c1(a3a5-b1b3)];
a7=Q-b2;
a8=Q-b4;
According to the flight time of the unmanned aerial vehicle in the mode 1 under the limitation that the number of flying turns n is a non-integer number of turnsDetermining the optimal number of flying turns of the unmanned aerial vehicle in the mode 1The concrete formula is as follows:
wherein the content of the first and second substances,the number of flying turns above the source node for the circular trajectory of mode 1,andrespectively the flying speed and the flying radius of the unmanned plane under the mode 1 when n is the limit of non-integer turns,the flight time of the unmanned plane in the mode 1 under the limitation that the number of flying turns n is a non-integer number of turns is disclosed.
Based on the optimal number of flying turns of unmanned aerial vehicle under mode 1Further simplifying the first simplified formula (i.e. formula (11)) to obtain a second simplified formula, which is specifically:
constraint conditions are as follows: vmin≤v2≤Vmax,T3≥0 (16b)
Solving a second simplified formula, namely a joint optimization problem composed of the formula (16a), the formula (16b), the formula (16c) and the formula (16d), can obtain a corresponding closed solution formula, which is specifically:
The calculation formula of the information bit number is as follows:
wherein the content of the first and second substances,the number of information bits received is calculated for the drone in mode 1,
as shown in fig. 1, the present invention provides a method for jointly optimizing flight speed and trajectory, the method comprising:
step S1: initializing, and enabling the number of information bits received by the unmanned aerial vehicle in the mode 1 to be equal to the number of bits of information to be sent, and giving precision.
Step S2: determining optimal flight radius of unmanned aerial vehicle in mode 3And optimum flying speed
Step S3: determining the optimal number of flying turns of the unmanned aerial vehicle in the mode 1
Step S4: adopting a one-dimensional search algorithm, and according to the number of information bits received by the unmanned aerial vehicle in the mode 1And optimum number of turnsDetermining optimal flight radius of unmanned aerial vehicle in mode 1And optimum flying speed
Step S5: determining the number of information bits received by the unmanned aerial vehicle in mode 1 calculation
Step S6: calculating the number of received information bits calculated by the unmanned aerial vehicle in the mode 1Number of information bits received with the drone in mode 1The difference between them.
Step S7: judging whether the difference value is greater than the precision epsilon or not; if the difference is greater than the precision epsilon, orderJumping to step S4; if the difference is less than or equal to the precision ε, step S8 is performed.
Step S8: determining optimal flight duration of unmanned aerial vehicle in mode 1Optimal flight duration of unmanned aerial vehicle flight in mode 3Optimal flying speed of unmanned aerial vehicle flying in mode 2And optimal flight durationAt the same time orderOutputting optimal flight parameters so as to control the unmanned aerial vehicle to fly according to the optimal flight parameters; the optimal flight parameters include: optimal flight radius of unmanned aerial vehicle in mode 1Optimum flying speedOptimum duration of flightAnd an optimum number of flying turns n*Optimal flight radius for unmanned aerial vehicle flying in mode 3And optimum flying speedAnd optimal flight durationOptimal flying speed of unmanned aerial vehicle flying in mode 2And optimal flight duration
The individual steps are discussed in detail below:
as an embodiment, the method of the present invention further comprises:
step S9: and calculating the minimum total flight energy consumption according to the optimal flight parameters, wherein the specific formula is as follows:
wherein E is the minimum total energy consumption for flight, g is the acceleration of gravity, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARRepresenting the aspect ratio of the unmanned aerial vehicle wing,andrespectively the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 1,andrespectively the optimal flying speed and the optimal flying time of the unmanned aerial vehicle flying in the mode 2,andrespectively, the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle flying in the mode 3.
Step S1: initializing, wherein the bit number of information received by the unmanned aerial vehicle in the mode 1 is equal to the bit number of information to be sent, and the precision is given; specifically, the method comprises the following steps: order toGiving a precision epsilon; wherein the content of the first and second substances,the number of information bits received by the unmanned aerial vehicle in mode 1, Q being the number of bits of information to be transmitted, ε>0。
Step S2: determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 3, specifically comprising the following steps:
step S21: determining the optimal flying speed of the unmanned aerial vehicle in the mode 3 according to the formula (10)
Step S22: substituting the optimal flying speed of the unmanned aerial vehicle in the mode 3 into the flying energy consumption optimization formula (formulas (9a), (9b) and (9c)) of the unmanned aerial vehicle in the mode 3 by adopting a one-dimensional search algorithm to obtain the optimal flying radius of the unmanned aerial vehicle in the mode 3
Step S3: determining the optimal number of flying turns of the unmanned aerial vehicle in the mode 1The concrete formula is as follows:
wherein the content of the first and second substances,represents the optimal number of turns of the drone in mode 1,andrespectively representing the flight time, the flight speed and the flight radius of the unmanned plane in the mode 1 under the condition that the flight number n is a non-integer number of turns.
