A safe air-drop method for unmanned aerial vehicle multi-air-drop pieces

Abstract

The application relates to the technical field of unmanned aerial vehicles, and discloses a safe air-drop method for multiple air-drop pieces of unmanned aerial vehicles, which comprises the following steps: determining an air-drop piece time interval according to the air-drop piece speed of an unmanned aerial vehicle, the height and diameter of the air-drop piece after a parachute is completely unfolded; generating all feasible air-drop delivery sequences according to the number of air-drop pieces carried on the belly of the unmanned aerial vehicle; taking a first constraint condition as a screening basis to eliminate delivery sequences that do not meet the requirements, so as to obtain an initial delivery sequence set; screening the initial delivery sequence set based on a second constraint condition to determine an air-drop reference delivery sequence; obtaining an air-drop time line according to the air-drop piece time interval and the air-drop reference delivery sequence; and delivering corresponding air-drop pieces according to the air-drop time line. On the basis of guaranteeing the flight safety and attitude stability of the unmanned aerial vehicle, the overall delivery efficiency of the multiple air-drop pieces is effectively improved.

Description

Technical Field

[0001] This application relates to the field of unmanned aerial vehicle (UAV) technology, and in particular to a method for the safe airdrop of multiple airdrop components from a UAV. Background Technology

[0002] With the development of drone technology, its application in fields such as material delivery and emergency rescue is becoming increasingly widespread. Among these, continuous parachute airdrops of multiple supplies are a key capability for improving delivery efficiency. However, in actual flight testing and airdrop missions, especially when multiple supplies need to be continuously dropped from the fuselage belly, the following technical challenges are encountered: First, there is the risk of entanglement. During continuous delivery, the parachute of the previous item may not have fully deployed before the next item is dropped. The parachute of the subsequent item is easily affected by the wake of the preceding item, and the two are very likely to become entangled in close airspace, leading to airdrop failure.

[0003] Second, there is a drastic shift in the center of gravity. The delivery of supplies will instantly change the weight distribution and longitudinal center of gravity of the drone. During the delivery of multiple items, the longitudinal center of gravity may undergo drastic and non-linear longitudinal changes. If this exceeds the compensation capability of the flight control system, it will cause the drone to lose pitch control or even crash.

[0004] Thirdly, there is the uncertainty of malfunctions. In complex environments, the airdrop mechanism may jam, causing the planned supplies to fail to be dropped. In this case, this unplanned extra load and its location, the actual weight and longitudinal center of gravity of the drone are seriously inconsistent with the flight control system's expectations, which will disrupt the drone's balance and maneuverability. If not handled properly, it will directly lead to test flight failure or even cause an accident.

[0005] Currently, most publicly available technical solutions focus on the design of the airdrop mechanism itself, single airdrops, or simple multiple consecutive airdrops. They lack systematic solutions to the aforementioned problems of multiple coupled constraints. There is still a lack of a complete method for how to systematically plan, verify, and ensure the entire process of multiple consecutive airdrops in real flight test subjects, including coordinating airdrop intervals, sequence, and fault response. Summary of the Invention

[0006] In view of this, this application provides a method for the safe airdrop of multiple airdropped items by drones, which effectively improves the overall efficiency of multiple airdropped item delivery operations while ensuring the safety and attitude stability of drone airdrop flight.

[0007] This application discloses a method for the safe airdrop of multiple airdropped items by a drone, which includes: Step 1: Determine the time interval for dropping airdropped items based on the drone's drop speed, the height and diameter of the airdropped items after the parachute is fully deployed; Step 2: Based on the number of airdrop items carried on the belly of the drone, generate all feasible airdrop sequences; using the first constraint as the filtering criterion, remove the airdrop sequences that do not meet the requirements to obtain an initial set of airdrop sequences; then filter the initial set of airdrop sequences based on the second constraint to determine the baseline airdrop order. Step 3: Obtain the airdrop timeline based on the airdrop interval and the airdrop baseline order; Step 4: Deploy the corresponding airdrop items according to the airdrop timeline.

