Autonomous cooperative control method and device for hard-in-air refueling and storage medium

Abstract

The application relates to an autonomous cooperative control method and device for hard in-flight refueling and a storage medium. The application communicates a main controller with multiple navigation subsystems and multiple sub-controllers. In response to receiving a refueling task instruction, multiple-source state data of a tanker, a receiver and a refueling boom can be collected in real time through the multiple navigation subsystems. Then, expected docking trajectories including multiple control nodes and corresponding safety constraints of each expected docking trajectory are generated. Next, based on the docking trajectories, the safety constraints and the multiple-source state data, a cooperative control instruction is calculated through a preset cooperative control law, and the cooperative control instruction is solved to obtain multiple sub-control instructions. Finally, the sub-control instructions are sent to the sub-controllers corresponding to the sub-control instructions to control the tanker, the receiver and the refueling boom to cooperatively execute the refueling task. In this way, the docking accuracy and efficiency of hard in-flight refueling can be improved while the safety of hard in-flight refueling is ensured.

Description

Technical Field

[0001] This application relates to the field of aircraft control technology, specifically to an autonomous cooperative control method, device, and storage medium for rigid aerial refueling. Background Technology

[0002] There are two main methods of aerial refueling: soft refueling and hard refueling. Compared with soft refueling, hard refueling has significant advantages due to its larger refueling flow rate, lighter operational burden on the receiver aircraft, and simpler refueling equipment, and is the future direction of aerial refueling technology.

[0003] Currently, mainstream rigid aerial refueling technology typically relies on a high degree of coordination and manual operation among the tanker pilot, receiver aircraft pilot, and refueling operator. During rigid refueling, the pilots of both the tanker and receiver aircraft must first manually operate the system to form a stable pre-docking formation. Once the tanker and receiver aircraft are in refueling mode, the refueling operator on the tanker lowers the telescopic boom. By controlling the deflection of the winglets, the operator alters the aerodynamic forces of the winglets, controlling the pitch and roll motion of the boom. The extension and retraction of the boom is controlled by the control system, allowing the refueling connector at the end of the boom to insert into the refueling receiver on the receiver aircraft's back. After docking is complete, the boom serves as a fuel channel for in-flight refueling.

[0004] Rigid in-flight refueling is a high-precision control technology that places high demands on the refueling operator's skills and imposes a heavy workload. Due to the limited field of vision of the refueling operator, excessive manipulation, incorrect or delayed actions during refueling can lead to serious accidents such as aircraft collisions or damage to the refueling boom, failing to complete the refueling mission and jeopardizing flight safety. Furthermore, the in-flight refueling process is time-consuming, especially at night or in complex weather conditions, resulting in lower refueling efficiency. Summary of the Invention

[0005] The purpose of this application is to provide an autonomous collaborative control method, device, and storage medium for rigid aerial refueling, in order to solve the problems of low docking accuracy and efficiency and poor safety of traditional rigid aerial refueling.

[0006] To achieve the above objectives, the first aspect of this application provides an autonomous cooperative control method for rigid aerial refueling, applied to a main controller. The main controller communicates with multiple navigation subsystems and multiple sub-controllers, respectively. The multiple navigation subsystems and multiple sub-controllers communicate with the tanker aircraft, the receiving aircraft, and the refueling boom, respectively. The autonomous cooperative control method includes:

[0007] In response to receiving a refueling task instruction, the system collects multi-source status data of the refueling machine, the receiving machine, and the refueling boom in real time through multiple navigation subsystems.

[0008] Generate a desired docking trajectory that includes multiple control nodes and a safety constraint corresponding to each desired docking trajectory;

[0009] Based on the docking trajectory, the safety constraints, and the multi-source state data, a cooperative control command is calculated using a preset cooperative control law, and the cooperative control command is solved to obtain multiple sub-control commands, including refueling machine commands, receiving machine commands, and refueling boom commands.

[0010] The sub-control commands are sent to the sub-controllers corresponding to the sub-control commands to control the refueling machine, the receiving machine and the refueling boom to work together to perform the refueling task.

[0011] A second aspect of this application provides an autonomous cooperative control device for rigid aerial refueling, applied to a main controller. The main controller communicates with multiple navigation subsystems and multiple sub-controllers, and the multiple navigation subsystems and multiple sub-controllers communicate with a tanker aircraft, a receiver aircraft, and a refueling boom, respectively. The autonomous cooperative control device includes:

[0012] The data acquisition module is used to collect multi-source status data of the fuel dispenser, the receiving machine, and the fuel pump in real time through multiple navigation subsystems in response to receiving a refueling task instruction.