Step S4: adopting a one-dimensional search algorithm, and according to the number of information bits received by the unmanned aerial vehicle in the mode 1And optimum number of turnsDetermining optimal flight radius of unmanned aerial vehicle in mode 1And optimum flying speedSpecifically, a one-dimensional search algorithm is adopted to determine the number of information bits received by the unmanned aerial vehicle in the mode 1And optimum number of turnsSubstituting the flying energy consumption optimization formulas (8a), (8b) and (8c)) of the unmanned aerial vehicle in the mode 1 to determine the optimal flying radius of the unmanned aerial vehicle in the mode 1And optimum running speed
Step S5: determining the number of information bits received by the unmanned aerial vehicle in mode 1 calculationThe method specifically comprises the following steps: optimizing flight radius of unmanned plane in mode 1Optimum airspeed in mode 2And optimal flight radius in mode 3And time of flightSubstituting the information bit number calculation formula (19) for solving to obtain the information bit number received by the unmanned aerial vehicle in the mode 1 calculationWhereinAndcalculated according to the equations (17) and (18), respectively.
Step S6: calculating the number of received information bits calculated by the unmanned aerial vehicle in the mode 1Number of information bits received with the drone in mode 1The specific formula of the difference value is as follows:
wherein, the delta Q is a difference value,the number of information bits received is calculated for the drone in mode 1,the number of information bits received by the drone in mode 1.
Step S8 specifically includes:
step S81: according toDetermining the optimal flight time of the unmanned aerial vehicle in the mode 1 by n-1, 2 and …; wherein the content of the first and second substances,for the optimal flight duration of the drone in mode 1,the optimal flight radius of the unmanned aerial vehicle in the mode 1 is obtained, the optimal flight speed of the unmanned aerial vehicle in the mode 1 is obtained, and n is the number of flying turns of the unmanned aerial vehicle above the source node according to the mode 1.
Step S82: according toDetermining optimal flight duration of unmanned aerial vehicle flight in mode 2Wherein the content of the first and second substances,for the optimal flight duration of the drone in mode 2,for the optimal flight radius of the drone in mode 1,for the optimal flight radius of the drone in mode 3, L is the horizontal distance between the source node S and the destination node D,the optimal flying speed of the unmanned plane in the mode 2 is obtained.
Step S83: determining the optimal flight time of the unmanned aerial vehicle in the mode 3 according to the formula (18)
Step S84: determining the optimal flying speed of the unmanned aerial vehicle flying in the mode 2 according to the formula (17)
Step S86: outputting optimal flight parameters so as to control the unmanned aerial vehicle to fly according to the optimal flight parameters; the optimal flight parameters include: optimal flight radius of unmanned aerial vehicle in mode 1Optimum flying speedOptimum duration of flightAnd an optimum number of flying turns n*Optimal flight radius for unmanned aerial vehicle flying in mode 3And optimum flying speedAnd optimal flight durationOptimal flying speed of unmanned aerial vehicle flying in mode 2And optimal flight duration
It should be noted that: the optimal number of flying turns of the unmanned aerial vehicle in the mode 1 is determinedWhen the value is in the formula (15)Two different values are likely to exist, so that two situations are needed to be distinguished according to two different valuesValue calculation of all optimal flight parameters under each condition, and final calculation of the two types of flight parametersComparing the total flying energy consumption of the unmanned aerial vehicle obtained according to the value condition, wherein the optimal flying energy consumption is obtained when the energy consumption is smallValue, which corresponds to The optimal solution of the problem (8), namely the optimal solution of the unmanned aerial vehicle flight speed and flight trajectory joint optimization problem.
