Unmanned system communication loss early warning method based on PLE and radial speed dynamic cooperation

Abstract

The invention discloses an unmanned system communication loss early warning method based on path loss index PLE and radial speed dynamic cooperation. The method comprises the following steps: 1) system initialization; 2) setting a navigation starting distance threshold and an early warning time threshold of the current unmanned system; 3) determining coordinates of a control end; 4) the current unmanned system returns parameters to the control end; (5) the control end detects the intensity of a return signal of the current unmanned system; 6) judging whether the current unmanned system reaches a starting condition or not; 7) calculating the PLE of the current unmanned system return link; the method comprises the steps of (1) calculating the current unmanned system, (2) calculating the current unmanned system, (3) calculating the current unmanned system, (4) calculating the current unmanned system, (5) calculating the farthest communication distance of the current unmanned system, (6) calculating the radial speed of the current unmanned system, and (7) judging whether the current unmanned system is in a safe distance range The method has higher reliability and real-time performance, can remarkably improve the control safety and task success rate of the unmanned system, and reduces the economic loss caused by communication loss of the unmanned system.

Description

Technical Field

[0001] The present invention relates to the lost connection warning technology for the low-altitude flight of unmanned aerial vehicles and the surface navigation of unmanned vessels, and specifically to a method for warning of lost connection of unmanned systems based on the dynamic cooperation of the path loss exponent (PLE) and the radial velocity. Background Art

[0002] With the wide application of unmanned aerial vehicles and unmanned vessels in beyond-visual-line-of-sight missions, the security and reliability of communication links face higher challenges. Currently, unmanned systems generally adopt a lost connection determination mechanism based on a static received power threshold: when the signal strength continuously drops below a preset fixed threshold, the system determines that the communication is lost and triggers the return-to-base procedure. Specifically, when no valid signal is detected for several consecutive seconds, the system will start the autonomous return-to-base mode. However, this mechanism has significant deficiencies: due to the lag in the determination timing, when the system triggers the return, the communication link has been completely interrupted. At this time, relying solely on autonomous return poses a greater risk in a complex environment, which may lead to mission failure or equipment loss. A more optimized solution should establish a warning mechanism to give an early warning before the communication link is completely interrupted, reserve sufficient intervention time for the control operator, and ensure the safety of the system through manual intervention control.

[0003] In addition, the prior art does not fully consider the dynamic characteristics of signal attenuation and the motion state of unmanned systems, and has the following two limitations:

[0004] Firstly, the signal attenuation characteristic not only depends on the communication distance, but is also significantly affected by the dynamic change of PLE. PLE reflects the attenuation rate of the signal during propagation, and its value will change in real time due to factors such as obstacle occlusion, meteorological conditions, and terrain environment. The prior art usually sets PLE as a fixed value (such as PLE = 2 in the free space propagation model), which cannot adapt to the complex and changeable actual environment. For example, in an urban environment, due to building occlusion, PLE may suddenly increase to more than 4, and at this time, the actual attenuation rate of the signal will be much higher than the theoretical prediction based on the fixed PLE value. This dynamic change of PLE will lead to two adverse situations: one is warning delay, that is, the actual signal attenuates too fast, and the system is lost before giving an early warning in time; the other is false triggering, that is, giving an early warning prematurely in a low-attenuation environment, reducing the mission execution efficiency.

[0005] Secondly, the lost connection warning time of unmanned systems is also closely related to the current radial navigation speed. When an unmanned system moves away from the control end at a relatively fast speed, the attenuation rate of the signal strength will increase significantly, resulting in the system approaching the lost connection boundary faster. In this case, the reaction time available to the control operator will be greatly shortened, increasing the mission risk. Since the prior art adopts a static method and does not consider the speed factor, there is often a problem of insufficient warning time in high-speed scenarios. Summary of the Invention

[0006] The object of the present invention is to provide a method for warning of loss of connection of an unmanned system based on dynamic cooperation between PLE and radial velocity in view of the deficiencies of the prior art. This method takes into account the dynamic changes of PLE and the radial velocity of the unmanned system in the actual environment, adjusts the safety distance of the unmanned system in real time, and reserves sufficient reaction time for the operator at the control end, so as to achieve accurate evaluation of the communication link quality of the unmanned system and real-time warning of the risk of loss of connection.