[0013] The planning module is used to generate a desired docking trajectory including multiple control nodes and a safety constraint corresponding to each desired docking trajectory;

[0014] The calculation module is used to calculate the cooperative control command based on the docking trajectory, the safety constraints, and the multi-source state data through a preset cooperative control law, and to solve the cooperative control command to obtain multiple sub-control commands, including refueling machine command, receiving machine command, and refueling boom command.

[0015] The control module is used to send the sub-control commands to the sub-controllers corresponding to the sub-control commands, so as to control the refueling machine, the receiving machine and the refueling boom to work together to perform the refueling task.

[0016] A third aspect of this application provides a computer-readable storage medium storing a program that can be loaded by a processor and executed by the above-described autonomous cooperative control method for hard-wired aerial refueling.

[0017] The beneficial effects of this application are:

[0018] This application utilizes a main controller to communicate with multiple navigation subsystems and multiple sub-controllers. These navigation subsystems and multiple automatic control systems communicate with the tanker aircraft, receiver aircraft, and refueling boom, respectively. Based on this, upon receiving a refueling mission command, the main controller can collect multi-source state data from the tanker aircraft, receiver aircraft, and refueling boom in real time through multiple navigation subsystems, laying the data foundation for coordinated control. Then, it generates desired docking trajectories including multiple control nodes and corresponding safety constraints for each trajectory, achieving a balance between optimal path and flight safety, and dynamically adapting to multiple scenarios. Next, based on the docking trajectory, safety constraints, and multi-source state data, it calculates coordinated control commands using a preset coordinated control law, and solves these commands to obtain multiple sub-control commands, which may include tanker aircraft commands, receiver aircraft commands, and refueling boom commands. Finally, each sub-control command is sent to its corresponding sub-controller to control the tanker aircraft, receiver aircraft, and refueling boom to coordinately execute the refueling mission. Through the coordinated control law and sub-control command calculations, the coordination of the actions of the tanker aircraft, receiver aircraft, and refueling boom can be ensured, reducing docking deviations and improving docking accuracy. Meanwhile, embedding safety constraints during the calculation process can reduce the possibility of control commands exceeding safe limits. Thus, through global acquisition of multi-source data, trajectory planning with safety constraints, calculation of collaborative control commands using collaborative control laws, and separate control of the refueling aircraft, receiver aircraft, and refueling boom to execute sub-control commands, the docking accuracy and efficiency of rigid aerial refueling can be improved while ensuring its safety.

[0019] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating an application scenario of an autonomous cooperative control method for rigid aerial refueling provided in this application embodiment;

[0021] Figure 2 This is a flowchart illustrating an autonomous cooperative control method for rigid aerial refueling provided in an embodiment of this application.

[0022] Figure 3 This is a schematic diagram of the structure of an autonomous cooperative control device for rigid aerial refueling provided in the embodiments of this application.

[0023] Explanation of reference numerals in the attached figures

[0024] 110. Main controller; 120. Navigation subsystem; 121. First navigation subsystem; 122. Second navigation subsystem; 123. Third navigation subsystem; 130. Sub-controller; 131. First sub-controller; 132. Second sub-controller; 133. Third sub-controller; 140. Fuel dispenser; 150. Receiving unit; 160. Fueling boom. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified. In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to implement and use this application. In the following description, details are set forth for illustrative purposes. It should be understood that those skilled in the art will recognize that this application can be implemented without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid unnecessary detail that would obscure the description of this application. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0027] Traditional rigid aerial refueling typically involves independent control of the tanker, receiver aircraft, and refueling boom, resulting in poor system coordination. Therefore, this application provides a coordinated control scenario for rigid aerial refueling that achieves full automation, high precision, and high safety. Figure 1 As shown, Figure 1This is a schematic diagram illustrating an application scenario of an autonomous cooperative control method for rigid aerial refueling provided in this application embodiment. The application scenario of the autonomous cooperative control method for rigid aerial refueling in this application embodiment includes a main controller 110 for the autonomous cooperative control method for rigid aerial refueling. The main controller 110 integrates an autonomous cooperative control device for rigid aerial refueling to run a computer-readable storage medium corresponding to the autonomous cooperative control method for rigid aerial refueling, so as to execute the steps of the autonomous cooperative control method for rigid aerial refueling.