The invention discloses a combined optimization system of flight speed and trajectory, which comprises:
and the initialization module is used for initializing, so that the bit number of the information received by the unmanned aerial vehicle in the mode 1 is equal to the bit number of the information to be sent, and the precision is given.
The first determining module is used for determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 3.
The second determining module is used for determining the optimal number of flying turns of the unmanned aerial vehicle in the mode 1;
and the third determining module is used for determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 1 according to the number of information bits and the optimal number of flight turns received by the unmanned aerial vehicle in the mode 1 by adopting a one-dimensional search algorithm.
And the information bit number determining module is used for determining the number of the information bits which are calculated and received by the unmanned aerial vehicle in the mode 1.
And the difference value determining module is used for calculating the difference value between the information bit number received by the unmanned aerial vehicle in the mode 1 and the information bit number received by the unmanned aerial vehicle in the mode 1.
The judging module is used for judging whether the difference value is greater than the precision; if the difference is greater than the precision, enabling the number of information bits received by the unmanned aerial vehicle in the mode 1 to be equal to the number of information bits calculated and received by the unmanned aerial vehicle in the mode 1, and jumping to a third determining module; if the difference is less than or equal to the precision, an output control module is executed.
The output control module is used for determining the optimal flight time of the unmanned aerial vehicle in the mode 1, the optimal flight time of the unmanned aerial vehicle in the mode 3, the optimal flight speed and the optimal flight time of the unmanned aerial vehicle in the mode 2; outputting optimal flight parameters so as to control the unmanned aerial vehicle to fly according to the optimal flight parameters; the optimal flight parameters include: the optimal flight radius, the optimal flight speed, the optimal flight duration and the optimal number of flight turns of the unmanned aerial vehicle in the mode 1, the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 3, and the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 2.
The various modules are discussed in detail below:
as an embodiment, the system of the present invention further includes:
the initialization module is used for initializing, so that the bit number of the information received by the unmanned aerial vehicle in the mode 1 is equal to the bit number of the information to be sent, and the precision is given; specifically, the method comprises the following steps: order toGiving a precision epsilon; wherein the content of the first and second substances,the number of information bits received by the unmanned aerial vehicle in mode 1, Q being the number of bits of information to be transmitted, ε>0。
The first determining module is configured to determine an optimal flight radius and an optimal flight speed of the unmanned aerial vehicle in mode 3, and specifically includes:
a first determining unit, configured to determine an optimal flying speed of the drone in mode 3 according to equation (10).
And the second determining unit is used for substituting the optimal flying speed of the unmanned aerial vehicle in the mode 3 into the flying energy consumption optimization formula (formulas (9a), (9b) and (9c)) of the unmanned aerial vehicle in the mode 3 by adopting a one-dimensional search algorithm to obtain the optimal flying radius of the unmanned aerial vehicle in the mode 3.
A second determination module for determining the optimal number of flying turns of the unmanned aerial vehicle in the mode 1The method specifically comprises the following steps:
a third determining unit, configured to solve an optimal solution for the flight energy consumption optimization formulas (8a), (8b), and (8c)) of the unmanned aerial vehicle in the mode 1 by using a one-dimensional search algorithm, so as to obtain the flight time of the unmanned aerial vehicle in the mode 1
A fourth determination unit for determining the time of flight of the unmanned aerial vehicle in mode 1Determining the optimal number of flying turns of the unmanned aerial vehicle in the mode 1Specifically, willSubstituting formula (12) to determine the optimal number of flying turns of the unmanned aerial vehicle in mode 1
A third determining module, configured to use a one-dimensional search algorithm according to the number of bits of information received by the drone in mode 1And optimum number of turnsDetermining optimal flight radius of unmanned aerial vehicle in mode 1And optimum flying speedSpecifically, a one-dimensional search algorithm is adopted to determine the number of information bits received by the unmanned aerial vehicle in the mode 1And optimum number of turnsSubstituting into the flight energy consumption optimization formulas (8a), (8b) and (8c)) of the unmanned aerial vehicle in the mode 1 to determine that the unmanned aerial vehicle is unmannedOptimum flight radius of the aircraft in mode 1And optimum running speed
An information bit number determination module used for determining the optimal flight radius of the unmanned aerial vehicle in the mode 1Determining the number of information bits received by the unmanned aerial vehicle in mode 1 calculationThe method specifically comprises the following steps: optimizing flight radius of unmanned plane in mode 1Optimum airspeed in mode 2And optimal flight radius in mode 3And time of flightSubstituting the information bit number calculation formula (19) for solving to obtain the information bit number received by the unmanned aerial vehicle in the mode 1 calculationWhereinAndcalculated according to the equations (17) and (18), respectively. A difference determination module for calculating the calculated mode 1 of the unmanned aerial vehicleNumber of received information bitsNumber of information bits received with the drone in mode 1The specific formula of the difference value is as follows:
wherein, the delta Q is a difference value,the number of information bits received is calculated for the drone in mode 1,the number of information bits received by the drone in mode 1.
