Optimal obstacle avoidance method for wireless ultraviolet light cooperative UAV formation

Abstract

The present invention provides an optimal obstacle avoidance method for a wireless ultraviolet light cooperative unmanned aerial vehicle formation, comprising: step 1, establishing an ultraviolet light communication model and completing a communication connection; step 2, obtaining status information of unmanned aerial vehicles in a communication neighborhood; step 3, ensuring that all unmanned aerial vehicles in the formation are kept within a desired distance; step 4, detecting whether there are obstacles around the unmanned aerial vehicles; if so, proceeding to step 5; if not, proceeding to step 6; step 5, determining whether the speed direction of the unmanned aerial vehicle is perpendicular to the direction between the unmanned aerial vehicle and the obstacle; if so, proceeding to step 6; if not, deviating the unmanned aerial vehicle from the obstacle by adjusting the unmanned aerial vehicle acceleration and increasing the repulsive force field between the unmanned aerial vehicle and the obstacle; step 6, determining whether the unmanned aerial vehicle has reached the target point; if so, the mission is terminated; if not, repeating step 2. The present invention can improve the environmental adaptability of the formation and provide an effective guarantee for the formation's ability to perform tasks.

Description

Technical Field

[0001] The present invention belongs to the technical field of obstacle avoidance for UAV formations, and in particular relates to an optimal obstacle avoidance method for wireless ultraviolet light cooperative UAV formations. Background Art

[0002] With the rapid development and technological innovations of drone technology in recent years, drones have been widely used in both military and civilian fields. However, single drones often suffer from short flight time, limited strike range, and low efficiency, making them difficult to complete complex missions. Drone formations, through collaborative collaboration, can overcome these shortcomings. Their enhanced adaptability to environmental conditions can play a vital role in disaster relief, resource exploration, and military strikes.

[0003] Obstacle avoidance control for drone formations is a research hotspot in drone formation control technology. Common obstacle avoidance methods include artificial potential field methods, behavior-based methods, pilot-follow methods, and virtual structure methods. The artificial potential field method is widely used due to its low computational complexity, ease of implementation, and strong real-time performance. However, when avoiding obstacles in drone formations, external factors must be considered. For example, complex electromagnetic interference and areas with strong nuclear radiation can affect the stability of the drone formation network and the ability to exchange information, thereby affecting the obstacle avoidance effectiveness within the formation.

[0004] As a new type of optical communication technology, wireless ultraviolet light communication has the advantages of strong anti-interference ability, all-weather communication, and low eavesdropping rate. It can well meet the communication needs of the above-mentioned UAV formations in special environments. Moreover, the non-line-of-sight single scattering model of wireless ultraviolet light communication is more suitable for the dynamic characteristics of information interaction between UAV formations. Therefore, applying wireless ultraviolet light communication to the obstacle avoidance of UAV formations can improve the environmental adaptability of the formation and provide an effective guarantee for the formation's ability to perform tasks.

[0005] We need to design an ultraviolet light communication model that is compatible with the UAV formation network and improve the artificial potential field method to obtain the optimal obstacle avoidance method for wireless ultraviolet light collaborative UAV formations. Summary of the Invention

[0006] The purpose of the present invention is to provide an optimal obstacle avoidance method for a wireless ultraviolet light cooperative UAV formation, which can improve the environmental adaptability of the formation and provide an effective guarantee for the formation's ability to perform tasks.

[0007] The technical solution adopted in the present invention is:

[0008] The optimal obstacle avoidance method for wireless ultraviolet light cooperative UAV formation includes the following steps:

[0009] Step 1: The UAVs in the formation establish a UV communication model with each other to complete the communication connection;

[0010] Step 2: The current UAV obtains the status information of other UAVs in the communication neighborhood, including speed, spatial position, and heading angle;

[0011] Step 3: Introduce the potential field design between UAV formations, the potential field design between UAV formations and the status information to ensure that all UAVs in the formation remain within the desired distance;

[0012] Step 4: The onboard sensor detects whether there are obstacles around the drone. If yes, proceed to step 5; if not, proceed to step 6.

[0013] Step 5: Determine whether the speed direction of the drone is perpendicular to the direction between the drone and the obstacle. If so, proceed to step 6. If not, adjust the drone's acceleration and increase the repulsive force field between the drone and the obstacle to deviate from the obstacle.

[0014] Step 6: Determine whether the drone has reached the target point. If it has, the mission ends. If not, repeat step 2.

[0015] The present invention is also characterized in that:

[0016] Specifically in step 1: By equipping each drone with a hemispherical UV LED array, all-round status perception between adjacent drones can be achieved.