[0007] The technical solution for realizing the object of the present invention is as follows:

[0008] A method for warning of loss of connection of an unmanned system based on dynamic cooperation between PLE and radial velocity, comprising the following steps:

[0009] 1) System initialization: Determine the minimum received power P required by the control end min , where the control end is a handheld mobile console, a ground control station, or an edge node controlled by a network cloud;

[0010] 2) Set the departure distance threshold D and warning time threshold T of the current unmanned system: The departure distance threshold D represents the minimum distance for the unmanned system to depart, used to determine whether the unmanned system meets the departure condition, and the warning time threshold T represents the remaining time margin of the unmanned system from the loss-of-connection boundary, which is the reaction time reserved for the operator at the control end and is used to determine whether to trigger a loss-of-connection warning;

[0011] 3) Determine the coordinates of the control end: Obtain the coordinates G of the control end from the control end r =(x r , y r , z r );

[0012] 4) The current unmanned system transmits parameters back to the control end: The coordinates G of the current unmanned system t =(x t , y t , z t ), the navigation speed , the maximum transmission power P max , and the current transmission power P t ;

[0013] 5) The control end detects the signal strength of the current unmanned system transmitted back: The received power of the signal transmitted back by the current unmanned system detected by the control end is P r ;

[0014] 6) Determine whether the current unmanned system meets the departure condition: Based on the coordinates G of the control end r and the coordinates G of the current unmanned system t , calculate the distance between the current unmanned system and the control end If d > D, proceed to the next step; otherwise, return to step 2;

[0015] 7) Calculate the PLE of the current unmanned system's backhaul link: According to the general path loss model Calculate the PLE of the current unmanned system's backhaul link as α = d0log d (KP t / P r ), where K is the path loss constant coefficient, determined by experimental measurement (fitting based on actual channel data) or propagation model (such as the free space model λ is the signal wavelength), d0 is the reference distance, and its value follows industry standards and scenario characteristics: usually 1m for short - range scenarios (such as indoors), while usually 100m (such as in urban areas) or 1km (such as in suburban areas) for wide - area coverage;

[0016] 8) Calculate the maximum communication distance of the current unmanned system: According to the path transmission loss, the transmit power of the unmanned system should satisfy P t d -α ≥P min . Therefore, the communication distance When the transmit power P t takes the maximum value P max , the maximum communication distance is reached

[0017] 9) Calculate the radial velocity of the current unmanned system: Taking the direction from the control end to the unmanned system as the radial direction, the actual navigation speed of the unmanned system can be decomposed into tangential speed and radial speed. The unit direction vector from the control end to the current unmanned system, then the radial velocity of the current unmanned system

[0018] Here, v r > 0 indicates that the current unmanned system is moving away from the control end, v r < 0 indicates that the current unmanned system is approaching the control end, and v r = 0 indicates that the current unmanned system is relatively stationary with respect to the control end in the radial direction;

[0019] 10) Determine whether the current unmanned system is within the safe distance range: If d + v r T < d max , then return to step 2; otherwise, trigger a loss - of - contact warning.

[0020] Based on the dynamic collaboration of PLE and radial velocity, this technical solution accurately matches the signal attenuation characteristics of different scenarios through real-time PLE measurement, and combines the dynamic change of radial velocity to adjust the safety distance range in real time, improving the timeliness of early warning in high-speed scenarios. By adopting the dynamic collaboration of PLE and radial velocity, sufficient reaction time is reserved for the operator at the control end to take intervention measures such as adjusting the navigation path or initiating a return command in a timely manner. Compared with traditional methods, this technical solution can trigger an early warning before the signal is completely interrupted, effectively reducing the uncertainty of autonomous return.

