A method for synchronously executing timing actions of a UAV cluster based on an idempotent gate at a future time

Abstract

The application discloses a kind of future time idempotent gate-based UAV cluster timing action synchronous execution method, it is related to UAV cluster cooperative control technical field.Ground station determines future GPS absolute time by current time with UAV flight control global satellite navigation system star clock homologous, and issues timing message carrying action code, action mask and the future GPS absolute time;UAV flight control firmware sets future time gate in the side of entering queue, only when local current absolute seconds are strictly less than target absolute seconds, temporarily store pending item, directly discard late timing message;Flight control firmware polls current absolute seconds by fixed frequency scheduling task, after point, dispatch to unified action executor and clear pending flag.The future GPS absolute time is used as trigger point, supplementary delivery deduplication key and entering queue criterion simultaneously, improve cluster action synchronism, anti-packet loss reliability and execution consistency.

Description

Technical Field

[0001] This invention relates to the field of collaborative control technology for unmanned aerial vehicle (UAV) swarms, specifically a method for synchronous execution of timed actions of UAV swarms based on idempotent gating of future moments. Background Technology

[0002] In drone swarm performances, drone swarm inspections, and drone swarm collaborative operations, the ground station needs to uniformly issue swarm action commands such as pause, continue, speed change, forward, reverse, emergency return, turn on lights, and turn off lights to multiple drones, and require each drone to execute the same action at the same time. The conventional approach usually involves the ground station broadcasting the action commands via wireless link or sending them to each drone individually, and the drone immediately invokes the action execution logic upon receiving the command.

[0003] The aforementioned "receive and execute" method means that the actual triggering time of each drone is affected by factors such as the fan-out order of the ground station, air interface propagation delay, link packet loss, and retransmission jitter. When the cluster size is large, there may be a visually noticeable difference between the time the first and last drone receives the command, leading to inconsistent action execution. To improve the success rate of reception, the same command is usually resent multiple times in practice; however, with the "receive and execute" method, multiple resentments may result in the same action being executed repeatedly. If deduplication is achieved using command sequence numbers and executed tables, additional protocol fields and flight control-side status tables need to be maintained, increasing protocol complexity and flight control resource overhead.

[0004] While existing time synchronization technologies can provide devices with a unified time base, they cannot solve the problem of executing the same time message only once after it has been retransmitted in a dense cluster. Furthermore, when calculating the target time using the ground station's local wall clock, discrepancies between the ground station's wall clock and the UAV's global navigation satellite system clock can cause the UAV to misjudge the time messages it should execute as expired and discard them in batches. Therefore, a technical solution is needed that can balance synchronous execution of cluster actions, reliability of dense retransmissions, and single-execution constraints even in the presence of packet loss and latency jitter in the wireless link. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides the following technical solution: a method for synchronized execution of timed actions in a UAV swarm based on idempotent gating of future times. This method is applied to a UAV swarm comprising a ground station and several UAVs, each equipped with flight control firmware and a Global Navigation Satellite System (GNSS) receiver. The ground station uses the current time, which is of the same origin as the GNSS clock in the flight control firmware, as its time base to determine the future absolute GPS time after the current time, and sends a time message carrying an action code, an action mask, and the future absolute GPS time. The UAV flight control firmware sets a future time gate on the message enqueue side, temporarily storing pending execution items only when the current absolute second count is strictly less than the target absolute second count, and directly discarding late time messages. The flight control firmware then triggers a unified action execution entity through fixed-frequency task polling, and clears the pending execution flag after execution.

[0006] According to the above technical solution, the ground station uses a synchronous clock module to determine the future GPS absolute time. Upon first receiving the GPS time event transmitted from the UAV, the synchronous clock module uses a monotonic clock as an anchor point to lock the offset. After the initial synchronization is complete, the monotonic clock automatically generates the current time, and performs monotonically increasing anti-backtracking checks upon receiving new GPS time events. Only when the current error exceeds the relock threshold does the synchronous clock module relock the offset based on the new difference. This ensures that the future GPS absolute time transmitted by the ground station is consistent with the GPS time base used by the UAV flight control firmware.