[0017] The hemispherical UV LED array consists of a hemispherical array with M longitudes and N latitudes intersecting on its surface. UV LEDs are installed at the intersections of the longitudes and latitudes. Each LED is coded according to its position on the longitudes and latitudes. The drones send their own coded information in real time within the formation. The received optical power of the UV communication is:

[0018]

[0019] Among them, P r,NLOS is the received optical power, P t is the transmitted optical power, A r is the receiving aperture area, K e is the atmospheric channel attenuation coefficient, P s is the scattering phase function. According to formula (1) and Lambertw function, the maximum communication distance between the transmitting and receiving UAVs can be obtained as follows:

[0020]

[0021] Assume that the coordinates of the two drones are O(0,0,0), B(x,y,z), r is the distance between the two drones, β is the angle between OB and the Z axis in the OAB plane, and α is the angle between the projection of the drone at point B onto the XOY plane and the x axis. Then the position of the drone at point B relative to the drone at point O is:

[0022]

[0023] The design method of the potential field between UAV formations in step 2 is:

[0024] Assume that the spatial position of any UAV i in the formation is q i =(x i ,y i ,z i ) T , the position of drone j is q j =(x j ,y j ,z j ) T , then the potential field between UAVs i and j is ψ(||q ij ||);

[0025] The virtual force on drone i from drone j is:

[0026]

[0027] in, represents ψ(||q ij ||) in q i The negative gradient at ||q ij ||=||q i -q j || is the distance between UAV i and UAV j;

[0028] The gravitational potential between drones is defined as:

[0029]

[0030] Among them, k1 is the coefficient of the gravitational field, a ij is the topological communication relationship between formations, and D is the influence range of the gravitational field;

[0031] The repulsive force potential between UAV formations is defined as:

[0032]

[0033] Among them, b determines the change amplitude of the repulsive field, c determines the change speed of the repulsive field, and a ij is the communication relationship between formations, D is the influence range of the repulsive field;

[0034] To avoid external obstacles, the drone can only avoid them by adjusting itself. Therefore, it is only necessary to introduce a repulsive field between the drone and the obstacle. When the sensor on the drone detects an obstacle, it can perform an obstacle avoidance action. The obstacle position in space is q o =(x o ,y o ,z o ) T , the repulsive field between the drone and the obstacle is defined as:

[0035]

[0036] in,

[0037]

[0038] In formula (7), b o ,c o They respectively determine the amplitude and change speed of the repulsive field and are both constants; ||q io || min is the minimum safe distance between the drone and the obstacle, ||q io || max The obstacle avoidance boundary of the UAV is greater than this value, and no obstacle avoidance is required; V o is the relative speed between the UAV and the obstacle, V o When V > 0, it means the obstacle is approaching the drone; otherwise, o ≤0.

[0039] The specific method of step 3 is:

[0040] Determine whether the distance between the drones in the formation is the expected distance d. If so, execute step 4. If the distance between the drones is too large, increase the gravitational field between the drones to make them gather together. If the distance between the drones is too small, increase the repulsive field to separate the drones until the distance between the drones in the formation is the set expected distance d.

[0041] The beneficial effects of the present invention are:

[0042] (1) Construct an ultraviolet light communication model between UAV formations, rely on the anti-interference characteristics of ultraviolet light communication to provide network services for UAV formations in special environments, and improve the UAV formation's ability to perform tasks such as obstacle avoidance control.

[0043] (2) In order to solve the problem of excessive obstacle avoidance trajectory when using the artificial potential field method, an improved method for optimizing the trajectory is proposed, which provides some ideas for the obstacle avoidance control of UAV formations. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flow chart of the method of the present invention.

[0045] Figure 2 This is the ultraviolet light communication model between UAV formations of the present invention.

[0046] Figure 3 1 is a diagram of a hemispherical ultraviolet LED array of the present invention.

[0047] Figure 4 This is a spatial geometric relationship diagram of the drone of the present invention. DETAILED DESCRIPTION

[0048] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] The optimal obstacle avoidance method for wireless ultraviolet cooperative UAV formation of the present invention is as follows Figure 1 The specific steps are as follows:

[0050] Step 1: Initialize the UAV information network. The UAVs in the formation establish ultraviolet light communication links with each other to complete the communication connection.

[0051] Step 2: The current UAV obtains the status information (speed, spatial position, heading angle, etc.) of other UAVs in the communication neighborhood.

[0052] Step 3: Based on the potential field design between the UAV formations, determine whether the distance between the UAVs in the formation is the expected distance d. If so, execute step 4. If the distance between the UAVs is too large, increase the gravitational field between the UAVs to bring the UAVs together. If the distance between the UAVs is too small, increase the repulsive field to separate the UAVs until the distance between the UAV formations reaches the set expected distance d.