The output control module specifically comprises:
a fifth determination unit for determining based onDetermining the optimal flight time of the unmanned aerial vehicle in the mode 1 by n-1, 2 and …; wherein the content of the first and second substances,for the optimal flight duration of the drone in mode 1,the optimal flight radius of the unmanned aerial vehicle in the mode 1 is obtained, the optimal flight speed of the unmanned aerial vehicle in the mode 1 is obtained, and n is the number of flying turns of the unmanned aerial vehicle above the source node according to the mode 1.
A sixth determination unit for determining based onDetermining that the unmanned aerial vehicle is flyingOptimal flight duration in mode 2Wherein the content of the first and second substances,for the optimal flight duration of the drone in mode 2,for the optimal flight radius of the drone in mode 1,for the optimal flight radius of the drone in mode 3, L is the horizontal distance between the source node S and the destination node D, and v2 is the flight speed of the drone in mode 2.
A seventh determining unit, configured to determine an optimal flight duration of the unmanned aerial vehicle flying in mode 3 according to formula (18)
An eighth determining unit for determining the optimal flying speed of the unmanned aerial vehicle flying in the mode 2 according to the formula (17)
A tenth determining unit, configured to output an optimal flight parameter, so as to control the unmanned aerial vehicle to fly according to the optimal flight parameter; the optimal flight parameters include: optimal flight radius of unmanned aerial vehicle in mode 1Optimum flight speedDegree of rotationOptimum duration of flightAnd an optimum number of flying turns n*Optimal flight radius for unmanned aerial vehicle flying in mode 3And optimum flying speedAnd optimal flight durationOptimal flying speed of unmanned aerial vehicle flying in mode 2And optimal flight duration
According to the method and the device, the flight speed and the flight track of the relay node of the unmanned aerial vehicle are jointly adjusted according to the bit number of the information to be transmitted by the source node and the distance between the source node and the destination node, and the minimization of the total flight energy consumption of the unmanned aerial vehicle is realized under the condition that the information to be transmitted by the source node can be completely transmitted to the destination node.
As shown in fig. 2, assume that the initial position of the drone relay node is (r)10, H). The unmanned aerial vehicle relay node firstly flies n circles above the source node according to the circular track of the mode 1; then, flying towards the direction of a target node according to the linear track of the mode 2; and finally, flying over the destination node according to the circular track of the mode 3 until the transmission of the Qbit information is completed.
The combined implementation method provided by the invention is used for carrying out simulation experiments on the flight path, the flight speed and the total flight energy consumption of the unmanned aerial vehicle, and is a model which is linear and circular with the flight path of the unmanned aerial vehicleThe formula is compared, and the experimental environment is the Matlab environment. Assuming that the flying height H of the drone is 200m, the noise power σ received by each node2-110dB, channel power is set to β0-50dB, in addition, has c1=9.26×10-4,c2=2250,vmin10m/s and vmax=50m/s。
Fig. 3 shows the flight trajectory and flight speed (labeled "suboptimal radius" and "suboptimal speed") of the unmanned aerial vehicle given by the proposed algorithm and the solution (labeled "optimal radius" and "optimal speed") obtained by calculating the problem (2) by the search algorithm. Setting the distance L between a source node S and a destination node D to be 5000m, and setting the transmitting power of the source S and the unmanned aerial vehicle relay node R to be PS=PR1W. As shown in fig. 3(a) and 3(b), for Q e (200,280), the drone flight radius r1With monotonic increase in Q, and flight velocity v1Monotonically decreasing with Q, since as Q increases, the number of information bits the drone receives during mode 1 phaseIt must also be added that in order to make the drone receive more information in the mode 1 phase, the radius and the flying speed of the mode 1 circular trajectory need to be jointly optimized, and at the same time, increasing the flying radius and decreasing the flying speed can ensure that more information is received with the minimum flying energy consumption. In addition, the flight radius r of the unmanned aerial vehicle can be found1And the flying speed v1A jump occurs at Q e (280,300) because as Q increases, less flight energy consumption can be achieved by increasing the number of flight turns n during mode 1. The change of the number of flying turns n can cause the flying radius r of the unmanned aerial vehicle1And the flying speed v1Table 1 shows the relationship between the number of turns of the drone flying in the mode 1 phase and Q. Meanwhile, the flight radius r of the unmanned aerial vehicle in the mode 3 stage2And the flying speed v3Almost invariable, since there is no limit to the number of turns n in flight during mode 3, the drone only has to fly in an energy efficient manner.
