Method for predicting link communication state of unmanned aerial vehicle in full task process

Abstract

The invention belongs to the technical field of unmanned aerial vehicle control, and particularly relates to a full-task process unmanned aerial vehicle link communication state prediction method which is used for predicting the link communication state of an unmanned aerial vehicle in a full-task process in advance when a task is executed, assisting ground control personnel in mastering the link communication state of the unmanned aerial vehicle in the full-task process, and improving the task performance. Whether link interruption is caused after the unmanned aerial vehicle executes the maneuvering action and the link interruption time are predicted in advance, so that a decision can be made in advance according to the task execution state, for example, the maneuvering action is not executed to ensure link communication, or the maneuvering action is limited, and the unknown state of unmanned aerial vehicle link-free flight is eradicated. Unpredictable and controllable risks are reduced, and the task applicability of the unmanned aerial vehicle is improved.

Description

Technical Field

[0001] The present application belongs to the field of drone control technology, and specifically relates to a method for predicting the communication status of a drone link in a full mission process. Background Art

[0002] With the development of science and technology, drones have continuously achieved breakthroughs in communication, navigation, and reconnaissance, and their applications are becoming increasingly widespread. In the civilian sector, drones are mainly used in agricultural plant protection, emergency rescue, logistics and express delivery, environmental testing, aerial photography, and traffic inspection. In the scientific research field, drones are mainly used in scientific research, education, and teaching.

[0003] There are significant differences between drones and manned aircraft in many aspects, as follows:

[0004] From a usage perspective, the main difference between drones and manned aircraft is that the pilot of a manned aircraft can directly observe the aircraft's altitude and speed through the display, and sense the aircraft's attitude, speed, and overload changes through their senses. However, because the controller of a drone is on the ground, he can only observe the drone's flight status through status information transmitted via the wireless link, and remotely control the drone by uploading control commands via the wireless link. Therefore, there are significant differences between drones and manned aircraft in terms of links, which are mainly reflected in the following aspects:

[0005] Current drone designs generally deploy omnidirectional communication antennas for line-of-sight links, ensuring that the drone can establish a link connection with the ground control station during various maneuvers. However, for satellite communication links, due to internal layout and cost reasons, only a single satellite communication antenna is deployed on the back of the drone. This causes the satellite communication link to be interrupted when the drone performs large-angle roll maneuvers and is far away from the satellite. As a result, when the drone is used beyond visual range, link communication cannot be guaranteed. Ground control personnel cannot obtain the drone's flight status or send uplink commands to control the drone. They can only wait for the drone to level off and then the satellite communication link to automatically recover, obtain the drone's flight status, and send relevant control commands as needed. This poses unpredictable and controllable risks.

[0006] This application is proposed in view of the above-mentioned technical defects. Summary of the Invention

[0007] The purpose of this application is to provide a full-mission process UAV link communication status prediction method to overcome or alleviate at least one of the known technical defects.

[0008] The technical solution of this application is:

[0009] A full-mission process UAV link communication state prediction method includes:

[0010] Set the link communication status flag L, where L=0 indicates that the UAV link communication status is predicted to be normal, and L=1 indicates that the UAV link communication status is predicted to be interrupted;

[0011] Determine the positions of ground control stations and communication satellites in the Earth's coordinate system

[0012] Periodically calculate the position of the drone in the Earth coordinate system and its posture in the body coordinate system

[0013] Calculate the distance between the drone and the ground control station Determine whether the drone is within visual range;

[0014] If s < D, the UAV is within the line of sight range, and the link communication status is predicted to be normal, and the link communication status flag L is set to 0, where D is the line of sight communication range;

[0015] If s≥D, the drone is out of sight, and the satellite antenna pointing unit vector in the earth coordinate system is calculated. Calculate the connection vector between the drone and the communication satellite in the Earth coordinate system Then calculate the angle between the satellite antenna pointing unit vector and the connection vector between the drone and the communication satellite in the earth coordinate system Determine whether the communication satellite is within the angular range of the satellite communication antenna, where: is the direction cosine matrix from the body coordinate system to the earth coordinate system, is the satellite communication antenna pointing unit vector in the body coordinate system;

[0016] If θ<K, the communication satellite is within the angular range of the satellite communication antenna, and the link communication state is predicted to be normal, and the link communication state flag L is set to 0, where K is the effective angular range of the satellite communication antenna;

[0017] If θ≥K, the communication satellite is not within the angular range of the satellite communication antenna, and the link communication state is predicted to be interrupted, and the link communication state flag L is set to 1;

[0018] When the link communication status flag L changes from 0 to 1, the time starts from 0;

[0019] When the link communication status flag L changes from 1 to 0, the timing is ended and the timing time is output as the predicted time of link communication status interruption.