[0008] Further, step 1 includes: Step 11: The fully deployed airdrop component is equivalent to a three-dimensional safety envelope, where the three-dimensional safety envelope is based on the center of the parachute and has a horizontal expansion diameter equal to the diameter of the fully deployed airdrop component. The vertical extension height is defined as the height of the airdropped component after the parachute has fully deployed. The resulting cylinder; each airdrop component is equipped with a parachute; Step 12: Based on the horizontal expansion diameter and vertical expansion height Determine the horizontal safety clearance and vertical safety clearance : Step 13: Adjust the horizontal safety clearance and vertical safety clearance Converted into horizontal constraint time respectively and vertical constraint time ; Horizontal constraint time Used to ensure that adjacent parachutes are staggered in the horizontal direction, and to constrain the time vertically. Used to ensure that adjacent parachutes are staggered in the vertical direction; Step 14: Based on the horizontal constraint time and vertical constraint time Determine the time interval for airdropping items. .

[0009] Further, step 12 includes: The horizontal safety clearance is obtained using the following formula. and vertical safety clearance :

[0010]

[0011] in, As a horizontal safety margin, the value is taken as... related; For vertical safety margin, the value is taken as... related.

[0012] Further, step 13 includes: According to horizontal safety clearance and the speed of drone delivery of airdropped items Determine the horizontal constraint time :

[0013] Pre-drop items Distance at any moment for:

[0014] in, It is the acceleration due to gravity. This refers to the time from when the airdropped item is dropped until the parachute fully deploys. This refers to the descent time of the preceding airdropped item; Subsequent airdrop items Distance at any moment for:

[0015] The vertical distance between the preceding and following airdropped items is the difference in their descent distances, and must be greater than or equal to the vertical safety clearance. :

[0016] Right now:

[0017] Seeking answers regarding Taking the positive root of the two linear equations in two variables, we obtain the minimum time interval that satisfies vertical safety: .

[0018] Further, step 14 includes: The time interval for airdropping items can be obtained using the following formula:

[0019] in, It is a function for maximizing the value.

[0020] Furthermore, the first constraint is that the longitudinal center of gravity of the UAV is located between the front and rear limits of the longitudinal center of gravity of the UAV throughout the entire process of airdropping all the airdropped items; the longitudinal center of gravity is the position of the center of gravity on the longitudinal axis, which points from the nose of the UAV to the tail. The second constraint is that after the airdrop mission is paused due to any airdrop component stuck on the drone, the drone's longitudinal center of gravity position is closer to the neutral position of the preset safety envelope; the neutral position is the average of the front and rear limits of the drone's longitudinal center of gravity position.

[0021] Furthermore, the formula for calculating the longitudinal center of gravity position of the drone throughout the entire airdrop process is as follows:

[0022] in, To determine the longitudinal center of gravity position of the drone throughout the entire process of airdropping all items. This refers to the empty weight of the drone, including its fuel weight. This represents the longitudinal center of gravity of the drone when it is empty, including its fuel weight. For the first The quality of each airdrop item For the first The longitudinal center of gravity of each airdropped item within the belly of the drone. This represents the total number of items airdropped by the drone.

[0023] Further, step 4 includes: The drone flies to the airdrop area according to the predetermined route and enters level flight. During the drop phase, each airdrop item is dropped in sequence according to the airdrop timeline. After each airdrop item successfully detaches from the drone, the drone's total weight and longitudinal center of gravity are updated in real time. After the drop mission is completed, the drone returns and lands.

[0024] Furthermore, during the delivery phase, the drone's delivery status is monitored in real time using gravity sensors embedded at the installation location of each delivery unit.

[0025] Furthermore, during the delivery phase, if the gravity sensor detects that the airdrop item is stuck and has not been delivered, a fault handling procedure is immediately triggered. This fault handling procedure includes: Suspend subsequent delivery plans, treat the stuck and undelivered airdrops and those delivered after them as mass points permanently fixed in their original positions, and recalculate the longitudinal center of gravity of the drone; the original position is the longitudinal center of gravity of the stuck and undelivered airdrops and those delivered after them on the drone. Based on the latest drone weight and longitudinal center of gravity position, new safe flight control commands are automatically generated to ensure that the drone has sufficient attitude stability margin for safe return and landing.