[0028] This application embodiment employs a hierarchical centralized control strategy, using a main controller 110 as the central hub to integrate multi-source status data and output coordinated control commands. In this embodiment, the main controller 110 can communicate with multiple navigation subsystems 120 and multiple sub-controllers 130. The multiple navigation subsystems 120 and multiple sub-controllers 130 communicate with the refueling machine 140, the receiving machine 150, and the refueling boom 160, respectively. The controlled objects in this application embodiment include the refueling machine 140, the receiving machine 150, and the refueling boom 160. The refueling machine 140 is equipped with a unified main controller 110 and the refueling boom 160, and provides fuel. The receiving machine 150 is used to receive fuel. The refueling boom 160 includes a retractable, rollable, and pitchable rigid refueling telescopic sleeve, which is the key terminal for directly performing docking operations.

[0029] In a rigid aerial refueling system, the refueling boom 160 is a dedicated accessory of the tanker aircraft 140, fixed to one end of the tanker aircraft 140, for example, at the tail. When not performing a refueling mission, the refueling boom 160 can be retracted to reduce aerodynamic interference with the tanker aircraft 140 and its impact on flight attitude. During a refueling mission, the refueling boom 160 can adjust its spatial position through extension, retraction, and joint deflection. Its range of motion can extend longitudinally, as well as roll and pitch, with the tail base of the tanker aircraft 140 as the origin.

[0030] The main controller 110, acting as the "brain" and command center, can be deployed on the refueling aircraft 140 and possesses the highest level of decision-making authority. As an information fusion center, the main controller 110 receives and processes status data from the refueling aircraft 140, the receiving aircraft 150, and the refueling boom 160. Based on the global information from the fused status data, it runs relevant algorithms to calculate the optimal coordinated control command and obtains multiple sub-control commands through the calculation of the coordinated control command. Then, through a command distributor, the generated control commands are distributed to multiple sub-controllers 130, and the execution status of the sub-control commands is monitored.

[0031] The navigation subsystem 120 is responsible for providing high-precision and real-time status awareness information to the unified main controller 110. Multiple navigation subsystems 120 include a first navigation subsystem 121 located on the refueling unit 140, a second navigation subsystem 122 located on the receiving unit 150, and a third navigation subsystem 123 located on the refueling boom 160. Each navigation subsystem 120 is equipped with sensors according to the requirements of its platform and provides sensor data to the main controller 110.

[0032] In one example, the first navigation subsystem 121 may be equipped with a Global Navigation Satellite System (GNSS) / Inertial Navigation System (INS) integrated navigation system, an atmospheric data computer, and a laser / radar rangefinder to provide sensor data such as the tanker 140's own attitude angle, ground speed, and relative position and relative velocity with the receiver 150. The second navigation subsystem 122 may be equipped with a GNSS / INS integrated navigation system, visual sensors, and cooperation markers to provide sensor data such as the receiver 150's own latitude, longitude, altitude, attitude angle, ground speed, and airspeed. The third navigation subsystem 123 may be equipped with an Inertial Measurement Unit (IMU), angle sensors, stress sensors, and visual / laser sensors to provide sensor data such as the extension length of the refueling boom 160, pitch / roll angles, and the relative position of the boom end with the receiver port of the receiver 150.

[0033] In another example, the multiple sub-controllers 130 may include a first sub-controller 131 located on the tanker aircraft 140, a second sub-controller 132 located on the receiver aircraft 150, and a third sub-controller 133 located on the refueling boom 160. The first sub-controller 131 controls the throttle and control surfaces (such as ailerons, elevators, and rudder) of the tanker aircraft 140, adjusting its flight attitude and speed according to sub-control commands to actively cooperate with the receiver aircraft 150 and create a better and more stable rendezvous environment. The second sub-controller 132 controls the throttle and control surfaces of the receiver aircraft, performing fine-tuning of its flight trajectory according to sub-control commands to accurately and smoothly complete the docking with the refueling boom 160. The third sub-controller 133 controls the refueling boom motors and servos, adjusting the boom's length, roll angle, and pitch angle according to sub-control commands to actively meet the receiver aircraft 150, widen the docking window, compensate for relative motion, and ultimately achieve insertion, docking, and locking operations.

