CN108646782A - A kind of unmanned plane safe flight method - Google Patents

Abstract

The application provides a kind of unmanned plane safe flight method, includes the following steps：S1 initializes flight path；S2, differentiation setting；S3, safe distance setting；The communication dispatch relationship of S4 unmanned planes and ground node is arranged；S5, optimization unmanned plane track；S6 judges whether the route after optimization is optimum state；If being judged as YES, enter S7；If being judged as NO, return to step S4；S7, output：Unmanned plane flies according to the route after S6 optimization orders.The application has coordinated the communication dispatch relationship between unmanned plane and ground node, while improving the safety flown between multiple no-manned plane system unmanned plane, has effectively evaded the risk of collision between unmanned plane by the way that the differentiation factor is arranged.

Description

A method for safe flight of unmanned aerial vehicles

technical field

The present application relates to the technical field of safe flight of unmanned aerial vehicles, and in particular to a method for safe flight of unmanned aerial vehicles.

Background technique

In the prior art, unmanned aerial vehicle (UAV) has obtained more and more attention and application in the field of wireless communication. Compared with the traditional ground communication system, the UAV communication system has a series of advantages such as flexible maneuverability, simple structure, and controllable movement. The system is used to carry out a series of communication operations, such as serving as a temporary base station in the air to distribute data for hotspot areas, or to re-establish communication connections for areas where communication facilities have been damaged after disasters. However, due to the extremely limited endurance of UAVs, the research on UAVs generally focuses on the trajectory optimization of UAVs and the allocation of communication resources.

Using multiple UAVs to provide services to multiple users on the ground at the same time is a more common way in future UAV communication scenarios. For multi-UAV cooperative communication systems, the current research is mainly reflected in the research of static deployment and non-differentiated multi-machines. No differentiation means that the communication performance between multiple UAVs is the same, regardless of individual differences and special features. Task scenarios require differentiated design, which may not meet the needs of some actual scenarios. In addition, there is a lack of discussion on flight safety between UAVs in the prior art, such as how to effectively avoid the risk of collision between UAVs.

Contents of the invention

In order to achieve the above purpose, the present application provides a method for safe flight of unmanned aerial vehicles, comprising the following steps:

S1, initialize the flight trajectory: set the initial flight trajectory of the UAV in the flight area as a circle, take the geometric center of the flight area as the origin, take the line parallel to the ground as the x-axis, and the line perpendicular to the ground as y axis to establish a coordinate system, then the center of the initial flight trajectory of UAV m is: O _m = [x _m , y _m ] ^T , where T is the flight period of UAV m;

From the flight speed V _m of UAV m and the flight period T of UAV m, the radius of the flight trajectory of UAV m can be obtained

Set N as the total time slot used by the UAV to fly for one week, and _δt represents the length of the time slot after time discretization, expressed as:

Then the position of UAV m in the nth time slot can be obtained as:

S2, Differentiation setting: set the differentiation factor θ _m , the relationship between the differentiation factor θ _m and the throughput C _m of the UAV m and the total throughput C of the system is expressed as:

where, θ _m ≥ 0 and Where M is the number of drones in the system;

S3, safety distance setting: setting another UAV l different from the UAV m, then the positional relationship between the two UAVs is:

Where q _m [n] represents the position of UAV m in the nth time slot, q _l [n] represents the position of UAV l in the nth time slot, and D is the minimum safe distance;

S4. Setting the communication scheduling relationship between the UAV and the ground node: set the communication scheduling factor α _m,k [n], then the scheduling relationship between the UAV m and the ground node k at time slot n is:

where K is the number of ground nodes in the system;

S5, optimize the UAV trajectory;

S6, judging whether the optimized route is in the best state; if it is judged to be yes, then enter S7; if it is judged to be no, then return to step S4;

S7, output: the drone flies according to the route optimized in step S6.

Preferably, the positions of the centers of the flight trajectories of different drones do not coincide.

Preferably, where V _max is set as the maximum flight speed of the UAV, and V _min is set as the minimum flight speed of the UAV, then V _max ≥ V _m ≥ V _min .

Preferably, wherein, in step S4, the communication rate of UAV m at node k

Where p _k [n] is the instantaneous transmission power of ground node k in time slot n; w _k is the position vector of node k, γ ₀ is the received signal-to-noise ratio, and H is the height of UAV m from the ground.