[0026] Due to the adoption of the above technical solution, this application has the following advantages: 1. This application aims to ensure the safety and success rate of continuous airdrop test flights of multiple items of supplies under the fuselage.

[0027] 2. This application scientifically sets the drop interval to avoid parachute system interference, determines the airdrop baseline sequence to control longitudinal center of gravity changes, and establishes a fault handling procedure to deal with airdrop mechanism jamming, forming a complete and closed-loop safety verification process for airdrop of multiple parts under the fuselage. It has the technical characteristics of being systematic, safe, and efficient. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0029] Figure 1 This is a flowchart illustrating a method for the safe airdrop of multiple airdropped items from a drone, according to an embodiment of this application. Figure 2 This is a flowchart illustrating another method for the safe airdrop of multiple airdropped components from a drone, according to an embodiment of this application. Figure 3 This is a schematic diagram of the three-dimensional security envelope theoretical model according to an embodiment of this application; Figure 4 This is a schematic diagram of the theoretical model of the minimum safety distance in an embodiment of this application; Figure 5 This is a schematic diagram of the airdrop timeline according to an embodiment of this application. Detailed Implementation

[0030] The present application will be further described in conjunction with the accompanying drawings and embodiments. The described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by those skilled in the art should fall within the protection scope of the embodiments of the present application.

[0031] See Figure 1 This application provides an embodiment of a method for the safe airdrop of multiple airdropped items by a drone, which includes: Step 1: Determine the time interval for dropping airdropped items based on the drone's drop speed, the height and diameter of the airdropped items after the parachute is fully deployed; Step 2: Based on the number of airdrop items carried on the belly of the drone, generate all feasible airdrop sequences; using the first constraint as the filtering criterion, remove the airdrop sequences that do not meet the requirements to obtain an initial set of airdrop sequences; then filter the initial set of airdrop sequences based on the second constraint to determine the baseline airdrop order. Step 3: Obtain the airdrop timeline based on the airdrop interval and the airdrop baseline order; Step 4: Deploy the corresponding airdrop items according to the airdrop timeline.

[0032] Optionally, step 1 includes: Step 11: The fully deployed airdrop component is equivalent to a three-dimensional safety envelope, where the three-dimensional safety envelope is based on the center of the parachute and has a horizontal expansion diameter equal to the diameter of the fully deployed airdrop component. The vertical extension height is defined as the height of the airdropped component after the parachute has fully deployed. The resulting cylinder; each airdrop component is equipped with a parachute; Step 12: Based on the horizontal expansion diameter and vertical expansion height Determine the horizontal safety clearance and vertical safety clearance : Step 13: Adjust the horizontal safety clearance and vertical safety clearance Converted into horizontal constraint time respectively and vertical constraint time ; Horizontal constraint time Used to ensure that adjacent parachutes are staggered in the horizontal direction, and to constrain the time vertically. Used to ensure that adjacent parachutes are staggered in the vertical direction; Step 14: Based on the horizontal constraint time and vertical constraint time Determine the time interval for airdropping items. .

[0033] Optionally, step 12 includes: The horizontal safety clearance is obtained using the following formula. and vertical safety clearance :

[0034]

[0035] in, As a horizontal safety margin, the value is taken as... related; For vertical safety margin, the value is taken as... related.

[0036] Optionally, step 13 includes: According to horizontal safety clearance and the speed of drone delivery of airdropped items Determine the horizontal constraint time :

[0037] Pre-drop items Distance at any moment for:

[0038] in, It is the acceleration due to gravity. This refers to the time from when the airdropped item is dropped until the parachute fully deploys. This refers to the descent time of the preceding airdropped item; Subsequent airdrop items Distance at any moment for:

[0039] The vertical distance between the preceding and following airdropped items is the difference in their descent distances, and must be greater than or equal to the vertical safety clearance. :

[0040] Right now:

[0041] Seeking answers regarding Taking the positive root of the two linear equations in two variables, we obtain the minimum time interval that satisfies vertical safety: .

[0042] Optionally, step 14 includes: The time interval for airdropping items can be obtained using the following formula:

[0043] in, It is a function for maximizing the value.

