RU2772594C1 - Method for organizing the air traffic of a group of unmanned aerial vehicles in the landing zone - Google Patents

Abstract

FIELD: flight management.

SUBSTANCE: invention relates to a method for organizing the air traffic of a group of UAVs in the landing zone. For the organization of air traffic, the horizontal and altitude distances between neighboring UAVs are measured using a UAV, an artificial potential field of dangerous approach is calculated for each UAV as well as the value of the artificial force created by each UAV in the group to avoid collisions, which are transmitted to the ground service station, where the normalized values of the dangerous approach potentials and the artificial potential field of dangerous approach are calculated, a command to exit the waiting area to the landing zone is formed and transmitted the UAV with the highest value of the normalized value.

EFFECT: improved flight safety in the landing zone is provided.

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Description

The invention relates to a method for improving the flight safety of a group of unmanned aerial vehicles (UAVs) in a waiting area when landing UAV swarm structures on at least one landing platform and is designed to minimize the risk of collisions of UAVs in the waiting area when they move in a group structure under conditions of destabilizing factors. It can be used in the modernization of existing systems for landing robotic platforms for UAVs, in the conditions of landing of swarm structures of UAVs, the creation of promising transit-terminal stations for servicing UAVs with a high intensity of their landing for service by one or more platforms and network interaction of many similar stations.

One of the ways to improve the safety of UAV movement in the landing area is to eliminate the human factor through the use of automatic landing systems.

There is a known method for precise landing of a UAV on a landing platform according to patent RU 2 722 521 C1 (dated 2020.06.01, IPC G05D01/06 H04B1/3827 G06T7/55 G01B11/00 B64F1/00). To implement the method, a video frame is obtained with a clearly distinguishable image of the UAV when it is in the landing zone using a video camera fixed on the landing platform of the base station or launch container, the position of the UAV on the video image is determined by computer vision methods. They receive data on the coordinates of the UAV from sensors located on its board. The data obtained on the landing platform and the data from the UAV are compared. Control signals are transmitted to correct the landing trajectory, taking into account the correction factors obtained on the basis of a comparison of the above data.

Improving the accuracy of UAV landing on the platform according to patent RU 2722249 C1 (dated 2020.05.28, IPC B64F 1/22 B64C 39/02) is based on the use of a positioning device, which is made in the form of iris diaphragms connected to the closing / opening drive, and funnels, moreover, the total number of iris diaphragms and funnels is not more than the maximum number of UAV supports.

The disadvantage of the above patents is the solution of the problem of landing a single UAV on the surface of the platform and its positioning for the purpose of further maintenance, for example, replacing or charging the battery, reloading cargo, etc.

The task of landing a group (swarm) of UAVs or a plurality of UAVs with an arrival rate higher than the landing speed of a single UAV on a landing platform involves the use of the landing system as a queuing system [Pasechnikov, I. I., Pasechnikov, R. I., Nazarov, A. S., & Rodionov, D. V. (2021, May ). Design features of an information-measuring and control system for landing a swarm of small unmanned aerial vehicles. In Journal of Physics: Conference Series (Vol. 1902, No. 1, p. 012128). IOP Publishing], which has a service device 1 (Fig. 1) with a given performance G - a landing platform with an appropriate landing system that implements an alternate landing of the UAV at a given speed, an accumulation device 2 (Fig. 1) with the maximum allowable queue value N - zone waiting for the landing of a plurality of UAVs with the limit value of the UAV group (swarm) and the recommended landing buffer zone 3 (Fig. 1), which is designed to equalize the UAV speed when leaving the waiting area and the UAV speed when entering the landing line. There can be more than one UAV in the buffer zone. In the system under consideration, air traffic safety is determined by the safety of flights in the UAV waiting area and is carried out by assigning an independent closed route to each UAV in the waiting area, and there can be several UAVs in such a route, but due to the temporary distributed control of the UAV arrival rate on the routes, their collision is excluded. However, with destabilizing factors, for example, gusts of wind, etc., the protective intervals between UAVs are violated and the risk of an emergency increases. The disadvantage is the lack of a way to improve the flight safety of a group of UAVs when landing on a landing platform in conditions of destabilizing factors leading to a violation of the UAV trajectories.