[0021] Compared with the traditional method of setting a static power threshold for judgment, this technical solution has higher reliability and timeliness, can significantly improve the operation safety and mission success rate of the unmanned system, is applicable to complex and changeable actual application scenarios, can trigger an early warning before the signal is completely interrupted, and effectively reduces the uncertainty of autonomous return.

[0022] This method takes into account the dynamic changes of PLE and the radial velocity of the unmanned system in the actual environment, adjusts the safety distance of the unmanned system in real time, reserves sufficient reaction time for the operator at the control end, and thus realizes the accurate evaluation of the communication link quality of the unmanned system and the real-time early warning of the risk of loss of connection. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the communication structure of the unmanned system in the embodiment;

[0024] Figure 2 It is a schematic diagram of the decomposition of the navigation speed of the unmanned system in the embodiment;

[0025] Figure 3 It is a schematic flow diagram of the method in the embodiment;

[0026] Figure 4 It is a comparison chart of the early warning success rates of this embodiment and the traditional method. Detailed Implementation Manner

[0027] The following further elaborates on the content of the present invention in conjunction with the drawings and embodiments, but does not limit the present invention.

[0028] Embodiment:

[0029] Refer to Figure 3 , a method for warning of loss of connection of an unmanned system based on the dynamic collaboration of PLE and radial velocity, includes the following steps:

[0030] 1) System initialization: Determine the minimum received power P required by the control end min , the control end is a handheld mobile console, a ground control station, an edge node controlled by a network cloud, and in this example, it is a handheld mobile console;

[0031] 2) Set the departure distance threshold D and the warning time threshold T for the current unmanned system: The departure distance threshold D represents the minimum distance for the unmanned system to depart, used to determine whether the unmanned system meets the departure condition. The warning time threshold T represents the remaining time margin of the unmanned system from the disconnection boundary, which is the reaction time reserved for the control terminal operator and is used to determine whether to trigger a disconnection warning;

[0032] 3) Determine the coordinates of the control terminal: Obtain the coordinates G of the control terminal from the control terminal r =(x r ,y r ,z r );

[0033] 4) The current unmanned system transmits parameters back to the control terminal: The coordinates G of the current unmanned system t =(x t ,y t ,z t ), the navigation speed the maximum transmission power P max , the current transmission power P t ;

[0034] 5) The control terminal detects the signal strength of the current unmanned system's feedback: The received power of the feedback signal from the current unmanned system detected by the control terminal is P r ;

[0035] 6) Determine whether the current unmanned system meets the departure condition: Based on the coordinates G of the control terminal r and the coordinates G of the current unmanned system t , calculate the distance between the current unmanned system and the control terminal If d > D, go to the next step; otherwise, return to step 2;

[0036] 7) Calculate the PLE of the current unmanned system's feedback link: According to the general path loss model Calculate the PLE of the current unmanned system's feedback link as α = d0log d (KP t / P r ), where K is the path loss constant coefficient, determined by experimental measurement (fitting based on actual channel data) or propagation model (such as free space model λ is the signal wavelength), d0 is the reference distance, and its value follows industry standards and scene characteristics: usually 1m for short - range scenarios (such as indoors), while usually 100m (such as in urban areas) or 1km (such as in suburban areas) for wide - area coverage. In this example, take d0 = 1km;

[0037] 8) Calculate the maximum communication distance of the current unmanned system: According to the path transmission loss, the transmit power of the unmanned system should satisfy P t d -α ≥P min , so the communication distance When the transmit power P t takes the maximum value P max , the maximum communication distance is reached

[0038] 9) Calculate the radial velocity of the current unmanned system: Taking the direction from the control end to the unmanned system as the radial direction, the actual navigation speed of the unmanned system can be decomposed into the tangential velocity and the radial velocity. The unit direction vector from the control end to the current unmanned system, then the radial velocity of the current unmanned system

[0039] Here, v r >0 indicates that the current unmanned system is moving away from the control end, v r <0 indicates that the current unmanned system is approaching the control end, and v r =0 indicates that the current unmanned system is relatively stationary with respect to the control end in the radial direction;

[0040] 10) Determine whether the current unmanned system is within the safe distance range: If d + v r T < d max then return to step 2, otherwise trigger the loss-of-contact warning.