TABLE 1
Fig. 4 shows a comparison of the flight energy consumption of the drone for three different flight trajectories: (1) "hybrid circular/straight trajectory"; (2) "straight trajectory"; (3) "circular trajectory". In fig. 4(a), the distance L between the source node S and the destination node D is 5000m, and the transmission power of the source node S and the drone relay node R is PS=PRWhen the quantity Q of information to be transmitted by the source node is large, the mentioned "mixed circle/straight track" has better energy consumption performance than the "straight track". It can be found that when Q is 200bit, 18.4kW of energy can be saved compared to "straight trajectory", "hybrid circle/straight trajectory". In fig. 4(b), Q is set to 300bit, and the transmission power of the source S and the drone relay node R is PS=PRWhen the distance L between the source node S and the destination node is larger than 1W, the mentioned "hybrid circular/linear trajectory" has better energy consumption performance than the "circular trajectory". It can be found that when L is 1000m, 2.7kW of energy can be saved compared to "straight trajectory", "mixed circle/straight trajectory".
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (10)
1. A method for joint optimization of airspeed and trajectory, the method comprising:
step S1: initializing, wherein the bit number of information received by the unmanned aerial vehicle in the mode 1 is equal to the bit number of information to be sent, and the precision is given;
step S2: determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 3;
step S3: determining the optimal number of flying turns of the unmanned aerial vehicle in the mode 1;
step S4: determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 1 according to the number of information bits and the optimal number of flight turns received by the unmanned aerial vehicle in the mode 1 by adopting a one-dimensional search algorithm;
step S5: determining the number of information bits received by the unmanned aerial vehicle in the mode 1;
step S6: calculating the number of received information bits calculated by the unmanned aerial vehicle in the mode 1The difference value between the information bit number received by the unmanned aerial vehicle in the mode 1;
step S7: judging whether the difference is greater than the precision; if the difference is greater than the precision, the number of information bits received by the unmanned aerial vehicle in the mode 1 is equal to the number of information bits calculated and received by the unmanned aerial vehicle in the mode 1, and the step S4 is skipped; if the difference is less than or equal to the precision, performing step S8;
step S8: determining the optimal flight time of the unmanned aerial vehicle in the mode 1, the optimal flight time of the unmanned aerial vehicle in the mode 3, the optimal flight speed and the optimal flight time of the unmanned aerial vehicle in the mode 2; outputting optimal flight parameters so as to control the unmanned aerial vehicle to fly according to the optimal flight parameters; the optimal flight parameters include: the method comprises the following steps that an optimal flight radius, an optimal flight speed, an optimal flight duration and an optimal number of flight turns of the unmanned aerial vehicle in a mode 1, an optimal flight radius, an optimal flight speed and an optimal flight duration of the unmanned aerial vehicle in a mode 3, and an optimal flight speed and an optimal flight duration of the unmanned aerial vehicle in a mode 2 are determined;
mode 1: the unmanned aerial vehicle takes (0,0, H) as the circle center and flies in a circular track in the air with the flying height H;
mode 2: unmanned plane (r)10, H) is the starting point, (L-r)20, H) as an end point for a linear trajectory flight, r1Is a first flight radius, r2Is a second flight radius, and L is the horizontal distance between the source node S and the destination node D;
mode 3: and (3) the unmanned aerial vehicle takes (L,0, H) as a circle center and flies in the air of the flying height H in a circular track.
2. The method of joint optimization of airspeed and trajectory according to claim 1, further comprising:
and calculating the minimum total flight energy consumption according to the optimal flight parameters.
