阅读说明：本技术 无人机安全返航路线规划方法 (Unmanned aerial vehicle safety return route planning method ) 是由 马云峰 郭有威 周黎明 肖兆骞 于 2019-11-27 设计创作，主要内容包括：本发明公开了一种无人机安全返航路线规划方法,包括以下步骤：建立直角坐标系、确定航线方位角、查找方位角范围内的高程数字地图、无人机存储标记和对应的角度值和失联无人机自动规划安全路径,本发明的无人机安全返航路线规划方法,在无人机起飞前通过地面PC端根据相应的参数制作出高程查找表并传输至无人机进行存储,在无人机失联后可通过计算选择一条安全的路径作为返航路线,解决了无人机无法确定地面高程导致无人机坠毁的问题；同时也解决了无人机无法存储大面积的高程数字地图问题。(The invention discloses a planning method for a safe return route of an unmanned aerial vehicle, which comprises the following steps: the method for planning the safe return route of the unmanned aerial vehicle comprises the steps of establishing a rectangular coordinate system, determining a route azimuth angle, searching an elevation digital map within an azimuth angle range, storing a mark and a corresponding angle value of the unmanned aerial vehicle, and automatically planning a safe route of the unmanned aerial vehicle, wherein an elevation lookup table is manufactured by a ground PC (personal computer) end before the unmanned aerial vehicle takes off according to corresponding parameters and is transmitted to the unmanned aerial vehicle for storage, and a safe route can be selected as a return route through calculation after the unmanned aerial vehicle loses connection, so that the problem that the unmanned aerial vehicle crashes due to the fact that the unmanned aerial vehicle cannot determine the ground elevation is solved; meanwhile, the problem that the unmanned aerial vehicle cannot store large-area elevation digital maps is solved.)

1. The safe return route planning method for the unmanned aerial vehicle is characterized by comprising the following steps: the method comprises the following steps:

a, establishing a rectangular coordinate system: before the unmanned aerial vehicle takes off, planning a flying starting point, a flight line (A) and a flight line height on the ground PC end, and establishing a rectangular coordinate system by taking a plane where the flight line height is located as a reference plane and taking an orthographic projection of the flying starting point on the plane where the flight line height is located as an origin point (P);

b, determining the azimuth angle of the flight path, namely making an azimuth angle (gamma) in a rectangular coordinate system to ensure that two sides of the azimuth angle (gamma) form two included angles (α, β) with the positive direction of the y axis within the range of the azimuth angle (A), wherein α is less than β;

c, searching an elevation digital map within the azimuth angle range, namely selecting an angle increment (delta), increasing the angle increment (delta) each time by taking (α) as an initial angle, then taking a new angle (α + N delta, N is the increment times and N is a natural number) as a direction vector, finding out an intersection point of the direction vector and a flight path (A), then inquiring and recording the elevation digital map corresponding to a connecting line between the intersection point and the initial point (P), and repeatedly executing the step c until the elevation digital map corresponding to the direction vector of each angle increment (delta) within the azimuth angle (gamma) range of the flight path is obtained, wherein the range of the angle increment (delta) is more than 0 degree and less than gamma;

d unmanned plane stores the tag and the corresponding angle value: c, comparing the ground maximum elevation value corresponding to the direction vector of each angle increment (delta) acquired in the step c with the height of the air route (A); if the elevation digital map of the direction vector of the angle value is larger than the height of the air route, marking as a danger; if the elevation digital map of the direction vector of the angle value is smaller than the height of the air route, marking as safe; transmitting the marks and the corresponding angle values of the marks to the unmanned aerial vehicle for storage;

e, automatically planning a safety path of the loss-of-connection unmanned aerial vehicle: after the unmanned aerial vehicle takes off and loses contact, the unmanned aerial vehicle obtains a current angle through calculation according to an original point (P) and the current position of the unmanned aerial vehicle, calculates an angle value closest to the current angle and searches for a mark corresponding to the angle value; if the mark position is safe, the safety of the flight path corresponding to the azimuth angle is indicated, and the flight path can return along the flight path; and if the mark position is dangerous, calculating a new azimuth value again until the azimuth value which is closest to the advancing direction and is marked as safe is found, and automatically returning to the flying point by taking the connecting line of the point and the origin (P) as a path.