[0044] Optionally, the first constraint is that the longitudinal center of gravity of the UAV is located between the front and rear limits of the longitudinal center of gravity of the UAV throughout the entire process of airdropping all the airdropped items; the longitudinal center of gravity is the position of the center of gravity on the longitudinal axis, which points from the nose to the tail of the UAV. The second constraint is that after the airdrop mission is paused due to any airdrop component stuck on the drone, the drone's longitudinal center of gravity position is closer to the neutral position of the preset safety envelope; the neutral position is the average of the front and rear limits of the drone's longitudinal center of gravity position.

[0045] Optionally, the formula for calculating the longitudinal center of gravity position of the drone throughout the entire airdrop process is as follows:

[0046] in, To determine the longitudinal center of gravity position of the drone throughout the entire process of airdropping all items. This refers to the empty weight of the drone, including its fuel weight. This represents the longitudinal center of gravity of the drone when it is empty, including its fuel weight. For the first The quality of each airdrop item For the first The longitudinal center of gravity of each airdropped item within the belly of the drone. This represents the total number of items airdropped by the drone.

[0047] Optionally, step 4 includes: The drone flies to the airdrop area according to the predetermined route and enters level flight. During the drop phase, each airdrop item is dropped in sequence according to the airdrop timeline. After each airdrop item successfully detaches from the drone, the drone's total weight and longitudinal center of gravity are updated in real time. After the drop mission is completed, the drone returns and lands.

[0048] Optionally, during the delivery phase, the drone delivery process can be monitored in real time using gravity sensors embedded at the installation location of each delivery unit.

[0049] Optionally, during the delivery phase, if the gravity sensor detects that the airdrop item is stuck and has not been delivered, a fault handling procedure is immediately triggered, which includes: Suspend subsequent delivery plans, treat the stuck and undelivered airdrops and those delivered after them as mass points permanently fixed in their original positions, and recalculate the longitudinal center of gravity of the drone; the original position is the longitudinal center of gravity of the stuck and undelivered airdrops and those delivered after them on the drone. Based on the latest drone weight and longitudinal center of gravity position, new safe flight control commands are automatically generated to ensure that the drone has sufficient attitude stability margin for safe return and landing.

[0050] For ease of understanding, see Figure 2 This application provides a more specific embodiment: S1: Pre-flight planning phase.

[0051] 1.1 Total number of test-dropped items N=3 items, mass of each item (i=1,2,3) are all 300 kg. The longitudinal arrangement of each airdropped item within the fuselage. (i=1,2,3) represent 3250 mm, 4450 mm, and 5650 mm respectively, indicating longitudinal arrangement positions. The starting point is the location of the drone's nose, and the direction in which the drone's nose points to the end is the positive direction.

[0052] 1.2 Empty weight of the drone (including fuel weight) The longitudinal center of gravity of the unmanned aerial vehicle (including fuel) is 3000 kg. The longitudinal center of gravity of the UAV is 4450 mm ahead. The longitudinal center of gravity of the UAV is 4360 mm, which is the rear limit. The diameter is 4580 mm, and the speed of drone delivery of airdropped items is [not specified]. The speed is 40 meters per second.

[0053] 1.3 Establishing a three-dimensional safety envelope theoretical model Preventing entanglement between parachutes deployed one after the other essentially means ensuring that the three-dimensional safety envelopes of adjacent parachutes do not overlap in space during the deployment and stable descent phases.

[0054] The so-called three-dimensional safety envelope is based on the center of the umbrella system, with the diameter of the umbrella system in the open state as the horizontal expansion diameter. The vertical extension height is 20 meters, with the height of the umbrella system in the open state as the vertical extension height. A cylinder, 25 meters in length, is formed, such as Figure 3 As shown.

[0055] 1.4 Establishing a theoretical model for minimum safety distance Definition: Minimum safety clearance theoretical model (e.g.) Figure 4 Based on the three-dimensional safety envelope theoretical model at the physical space level, it takes into account horizontal and vertical safety distances to prevent the strong wake around the umbrella and the risk that the umbrella lines may still be sucked into the vortex of adjacent umbrellas during the opening process.