As a prototype, a method for ensuring the safety of UAV flights as part of a group [Kuriki Y., Namerikawa T. Consensus-based cooperative formation control with collision avoidance for a multi-UAV system //2014 American Control Conference. - IEEE, 2014. - S. 2077-2082.].

The essence of the prototype lies in the fact that a modified algorithm of the artificial potential field is used to avoid collisions when the UAV moves in a group based on the data of the onboard passive sensors and the corrective data of the ground service station with active airspace surveillance systems. UAVs with vertical takeoff and landing evade only in the vertical direction. As shown in FIG. 2, the safety zone is formed around the center of gravity of the aircraft and is a cylindrical area with a height of 2ΔH and a radius of ΔR. If the security zone of one UAV intersects with the zones of neighboring UAVs, then all UAVs with intersecting areas begin to perform an evasive maneuver. This action is performed until the intersection of the UAV safety zones disappears.

In FIG. 2 adopted designations: r _i and h _i - the position on the horizontal plane and the flight altitude of the i -th UAV, respectively; | rij _| - projection of the distance between the UAV i and j on the horizontal plane; | h _ij | is the height difference between them.

The indicated distances are determined by the expressions:

(1)

(one)

The artificial potential field created by the UAV i and j is defined as

(2)

(2)

- положительный коэффициент управления. Как видно из выражения (2), искусственный потенциал возникает при пересечении зон безопасности, при этом его значение становится выше, чем сильнее имеет место пересечение зон безопасности, в частности, при уменьшении разности высот между БЛА i и j. Искусственный потенциал равен нулю, если зоны безопасности БЛА не пересекаются.where

- positive control coefficient. As can be seen from expression (2), an artificial potential arises when crossing safety zones, and its value becomes higher, the stronger the intersection of safety zones takes place, in particular, when the height difference between UAVs i and j decreases. The artificial potential is equal to zero if the safety zones of the UAV do not intersect.

From (2) the averaged potential field created by the i -th UAV is found:

(3)

(3)

From (3), the total artificial potential field created by all UAVs is determined as follows:

(4)

(four)

In this work, it is proposed to introduce an artificial force created by the i -th UAV to avoid collisions with neighboring vehicles:

(5)

(5)

There is no local minimum here, since full potential fieldU _c formed only from repulsive potential fields. Expression (5) in vector form has the form:

(6)

(6)

The artificial force acts in the direction opposite to the potential gradient, thus, the impact of the potential field decreases and this leads to an increase in the sum of the distances between the UAVs along the vertical axis.

The disadvantage of this method is that the flight safety of UAVs in a group is ensured by solving the problem of collision avoidance by each UAV, however, when landing a UAV group on at least one landing platform, the possibility of the information-measuring and landing control system to change the structure of the UAV group in the waiting area is not taken into account by reducing their number in the conflict spatial area.

The aim of the invention is to improve the air traffic safety of a group of UAVs when landing on at least one landing platform under conditions of destabilizing factors through the use of the control action of the landing system on the conflicted spatial section of the waiting area.

The proposed method is based on the features of the landing system with the presence of a UAV waiting area, namely: firstly, the landing platform, or a system of several landing platforms, has an information-measuring landing system, which, using the airspace control system of the waiting area, has the ability to form zones safety for each UAV and calculate the artificial potential field of dangerous proximity, which characterizes the degree of intersection of the UAV safety zones, secondly, in the conditions of landing of the UAV swarm structure, there is a continuous, periodic process of moving from the UAV waiting area to the landing buffer zone, or directly to the landing line , to implement the UAV landing procedure on at least one platform, while the information-measuring system organizes multiple UAV access, including with priority service. As a result, it is possible, based on the analysis of the roughness of security zones under conditions of destabilizing factors, to carry out a forced landing of at least one UAV that creates the greatest risk of collision in the holding area.

The technical result of the proposed method is to find safety zones for each UAV, normalized field potential values:

, (8)

, (eight)

characterizing the risks of a collision, choosing the largest one at least at one point, corresponding to the UAV with the highest risk of an emergency, which is commanded to exit the holding area to implement the process of landing on the landing platform.