[0007] According to the above technical solution, the future time gate reads the current hour, minute, and second derived from the positioning speed and time data of the local global satellite navigation system and converts them into the current absolute number of seconds. Simultaneously, it reads the target hour, minute, and second from the transmitted message and converts them into the target absolute number of seconds. If the current absolute number of seconds is strictly less than the target absolute number of seconds, it indicates that the message is still within the future execution window, and the flight control firmware temporarily stores the action code, action parameters, and target time as pending execution items. If the current absolute number of seconds is not less than the target absolute number of seconds, it indicates that the message is late, and the flight control firmware directly discards the message.

[0008] According to the above technical solution, the fixed-frequency scheduling task operates at 30Hz. Each cycle, it reads the current absolute number of seconds derived from the local GPS positioning speed and time data and compares it with the target absolute number of seconds in the pending execution item. When the current absolute number of seconds is greater than or equal to the target absolute number of seconds and the pending execution flag is true, the flight control firmware assigns the corresponding cluster action to a unified action executor according to the action code. After execution, the pending execution flag is cleared and the action code is reset to zero. Since the polling cycle of the 30Hz scheduling task is approximately 33 milliseconds, the action triggering error of each UAV is limited to one polling cycle after the same second edge.

[0009] According to the above technical solution, the authorization message is a custom MAVLink v2 message with message number 78, checksum value of 43, and payload in the specified format. <hbbbbb>The payload is packaged and sequentially includes action parameters in 16-bit unsigned integer form, action codes in 8-bit unsigned integer form, action masks in 8-bit unsigned integer form, hours in 8-bit unsigned integer form, minutes in 8-bit unsigned integer form, and seconds in 8-bit unsigned integer form, with a payload length of 7 bytes. The sender calculates a cyclic redundancy check (CRC) on the payload using the X25 algorithm, and adds a checksum 43 to the checksum calculation; the receiver performs the checksum using the same algorithm and the same checksum 43. Only after the checksum passes does the payload proceed to the future time gate for processing. The time transmission message does not contain a command sequence number or a unique command identifier field.

[0010] According to the above technical solution, the unified action executor is shared by eight types of cluster actions: pause, continue, speed change, forward, reverse, emergency return, turn on lights, and turn off lights. Action code 1 corresponds to pause, action code 2 corresponds to continue, action code 3 corresponds to speed change, action code 4 corresponds to forward, action code 5 corresponds to reverse, action code 6 corresponds to emergency return, action code 7 corresponds to turn on lights, and action code 8 corresponds to turn off lights. When the action code indicates speed change, the action parameter is the speed gear. The unified action executor maps the task speed according to the speed gear and performs timing compensation. Pause, continue, and reverse actions also perform corresponding timing compensation within the unified action executor, ensuring that the immediate command path and the timed message path have consistent execution behavior.

[0011] According to the above technical solution, the ground station performs intensive retransmission of the same authorization message via dual links within a window before the future absolute GPS time. The WiFi / UDP link transmits the authorization message each time; when the data radio broadcast link is connected, the ground station uses the data radio broadcast link to transmit the same authorization message. For timed action authorization messages with an action mask of 180, the ground station retransmits them every 200 milliseconds within a window before the future absolute GPS time, with the number of retransmissions being the window length divided by 200 and no less than 3 times. For timed takeoff authorization messages or emergency return authorization messages with an action mask of 166, the ground station retransmits them evenly a set number of times within a given window duration. When the set number is greater than 1, the retransmission interval is determined according to the formula: Retransmission Interval = Window Duration × 1000 ÷ (Set Number - 1). When the set number is equal to 1, the retransmission interval is 0.