[0020] Optionally, in the above-mentioned full-mission process UAV link communication status prediction method, in the earth coordinate system, the z-axis is along the direction of the earth's rotation, the x-axis intersects the 0 degree meridian in the equatorial plane, and the y-axis forms a right-handed system;

[0021] In the body coordinate system, the right side of the body is the x-axis, the forward direction is the y-axis, and the upward direction is the z-axis.

[0022] Optionally, in the above-mentioned full-mission process UAV link communication status prediction method, the positions of the ground control station and the communication satellite in the earth coordinate system Take a fixed value.

[0023] Optionally, in the above-mentioned full-mission process UAV link communication state prediction method, the position of the UAV in the earth coordinate system is periodically calculated. and its posture in the body coordinate system The period is t=1s.

[0024] Optionally, in the above-mentioned full-mission process UAV link communication state prediction method, the satellite communication antenna pointing unit vector in the body coordinate system is Take [0,0,1].

[0025] This application has at least the following beneficial technical effects:

[0026] A method for predicting the link communication status of a UAV in the entire mission process is provided. The method is used to predict the link communication status of the UAV in the entire mission process in advance when the mission is executed, assisting ground control personnel in mastering the link communication status of the UAV in the entire mission process, and predicting in advance whether the link will be interrupted after the UAV performs a maneuver and the duration of the link interruption. In this way, advance decisions can be made according to the mission execution status, such as not performing maneuvers to ensure link communication, or restricting maneuvers, thereby eliminating the unknown state of the UAV flying without a link, reducing unpredictable and controllable risks, and improving the mission applicability of the UAV. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the full-mission process drone link communication status prediction method provided in an embodiment of the present application.

[0028] In order to better illustrate this embodiment, some contents of the drawings may be omitted, enlarged or reduced, which is only used for illustrative purposes and should not be construed as limiting the present application. DETAILED DESCRIPTION

[0029] To make the technical solution and its advantages of this application more clear, the technical solution of this application will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only some of the embodiments of this application and are only used to explain this application, not to limit this application. It should be noted that for ease of description, only the parts relevant to this application are shown in the accompanying drawings, and other relevant parts can refer to the general design.

[0030] In addition, unless otherwise defined, the technical or scientific terms used in the description of this application shall have the ordinary meanings understood by those skilled in the art to which this application belongs. The term "include" as used in the description of this application means that the concepts preceding the term include the concepts listed after the term and their equivalents, without excluding other related concepts.

[0031] The present application embodiment provides a method for predicting the communication status of a UAV link in a full mission process, such as Figure 1 As shown in the figure, for the UAV mission execution, the real-time position and attitude of the UAV are simulated, the angular range between the UAV and the communication satellite is calculated, and the link communication status of the UAV in the whole mission process is predicted.

[0032] The link communication status flag L is set, where L=0 indicates that the UAV link communication status is predicted to be normal, and L=1 indicates that the UAV link communication status is predicted to be interrupted.

[0033] Define the earth coordinate system, geographic coordinate system, and body coordinate system, where:

[0034] Earth coordinate system: the z-axis is along the direction of the Earth's rotation, the x-axis intersects the 0-degree meridian in the equatorial plane, and the y-axis forms a right-handed system;

[0035] Geographic coordinate system: east is the x-axis, north is the y-axis, and celestial direction is the z-axis;

[0036] Body coordinate system: the right side of the body is the x-axis, the forward direction is the y-axis, and the upward direction is the z-axis.

[0037] Clarify the positions of the ground control station and communication satellite in the Earth coordinate system. Generally, communication satellites are geosynchronous satellites, and their positions in the Earth coordinate system are fixed values. The ground control station is generally a fixed ground control station, and its position in the earth coordinate system is a fixed value.

[0038] Periodically calculate the position of the drone in the Earth coordinate system and its posture in the body coordinate system

[0039]

[0040] The position and attitude of the UAV in the whole mission process are periodically selected, and the period t = 1s can generally be set.

[0041] Calculate the distance between the drone and the ground control station Determine whether the drone is within the visual range.

[0042] If s<D, D is the line-of-sight communication range, usually 150~400km, then the UAV is within the line-of-sight range, the link communication status is predicted to be normal, and the link communication status flag L is set to 0.

[0043] If s ≥ D, the drone is out of sight and has exceeded the communication distance of the line-of-sight link. At this time, the drone only has the satellite link to work normally. It is necessary to determine whether the communication satellite is within the angular range of the satellite antenna based on the position of the communication satellite and the attitude of the drone. That is, it is necessary to calculate the angle between the satellite antenna pointing unit vector and the connection vector between the drone and the communication satellite.

