UWB-based inter-cluster unmanned aerial vehicle collision avoidance method and system, and storage medium

Abstract

The invention provides a UWB-based inter-cluster unmanned aerial vehicle collision avoidance method and system and a storage medium, and belongs to the technical field of unmanned aerial vehicle collision avoidance, and the method comprises the steps: receiving UWB detection data, carrying out the filtering processing, and judging whether the UWB detection data is valid or not according to the change condition of the data of two frames before and after; based on the preprocessed UWB detection data, whether the distance between the cluster unmanned aerial vehicles is smaller than the critical area radius or the dangerous area radius or not is judged, and if the distance between the cluster unmanned aerial vehicles is smaller than the critical area radius or the dangerous area radius, a collision avoidance instruction is sent; after a collision avoidance instruction is received, whether the collision avoidance instruction is executed or not is selected according to the current task stage; after the corresponding collision avoidance strategy is completed according to the collision avoidance instruction, the distance between the cluster unmanned aerial vehicles is larger than the radius of the critical area, and the unmanned aerial vehicles return to the original route and the original flight speed. According to the invention, the accuracy, the real-time performance, the expandability, the energy efficiency and the use convenience of collision avoidance of the unmanned aerial vehicle cluster are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicle (UAV) collision avoidance, and in particular to a method, system and storage medium for inter-uav collision avoidance of clustered UAVs based on UWB. Background Art

[0002] With the rapid development of drone technology, the application of swarm drones has become more and more extensive. Swarm drones can show great advantages in agriculture, logistics, mapping, power detection, emergency rescue and other fields through the collaborative work of multiple drones. Swarm drones improve the efficiency and reliability of task execution through collaborative control and distributed task allocation. However, during the collaborative flight of swarm drones, the collision problem between drones has become an important factor affecting the stability and safety of swarm drones.

[0003] At present, the methods of collision avoidance between swarm drones are mainly divided into the following categories: 1. Using visual or laser sensors to detect obstacles and adopt obstacle avoidance strategies to avoid them. The disadvantage of this technology is that the price of this type of sensor is generally high, and it can usually only detect in one direction. If omnidirectional detection is performed, the number of sensors needs to be increased, which increases the cost, body weight and power consumption of the whole machine. 2. Using communication-based collaborative obstacle avoidance technology, through radio signal exchange, real-time capture and analysis of key parameters such as the position, speed, and heading of other drones in the surrounding airspace. The disadvantage of this technology is that it is expensive and must rely on communication links, which will occupy information transmission bandwidth, the number of drones in the cluster is limited, and communication is easily interfered and suppressed. 3. Using drone positioning technology, by setting up ground base stations, confirming the relative position of each drone, so as to achieve collision avoidance between drones, such as RTK. The disadvantage of this technology is that at least one ground base station needs to be set up, which is not conducive to the portable use of swarm drones.

[0004] In summary, the prior art has the following problems: 1) In the existing methods, vision or laser sensors are used, which are expensive, heavy and consume a lot of power.

[0005] 2) Among the existing methods, collaborative obstacle avoidance using communication is expensive and must rely on communication links, which will occupy information transmission bandwidth and is easily interfered with.

[0006] 3) In the existing methods, the technology of setting up ground base stations is not conducive to the use of cluster drones that require portable functions for surveying and mapping, emergency rescue, etc. Summary of the invention

[0007] The present invention provides a UWB-based cluster UAV inter-collision avoidance method, system and storage medium, aiming to improve the accuracy, real-time performance, scalability, energy efficiency and ease of use of UAV cluster collision avoidance, and realize stable and safe flight of cluster UAVs.

[0008] On the one hand, this specification discloses a method for avoiding collision between clustered drones based on UWB, including: Receive UWB detection data, perform filtering, and determine whether the UWB detection data is valid based on the changes in the previous and next two frames of data; Based on the pre-processed UWB detection data, determine whether the distance between the cluster drones is less than the critical area radius or the danger area radius. If the distance between the cluster drones is less than the critical area radius or the danger area radius, send a collision avoidance command; After receiving the collision avoidance command, choose whether to execute the collision avoidance command according to the current mission stage; After completing the corresponding collision avoidance strategy according to the collision avoidance command, the distance between the cluster drones is greater than the critical area radius, and the drones return to the original route and original flight speed.

[0009] In this specification, the UWB detection data includes the UWB tag number and the spacing thereof; If the distance between the swarm drones is less than the critical area radius or the danger area radius, a collision avoidance command is sent, as follows: With the current drone as the center of the circle, when other drones with UWB tags are detected in the critical area with a radius of R2, a deceleration and collision avoidance operation is performed; With the current drone as the center of the circle, when other drones with UWB tags are detected in the danger zone with a radius of R1, an emergency stop is performed to avoid collision; Among them, R2 is greater than R1.