[0012] According to the above technical solution, the ground station maintains an atomic generation counter. Each time a retransmission is initiated, the ground station atomically increments the atomic generation counter to obtain the generation value for this retransmission. Before each round of transmission, the retransmission loop checks whether the current global generation is still equal to the generation value for this retransmission. When the ground station receives a new instruction or issues a cancellation message, it atomically increments the atomic generation counter again, causing the old retransmission thread to stop retransmitting in subsequent checks. The cancellation message is a message with an action mask of 166 and an action code of 0.

[0013] According to the above technical solution, when canceling the entire field, resetting, or taking off from a new field, the flight control firmware calls a clearing step, setting the pending execution flag to false and clearing the temporarily stored action codes. The ground station obtains the list of online UAV identifiers for the entire field when issuing authorization messages and covers the entire field via WiFi / UDP links; emergency return-to-home actions are superimposed on the data transmission radio broadcast link. In self-stabilization mode, the flight control firmware determines the link status based on the most recent visible heartbeat time from the ground station; after a heartbeat timeout, a heartbeat failure flag is set and the system enters a protection state. Speed ​​change actions take effect under low-speed interlock conditions where the aircraft speed does not exceed 0.5 meters per second.

[0014] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: This invention changes the execution of UAV swarm actions from immediate receipt to point-to-point execution based on future GPS absolute time, so that the actual trigger time of each UAV's actions is determined by the future target time under the same time base, and is not affected by the fan-out order of the ground station, air interface propagation delay, and the arrival time of retransmissions; by using a future time gate to simultaneously use the future GPS absolute time as the trigger point, retransmission deduplication key, and enqueue criterion, dense retransmissions and single executions can coexist, eliminating the need to set command sequence numbers in the time message and the need to maintain an executed command table on the flight control side; by using the same clock of the ground station, it eliminates the misjudgment of large-scale expiration caused by the wall clock deviation of the ground station; by unifying the action execution body, it ensures that pause, continue, speed change, forward, backward, emergency return, light on, and light off actions under the immediate path and timed path maintain consistent execution logic and timing compensation; by using dual-link dense retransmissions and atomic generation interruption, it improves the reliability of the arrival of time messages and prevents old retransmission threads from continuing to send after cancellation, thereby improving the synchronization, reliability, and security of large-scale UAV swarm actions. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is an overall flowchart of the present invention; Figure 2 This is a flowchart of the ground station clock synchronization and future time generation process of the present invention; Figure 3 This is a flowchart of the future gated state of the UAV according to the present invention; Figure 4 This is a diagram of the ground station and unmanned aerial vehicle system architecture of the present invention; Figure 5 This is a flowchart of the dual-link dense retransmission and atomic generation interrupt control of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Please see Figures 1-5 This invention provides a technical solution: a method for synchronizing the timing actions of a drone swarm based on idempotent gating of future time intervals, applicable to a drone swarm including a ground station and several drones. The drones are equipped with flight control firmware and configured with a global navigation satellite system receiver. Communication between the ground station and the drones occurs via WiFi / UDP links and data transmission radio broadcast links. The ground station includes a co-source clock module, a timing message construction module, and a dual-link retransmission module, the latter maintaining an atomic generation counter. The drone flight control firmware includes a future time interval gate, a pending execution register, a fixed-frequency scheduling task, and a unified action execution entity.

[0018] During a performance or swarm operation, when the operator triggers a swarm action at the ground station, the ground station does not issue a normal action command that is executed immediately upon receipt. Instead, it first obtains the current time, which is from the same source as the satellite clock of the UAV flight control global satellite navigation system, through a shared clock module. Then, it adds a delay of seconds to this current time to obtain the future GPS absolute time. This future GPS absolute time is expressed in hours, minutes, and seconds, and is used to ensure that each UAV triggers the same swarm action when the target time arrives.

[0019] The same-source clock module performs calibration upon receiving GPS time events transmitted from the UAV. During initial synchronization, the ground station uses a monotonic clock as an anchor point, locking the difference between its local clock and the received GPS time as the offset, and setting a synchronized flag. After initial synchronization, the ground station generates the current time using its monotonic clock, calculated from the anchor time, the elapsed time since the anchor point, and the offset. The ground station only accepts GPS times older than the last recorded time; old time values ​​from different UAVs and outdated GPS time values ​​do not update the offset. When the current error exceeds 2 seconds, the same-source clock module relocks the offset based on the new difference.