[0034] Based on the above structure, the data flow and control flow are illustrated below. The uplink data flow consists of real-time sensing data uploaded by the three navigation subsystems 120 to the unified main controller 110. The downlink control flow consists of the unified main controller 110 issuing the calculated sub-control commands to the sub-controllers 130 of the tanker aircraft 140, receiver aircraft 150, and refueling boom 160. Traditional rigid aerial refueling systems often only control the refueling boom 160 to insert into the refueling port of the receiver aircraft 150. However, this application allows for global coordination through the main controller 110. The tanker aircraft 140 actively adjusts its attitude, the receiver aircraft 150 performs precise tracking, and the refueling boom 160 accurately docks with the refueling port of the receiver aircraft 150. With the coordination of the unified main controller 110, the success rate, safety, and efficiency of docking are greatly improved.

[0035] Understandable, Figure 1 The electronic devices in the application scenario of the autonomous cooperative control method for rigid aerial refueling, or the devices contained in the electronic devices, do not constitute a limitation on the embodiments of this application. That is, the number or type of equipment in the application scenario of the autonomous cooperative control method for rigid aerial refueling, or the number or type of devices contained in each equipment, do not affect the overall implementation of the technical solution in the embodiments of this application, and can all be considered as equivalent substitutions or derivatives of the technical solutions claimed in the embodiments of this application.

[0036] In this embodiment, the main controller 110 can be a standalone device, or a network of devices or a cluster of devices. For example, the main controller 110 described in this embodiment includes, but is not limited to, a computer, a network host, a single network device, a set of multiple network devices, or a cloud device composed of multiple devices. The cloud device consists of a large number of computers or network devices based on cloud computing.

[0037] Those skilled in the art will understand that Figure 1 The application scenarios shown are merely one application scenario corresponding to the technical solution of this application, and do not constitute a limitation on the application scenarios of the technical solution of this application. Other application scenarios may include more than one application scenario. Figure 1 The number of more or fewer electronic devices shown, or the network connectivity of electronic devices, for example Figure 1 Only one electronic device is shown in the diagram. It is understood that the scenario of the autonomous cooperative control method for rigid aerial refueling may also include one or more other electronic devices, which are not specifically limited here. The main controller 110 may also include a memory and a processor. The memory is used to store information related to the autonomous cooperative control method for rigid aerial refueling.

[0038] It should be noted that, Figure 1The application scenario of the autonomous cooperative control method for rigid aerial refueling shown is merely an example. The application scenario of the autonomous cooperative control method for rigid aerial refueling described in the embodiments of this application is to more clearly illustrate the technical solution of the embodiments of this application and does not constitute a limitation on the technical solution provided in the embodiments of this application.

[0039] Based on the application scenario of the aforementioned autonomous cooperative control method for rigid aerial refueling, an embodiment of the autonomous cooperative control method for rigid aerial refueling is proposed. A detailed description is provided below with reference to the accompanying drawings.

[0040] Figure 2 This is a flowchart illustrating an autonomous cooperative control method for rigid aerial refueling provided in an embodiment of this application. Figure 2 As shown, in one embodiment, this application provides an autonomous cooperative control method for rigid aerial refueling. This autonomous cooperative control method can execute steps 201-204 through the processor in the main controller 110, which will be described in detail below.

[0041] Step 201: In response to receiving the refueling task instruction, collect multi-source status data of the refueling machine, receiving machine and refueling boom in real time through multiple navigation subsystems.

[0042] A refueling mission command is an instruction that triggers the refueling process. It can be issued by the command center, the refueling aircraft pilot, or preset by the system. In one example, the refueling mission command may include the mission type (e.g., routine refueling or emergency refueling), the target receiver aircraft model, the expected docking time, and the target refueling quantity; it serves as a switch signal to initiate coordinated control. Multiple navigation subsystems are deployed on the refueling aircraft, receiver aircraft, and refueling boom, respectively, and can collect sensor data from each device to obtain multi-source status data. This multi-source status data is a real-time status data set covering the three-dimensional platform of the refueling aircraft, receiver aircraft, and refueling boom, and may include real-time data such as position data, attitude data, motion data, and equipment status data.

[0043] After receiving the refueling task command, the main controller acquires data collected by multiple navigation subsystems. Upon receiving the raw status data returned by these subsystems, it can fuse the data to obtain multi-source status data. This breaks down information silos, enabling the main controller to have a global grasp of the dynamics of multiple platforms and providing a complete data foundation for subsequent collaborative decision-making.

[0044] Step 202: Generate the desired docking trajectory including multiple control nodes and the corresponding safety constraints.