[0010] In this manual, the calculation formula of R1 is as follows: ; Among them, r is the safety radius of the drone, is the average deceleration acceleration of the UAV body during speed control, To control the maximum flight speed of the drone; The calculation formula for R2 is as follows: ; Among them, v is the current flight speed of the drone, It means that R2 is a function related to the current flight speed v of the UAV, and K1 and K2 are constants.

[0011] In this manual, the selection of whether to execute the collision avoidance instruction according to the current mission stage includes: If the current swarm drones are in a mission phase with a low collision probability, the collision avoidance command will not be executed; If the current swarm drones are in a mission phase with a high probability of collision, execute collision avoidance instructions to prevent collisions between drones; Mission phases with low collision probability include takeoff or landing mission phases; Mission phases with high collision probability include flight mission execution phases other than take-off or landing mission phases.

[0012] In this specification, the collision avoidance strategy includes: When other drones reach the danger zone of the current drone, all drones in the danger zone of the current drone will brake urgently and execute the collision avoidance plan after they have completely stopped. When other drones reach the critical area of ​​the current drone, all drones in the critical area of ​​the current drone slow down and perform collision avoidance planning.

[0013] In this specification, the collision avoidance plan is: when there are multiple drones in the critical area or dangerous area at the same time, collision avoidance is performed in sequence according to the size of the UWB tag number of the drone.

[0014] In this manual, the collision avoidance process is carried out in sequence according to the size of the UWB tag number of the drone as follows: The drone with the largest UWB tag number will avoid collision first, and other drones will hover and wait until the drone with the largest UWB tag number moves out of the critical area or danger area of ​​other drones.

[0015] In this manual, the drone movement strategy during the collision avoidance process is as follows: The current drone first moves forward at the first speed. If the relative distance with other drones in the area decreases, it moves backward at the second speed until other drones are outside the area, and then returns to the original route. If the relative distance with other drones decreases when the current drone moves forward and backward, it moves upward at the third speed until other drones are outside the area, and after hovering, it descends to the original route height.

[0016] Another aspect of the present specification discloses a UWB-based cluster UAV inter-collision avoidance system, which is used to implement any one of the above-mentioned UWB-based cluster UAV inter-collision avoidance methods. The UWB-based cluster UAV inter-collision avoidance system includes: The data module is used to receive UWB detection data, perform filtering, and determine whether the UWB detection data is valid based on the changes in the previous and next two frames of data; A judgment module is used to judge whether the distance between the cluster drones is less than the critical area radius or the dangerous area radius based on the pre-processed UWB detection data, and send a collision avoidance command if the distance between the cluster drones is less than the critical area radius or the dangerous area radius; A collision avoidance instruction module is used to select whether to execute the collision avoidance instruction according to the current task stage after receiving the collision avoidance instruction; The collision avoidance return module is used to complete the corresponding collision avoidance strategy according to the collision avoidance instruction, and when the distance between the cluster drones is greater than the critical area radius, the drones return to the original route and original flight speed.

[0017] The present specification also discloses a computer-readable storage medium, which stores computer instructions. When a computer reads the computer instructions, the computer executes the UWB-based cluster drone inter-machine collision avoidance method as described in any one of the above.

[0018] The embodiments of this specification can at least achieve the following beneficial effects: The present invention adopts UWB inter-machine transmission technology, does not require a ground base station, can omnidirectionally sense the distance between machines and perform relevant logical judgments, has good inter-machine collision avoidance capability, simple logic, anti-interference, is not restricted by the cluster structure, has a small weight and low power consumption, can be installed in micro-cluster UAVs, and can achieve inter-machine collision avoidance capability for cluster UAVs of different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of a UWB-based cluster UAV inter-machine collision avoidance method involved in some embodiments of the present invention.

[0021] Figure 2 Schematic diagram of critical areas and dangerous areas involved in some embodiments of the present invention.

[0022] Figure 3 The present invention is a flowchart of a UWB-based cluster UAV inter-machine collision avoidance method involved in some embodiments of the present invention.