Preferably, where the maximum instantaneous transmit power of the ground node k is set to P _max , then 0≤p _k [n]≤P _max .

Preferably, where the maximum value of the total energy generated during the launch process of the ground node k is set as W _t , then:

Preferably, wherein, in step S6, the method for judging whether the optimized route is in the best state is: setting the precision u, comparing the difference between two adjacent optimized routes with the precision u, if the difference is within the precision , it is judged as yes.

Preferably, wherein, in step S5, the optimization method of the trajectory of the UAV includes a direct shooting method, a configuration method and a differential inclusion method.

The beneficial effects achieved by this application are as follows: the present invention designs a differentiated multi-UAV safe flight method, and by introducing differentiation factors, it solves the difference in how different UAVs realize UAV work in different situations and different needs At the same time, through the differentiation factor, the communication scheduling relationship between the UAV and the ground node is coordinated, so that only one ground node communicates with any UAV in any time slot, and there is only one UAV Establish a connection with any ground node to eliminate co-channel interference; the invention also provides a multi-UAV safe flight method, which can effectively ensure the safe flight between multiple UAVs, avoid collisions, and make the system safe and sustainable. secured.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in this application, and those skilled in the art can also obtain other drawings based on these drawings.

Figure 1 is a schematic diagram of the steps of the method of the present invention.

Detailed ways

The technical solutions in the embodiments of the present application are clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of this application.

The safe flight method of UAV provided by the present invention, this embodiment is applied to the safe flight system of UAV, and the safe flight system of UAV includes UAV, ground node user and control system, and the control system and ground node The communication connection between the user and the UAV is used to control the flight of the UAV and carry out communication scheduling between the UAV and the node.

As shown in Figure 1, methods to achieve safe flight include:

S1: Set the initial flight trajectory of the UAV in the flight area as a circle, take the geometric center of the flight area as the origin, take the line parallel to the ground as the x-axis, and the line perpendicular to the ground as the y-axis to establish a coordinate system , then the center of the initial flight trajectory of UAV m is: O _m = [x _m ,y _m ] ^T , where T is the flight period of UAV m;

From the flight speed V _m of UAV m and the flight period T of UAV m, the radius of the flight trajectory of UAV m can be obtained

Set N as the total time slot used by the UAV to fly for one week, and _δt represents the length of the time slot after time discretization, expressed as:

Then the position of UAV m in the nth time slot can be obtained as:

S2: Set a differentiation factor θ _m . The setting of the differentiation factor can be set according to individual differences of UAVs (such as performance differences, battery life, etc.) and special task scenarios. The relationship between the differentiation factor θ _m and the throughput C _m of the drone m and the total system throughput C is expressed as: where, θ _m ≥ 0 and M is the number of drones in the system.

S3: Set another UAV l different from the UAV m, then the positional relationship between the two UAVs m and l is:

Where q _m [n] represents the position vector of UAV m in the nth time slot, q _l [n] represents the position vector of UAV l in the nth time slot, and D is the distance between two UAVs minimum safe distance.

After being limited by this formula, in any time slot, a minimum safe distance needs to be maintained between any two UAVs to avoid collisions and ensure the safe operation of the system.

S4: Carry out the communication scheduling between the ground node and the UAV and the distribution of the transmission power of the ground node. In this embodiment, at most one ground node is allowed to communicate with any UAV in any time slot, and at the same time, in order to eliminate co-channel interference, at most one UAV can establish a connection with any ground node in any time slot. Mathematically, a communication scheduling factor α _m,k [n] can be used to represent the scheduling relationship between UAV m and node k in time slot n, the formula is expressed as:

Among them, the communication rate of UAV m at node k where p _k [n] is the instantaneous transmission power of ground node k in time slot n; w _k is the position vector of node k, γ ₀ is the receiving signal-to-noise ratio, H is the height of UAV m from the ground, and K is the system The number of ground nodes in .

Wherein, for the transmit power of ground node k, its maximum instantaneous transmit power does not exceed the upper limit P _max , namely: 0≤p _k [n]≤P _max ;

At the same time, set the maximum value of the total energy generated by the ground node k during the launch process as W _t , expressed as:

S5: enter the UAV trajectory optimization step, and optimize the trajectory of the UAV.