[0020] In one specific implementation, the ground station records the monotonic clock anchor point, the Global Navigation Satellite System (GNSS) time anchor point, the offset, and the synchronization flag. Upon initial synchronization, the ground station writes the difference between its local self-running time and the transmitted GNSS time into the offset and sets the synchronization flag to true. Subsequent time generation involves adding the offset to the elapsed time from the monotonic clock anchor point. When a new GNSS time event arrives, the ground station first checks if the new time value is greater than the previously recorded time. If it is not greater, it is ignored. If the error calculated based on the new time value exceeds 2000 milliseconds, the offset is relocked. The ground station then adds a delay of seconds to the current time to obtain the hour, minute, and second of the future GPS absolute time.

[0021] The time-granting message construction module builds the time-granting message based on the future absolute GPS time. The time-granting message is a custom MAVLink v2 message with message number 78, checksum 43, and payload in the specified format. <hbbbbb>The payload consists of a 16-bit unsigned integer and five 8-bit unsigned integers arranged sequentially as action parameters, action code, action mask, hour, minute, and second, with a payload length of 7 bytes. The sender calculates a cyclic redundancy check (CRC) on the payload using the X25 algorithm, and adds a checksum 43 to the checksum calculation. The UAV receives the payload and performs a checksum verification using the same algorithm and the same checksum 43. If the checksum passes, the payload proceeds to the future time gate for processing. This time message fully carries the action content, action category, action parameters, and future GPS absolute time within the 7-byte payload, and does not include a command sequence number or unique command identifier field.

[0022] After receiving the message, the UAV reads the current hour, minute, and second from its GPS positioning speed and time data. It then adds the current hour to the East 8 time zone difference, modulo 24, and calculates the current absolute second. Simultaneously, the future time gate reads the hour, minute, and second from the message and calculates the target absolute second. If the current absolute second is significantly less than the target absolute second, the message is still within the future execution window. The flight control firmware temporarily stores the action code, action parameters, and target time in the pending execution register and sets the pending execution flag to true. If the current absolute second is not less than the target absolute second, the message is late, and the future time gate discards it without writing it to the pending execution register.

[0023] The flight control firmware's fixed-frequency scheduling task operates at 30Hz. Within each scheduling cycle, the flight control firmware reads the current absolute second count derived from the local GPS positioning speed and time data, and compares it with the target absolute second count stored in the pending execution register. When the current absolute second count is greater than or equal to the target absolute second count and the pending execution flag is true, the flight control firmware calls the unified action executor according to the action code to execute the corresponding cluster action, then clears the pending execution flag and resets the action code to zero. Since the 30Hz scheduling task cycle is approximately 33 milliseconds, each UAV triggers its next polling point after the same GPS second edge, limiting the cluster action synchronization error to approximately one polling cycle.

[0024] The future GPS absolute time serves three purposes in this scheme: first, it acts as the trigger point for each UAV to initiate cluster actions upon arrival; second, it serves as an idempotent deduplication key when the same authorized message is resent multiple times; and third, it serves as the criterion for the future time gate to determine whether the authorized message is still within the valid window. For multiple resent packets pointing to the same future GPS absolute time, if the current absolute second is strictly less than the target absolute second, the future time gate only overwrites and refreshes the same pending item with the same action code and the same target time, without generating new execution; if the current absolute second is not less than the target absolute second, the future time gate directly discards the late resent packet. Therefore, no matter how many times the same authorized message is resent within the window, it will trigger action execution at most once.