2. The method for planning the safe return route of the unmanned aerial vehicle as claimed in claim 1, wherein in the step b, two sides of the azimuth angle (γ) are tangent to the route, the α is a minimum azimuth angle, the minimum azimuth angle is an angle at which a line connecting a point on the route and an origin (P) and a y-axis positive direction form a minimum angle, the β is a maximum azimuth angle, and the maximum azimuth angle is an angle at which a line connecting the point on the route (A) and the origin (P) and the y-axis positive direction form a maximum angle.

3. The unmanned aerial vehicle safety return route planning method of claim 1, characterized in that: in the step c, the intersection point of the direction vector of the angle increment (delta) and the route (A) is the intersection point of the farthest end of the route (A) far away from the origin (P).

4. The unmanned aerial vehicle safety return route planning method of claim 1, characterized in that: in the step c, the range of the angle increment (delta) is as follows: delta is more than 0.1 degree and less than 1 degree.

5. The unmanned aerial vehicle safe return route planning method of claim 4, characterized in that: the angular increment (δ) is: 0.5 degree.

6. The unmanned aerial vehicle safety return route planning method of claim 1, characterized in that: in the step d, the danger and the safety are marked in a binary mode, the danger is marked as 1, and the safety is marked as 0.

7. The unmanned aerial vehicle safety return route planning method of claim 6, characterized in that: and making the marks and the corresponding angle values into an elevation lookup table and transmitting the elevation lookup table to the unmanned aerial vehicle for storage:

table 1: elevation lookup table

Marking 0 0 1 … 0 0 Angle value α α+δ α+2*δ … α+N*δ β

In the table, N is the number of increments and N is a natural number.

Technical Field

The invention relates to the technical field of unmanned aerial vehicles, in particular to a planning method for a safe return route of an unmanned aerial vehicle.

Background

In recent years, the production and application of unmanned aerial vehicles are developed vigorously at home and abroad, and the unmanned aerial vehicles are applied more and more widely in various fields, such as surveying and mapping, monitoring, agricultural plant protection, traffic inspection and the like. The unmanned aerial vehicle system usually includes unmanned aerial vehicle and ground basic station, and its theory of operation is that the basic station passes through wireless link and unmanned aerial vehicle communication, and unmanned aerial vehicle takes place the airline for unmanned aerial vehicle before taking off, and unmanned aerial vehicle flight in-process need monitor unmanned aerial vehicle's state and send control command etc.. But due to current technology, the link between the base station and the drone may fail (e.g., electromagnetic interference, distance overrun, base station damage, etc.) while the drone is in an offline mode. All states of the unmanned aerial vehicle are unknown in the loss of connection mode, and the situation is dangerous. Consequently, most unmanned aerial vehicle producers all can design the follow-up action of unmanned aerial vehicle under the loss of connection mode, and current follow-up action mainly includes two kinds of modes: lost link return and in-situ hover.

The original circling is limited by the storage battery of the unmanned aerial vehicle, the circling time is short, the unmanned aerial vehicle can crash when the power supply is exhausted, and certain limitation is realized; therefore, most manufacturers can set that the unmanned aerial vehicle returns immediately after the unmanned aerial vehicle loses contact and exceeds a certain time, and the return route is a straight line of a connecting line between the unmanned aerial vehicle losing contact position and the flying starting point. Under this kind of condition, unmanned aerial vehicle does not know the height digital map on the route of returning a voyage, and the height that is greater than unmanned aerial vehicle flight when the high mountain on the route of returning a voyage or building promptly makes unmanned aerial vehicle striking high mountain or building, and then leads to unmanned aerial vehicle crash lightly, then endangers ground personal and property safety seriously.

In addition, because the computing resources of the unmanned aerial vehicle are limited, a large-area elevation digital map cannot be stored generally, because the large-area elevation digital map usually occupies a large amount of storage space, and accessing the elevation digital map consumes resources and computing power relatively.

Disclosure of Invention

The invention provides a method for planning a safe return route of an unmanned aerial vehicle, which aims to solve the technical problems that a height digital map in the return route of an unconnection unmanned aerial vehicle cannot be determined and the height digital map cannot be stored in a large area.