[0056] Horizontal safety clearance satisfy:

[0057] in For horizontal safety margin, we take... It is 10 meters.

[0058] Vertical safety clearance Should meet:

[0059] in For vertical safety margin, we take [the following value] here. It is 40 meters.

[0060] 1.5. Set the time interval for dropping airdrop items. horizontal safety clearance and vertical safety clearance These are converted into two independent safety time constraints, denoted as the horizontal constraint time. and vertical constraint time .

[0061] Horizontal constraint time Mainly composed of horizontal safety clearance and the speed of drone delivery of airdropped items The decision is made to ensure that adjacent umbrellas are horizontally staggered.

[0062]

[0063] Vertical constraint time Mainly composed of vertical safety clearance The difference between the free fall velocity and the free fall velocity determines the vertical offset between adjacent umbrellas.

[0064] set up If the time from the drop of an airdrop item to the main parachute fully inflating is 3 seconds, then the descent time of the preceding airdrop item is... The preceding airdrop items are at the time Falling distance :

[0065] in This is the acceleration due to gravity, with a value of 9.80665, measured in meters per second. 2 .

[0066] The subsequent airdrop time is Subsequent airdrops at the time Falling distance :

[0067] The vertical distance between the preceding and following airdropped items is the difference in their descent distances, and must not be less than the vertical safety distance. The following equation is obtained:

[0068] That is:

[0069] Solve the above regarding Taking the positive root of the two linear equations in two variables gives the minimum time interval that satisfies vertical safety:

[0070] Airdrop interval Both horizontal and vertical constraint times must be satisfied; the horizontal constraint time will be used. and vertical constraint time The larger value in:

[0071] S2: Intelligent planning of airdrop sequence.

[0072] 2.1 Calculate all possible delivery sequences.

[0073] For a total of N=3 test-flight airdropped items, there are a total of 6 possible drop sequences, namely: First method: 1→2→3 The second method: 1→3→2 The third type: 2→1→3 The fourth type: 2→3→1 Fifth type: 3→1→2 The sixth type: 3→2→1 2.2 Determine the basic order of airdrops.

[0074] With the core constraint that the drone's longitudinal center of gravity remains within a preset safety envelope throughout the entire mission, and with the auxiliary constraint that the drone's longitudinal center of gravity is closer to a neutral position within the preset safety envelope after any drop item jams and the mission is paused, at least one theoretical drop order can be generated. If one theoretical drop order is generated, it is selected as the baseline drop order. If two or more drop orders are generated, the theoretical drop order with the higher ranking is selected as the baseline drop order.

[0075] The preset safety envelope ensures that the longitudinal center of gravity position remains within the range defined by the front and rear limits of the UAV's longitudinal center of gravity position throughout the entire flight. for The neutral position of the preset safety envelope is the average of the front and rear limits of the UAV's longitudinal center of gravity position, which is... .

[0076] The following is based on The airdrop interval is set at 1.72 seconds. Airdrop preparation begins at 0 seconds, and the first airdrop item is dropped at 1.72 seconds. The second airdrop item was dropped. The third airdrop item is dropped, and the longitudinal center of gravity position of the drone throughout the entire flight is calculated for the six drop sequences. The drone is initially screened based on the core constraint that its longitudinal center of gravity position is within the preset safety envelope throughout the entire flight.