[0025] The dual-link retransmission module performs intensive retransmission of the same message within a window preceding the future GPS absolute time. For timed action message transmissions with an action mask of 180, the module retransmits the message every 200 milliseconds within the window preceding the future GPS absolute time, with the retransmission count being the window duration divided by 200 and no less than 3 times. For timed takeoff or emergency return message transmissions with an action mask of 166, the module retransmits the message evenly a set number of times within a given window duration; when the set number is greater than 1, the retransmission interval is determined by retransmission interval = window duration × 1000 ÷ (set number - 1), and when the set number is equal to 1, the retransmission interval is 0. WiFi / UDP links transmit every round, and data transmission radio broadcast links superimpose the same message transmission when they are already connected. Because the UAV side uses a future time gate for idempotent deduplication, intensive dual-link retransmission improves the arrival probability without causing duplicate actions.

[0026] In one example, the ground station triggers an emergency return to base at GPS absolute time 10:20:00 with a delay of 5 seconds, resulting in a future GPS absolute time of 10:20:05. The ground station retransmits packets every 200 milliseconds within a 4.5-second window preceding this target time, for a total of approximately 22 packets. All retransmitted packets contain the time (hour, minute, and second) pointing to 10:20:05. If the probability of losing a single packet is 10%, the probability of losing all 22 packets is approximately 10 to the power of -22, significantly improving the reception success rate. When a drone first receives one of the packets at 10:20:01, the current absolute second is less than the target absolute second. The future time gate allows the packet to pass and temporarily stores the pending execution item. Subsequent retransmission packets only overwrite and refresh the same pending execution item. When the drone's global satellite navigation system time exceeds 10:20:05, the fixed frequency scheduling task triggers the unified action execution body to perform an emergency return at the next query point and clears the pending execution flag. Subsequent retransmission packets to the same target are discarded by the future time gate as late messages.

[0027] If a drone does not receive any retransmission packet before the target time, but only receives the authorization message after the current absolute number of seconds has become no less than the target absolute number of seconds, the future time gate will discard the message directly, and the drone will not perform the action in this instance. This boundary handling ensures that late messages will not trigger actions at incorrect times, avoiding disruption of overall synchronization due to the late execution of individual drones.

[0028] To prevent the old retransmission thread from continuing to send old authorized messages after cancellation, the dual-link retransmission module maintains an atomic generation counter. Each time a retransmission is initiated, the ground station atomically increments the atomic generation counter to obtain the generation value for this retransmission. Before each round of the retransmission cycle, it checks whether the current global generation is still equal to the generation value for this retransmission. When the ground station receives a new instruction or issues a cancellation message, it atomically increments the atomic generation counter again, causing the still-running old retransmission thread to stop retransmitting in subsequent checks. The cancellation message uses an action mask of 166 and an action code of 0.

[0029] The unified action executor is shared by eight types of cluster actions. Action code 1 corresponds to pause, action code 2 to continue, action code 3 to acceleration, action code 4 to forward, action code 5 to reverse, action code 6 to emergency return, action code 7 to turn on lights, and action code 8 to turn off lights. When action code 3 is used, the action parameter represents the gear shift. The unified action executor maps the gear shift to the task speed, which is determined by the formula: Task speed = (5 - gear shift) × 25 + 100, where a smaller gear shift results in a higher task speed, and a larger gear shift results in a lower task speed. The unified action executor performs timing compensation based on the product of the task speed change and the current index, increasing runtime during deceleration and decreasing runtime during acceleration. The pause action records the pause duration, the continue action is compensated based on the pause duration, and the reverse action is compensated based on the current index. Both immediate command paths and timed message paths fall into the same unified action executor, ensuring consistent execution behavior for the same action across different delivery paths.