The technical scheme adopted by the invention is as follows: the safe return route planning method for the unmanned aerial vehicle comprises the following steps:

a, establishing a rectangular coordinate system: before the unmanned aerial vehicle takes off, planning a flying starting point, a flight line A and a flight line height on the ground PC end, and establishing a rectangular coordinate system by taking a plane where the flight line height is located as a reference plane and taking an orthographic projection of the flying starting point on the plane where the flight line height is located as an origin point P;

b, determining a lane azimuth angle, namely making an azimuth angle gamma in a rectangular coordinate system to ensure that two sides of the azimuth angle gamma form two included angles (α, β) with the positive direction of a y-axis within the range of the azimuth angle A, wherein α is less than β;

c, searching an elevation digital map within the azimuth angle range, namely selecting an angle increment delta, taking α as an initial angle, increasing the angle increment delta each time, then taking a new angle (α + N delta, N is the increment times and N is a natural number) as a direction vector, finding out an intersection point of the direction vector and the flight path A, then inquiring and recording the elevation digital map corresponding to a connecting line between the intersection point and an original point P, and repeatedly executing the step c until the elevation digital map corresponding to the direction vector of each angle increment delta within the azimuth angle gamma range of the flight path is obtained, wherein the range of the angle increment delta is more than 0 degree delta and less than gamma;

d unmanned plane stores the tag and the corresponding angle value: c, comparing the ground maximum elevation value corresponding to the direction vector of each angle increment delta acquired in the step c with the height of the air route A; if the elevation digital map of the direction vector of the angle value is larger than the height of the air route, marking as a danger; if the elevation digital map of the direction vector of the angle value is smaller than the height of the air route, marking as safe; transmitting the marks and the corresponding angle values of the marks to the unmanned aerial vehicle for storage;

e, automatically planning a safety path of the loss-of-connection unmanned aerial vehicle: after the unmanned aerial vehicle takes off and loses contact, the unmanned aerial vehicle obtains a current angle through calculation according to the original point P and the current position of the unmanned aerial vehicle, calculates an angle value closest to the current angle and searches a mark corresponding to the angle value; if the mark position is safe, the safety of the flight path corresponding to the azimuth angle is indicated, and the flight path can return along the flight path; and if the mark position is dangerous, calculating a new azimuth value again until the azimuth value which is closest to the advancing direction and is marked as safe is found, and automatically returning to the flying point by taking the connecting line of the point and the origin point P as a path.

The altitude digital map is the height of a ground building, the altitude digital map is stored at a ground PC end, a rectangular coordinate system is established according to a starting point P, a route A and the route height before the unmanned aerial vehicle takes off, the azimuth gamma of the route is made, and the route A is ensured to be in the range of the azimuth, so that the altitude values in the whole route range can be searched and compared; and by defining an angular increment δ; comparing the elevation digital maps corresponding to the angular values in the different angle increments delta through the PC terminal, marking the elevation digital maps, transmitting the marks and the angular values corresponding to the marks to the unmanned aerial vehicle for storage, and finishing the takeoff of the unmanned aerial vehicle after the transmission is finished. Compared with the traditional mode, the method and the system do not need to directly store a large number of elevation digital maps on the unmanned aerial vehicle, and solve the technical problem that the computing resources of the unmanned aerial vehicle are limited. After the unmanned aerial vehicle loses connection during takeoff, the unmanned aerial vehicle obtains a current azimuth angle through calculation according to an original point P and the current position of the unmanned aerial vehicle, calculates an angle value closest to the current azimuth angle and searches a mark corresponding to the angle value; if the mark position is safe, the safety of the flight path corresponding to the azimuth angle is indicated, and the flight path can return along the flight path; and if the mark position is dangerous, calculating a new azimuth value again until the azimuth value which is closest to the advancing direction and is marked as safe is found, and automatically returning to the flying point by taking the connecting line of the point and the origin point P as a path. Compared with the traditional mode of in-situ circling after the unmanned aerial vehicle loses connection, the unmanned aerial vehicle loss-of-connection route planning method can plan a route marked as safety for return voyage through the unmanned aerial vehicle loss-of-connection position, avoids the risk of crash caused by loss of a storage battery, and can also successfully avoid mountains or buildings on the return route.