Optimization methods include but are not limited to the direct shooting method, configuration method and differential inclusion method in the prior art.

S6: After trajectory optimization, the control system judges whether the optimized route is in the best state. The specific method is: set the accuracy u, and compare the difference between the two adjacent optimized routes with the accuracy u. Within, it is judged as yes.

In this step, if the judgment is yes, then execute S7: send the optimized trajectory to the UAV, and the UAV starts to fly according to the optimized trajectory; step.

While preferred embodiments of the present application have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once the basic inventive concept is appreciated. Therefore, the appended claims are intended to be construed to cover the preferred embodiment and all changes and modifications which fall within the scope of the application. Obviously, those skilled in the art can make various changes and modifications to the application without departing from the spirit and scope of the application. In this way, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims (8)

1. A method for unmanned aerial vehicle safe flight, comprising the following steps: S1, initialize the flight trajectory: set the initial flight trajectory of the UAV in the flight area as a circle, take the geometric center of the flight area as the origin, take the line parallel to the ground as the x-axis, and the line perpendicular to the ground as y axis to establish a coordinate system, then the center of the initial flight trajectory of UAV m is: O _m = [x _m , y _m ] ^T , where T is the flight period of UAV m; From the flight speed V _m of UAV m and the flight period T of UAV m, the radius of the flight trajectory of UAV m can be obtained Set N as the total time slot used by the UAV to fly for one week, and _δt represents the length of the time slot after time discretization, expressed as: Then the position of UAV m in the nth time slot can be obtained as: S2, Differentiation setting: set the differentiation factor θ _m , the relationship between the differentiation factor θ _m and the throughput C _m of the UAV m and the total throughput C of the system is expressed as: C _m ≥ θ _m C, where, θ _m ≥ 0 and Where M is the number of drones in the system; S3, safety distance setting: setting another UAV l different from the UAV m, then the positional relationship between the two UAVs is: ||q _m [n]-q _l [n]|| ² ≥ D ² , m,l,m≠l Where q _m [n] represents the position of UAV m in the nth time slot, q _l [n] represents the position of UAV l in the nth time slot, and D is the minimum safe distance; S4. Setting the communication scheduling relationship between the UAV and the ground node: set the communication scheduling factor α _m,k [n], then the scheduling relationship between the UAV m and the ground node k at time slot n is: α _m,k [n]∈{0,1}, k,n; where K is the number of ground nodes in the system; S5, optimize the UAV trajectory; S6, judging whether the optimized route is in the best state; if it is judged to be yes, then enter S7; if it is judged to be no, then return to step S4; S7, output: the drone flies according to the route optimized in step S6. 2. The safe flying method for unmanned aerial vehicles according to claim 1, wherein the center positions of the flight trajectories of different unmanned aerial vehicles do not coincide. 3. The safe flying method of UAV according to claim 1, wherein V _max is set as the maximum flying speed of the UAV, and V _min is set as the minimum flying speed of the UAV, then V _max ≥ V _m ≥ V _min . 4. The safe flight method for unmanned aerial vehicle according to claim 1, wherein, in step S4, the communication rate of unmanned aerial vehicle m at node k Where p _k [n] is the instantaneous transmit power of ground node k in time slot n; w _k is the position of node k, γ ₀ is the receiving signal-to-noise ratio, and H is the height of UAV m from the ground. 5. The safe flight method of UAV according to claim 4, wherein, if the maximum instantaneous transmission power of the ground node k is set to P _max , then 0≤p _k [n]≤P _max . 6. The safe flight method of unmanned aerial vehicle according to claim 4, wherein, the maximum value of total energy produced in the launching process of setting ground node k is W _t , then there are: n=1,2,...,N. 7. The method for safe flight of unmanned aerial vehicles according to claim 1, wherein, in step S6, the method for judging whether the optimized route is in the best state is: setting the accuracy u, the difference between two adjacent optimized routes The value is compared with the precision u, if the difference is within the precision, it is judged as yes. 8. The method for safe flight of unmanned aerial vehicle according to claim 1, wherein, in step S5, the optimization method of the trajectory of the unmanned aerial vehicle comprises a direct shooting method, a configuration method and a differential inclusion method.