The technical result is achieved by the fact that the UAV, when approaching the nearest aircraft, in accordance with the collision avoidance algorithm, calculates the potential for dangerous approach, which is transmitted to the ground service station to the access control unit to the landing system, where the UAV with the largest value is analyzed and selected. of the normalized dangerous proximity potential, the formation and transmission of a control command to land the specified UAV (figure 3), or the calculation of the geometric coordinates of all UAVs in the landing area using technical means for monitoring the airspace in the waiting area and transmitting data to the access control unit to the landing system, in which the normalized values of the potentials of the artificial dangerous proximity field are calculated, and according to the data obtained, a decision is made to select at least one UAV with the highest value of the normalized potential, to give it a command to land (Fig. 4), or to use one and the second methods with further analysis and comparison of the data obtained, as a result of which the UAV is determined to take it out of the waiting area for landing.

The difference between the proposed method and the prototype is that the safety of air traffic in the waiting area under conditions of destabilizing factors is increased not only by using the UAV collision avoidance method, but also by selecting at least one UAV with the highest risk of collision and withdrawal by the information-measuring landing system. him from the holding area to the boarding area. As a result, at the point with the highest normalized potential - at the spatial point of the greatest risk of collision, the waiting area structure is thinned out by at least one UAV, and as a result, the risk of UAV collision is reduced.

Brief description of the drawings.

In FIG. 1 shows a model of a system for landing UAV swarm groups on a robotic platform in the form of a queuing system, consisting of the main blocks:

1 - landing platform with a given capacity G;

2 - UAV waiting area with the number of UAVs in the queue N;

3 - buffer landing zone.

The UAV input stream is random with intensity γ _in .

In FIG. 2 shows the security zones of two UAVs closest to each other. Accepted designations:

r _i andh _i -position on the horizontal plane and flight altitudeith UAV, respectively; |r _ij | - projection of the distance betweeni-m andj-m UAV on a horizontal plane; |h _ij | - height difference between them; a cylindrical safety area for UAVs with a height of 2ΔH and a radius of ΔR.

In Fig.3. a block diagram of a method for improving the safety of UAV flights in the holding area with destabilizing factors based on data received from UAVs on dangerous approach potentials is disclosed. Accepted block designations:

4 - UAV computing unit;

5 - UAV;

6 – onboard passive sensor;

7 - ground service station;

8 - system of means of technical control of airspace in the waiting area;

9 – UAV communication modem;

10 – ground service station communication modem;

11 - control unit for access to the landing system;

12 - block for generating collision avoidance signals to UAV actuating devices.

In FIG. 4 shows a block diagram of a method for improving the safety of UAV flights in the holding area under destabilizing factors based on the calculation of an artificial potential field of UAV dangerous proximity using technical means of air traffic control in the holding area.

The landing system for groups (swarm structures) of UAVs is a UAV queuing system, with an input random UAV flow γ _in , consisting of at least one service device - landing platform 1 (Fig. 1a) and a storage device - UAV waiting area 2 (Fig. 1 a), the output of which is connected to the input of the landing platform 1. Since the speed of the UAV in the waiting area 2 differs from the speed of landing on the landing platform 1, an intermediate link is used to pair the speeds - the landing buffer zone 3 (Fig. 1 b). In the landing buffer zone 3, there can be more than one UAV in the case of a large number of UAVs in the waiting zone 2 and a high speed of service of the landing platform 1, or if there is more than one landing platform 1. UAVs that have arrived in the waiting zone 2 for landing move to it along independent routes at intervals in such a way that the security zones of two UAVs closest to each other (Fig. 2) do not intersect, while the condition is fulfilled:

. (9)

. (9)

Option 1 to improve the flight safety of the UAV group in the holding area under destabilizing factors (Fig. 3).