[0077] The first method: 1→2→3, total weight sequence: 3900 kg→3600 kg→3300 kg→3000 kg, longitudinal center of gravity position sequence: 4450 mm→4550 mm→4559 mm→4450 mm; all are within the front and rear limits of the UAV's longitudinal center of gravity position. Within this range, it is acceptable; The second method: 1→3→2, total weight sequence: 3900 kg→3600 kg→3300 kg→3000 kg, longitudinal center of gravity position sequence: 4450 mm→4550 mm→4450 mm→4450 mm; all are within the front and rear limits of the UAV's longitudinal center of gravity position. Within this range, it is acceptable; The third type: 2→1→3, with the total weight sequence as follows: 3900 kg → 3600 kg → 3300 kg → 3000 kg, and the longitudinal center of gravity position sequence as follows: 4450 mm → 4450 mm → 4559 mm → 4450 mm; all of which are within the front and rear limits of the UAV's longitudinal center of gravity position. Within this range, it is acceptable; The fourth option is 2→3→1, with the total weight sequence as follows: 3900 kg → 3600 kg → 3300 kg → 3000 kg, and the longitudinal center of gravity position sequence as follows: 4450 mm → 4450 mm → 4341 mm → 4450 mm; however, 4341 mm exceeds the rear limit of the longitudinal center of gravity position (4360 mm), so it is not acceptable. Fifth option: 3→1→2, total weight sequence: 3900 kg→3600 kg→3300 kg→3000 kg, longitudinal center of gravity position sequence: 4450 mm→4350 mm→4450 mm→4450 mm; where 4350 mm exceeds the rear limit of the longitudinal center of gravity position (4360 mm), and is not acceptable; The sixth option is 3→2→1, with the total weight sequence as follows: 3900 kg→3600 kg→3300 kg→3000 kg, and the longitudinal center of gravity position sequence as follows: 4450 mm→4350 mm→4341 mm→4450 mm; among which, 4341 mm exceeds the rear limit of the longitudinal center of gravity position (4360 mm), and is therefore unacceptable.

[0078] After initial screening based on the core constraint that the drone's longitudinal center of gravity remains within the preset safety envelope throughout the entire flight, three of the six deployment sequences remain: the first, the second, and the third.

[0079] The following is a comparison of the longitudinal center of gravity of the drone after one of its airdrop components jammed and the airdrop mission was paused, with the center of gravity closer to the preset safety envelope at a neutral position. A second screening is performed to provide auxiliary constraints.

[0080] The first type: 1→2→3, total weight sequence: 3900 kg→3600 kg→3300 kg→3000 kg, longitudinal center of gravity position sequence: 4450 mm→4550 mm→4559 mm→4450 mm.

[0081] If the No. 1 airdrop item is delayed, the longitudinal center of gravity of the entire aircraft (4450 mm) will be 20 mm away from the neutral position of the preset safety envelope (4470 mm). If the No. 1 airdrop is successfully dropped, the No. 2 airdrop will be delayed. The longitudinal center of gravity of the entire aircraft (4550 mm) will be 80 mm away from the neutral position of the preset safety envelope (4470 mm). If the drop of airdrop item 1 and item 2 is successful, and the drop of airdrop item 3 is delayed, the longitudinal center of gravity of the entire aircraft (4559 mm) is 89 mm away from the neutral position of the preset safety envelope (4470 mm).

[0082] Under the above three jamming conditions, the maximum distance between the longitudinal center of gravity of the entire aircraft and the neutral position of the preset safety envelope is [value missing]. .

[0083] The second type: 1→3→2, the sequence of changes in the total weight of the machine: 3900 kg→3600 kg→3300 kg→3000 kg, the sequence of longitudinal center of gravity position: 4450 mm→4550 mm→4450 mm→4450 mm.

[0084] If the No. 1 airdrop item is delayed, the longitudinal center of gravity of the entire aircraft (4450 mm) will be 20 mm away from the neutral position of the preset safety envelope (4470 mm). If the No. 1 airdrop is successfully dropped, the No. 3 airdrop will be delayed. The longitudinal center of gravity of the entire aircraft (4550 mm) will be 80 mm away from the neutral position of the preset safety envelope (4470 mm). If the drop of airdrop item 1 and item 3 are successfully dropped, and the drop of airdrop item 2 is delayed, the longitudinal center of gravity of the entire aircraft (4450 mm) will be 20 mm away from the neutral position of the preset safety envelope (4470 mm).

[0085] Under the above three jamming conditions, the maximum distance of the aircraft's longitudinal center of gravity from the neutral position of the preset safety envelope is [value missing]. .

[0086] The third type: 2→1→3, total weight sequence: 3900 kg→3600 kg→3300 kg→3000 kg, longitudinal center of gravity position sequence: 4450 mm→4450 mm→4559 mm→4450 mm.