[0053] Step 4: The onboard sensor detects whether there are obstacles around the drone. If yes, proceed to step 5; if not, proceed to step 6.

[0054] Step 5: Determine whether the speed direction of the drone is perpendicular to the direction between the drone and the obstacle, that is, V i With q io Is it vertical? If it is vertical, proceed to step 6. If it is not vertical, adjust the acceleration of the drone and increase the repulsive field between the drone and the obstacle to make the drone deviate from the obstacle.

[0055] Step 6: Determine whether the drone has reached the target point. If it has, the mission ends. If not, repeat step 2.

[0056] Ultraviolet light communication model between drone formations in step 1

[0057] Wireless ultraviolet light communication uses ultraviolet light in the solar-blind band for communication. It has the characteristics of non-line-of-sight, low eavesdropping rate, all-weather operation and strong anti-interference ability. It is more suitable for information sharing within the cluster formation. Therefore, the use of wireless ultraviolet light communication within the formation can ensure the stability and reliability of inter-machine communication. Figure 2 Shown is the wireless ultraviolet light communication model between drone formations.

[0058] During the flight, the UAV formation needs to share the relative position, speed, heading angle and other information of each UAV in real time to achieve the purpose of formation maintenance and collision avoidance. By equipping each UAV with a hemispherical UV LED array, all-round state perception between adjacent UAVs can be achieved. Figure 3 shown.

[0059] The hemispherical UV LED surface is formed by the intersection of M longitudes and N latitudes. UV LEDs are installed at the intersection of the longitudes and latitudes. Each LED is coded according to the position information of the longitude and latitude. Figure 3 In the figure, node (2,3) is communicating with node (4,2), and the UAV sends its own coded information in real time within the formation. The received optical power of its ultraviolet communication is:

[0060]

[0061] Among them, P r,NLOS is the received optical power, P t is the transmitted optical power, A r is the receiving aperture area, K e is the atmospheric channel attenuation coefficient, P s is the scattering phase function. According to formula (1) and Lambertw function, the maximum communication distance between the transmitting and receiving UAVs can be obtained as follows:

[0062]

[0063] After obtaining the distance between the UAVs, the relative position information of the UAVs can be obtained according to the geometric relationship of the UAVs in three-dimensional space. Figure 4 shown.

[0064] Assume that the coordinates of the two drones are O(0,0,0), B(x,y,z), r is the distance between the two drones, β is the angle between OB and the Z axis in the OAB plane, and α is the angle between the projection of the drone at point B onto the XOY plane and the x axis. Then the position of the drone at point B relative to the drone at point O is:

[0065]

[0066] In step 2, the potential field between UAV formations is designed as

[0067] Assume that the spatial position of any UAV i in the formation is q i =(x i ,y i ,z i ) T , the position of drone j is q j =(x j ,y j ,z j ) T , then the potential field between UAVs i and j is ψ(||q ij ||).

[0068] The virtual force on drone i from drone j is:

[0069]

[0070] in, represents ψ(||q ij ||) in q i The negative gradient at ||q ij ||=||q i -q j || is the distance between UAV i and UAV j.

[0071] The gravitational potential between drones is defined as:

[0072]

[0073] Among them, k1 is the coefficient of the gravitational field, a ij is the topological communication relationship between formations, and D is the influence range of the gravitational field.

[0074] The repulsive force potential between UAV formations is defined as:

[0075]

[0076] Among them, b determines the change amplitude of the repulsive field, c determines the change speed of the repulsive field, and a ij is the communication relationship between formations, and D is the influence range of the repulsive field.

[0077] To avoid external obstacles, the drone can only avoid them by adjusting itself, so it only needs to introduce a repulsive field between the drone and the obstacle, and when the drone's sensors detect an obstacle, it can perform an obstacle avoidance action. The obstacle position in space is q o =(x o ,y o ,z o ) T , the repulsive field between the drone and the obstacle is defined as:

[0078]

[0079] in,

[0080]

[0081] In formula (7), b o ,c o They respectively determine the amplitude and speed of change of the repulsive field and are both constants. io || min is the minimum safe distance between the drone and the obstacle, ||q io || max The obstacle avoidance boundary of the UAV is greater than this value, and no obstacle avoidance is required. o is the relative speed between the UAV and the obstacle, V o When V > 0, it means the obstacle is approaching the drone; otherwise, o ≤0.