[0030] When canceling an entire flight, resetting, or taking off from a new flight, the flight control firmware invokes a clearing step, setting the pending execution flag to false and clearing any temporarily stored action codes to prevent unintended actions from the previous flight from being mistakenly triggered upon arrival at the new flight. When the ground station sends a notification message, it retrieves a list of all online drones on the flight to avoid sending an empty list that would prevent full coverage. Emergency return-to-home actions are sent via a data transmission radio broadcast link on top of the WiFi / UDP link transmission. In self-stabilization mode, the flight control firmware uses the most recent visible heartbeat time from the ground station to determine the link status. When the difference between the current time and the most recent visible heartbeat time exceeds 15,000 milliseconds, a heartbeat failure flag is set and the system enters a protection state. Speed-changing actions take effect only under low-speed interlocking conditions where the drone's speed does not exceed 0.5 meters per second.

[0031] In one industrial application scenario, this method is applied to a drone swarm light show system. The system consists of a portable ground station and dozens to thousands of quadcopter performance drones. Each performance drone is equipped with a KZWLhawk flight control board, which uses an STM32H743 as the main controller and is derived from HolybroV6C. Each drone also carries a GPS receiver, an XBee data radio, an onboard WiFi module, an LED light driver board, and ESCs for the motors. The ground station runs swarm ground station software and communicates with all the drones via WiFi / UDP links and the XBee data radio RF link connected via a CP210x USB-serial bridge. It can also obtain RTK correction data via NTRIP differential access. Using this method, when the ground station issues swarm actions such as pause, continue, speed change, forward, reverse, emergency return, light on, and light off during the performance, each drone can execute them at the same future GPS absolute time, reducing action inconsistencies caused by link jitter and avoiding repeated execution of the same action due to frequent retransmissions.

[0032] On the ground station's front-end interface, a countdown control can be used to indicate the remaining time until the next GPS absolute time, such as indicating that the entire event will be executed uniformly in a few seconds, and indicating that the uniform execution has been completed when the time is up. The fixed-frequency scheduling task in the flight control firmware can be run as part of the light show task. For example, in the light action scheduling task, the current absolute number of seconds can be read at a frequency of 30Hz and the uniform action execution body can be triggered.

[0033] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," and any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0034] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.< / hbbbbb> < / hbbbbb>

Claims

1. A method for synchronizing the timing actions of a drone swarm based on idempotent gating of future moments, applied to a drone swarm including a ground station and several drones, each drone being equipped with flight control firmware and a global satellite navigation system receiver, characterized in that: Includes the following steps: The ground station uses the current time, which is of the same origin as the global satellite navigation system star clock in the flight control firmware, as the time base to determine a future absolute GPS time located after the current time. The ground station constructs a time authorization message and sends the time authorization message to the aforementioned drones. The time authorization message carries an action code, an action mask, and the hour, minute, and second of the future GPS absolute time. Each UAV's flight control firmware sets a future time gate on the queuing side of the authorized message. The future time gate reads the current absolute number of seconds derived from the local global satellite navigation system positioning speed and time data, and calculates the target absolute number of seconds from the authorized message. When the current absolute number of seconds is strictly less than the target absolute number of seconds, the future time gate temporarily stores the action code and the future GPS absolute time as an execution item and sets the execution flag to true; When the current absolute number of seconds is not less than the target absolute number of seconds, the future time gate discards the authorization message as a late authorization message; The flight control firmware periodically reads the current absolute number of seconds derived from the positioning speed and time data of the local global satellite navigation system at a fixed frequency, and compares it with the target absolute number of seconds in the pending execution item; When the current absolute number of seconds is greater than or equal to the target absolute number of seconds and the pending execution flag is true, the flight control firmware assigns the corresponding cluster action to the unified action execution body according to the action code, and clears the pending execution flag after execution; The future GPS absolute time serves as the trigger point for each UAV to arrive at its destination, as the deduplication key for idempotent deduplication of multiple resends of the same time message, and as the time window criterion for determining whether to enqueue the future time gate, so that multiple resend packets pointing to the same future GPS absolute time are refreshed as the same pending item and are executed at most once.