3. The method for jointly optimizing flying speed and trajectory according to claim 2, wherein the minimum total flying energy consumption is calculated according to the optimal flying parameters, and the specific formula is as follows:
wherein E represents minimum total energy consumption for flight, g represents gravitational acceleration, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2Representing the power of the received noise, beta0Denotes the channel power per unit distance, r1 *、And T1 *Respectively represents the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 1,andrespectively represent the optimal flying speed and the optimal flying time of the unmanned aerial vehicle flying in the mode 2,andrespectively representing the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 3.
4. The method for jointly optimizing flight speed and trajectory according to claim 1, wherein determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in mode 3 specifically comprises:
according toDetermining the optimal flying speed of the unmanned aerial vehicle in the mode 3; wherein the content of the first and second substances,represents the optimal flying speed of the unmanned plane in the mode 3, g represents the gravity acceleration, r2Representing a second radius of flight, vminAnd vmaxRespectively representing the minimum and maximum speed of flight of the drone, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Representing the wingspan efficiency, W representing the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2Representing the power of the received noise, beta0Expressed in unit distanceThe channel power of (a);
substituting the optimal flying speed of the unmanned aerial vehicle in the mode 3 into a flying energy consumption optimization formula of the unmanned aerial vehicle in the mode 3 by adopting a one-dimensional search algorithm to obtain the optimal flying radius of the unmanned aerial vehicle in the mode 3; the flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 3 is as follows:
vmin≤v3≤vmax,0<r2<L,T3≥0;
wherein the content of the first and second substances,indicating the optimal flight radius in drone mode 3,indicating the optimal flying speed of the drone in mode 3,representing the number of information bits received by the destination node in mode 3, g representing the acceleration of gravity, PRRepresenting the signal transmission power of the relay node of the unmanned aerial vehicle, L representing the horizontal distance between the source node S and the destination node D, v3And T3Respectively representing the flight speed and duration of the unmanned aerial vehicle in mode 3, r2Denotes the second radius of flight, H denotes the altitude of flight, vminAnd vmaxRespectively representing the minimum and maximum speed of flight of the drone, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Representing the zero lift drag coefficient, S representing the airfoil area,e0representing the wingspan efficiency, W representing the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2Representing the power of the received noise, beta0Representing the channel power per unit distance.
5. The method for jointly optimizing flying speed and trajectory according to claim 1, wherein the optimal number of turns of the unmanned aerial vehicle in mode 1 is determined according to the following formula:
wherein the content of the first and second substances,represents the optimal number of turns of the drone in mode 1,andrespectively representing the flight time, the flight speed and the flight radius of the unmanned plane in the mode 1 under the condition that the flight number n is a non-integer number of turns.
6. A system for joint optimization of airspeed and trajectory, the system comprising:
the initialization module is used for initializing, so that the bit number of the information received by the unmanned aerial vehicle in the mode 1 is equal to the bit number of the information to be sent, and the precision is given;
the first determining module is used for determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 3;
the second determining module is used for determining the optimal number of flying turns of the unmanned aerial vehicle in the mode 1;
the third determining module is used for determining the optimal flight radius and the optimal flight speed of the unmanned aerial vehicle in the mode 1 according to the number of information bits and the optimal number of flight turns received by the unmanned aerial vehicle in the mode 1 by adopting a one-dimensional search algorithm;
the information bit number determining module is used for determining the number of the information bits which are calculated and received by the unmanned aerial vehicle in the mode 1;
a difference determination module for calculating the bit number of the information received by the UAV in the mode 1The difference value between the information bit number received by the unmanned aerial vehicle in the mode 1;
the judging module is used for judging whether the difference value is greater than the precision; if the difference is greater than the precision, enabling the number of information bits received by the unmanned aerial vehicle in the mode 1 to be equal to the number of information bits calculated and received by the unmanned aerial vehicle in the mode 1, and jumping to a third determining module; if the difference is less than or equal to the precision, executing an output control module;
the output control module is used for determining the optimal flight time of the unmanned aerial vehicle in the mode 1, the optimal flight time of the unmanned aerial vehicle in the mode 3, the optimal flight speed and the optimal flight time of the unmanned aerial vehicle in the mode 2; outputting optimal flight parameters so as to control the unmanned aerial vehicle to fly according to the optimal flight parameters; the optimal flight parameters include: the method comprises the following steps that an optimal flight radius, an optimal flight speed, an optimal flight duration and an optimal number of flight turns of the unmanned aerial vehicle in a mode 1, an optimal flight radius, an optimal flight speed and an optimal flight duration of the unmanned aerial vehicle in a mode 3, and an optimal flight speed and an optimal flight duration of the unmanned aerial vehicle in a mode 2 are determined;
mode 1: the unmanned aerial vehicle takes (0,0, H) as the circle center and flies in a circular track in the air with the flying height H;
mode 2: unmanned plane (r)10, H) is the starting point, (L-r)20, H) as an end point for a linear trajectory flight, r1For the first flightRadius r2Is a second flight radius, and L is the horizontal distance between the source node S and the destination node D;
mode 3: and (3) the unmanned aerial vehicle takes (L,0, H) as a circle center and flies in the air of the flying height H in a circular track.