[0023] Reference numerals: 1. Current drone; 2. Dangerous area; 3. Critical area. DETAILED DESCRIPTION

[0024] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of the present invention are conventionally placed when used, or are the orientations or positional relationships conventionally understood by those skilled in the art, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0026] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0027] In addition, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] like Figure 1 As shown, the embodiment of this specification discloses a method for avoiding collision between clustered drones based on UWB (Ultra Wide-Band), including: Receive UWB detection data, perform filtering, and determine whether the UWB detection data is valid based on the changes in the previous and next two frames of data; Based on the pre-processed UWB detection data, determine whether the distance between the cluster drones is less than the critical area radius or the danger area radius. If the distance between the cluster drones is less than the critical area radius or the danger area radius, send a collision avoidance command; After receiving the collision avoidance command, choose whether to execute the collision avoidance command according to the current mission stage; After completing the corresponding collision avoidance strategy according to the collision avoidance command, the distance between the cluster drones is greater than the critical area radius, and the drones return to the original route and original flight speed.

[0030] In some embodiments, if the number of swarm drones needs to be increased or decreased in real time, the collision avoidance strategy is not affected by the structural changes of the swarm drones.

[0031] In some embodiments, the filtering process may be a Kalman filtering process.

[0032] The data collected by UWB sensors are susceptible to random noise caused by external electromagnetic interference, environmental noise interference, etc. These noises will cause data fluctuations or deviations, affecting the accuracy of the data. At the same time, UWB sensors may produce certain errors in the measurement process, such as measurement errors, system errors, etc. In view of the above phenomenon, the improved Kalman filtering method is used, combined with the filtering algorithm and the judgment criteria, to determine whether the UWB detection data is valid according to the changes in the two frames of data before and after.

[0033] In some embodiments, the UWB sensor used can perform omnidirectional and multi-angle detection. Therefore, the UWB sensor used for detection can be fixed at any position of the drone according to the body structure design; In some embodiments, the UWB detection data includes UWB tag numbers and their spacing (relative positions); If the distance between the swarm drones is less than the critical area radius or the danger area radius, a collision avoidance command is sent, as follows: With the current drone 1 as the center of the circle, when other drones with UWB tags are detected in the critical area 3 with a radius of R2, a deceleration and collision avoidance operation is performed; With the current drone 1 as the center of the circle, when other drones with UWB tags are detected in the danger zone 2 with a radius of R1, an emergency stop to avoid collision is performed; Among them, R2 is greater than R1.

[0034] In this manual, based on the machine's own performance and kinematic formula, the calculation formula for R1 is as follows: ; Among them, r is the safety radius of the drone, is the average deceleration acceleration of the UAV body during speed control, To control the maximum flight speed of the drone; According to the aircraft's own performance and collision avoidance safety distance, the calculation formula of R2 is as follows: ; Among them, v is the current flight speed of the drone, R2 is a function related to the current flight speed v of the UAV. K1 and K2 are constants set according to the system characteristics and collision avoidance requirements. When setting, the kinematic characteristics of the UAV body, braking performance, and environmental complexity must be considered comprehensively.

[0035] In some embodiments, selecting whether to execute the collision avoidance instruction according to the current mission stage includes: If the current swarm drones are in a mission phase with a low collision probability, the collision avoidance command will not be executed; If the current swarm drones are in a mission phase with a high probability of collision, execute collision avoidance instructions to prevent collisions between drones; Mission phases with low collision probability include takeoff or landing mission phases; Mission phases with high collision probability include flight mission execution phases other than take-off or landing mission phases (assembly, search, cruise, return, etc. mission phases).

[0036] If the current swarm drones are in the take-off, landing and other stages, the take-off and landing sites of the drones are limited by the usage scenarios, the cluster take-off spacing is relatively dense, and because it is a direct ascent and descent flight, the collision probability is low. In this stage, the collision avoidance command can be ignored to ensure the smooth progress of the stage; If the current UAV 1 is in a stage with a high probability of collision, such as assembly, search, or cruising, a collision avoidance command can be executed to prevent collisions between UAVs.

[0037] In some embodiments, the collision avoidance strategy includes: When other drones reach the danger zone 2 of the current drone 1, all drones in the danger zone 2 of the current drone 1 brake urgently and execute the collision avoidance plan after they have completely stopped. When other drones reach the critical area 3 of the current drone 1, all drones in the critical area 3 of the current drone 1 slow down and perform collision avoidance planning.

[0038] In some embodiments, the collision avoidance plan is as follows: when there are multiple drones in the critical area 3 or the dangerous area 2 at the same time, collision avoidance is performed in sequence according to the size of the UWB tag number of the drone.

[0039] In some embodiments, according to the size of the UWB tag number of the drone, the process of avoiding collision is as follows: The drone with the largest UWB tag number will avoid collision first, and other drones will hover and wait until the drone with the largest UWB tag number moves out of the critical area 3 or danger area 2 of other drones.