2. The method for synchronous execution of timed actions of a drone swarm based on idempotent gating of future time intervals as described in claim 1, characterized in that: The ground station maintains the same source current time on which it determines the future GPS absolute time in the following way: when the ground station receives the GPS time event transmitted back by the UAV, it performs the first synchronization with the monotonic clock as the anchor point, locks the difference between the ground station's local self-running clock and the received GPS time as the offset, and sets the synchronized flag. After the initial synchronization is completed, the ground station obtains the current time by the monotonic clock, which is equal to the anchor time plus the time elapsed since the monotonic clock started from the anchor point plus the offset. The ground station only accepts the global navigation satellite system time that is larger than the last recorded time to prevent time backtracking, and relocks the offset according to the new difference when the current error exceeds the relock threshold.

3. The method for synchronous execution of timed actions of a drone swarm based on idempotent gating of future moments, as described in claim 2, is characterized in that: The relock threshold is 2 seconds; the ground station does not update the offset for old time values ​​from different UAVs and outdated global navigation satellite system time values; the ground station obtains the hour, minute, and second of the future GPS absolute time by adding the delay seconds to the current time of the same source, so that the target time issued by the ground station is of the same source as the global navigation satellite system time base used by the UAV flight control firmware.

4. The method for synchronous execution of timed actions of a drone swarm based on idempotent gating of future moments, as described in claim 1, is characterized in that: The current absolute number of seconds is calculated by converting the current hour, minute, and second, and the target absolute number of seconds is calculated by converting the hour, minute, and second in the time message. The current hour is obtained by adding the time difference of the East 8 time zone to the hour derived from the positioning speed and time data of the Global Navigation Satellite System and taking the modulo 24. The future time gate uses a strict less-than relationship for queuing determination, and is enqueued only when the current absolute number of seconds is strictly less than the target absolute number of seconds.

5. The method for synchronous execution of timed actions of a drone swarm based on idempotent gating of future moments according to claim 1, characterized in that: The authorization message is a custom MAVLink v2 message, with message number 78 and checksum 43. The payload follows the specified format. <hbbbbb> The payload is packaged and sequentially includes action parameters in the form of 16-bit unsigned integers, action codes in the form of 8-bit unsigned integers, action masks in the form of 8-bit unsigned integers, hours in the form of 8-bit unsigned integers, minutes in the form of 8-bit unsigned integers, and seconds in the form of 8-bit unsigned integers; the payload length is 7 bytes; the sender calculates cyclic redundancy check on the payload using the X25 algorithm and adds the check value 43, and the receiver performs check using the same algorithm and the same check value; the action code is used to represent the action content, the action mask is used to represent the authorization message type, and the authorization message does not have a command sequence number and a unique command identifier field.< / hbbbbb> 6. The method for synchronous execution of timed actions of a drone swarm based on idempotent gating of future moments, as described in claim 5, is characterized in that: When the action mask is 180, it represents a timed action message; when the action mask is 166, it represents a timed takeoff message or an emergency return message. The unified action executor is shared by eight types of cluster actions: pause, continue, speed change, forward, reverse, emergency return, turn on lights, and turn off lights. Among them, action code 1 corresponds to pause, action code 2 corresponds to continue, action code 3 corresponds to speed change, action code 4 corresponds to forward, action code 5 corresponds to reverse, action code 6 corresponds to emergency return, action code 7 corresponds to turn on lights, and action code 8 corresponds to turn off lights.

7. The method for synchronous execution of timed actions of a drone swarm based on idempotent gating of future moments, as described in claim 6, is characterized in that: When the action code indicates a speed change, the action parameter is the gear shift. The unified action executor maps the gear shift to the task speed. The task speed is determined according to the formula: Task Speed ​​= (5 - Gear Shift) × 25 + 100, so that the smaller the gear shift, the higher the task speed, and the larger the gear shift, the lower the task speed. The unified action executor performs timing compensation based on the product of the change in task speed and the current index, so that the running time is increased when decelerating and decreased when accelerating. When the action code indicates a pause, the unified action executor records the pause duration and adds the pause duration for timing compensation when the action resumes execution; when the action code indicates a rewind, the unified action executor performs timing compensation based on the current index; both the immediate command path and the timed message path call the unified action executor, so that the same cluster action under the two paths has consistent execution behavior.