[0041] As Figure 1 shown, in the scenario where the control end remotely controls the unmanned system in this example, the backhaul link of the unmanned system is an airspace wireless communication link. In this example, the navigation speed of the unmanned system is decomposed into the tangential velocity and the radial velocity, as Figure 2 shown;

[0042] Figure 4 This is a comparison graph of the loss-of-contact warning success rates between this example and the traditional static power threshold method. The parameters used in the simulation graph are: the starting distance threshold is 2m, the warning time threshold is 10s, the minimum receiving power of the control end is -120dBm, the initial maximum transmit power of the current unmanned system is 30dBm, the path loss constant coefficient is -91.5dB, the reference distance is 1km, and the interference of the backhaul signals of other unmanned systems is not considered. In the airspace wireless communication scenario of this example, the control end system dynamically measures and calculates the PLE and the radial velocity of the unmanned system in the actual environment to adjust the safe distance in real time, reserving a reaction time for the control end. From Figure 4 it can be seen that the loss-of-contact warning success rate of the method in this example is significantly higher than that of the traditional static power threshold method, proving that the method in this example can effectively improve the operation safety and mission success rate of the unmanned system, thereby reducing the economic losses caused by the loss of contact of the unmanned system.

Claims

1. A method for warning of loss of contact of an unmanned system based on dynamic cooperation of PLE and radial velocity, characterized in that, The method includes the following steps: 1) System initialization: Determine the minimum received power P required by the control terminal min , where the control terminal is a handheld mobile console, a ground control station, or an edge node controlled by a network cloud 2) Set the departure distance threshold D and the warning time threshold T for the current unmanned system: The departure distance threshold D represents the minimum distance for the unmanned system to depart, which is used to determine whether the unmanned system meets the departure condition. The warning time threshold T represents the remaining time margin of the unmanned system from the disconnection boundary, which is the reaction time reserved for the control terminal operator and is used to determine whether to trigger the disconnection warning; 3) Determine the coordinates of the control end: Obtain the coordinates G of the control end from the control end r =(x r , y r , z r ); 4) The current unmanned system transmits parameters back to the control end: the coordinates G of the current unmanned system t =(x t , y t , z t ), the navigation speed the maximum transmission power P max , the current transmission power P t ; 5) The control terminal detects the strength of the feedback signal of the current unmanned system: The received power of the feedback signal of the current unmanned system detected by the control terminal is P r ; 6) Determine whether the current unmanned system meets the departure condition: Based on the coordinates G of the control terminal r and the coordinates G of the current unmanned system t , calculate the distance between the current unmanned system and the control terminal If d > D, proceed to the next step; otherwise, return to step 2; 7) Calculate the PLE of the current backhaul link of the unmanned system: According to the path loss model It is calculated that the PLE of the current backhaul link of the unmanned system is α = d0log d (KP t / P r ), where K is the path loss constant coefficient, which is taken according to the propagation model λ is the signal wavelength, d0 is the reference distance, and according to the industry standard and the characteristics of wide-area coverage, d0 is taken as 1 km; 8) Calculate the maximum communication distance of the current unmanned system: According to the path transmission loss, the transmit power of the unmanned system should satisfy P t d -α ≥P min , so the communication distance When the transmit power P t takes the maximum value P max , the maximum communication distance is reached 9) Calculate the radial velocity of the current unmanned system: Taking the direction from the control terminal to the unmanned system as the radial direction, the actual navigation speed of the unmanned system is decomposed into the tangential velocity and the radial velocity. The unit direction vector from the control terminal to the current unmanned system Then the radial velocity of the current unmanned system Here, v r > 0 indicates that the current unmanned system is moving away from the control terminal, v r < 0 indicates that the current unmanned system is approaching the control terminal, v r = 0 indicates that the current unmanned system is relatively stationary with respect to the control terminal in the radial direction; 10) Determine whether the current unmanned system is within the safe distance range: If d + v r T < d max Then return to step 2; otherwise, trigger a loss-of-contact warning.

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