Furthermore, in the step b, two sides of the azimuth angle gamma are tangent to the flight path, the α is the minimum azimuth angle, the minimum azimuth angle is the angle of the minimum angle formed by the line connecting the point and the origin (P) on the flight path and the forward angle of the y axis, the β is the maximum azimuth angle formed by the line connecting the point and the origin P on the flight path A and the forward angle of the y axis.

Further, in the step c, an intersection point of the direction vector of the angle increment δ and the route a is an intersection point of the farthest end of the route a away from the origin P. The flight path may be a back-and-forth curved path, so that the number of intersection points of the direction vector of the angle increment delta and the flight path is multiple, and in order to ensure that an elevation digital map in the flight path can be comprehensively detected and ensure the safe return distance of the unmanned aerial vehicle after the unmanned aerial vehicle is disconnected, the intersection point which is farthest away from a departure point is selected.

Further, in step c, the range of the angle increment δ is: delta is more than 0.1 degree and less than 1 degree. The suitable angle increment delta can be selected according to the computing power of different unmanned aerial vehicles, the large unmanned aerial vehicle with the strong computing power can select 0.1 degrees, and the altitude digital map corresponding to the direction vector can be accurately inquired, so that the return path is shorter or smaller, the small unmanned aerial vehicle with the weak computing power can select 1 degree, and the return path can be longer.

Further, the angle increment δ is: 0.5 degree.

Further, in the step d, a binary mode is adopted to mark the danger and the safety, the danger is marked as 1, and the safety is marked as 0. The reliability of the binary system is high, only two numbers of 0 and 1 are used in the binary system, errors are not easy to occur in transmission and processing, and therefore the reliability of return flight of the unmanned aerial vehicle can be guaranteed; meanwhile, the operation rule is simple, the operation rule of binary number is simple, the structure of the operator can be simplified, the operation speed is improved, the unmanned aerial vehicle can find the mark more quickly according to the angle value, the cruising ability of the unmanned aerial vehicle is guaranteed, and the situation that the unmanned aerial vehicle runs out of electric energy and is crashed is avoided.

Further, the marks and the corresponding angle values are made into an elevation lookup table:

table 1: elevation lookup table

Marking

0

0

1

…

0

0

Angle value

α

α+δ

α+2*δ

…

α+N*δ

β

In the table, N is the number of increments and N is a natural number.

The marks and the corresponding angle values are made into an elevation lookup table, so that the unmanned aerial vehicle can find the marks corresponding to the angle values more quickly, whether the return route is safe or not can be judged quickly, and the safe return of the unmanned aerial vehicle is guaranteed.

The invention has the beneficial effects that:

1. according to the safe return route planning method for the unmanned aerial vehicle, different angle values and corresponding marks are calculated through the ground PC terminal according to corresponding parameters before the unmanned aerial vehicle takes off, and the marks are stored in the marks and are stored in the unmanned aerial vehicle; meanwhile, the problem that the unmanned aerial vehicle cannot store large-area elevation digital maps is solved.

2. Two sides of the azimuth angle gamma are tangent to the air route, so that the elevation digital maps in all air routes can be recorded, the calculation of the elevation digital maps outside the air routes is avoided, a large amount of work is reduced, the work efficiency is improved, and the storage capacity of the unmanned aerial vehicle is reduced.

3. According to the invention, a binary system mode is adopted to mark danger and safety and produce an elevation lookup table, so that the reliability of return voyage of the unmanned aerial vehicle can be guaranteed; meanwhile, the operation rule is simple, the structure of the operator can be simplified, the operation speed can be improved, the unmanned aerial vehicle can find the mark more quickly according to the angle value, the cruising ability of the unmanned aerial vehicle is guaranteed, and the situation that the unmanned aerial vehicle runs out of electric energy and is crashed is avoided.

Drawings

Fig. 1 is a schematic structural diagram of the first embodiment.

Fig. 2 is a schematic structural diagram of the third embodiment.

Fig. 3 is a schematic view of the case of azimuth.

Fig. 4 is a schematic view of another case of azimuth.

Labeled as:

p, an origin; A. a route; B. starting a route; C. a course destination; delta, angle increment; gamma, azimuth.

Detailed Description

The invention is further described below with reference to the accompanying drawings.