[0082] Depend on Figure 1 It can be seen that when the sensors carried by the drones detect an obstacle, the drone formation starts the external obstacle avoidance control algorithm and detects whether the flight speed direction of the drone is perpendicular to the direction of the line connecting the drone and the obstacle. If it is perpendicular, it means that the current drone is not in danger of colliding with the obstacle. If it is not perpendicular, it means that the current drone may collide with the obstacle. At this time, it is necessary to indirectly adjust the heading of the current drone by changing the acceleration of the drone to avoid collision. The above obstacle avoidance steps can achieve the optimal obstacle avoidance requirements of the drone formation, thereby reducing the obstacle avoidance consumption of the drone formation.

Claims

1. The optimal obstacle avoidance method for wireless ultraviolet light cooperative UAV formation is characterized by: The following steps are involved: Step 1: The UAVs in the formation establish a UV communication model with each other to complete the communication connection; Specifically: by equipping each drone with a hemispherical UV LED array, all-round status perception between adjacent drones can be achieved; The hemispherical UV LED array includes a hemispherical array whose surface is formed by the intersection of M longitudes and N latitudes. UV LED lights are installed at the intersection of the longitudes and latitudes. Each LED is coded according to the position information of the longitude and latitude. The drones send their own coded information in real time within the formation. The received optical power of its ultraviolet communication is: Among them, P r,NLOS is the received optical power, P t is the transmitted optical power, A r is the receiving aperture area, K e is the atmospheric channel attenuation coefficient, P s is the scattering phase function. According to formula (1) and Lambertw function, the maximum communication distance between the transmitting and receiving UAVs can be obtained as follows: Assume that the coordinates of the two drones are O (0,0,0) , B(x,y,z), r is the distance between the two drones, β is the angle between OB and the Z axis in the OAB plane, and α is the angle between the projection of the drone at point B onto the XOY plane and the x axis. The position of the drone at point B relative to the drone at point O is: Step 2: The current UAV obtains the status information of other UAVs in the communication neighborhood, including speed, spatial position, and heading angle; Step 3: Introduce the potential field design between UAV formations, the potential field design between UAV formations and the status information to ensure that all UAVs in the formation remain within the desired distance; Step 4: The onboard sensor detects whether there are obstacles around the drone. If yes, proceed to step 5; if not, proceed to step 6. Step 5: Determine whether the speed direction of the drone is perpendicular to the direction between the drone and the obstacle. If so, proceed to step 6. If not, adjust the drone's acceleration and increase the repulsive force field between the drone and the obstacle to deviate from the obstacle. Step 6: Determine whether the drone has reached the target point. If it has, the mission ends. If not, repeat step 2.

2. The optimal obstacle avoidance method for wireless ultraviolet light cooperative UAV formation according to claim 1, characterized in that: The design method of the potential field between UAV formations described in step 2 is: Assume that the spatial position of any UAV i in the formation is q i =(x i ,y i ,z i ) T , the position of drone j is q j =(x j ,y j ,z j ) T , then the potential field between UAVs i and j is ψ(||q ij ||); The virtual force on drone i from drone j is: in, represents ψ(||q ij ||) in q i The negative gradient at ||q ij ||=||q i -q j || is the distance between UAV i and UAV j; The gravitational potential between drones is defined as: Among them, k1 is the coefficient of the gravitational field, a ij is the topological communication relationship between formations, and D is the influence range of the gravitational field; The repulsive force potential between UAV formations is defined as: Among them, b determines the change amplitude of the repulsive field, c determines the change speed of the repulsive field, and a ij is the communication relationship between formations, D is the influence range of the repulsive field; To avoid external obstacles, the drone can only avoid them by adjusting itself. Therefore, it is only necessary to introduce a repulsive field between the drone and the obstacle. When the sensor on the drone detects an obstacle, it can perform an obstacle avoidance action. The obstacle position in space is q o =(x o ,y o ,z o ) T , the repulsive field between the drone and the obstacle is defined as: in, In formula (7), b o ,c o They respectively determine the amplitude and change speed of the repulsive field and are both constants; ||q io || min is the minimum safe distance between the drone and the obstacle, ||q io || max The obstacle avoidance boundary of the UAV is greater than this value, and no obstacle avoidance is required; V o is the relative speed between the UAV and the obstacle, V o When V > 0, it means the obstacle is approaching the drone; otherwise, o ≤0.

3. The optimal obstacle avoidance method for wireless ultraviolet light cooperative UAV formation according to claim 2, characterized in that: The specific method of step 3 is: Determine whether the distance between the drones in the formation is the expected distance d. If so, execute step 4. If the distance between the drones is too large, increase the gravitational field between the drones to make them gather together. If the distance between the drones is too small, increase the repulsive field to separate the drones until the distance between the drones in the formation is the set expected distance d.

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