8. The method for synchronous execution of timed actions of a drone swarm based on idempotent gating of future moments according to claim 1, characterized in that: The ground station performs dual-link intensive retransmission of the same timing message within a window preceding the future absolute GPS time. This dual-link intensive retransmission includes sending the timing message via WiFi / UDP link each time, and sending the same timing message via data radio broadcast link when the data radio broadcast link is connected. For timed action timing messages with an action mask of 180, the ground station retransmits the message every 200 milliseconds within a window preceding the future absolute GPS time, with the retransmission count being the window milliseconds divided by 200 and not less than 3 times. For timed takeoff timing messages or emergency return timing messages with an action mask of 166, the ground station uniformly retransmits the message a set number of times within a given window duration. When the set number is greater than 1, the retransmission interval is determined according to retransmission interval = window duration × 1000 ÷ (set number - 1). When the set number is equal to 1, the retransmission interval is 0.

9. A method for synchronous execution of timed actions of a drone swarm based on idempotent gating of future moments, as described in claim 8, characterized in that: The ground station maintains an atomic generation counter. Each time a resend is initiated, the atomic generation counter is incremented to obtain the generation value for this resend. Before each resend cycle, the current global generation is checked to see if it is still equal to the generation value for this resend. When the ground station receives a new instruction or issues a cancellation message, it performs an atomic increment on the atomic generation counter again, causing the old retransmission thread that is still running to stop retransmission in subsequent verifications; the cancellation message is a message with an action mask of 166 and an action code of 0.

10. The method for synchronous execution of timed actions of a drone swarm based on idempotent gating of future moments according to claim 1, characterized in that: When canceling the entire field, resetting, or taking off from a new field, the flight control firmware calls a clearing step, sets the pending execution flag to false, and clears the temporarily stored action codes; when the ground station sends the authorization message, it obtains the list of online UAVs across the entire field and covers the entire field via WiFi / UDP links; when the cluster action is an emergency return, the ground station overlays the data transmission radio broadcast link to send the message; in self-stabilization mode, the flight control firmware judges the link status based on the most recent visible heartbeat time from the ground station, and sets the heartbeat failure flag and enters the protection state when the difference between the current time and the most recent visible heartbeat time exceeds 15,000 milliseconds; the speed change action takes effect under low-speed interlock conditions where the local speed does not exceed 0.5 meters per second.

11. A system for synchronously executing timed actions of a drone swarm, implementing the method of any one of claims 1 to 10, characterized in that: This includes a ground station and several drones equipped with flight control firmware; The ground station includes a source clock module, a time transmission message construction module, and a dual-link retransmission module. The source clock module is used to determine the current source time by means of single-time global satellite navigation system calibration locking offset, monotonic clock self-running, monotonic increment anti-backtracking, and relocking the offset when the error exceeds a threshold, and to determine the future GPS absolute time based on the source current time. The time transmission message construction module is used to construct a time transmission message carrying the action code, action mask, and the hour, minute, and second of the future GPS absolute time. The dual-link retransmission module is used to perform intensive retransmission within a window before the future GPS absolute time through WiFi / UDP links and data transmission radio broadcast links, and to control the retransmission interruption through an atomic generation counter. The UAV's flight control firmware includes a future time gate, a pending execution register, a fixed frequency scheduling task, and a unified action execution entity. The future time gate is used to allow authorization messages when the current absolute number of seconds on the local machine is strictly less than the target absolute number of seconds and to discard late authorization messages when the current absolute number of seconds on the local machine is not less than the target absolute number of seconds. The pending execution register is used to temporarily store action codes, future GPS absolute times, and pending execution flags. The fixed-frequency scheduling task is used to periodically read the current absolute number of seconds on the machine and trigger it when the target absolute number of seconds is reached; the unified action executor is used to perform actions such as pause, continue, speed change, forward, reverse, emergency return, turn on lights and turn off lights.

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