The relative position of the safety zones is determined by the computing unit 4 of the UAV 5 in the process of its movement based on the data coming from the L onboard passive sensors 6 and the corrective data of the ground service station 7 obtained using the airspace technical control system in the waiting area 8. Data from the ground station services 6 enter the computing unit 4 through the communication modem 9 UAV 5. In the case of destabilizing factors, when condition (9) neighboring UAV 5 is not met, the computing unit 4 of the i-th UAV 5, in accordance with expressions (2) and (3 ) is the average artificial close proximity potential generated by the i - m UAV 5. This result is sent to the communication modem 9 UAV 5 to generate and send an emergency proximity message with the value of the close proximity potential. The emergency approach signal with the UAV 5 proximity potential value is received by the ground service station 7 using the communication modem 10 and transmitted to the landing system access control unit 11. At the same time, the UAV 5 computing unit 4 calculates the artificial force, in accordance with the expression ( 5), to avoid collisions with the nearest UAVs 5, and the corresponding signal is transmitted to the block for generating collision avoidance signals to the actuators 12 of the UAVs 5. Based on the data received from one or more UAVs 5 with non-zero values of the average dangerous proximity potentials in the access control unit to the landing system 11 calculates an artificial potential field of dangerous proximity, determines the UAV with the highest value of the normalized dangerous proximity potential calculated in accordance with expression (8), generates and sends a command to it via the communication modem 10 to exit the waiting area to the landing area.

Option 2 to improve the flight safety of the UAV group in the holding area under destabilizing factors (Fig. 4).

The airspace technical control system in the waiting area 8 determines the coordinates of all N UAVs 5, which are transmitted via communication channels of the ground service station 7 using a communication modem 10 to the landing system access control unit 11. In the landing system access control unit 11, an artificial potential dangerous proximity field in accordance with expressions (2) and (3), at least one UAV 5 with the highest normalized dangerous proximity potential is determined using expression (8), a command is generated and transmitted using the communication modem 10 to exit the zone waiting in the boarding area.

Option 3 to improve the flight safety of the UAV group in the holding area under destabilizing factors.

Under the influence of destabilizing factors, the UAV 5 with non-zero calculated values of the average potentials of the dangerous proximity field transmits emergency approach signals with averaged values of the potentials of dangerous proximity via the communication channels of the ground service station 7 to the access control unit to the landing system 11, at the same time data on the coordinates of all UAVs 5 from the airspace technical control system in the waiting area 8 via communication channels also come to the ground service station 7 to the landing system access control unit 11, where the potential field of dangerous proximity and normalized potentials are calculated based on the data obtained by measurements and from the UAV 5, a comparative analysis is carried out and at least one UAV 5 with the highest value of the normalized dangerous approach potential is determined, a command is generated and transmitted using the communication modem 10 to exit the waiting area to the landing zone.

The proof of technical feasibility is the availability of the necessary technical and computing resources, at least the information and measuring system of the UAV swarm landing, measuring equipment and wireless communication systems in the landing area between the access control unit to the landing system and the plurality of UAVs.

Claims (3)

1. A method for organizing the air traffic of a group of UAVs in the landing area, which consists in measuring UAVs of the horizontal and vertical distances between adjacent UAVs, based on the given dimensions of the safety zone around the center of mass of the UAV and the obtained measurement values, an artificial potential field of dangerous approach is calculated for each UAV, characterizing the degree of intersection of UAV safety zones, using which the value of the artificial force created by each UAV in the group is calculated to avoid collisions with neighboring UAVs, characterized in that, in order to improve the air traffic safety of the UAV group in the waiting area, the obtained values of the field potential UAVs are transmitted to a ground service station, where they calculate the normalized values of the dangerous proximity potentials and the artificial potential field of dangerous proximity, determine at least one UAV with the highest value of the normalized value of the dangerous proximity potential, form and give him a command to exit the holding area to the landing area. 2. The method according to claim 1, characterized in that the coordinates of all UAVs are found by the system of technical control over the airspace in the waiting area and transmitted to the ground service station, where the safety zones around the center of mass of the UAV are determined for all UAVs, the normalized values of dangerous approach potentials are calculated and the UAV potential proximity field in the waiting area, at least one UAV with the highest value of the normalized potential is determined, to which a command is generated and sent to exit the waiting area to the landing area. 3. The method according to claim 1, characterized in that the obtained UAV dangerous proximity field potential values are transmitted to the ground service station, at the same time, data on the coordinates of all UAVs from the airspace technical control system in the waiting area are also received by the ground service station, where they calculate potential field of dangerous proximity on the basis of the measurements obtained, a comparative analysis of the received data from the UAV and the calculated ones is carried out, at least one UAV with the highest value of the normalized potential is determined, a command is generated and transmitted to it to exit the waiting area to the landing zone.

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