[0087] If the No. 2 airdrop item is delayed, the longitudinal center of gravity of the entire aircraft (4450 mm) will be 20 mm away from the neutral position of the preset safety envelope (4470 mm). If the No. 2 airdrop is successfully dropped, and the No. 1 airdrop is delayed, the longitudinal center of gravity of the entire aircraft (4450 mm) will be 20 mm away from the neutral position of the preset safety envelope (4470 mm). If both airdrop packages #2 and #1 are successfully dropped, and airdrop package #3 is delayed, the longitudinal center of gravity of the entire aircraft (4559 mm) is 89 mm away from the neutral position of the preset safety envelope (4470 mm).

[0088] Under the above three jamming conditions, the maximum distance of the aircraft's longitudinal center of gravity from the neutral position of the preset safety envelope is [value missing]. .

[0089] Based on the above analysis, among the three deployment sequences, the second sequence has the best overall longitudinal center of gravity position (the value of the neutral position from the preset safety envelope is...). It is closer to the neutral position of the preset safety envelope (4470 mm).

[0090] Therefore, the longitudinal center of gravity of the drone after one of its drop components jammed and the airdrop mission was paused was closer to the neutral position of the preset safety envelope. As an auxiliary constraint, after a second screening, the optimal order of the three drop sequences is the second one: 1→3→2. This theoretical drop sequence is selected as the baseline drop sequence.

[0091] 2.3 Combined with the time interval for airdropping items Based on the airdrop baseline order, generate an airdrop timeline.

[0092] The time interval for airdropping items The airdrop order is 1→3→2. See the airdrop timeline below. Figure 5 .

[0093] S3: Flight test execution and monitoring phase.

[0094] 3.1 The drone flies to the airdrop area along the predetermined route and enters level flight.

[0095] 3.2 During the delivery phase, the drone's delivery status is monitored in real time using longitudinal gravity sensors embedded at the installation location of each delivery component. If the delivery is successful, the drone's weight and center of gravity model is updated, and the aforementioned delivery timeline continues. After completing the mission, the drone successfully returns and lands.

[0096] 3.3 If the gravity sensor detects that the target airdrop item is stuck and has not been released, the fault handling procedure will be triggered immediately, including: 1) Status freeze: Suspend the planned deployment.

[0097] 2) Model reconstruction: Treat the stuck airdropped parts and the airdropped parts dropped after it as mass points permanently fixed in the original position, and recalculate the real-time longitudinal center of gravity position of the UAV.

[0098] 3) Mission replanning: Based on the reconstructed weight and center of gravity of the UAV, including the remaining undelivered supplies, new safe flight control commands are automatically generated to ensure that the UAV has sufficient attitude stability margin for safe return and landing.

[0099] This application integrates pre-flight planning, in-flight monitoring, and fault handling into a complete, closed-loop safety verification process for airdropping multiple components from the aircraft's belly. By combining theoretical calculations with real-time monitoring, it proactively manages the airdrop execution status and longitudinal center of gravity risk of the UAV. The unique fault handling procedure provides clear and safe operational guidelines for handling high-risk situations such as drop delays, effectively enhancing the safety boundaries of flight testing. By first determining the airdrop baseline sequence, it can optimize airdrop efficiency as much as possible while ensuring safety, shortening the entire flight test cycle.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this application. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of the claims of this application.

Claims

1. A method for the safe airdrop of multiple airdropped items by a drone, characterized in that, include: Step 1: Determine the time interval for dropping airdropped items based on the drone's drop speed, the height and diameter of the airdropped items after the parachute is fully deployed; Step 2: Based on the number of airdrop items carried on the UAV's belly, generate all feasible airdrop sequences; using the first constraint as a filtering criterion, eliminate airdrop sequences that do not meet the requirements to obtain an initial set of airdrop sequences; then, based on the second constraint, filter the initial set of airdrop sequences to determine the baseline airdrop order; the first constraint is that the UAV's longitudinal center of gravity is located between the front and rear limits of the UAV's longitudinal center of gravity throughout the entire airdrop process; the longitudinal center of gravity is the position of the center of gravity on the longitudinal axis, which points from the UAV's nose to its tail; the second constraint is that after pausing the airdrop mission due to any airdrop item jamming on the UAV, the UAV's longitudinal center of gravity is closer to the neutral position of the preset safety envelope; the neutral position is the average of the front and rear limits of the UAV's longitudinal center of gravity. Step 3: Obtain the airdrop timeline based on the airdrop interval and the airdrop baseline order; Step 4: Deploy the corresponding airdrop items according to the airdrop timeline.