[0044] Calculate the satellite communication antenna pointing unit vector in the earth coordinate system

[0045]

[0046] in,

[0047] is the direction cosine matrix from the body coordinate system to the earth coordinate system, based on the posture of the drone in the body coordinate system to obtain;

[0048] is the unit vector pointing to the satellite communication antenna in the body coordinate system, and is set to [0, 0, 1].

[0049] Calculate the connection vector between the drone and the communication satellite in the Earth coordinate system

[0050]

[0051] Calculate the angle θ between the satellite antenna pointing unit vector and the connection vector between the drone and the communication satellite in the Earth coordinate system:

[0052]

[0053] If θ<K, K is the effective angular range of the satellite communication antenna, usually 0°~90°, then the communication satellite is within the angular range of the satellite communication antenna, and the link communication status is predicted to be normal, and the link communication status flag L is set to 0.

[0054] If θ≥K, the communication satellite is not within the angular range of the satellite communication antenna, and the link communication status is predicted to be interrupted, and the link communication status flag L is set to 1.

[0055] Determine the change of the link communication status flag L:

[0056] When the link communication status flag L changes from 0 to 1, the link communication status changes from normal to interrupted, and the timing starts from 0. Then the next round of calculation is performed based on the drone position and attitude in the next cycle.

[0057] When the link communication status flag L changes from 1 to 0, that is, the link communication status changes from interrupted to normal, the timing ends, and the timing time is output, that is, the predicted time of link communication status interruption, and then the next round of calculation is performed based on the drone position and attitude in the next cycle.

[0058] When the link communication status flag L does not change, the next round of calculation is performed based on the drone position and attitude in the next cycle.

[0059] The method for predicting the link communication status of a UAV in the entire mission process disclosed in the above embodiment can realize the pre-management of the link communication status of the UAV before executing the mission, so that ground control personnel can pre-understand the link communication status of the UAV in real time in the entire mission process, and then carry out maneuvering strategy design based on the link communication status, and realize maneuvering restrictions while maintaining smooth links or link predictions under maneuvering conditions as needed. It can greatly improve the prediction and control of the UAV status by ground control personnel during the mission execution and enhance the mission applicability of the UAV.

[0060] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or replacements to the relevant technical features, and the technical solutions after these changes or replacements will fall within the scope of protection of the present application.

Claims

1. A full-mission process UAV link communication status prediction method, characterized by: include: Set the link communication status flag L, where L=0 indicates that the UAV link communication status is predicted to be normal, and L=1 indicates that the UAV link communication status is predicted to be interrupted; Determine the positions of ground control stations and communication satellites in the Earth's coordinate system Periodically calculate the position of the drone in the Earth coordinate system and its posture in the body coordinate system Calculate the distance between the drone and the ground control station Determine whether the drone is within visual range; If s < D, the UAV is within the line of sight range, and the link communication status is predicted to be normal, and the link communication status flag L is set to 0, where D is the line of sight communication range; If s≥D, the drone is out of sight, and the satellite antenna pointing unit vector in the earth coordinate system is calculated. Calculate the connection vector between the drone and the communication satellite in the Earth coordinate system Then calculate the angle between the satellite antenna pointing unit vector and the connection vector between the drone and the communication satellite in the earth coordinate system Determine whether the communication satellite is within the angular range of the satellite communication antenna, where: is the direction cosine matrix from the body coordinate system to the earth coordinate system, is the satellite communication antenna pointing unit vector in the body coordinate system; If θ<K, the communication satellite is within the angular range of the satellite communication antenna, and the link communication state is predicted to be normal, and the link communication state flag L is set to 0, where K is the effective angular range of the satellite communication antenna; If θ≥K, the communication satellite is not within the angular range of the satellite communication antenna, and the link communication state is predicted to be interrupted, and the link communication state flag L is set to 1; When the link communication status flag L changes from 0 to 1, the time starts from 0; When the link communication status flag L changes from 1 to 0, the timing is ended and the timing time is output as the predicted time of link communication status interruption.

2. The full mission process UAV link communication status prediction method according to claim 1 is characterized in that: In the Earth coordinate system, the z-axis is along the direction of the Earth's rotation, the x-axis intersects the 0-degree meridian in the equatorial plane, and the y-axis forms a right-handed system; In the body coordinate system, the right side of the body is the x-axis, the forward direction is the y-axis, and the upward direction is the z-axis.

3. The full mission process UAV link communication status prediction method according to claim 2 is characterized in that: Positions of ground control stations and communication satellites in Earth coordinates Take a fixed value.

4. The full mission process UAV link communication status prediction method according to claim 3 is characterized in that: Periodically calculate the position of the drone in the Earth coordinate system and its posture in the body coordinate system The period is t=1s.

5. The full mission process UAV link communication status prediction method according to claim 4 is characterized in that: Satellite communication antenna pointing unit vector in the body coordinate system Take [0,0,1].

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