7. The joint optimization system of airspeed and trajectory according to claim 6, further comprising:
and the minimum total flight energy consumption determining module is used for calculating the minimum total flight energy consumption according to the optimal flight parameters.
8. The system of claim 7, wherein the minimum total energy consumption for flight is calculated according to the optimal flight parameters, and the formula is as follows:
wherein E is the minimum total energy consumption for flight, g is the acceleration of gravity, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Is the wingspan efficiency, W represents the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2For receiving the power of the noise, beta0Is the channel power per unit distance, r1 *、And T1 *Respectively the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle in the mode 1,andrespectively the optimal flying speed and the optimal flying time of the unmanned aerial vehicle flying in the mode 2,andrespectively, the optimal flight radius, the optimal flight speed and the optimal flight duration of the unmanned aerial vehicle flying in the mode 3.
9. The system for joint optimization of airspeed and trajectory according to claim 6, wherein the first determining module specifically includes:
a first determination unit for determining based on
Determining the optimal flying speed of the unmanned aerial vehicle in the mode 3; wherein the content of the first and second substances,represents the optimal flying speed of the unmanned plane in the mode 3, g represents the gravity acceleration, r2Representing a second radius of flight, vminAnd vmaxRespectively representing the minimum and maximum speed of flight of the drone, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Representing the wingspan efficiency, W representing the overall weight of the drone, ARDenotes the aspect ratio, γ, of the unmanned wing0=β0/σ2,σ2Representing the power of the received noise, beta0Represents the channel power per unit distance;
the second determining unit is used for substituting the optimal flight speed of the unmanned aerial vehicle in the mode 3 into a flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 3 by adopting a one-dimensional search algorithm to obtain the optimal flight radius of the unmanned aerial vehicle in the mode 3; the flight energy consumption optimization formula of the unmanned aerial vehicle in the mode 3 is as follows:
vmin≤v3≤vmax,0<r2<L,T3≥0;
wherein the content of the first and second substances,indicating the optimal flight radius in drone mode 3,indicating the optimal flying speed of the drone in mode 3,representing the number of information bits received by the destination node in mode 3, g representing the acceleration of gravity, PRRepresenting the signal transmission power of the relay node of the unmanned aerial vehicle, L representing the horizontal distance between the source node S and the destination node D, v3And T3Respectively representing the flight speed and duration of the unmanned aerial vehicle in mode 3, r2Denotes the second radius of flight, H denotes the altitude of flight, vminAnd vmaxRespectively representing the minimum and maximum speed of flight of the drone, c1=ρCD0S/2 and c2=2W2/[(πe0AR)ρS]ρ represents air density, CD0Denotes the zero lift drag coefficient, S denotes the wing area, e0Representing the wingspan efficiency, W representing the overall weight of the drone, ARRepresenting the aspect of an unmanned wingRatio, gamma0=β0/σ2,σ2Representing the power of the received noise, beta0Is the channel power per unit distance.
10. The joint optimization system of flying speed and trajectory according to claim 6, wherein the optimal number of turns of the unmanned aerial vehicle in mode 1 is determined according to the following formula:
wherein the content of the first and second substances,represents the optimal number of turns of the drone in mode 1,andrespectively representing the flight time, the flight speed and the flight radius of the unmanned plane in the mode 1 under the condition that the flight number n is a non-integer number of turns.
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