[0040] Specifically, assuming that there are UAVs U1, U2, and U3 in the critical area 3 of the other two aircraft at the same time, according to the formula U1<U2<U3, U3 will first perform collision avoidance planning, and U1 and U2 will hover and wait until U3 moves out of its safe area.

[0041] In some embodiments, the drone movement strategy during the collision avoidance process is as follows: The current UAV 1 first moves forward at the first speed. If the relative distance with other UAVs in the area decreases, it moves backward at the second speed until other UAVs are outside the area, and then returns to the original route; if the relative distance with other UAVs decreases when the current UAV 1 moves forward and backward, it moves upward at the third speed until other UAVs are outside the area, and after hovering, it descends to the original route height.

[0042] Specifically, the U3 movement strategy is: first move forward at a speed of v1, and if the relative distance to other aircraft in the area decreases, then move backward at a speed of v2 until the other aircraft is outside the safe area, and then continue the route; if the safety distance to other aircraft decreases when U3 moves forward and backward, then move upward at a speed of v3 until the other aircraft is outside the safe area, hover for a period of time t, and then descend to the route altitude to continue the route mission. In this way, the drones perform collision avoidance actions in sequence.

[0043] Among them, the speeds v1, v2, v3 and time t need to be set according to the characteristics of the UAV platform system, the performance of the UAV cluster system, the system mission requirements and the system collision avoidance requirements (that is, set according to actual needs).

[0044] The embodiment of this specification also discloses a UWB-based cluster UAV inter-collision avoidance system, which is used to implement any one of the above-mentioned UWB-based cluster UAV inter-collision avoidance methods. The UWB-based cluster UAV inter-collision avoidance system includes: The data module is used to receive UWB detection data, perform filtering, and determine whether the UWB detection data is valid based on the changes in the previous and next two frames of data; A judgment module is used to judge whether the distance between the cluster drones is less than the critical area radius or the dangerous area radius based on the pre-processed UWB detection data, and send a collision avoidance command if the distance between the cluster drones is less than the critical area radius or the dangerous area radius; A collision avoidance instruction module is used to select whether to execute the collision avoidance instruction according to the current task stage after receiving the collision avoidance instruction; The collision avoidance return module is used to complete the corresponding collision avoidance strategy according to the collision avoidance instruction, and when the distance between the cluster drones is greater than the critical area radius, the drones return to the original route and original flight speed.

[0045] The embodiments of this specification also disclose a computer-readable storage medium, which stores computer instructions. When a computer reads the computer instructions, the computer executes the UWB-based cluster drone inter-machine collision avoidance method as described in any one of the above.

[0046] In order to clearly illustrate the technical solution of the present invention, the technical ideas of the solution are as follows: Using the millimeter-wave radar and binocular vision sensor (binocular camera) of a single drone in the swarm UAV system, the signal of the current area of ​​the drone is collected and processed to obtain the initial millimeter-wave radar signal and binocular image signal; Use the local millimeter-wave radar signal and binocular image signal to determine whether there are obstacles (other drones) in the current area, and use binocular vision to obtain image information and obstacle depth information of the current area; If an obstacle is detected and the obstacle avoidance strategy needs to be activated, the aircraft's location information will be recorded and broadcast to the cluster simultaneously; if other aircraft (other drones) approach the location area, they will slow down in advance and enter the obstacle avoidance preparation state; The aircraft's position information is passed to the mission control software to plan the global path, and the local flight trajectory is planned according to the actual mission environment and the motion characteristics of the single aircraft; After completing the corresponding collision avoidance strategy, if the millimeter-wave radar and binocular camera detect no obstacles, the drone returns to the original route and original flight speed.

[0047] In summary, multiple specific embodiments of the present invention are disclosed. Under the condition that there is no self-contradiction, the various embodiments can be freely combined to form new embodiments, that is, the embodiments belonging to the replacement schemes can be freely replaced but cannot be combined with each other; the embodiments that do not belong to the replacement schemes can be combined with each other, and these new embodiments also belong to the essential content of the present invention.

[0048] The above embodiments describe multiple specific implementations of the present invention, but those skilled in the art should understand that various changes or modifications may be made to these implementations without departing from the principles and essence of the present invention, but these changes and modifications are all within the scope of protection of the present invention.