2. The method according to claim 1, characterized in that, Step 1 includes: Step 11: The airdrop component after the parachute is fully deployed is equivalent to a three-dimensional safety envelope, wherein the three-dimensional safety envelope is based on the center of the parachute and the diameter of the airdrop component after the parachute is fully deployed is the horizontal expansion diameter. The vertical extension height is defined as the height of the airdropped component after the parachute has fully deployed. The resulting cylinder; each airdrop component is equipped with a parachute; Step 12: Based on the horizontal expansion diameter and vertical expansion height Determine the horizontal safety clearance and vertical safety clearance : Step 13: Adjust the horizontal safety clearance and vertical safety clearance Converted into horizontal constraint time respectively and vertical constraint time ; Horizontal constraint time Used to ensure that adjacent parachutes are staggered in the horizontal direction, and to constrain the time vertically. Used to ensure that adjacent parachutes are staggered in the vertical direction; Step 14: Based on the horizontal constraint time and vertical constraint time Determine the time interval for airdropping items. .

3. The method according to claim 2, characterized in that, Step 12 includes: The horizontal safety clearance is obtained using the following formula. and vertical safety clearance : in, As a horizontal safety margin, the value is taken as... related; For vertical safety margin, the value is taken as... related.

4. The method according to claim 2, characterized in that, Step 13 includes: According to horizontal safety clearance and the speed of drone delivery of airdropped items Determine the horizontal constraint time : Pre-drop items Distance at any moment for: in, It is the acceleration due to gravity. This refers to the time from when the airdropped item is dropped until the parachute fully deploys. This refers to the descent time of the preceding airdropped item; Subsequent airdrop items Distance at any moment for: The vertical distance between the preceding and following airdropped items is the difference in their descent distances, and must be greater than or equal to the vertical safety clearance. : Right now: Seeking answers regarding Taking the positive root of the two linear equations in two variables, we obtain the minimum time interval that satisfies vertical safety: 。 5. The method according to claim 2, characterized in that, Step 14 includes: The time interval for airdropping items can be obtained using the following formula: in, It is a function for maximizing the value.

6. The method according to claim 1, characterized in that, The formula for calculating the longitudinal center of gravity position of the drone throughout the entire airdrop process is as follows: in, To determine the longitudinal center of gravity position of the drone throughout the entire process of airdropping all items. This refers to the empty weight of the drone, including its fuel weight. This represents the longitudinal center of gravity of the drone when it is empty, including its fuel weight. For the first The quality of each airdrop item For the first The longitudinal center of gravity of each airdropped item within the belly of the drone. This represents the total number of items airdropped by the drone.

7. The method according to claim 1, characterized in that, Step 4 includes: The drone flies to the airdrop area according to the predetermined route and enters level flight. During the drop phase, each airdrop item is dropped in sequence according to the airdrop timeline. After each airdrop item successfully detaches from the drone, the drone's total weight and longitudinal center of gravity are updated in real time. After the drop mission is completed, the drone returns and lands.

8. The method according to claim 7, characterized in that, During the delivery phase, gravity sensors embedded at the installation location of each delivery unit are used to monitor the drone's delivery process in real time.

9. The method according to claim 8, characterized in that, During the deployment phase, if the gravity sensor detects that the airdrop item is stuck and has not been deployed, a fault handling procedure will be immediately triggered. The fault handling procedure includes: Suspend subsequent delivery plans, treat the stuck and undelivered airdrops and those delivered after them as mass points permanently fixed in their original positions, and recalculate the longitudinal center of gravity of the drone; the original position is the longitudinal center of gravity of the stuck and undelivered airdrops and those delivered after them on the drone. Based on the latest drone weight and longitudinal center of gravity position, new safe flight control commands are automatically generated to ensure that the drone has sufficient attitude stability margin for safe return and landing.

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