Claims

1. A UWB-based cluster UAV collision avoidance method, characterized in that: include: Receive UWB detection data, perform filtering, and determine whether the UWB detection data is valid based on the changes in the previous and next two frames of data; Based on the pre-processed UWB detection data, determine whether the distance between the cluster drones is less than the critical area radius or the danger area radius. If the distance between the cluster drones is less than the critical area radius or the danger area radius, send a collision avoidance command; After receiving the collision avoidance command, choose whether to execute the collision avoidance command according to the current mission stage; After completing the corresponding collision avoidance strategy according to the collision avoidance command, the distance between the cluster drones is greater than the critical area radius, and the drones return to the original route and original flight speed.

2. The UWB-based cluster UAV inter-machine collision avoidance method according to claim 1 is characterized in that: The UWB detection data includes UWB tag numbers and spacings thereof; If the distance between the swarm drones is less than the critical area radius or the danger area radius, a collision avoidance command is sent, as follows: With the current drone as the center of the circle, when other drones with UWB tags are detected in the critical area with a radius of R2, a deceleration and collision avoidance operation is performed; With the current drone as the center of the circle, when other drones with UWB tags are detected in the danger zone with a radius of R1, an emergency stop is performed to avoid collision; Among them, R2 is greater than R1.

3. The UWB-based cluster UAV inter-machine collision avoidance method according to claim 2 is characterized in that: The calculation formula of R1 is as follows: ； Among them, r is the safety radius of the drone, is the average deceleration acceleration of the UAV body during speed control, To control the maximum flight speed of the drone; The calculation formula of R2 is as follows: ； Among them, v is the current flight speed of the drone, It means that R2 is a function related to the current flight speed v of the UAV, and K1 and K2 are constants.

4. The UWB-based cluster UAV inter-machine collision avoidance method according to claim 1 is characterized in that: The following are the options for executing collision avoidance instructions based on the current mission phase: If the current swarm drones are in a mission phase with a low collision probability, the collision avoidance command will not be executed; If the current swarm drones are in a mission phase with a high probability of collision, execute collision avoidance instructions to prevent collisions between drones; Mission phases with low collision probability include takeoff or landing mission phases; Mission phases with high collision probability include flight mission execution phases other than take-off or landing mission phases.

5. The UWB-based cluster UAV inter-machine collision avoidance method according to claim 1 is characterized in that: Collision avoidance strategies include: When other drones reach the danger zone of the current drone, all drones in the danger zone of the current drone will brake urgently and execute the collision avoidance plan after they have completely stopped. When other drones reach the critical area of ​​the current drone, all drones in the critical area of ​​the current drone slow down and perform collision avoidance planning.

6. The UWB-based cluster UAV inter-machine collision avoidance method according to claim 1 is characterized in that: The collision avoidance plan is as follows: when there are multiple drones in the critical area or dangerous area at the same time, collision avoidance is performed in sequence according to the size of the UWB tag number of the drone.

7. The UWB-based cluster UAV inter-machine collision avoidance method according to claim 6 is characterized in that: According to the size of the UWB tag number of the drone, the collision avoidance process is as follows: The drone with the largest UWB tag number will avoid collision first, and other drones will hover and wait until the drone with the largest UWB tag number moves out of the critical area or danger area of ​​other drones.

8. The UWB-based cluster UAV inter-machine collision avoidance method according to claim 7 is characterized in that: The UAV movement strategy during the collision avoidance process is as follows: The current drone first moves forward at the first speed. If the relative distance with other drones in the area decreases, it moves backward at the second speed until other drones are outside the area, and then returns to the original route. If the relative distance with other drones decreases when the current drone moves forward and backward, it moves upward at the third speed until other drones are outside the area, and after hovering, it descends to the original route height.

9. The UWB-based cluster drone collision avoidance system is characterized by: For implementing the UWB-based cluster UAV inter-collision avoidance method according to any one of claims 1 to 8, the UWB-based cluster UAV inter-collision avoidance system comprises: The data module is used to receive UWB detection data, perform filtering, and determine whether the UWB detection data is valid based on the changes in the previous and next two frames of data; A judgment module is used to judge whether the distance between the cluster drones is less than the critical area radius or the dangerous area radius based on the pre-processed UWB detection data, and send a collision avoidance command if the distance between the cluster drones is less than the critical area radius or the dangerous area radius; A collision avoidance instruction module is used to select whether to execute the collision avoidance instruction according to the current task stage after receiving the collision avoidance instruction; The collision avoidance return module is used to complete the corresponding collision avoidance strategy according to the collision avoidance instruction, and when the distance between the cluster drones is greater than the critical area radius, the drones return to the original route and original flight speed.

10. A computer-readable storage medium, characterized in that The storage medium stores computer instructions. When a computer reads the computer instructions, the computer executes the UWB-based cluster UAV inter-machine collision avoidance method as described in any one of claims 1 to 8.

Images