[0045] The desired docking trajectory is the optimal path planned by the main controller based on the task requirements, environmental parameters, and equipment performance of the refueling mission command. It satisfies the conditions of shortest distance, lowest energy consumption, and highest stability. It is a continuous curve formed by multiple control nodes connected in series. The starting point of this continuous curve can be the pre-docking position, and the ending point can be the refueling separation position. The control nodes are key points that discretize the continuous docking trajectory into multiple stages. Each node includes corresponding position, attitude, motion parameters, and time parameters, used to guide the coordinated refueling action in stages. This embodiment dynamically generates the desired docking trajectory, making it applicable to refueling needs in multiple scenarios.

[0046] The core of rigid aerial refueling is the docking of the tanker and receiver aircraft during high-speed relative motion, with the distance gradually decreasing from hundreds of meters to several meters, and the refueling boom extending from a retracted state to over ten meters. The spatial positions of the three are highly coupled. Due to factors such as the receiver aircraft's excessively high engagement speed, trajectory planning deviations may cause the distance between the two aircraft to fall below the safe distance, potentially leading to a collision. Furthermore, as a rigid structure, the refueling boom may rub against the aircraft body due to slight attitude fluctuations in the receiver aircraft, causing structural damage. In addition, the refueling boom, the tanker, and the receiver aircraft's sub-controllers all have insurmountable mechanical limits; exceeding these limits can easily lead to equipment damage. Therefore, while generating the desired docking trajectory for multiple stages, it is also necessary to generate corresponding safety constraints for the desired docking trajectory. Safety constraints, by pre-setting a minimum safe distance, reduce the risk of collision and minimize mechanical failures from the source of trajectory planning. In this way, a balance between optimal path and safe refueling process can be achieved, ensuring that the aircraft moves along the shortest path without exceeding safety boundaries.

[0047] Step 203: Based on the docking trajectory, safety constraints, and multi-source state data, calculate the cooperative control command through the preset cooperative control law, and solve the cooperative control command to obtain multiple sub-control commands, including refueling machine command, receiving machine command, and refueling boom command.

[0048] The cooperative control law is a pre-defined coupled control algorithm used to establish the motion relationship between the refueling pump, the receiving pump, and the refueling boom. The main controller performs real-time optimization based on current state data and the desired docking trajectory using the cooperative control law. For example, by setting an objective function that considers tracking accuracy, safety, comfort, and fuel economy while satisfying the dynamic constraints of the three platforms, a cooperative control command is obtained. As an example, the main controller can compare multi-source state data with the desired docking trajectory to obtain a quantified deviation. This deviation is then input into the cooperative control law, which calculates the global cooperative adjustment based on pre-defined performance indicators, forming the cooperative control command. The cooperative control command is the global control instruction output by the cooperative control law, including the cooperative requirements.

[0049] Then, the collaborative control command is calculated, and considering the execution characteristics and security constraints of each platform, it is decomposed into multiple sub-control commands, including fuel dispenser commands to control the fuel dispenser, fuel receiver commands to control the receiving tanker, and fuel pump commands to control the fuel pump. As an example, after command calculation, the feasibility and security of each sub-control command, as well as the coordination, feasibility, and security among multiple sub-control commands, can be verified to ensure that there are no conflicts between them. Conflicts refer to abnormal states that violate verification rules (such as security constraints). In this way, adjustments can be made while meeting security constraints to ensure that multiple sub-control commands are executable and do not conflict.

[0050] Step 204: Send the sub-control commands to the sub-controllers corresponding to the sub-control commands to control the refueling machine, the receiving machine and the refueling boom to work together to perform the refueling task.

[0051] Sub-controllers are deployed at the refueling pump, receiving pump, and refueling boom, respectively, and drive each device to perform refueling tasks based on sub-control commands distributed by the main controller. Upon receiving a sub-control command, the sub-controller converts it into signals recognizable by the actuators. For example, it converts the refueling pump's sub-control commands into throttle increment commands and servo deflection commands to control the pump's speed and attitude; it converts the receiving pump's sub-control commands into throttle increment commands and servo deflection commands to control the receiving pump's speed and attitude; and it converts the refueling boom's sub-control commands into deflection angle commands for each servo surface segment and formation commands for the telescopic motor to control the boom's roll, pitch, and extension.

[0052] In actual execution, there may be deviations between actual data and preset theoretical data. Therefore, in one example, the navigation subsystem can also collect current status data in real time and feed it back to the main controller. The main controller recalculates the cooperative control commands based on the deviation and dynamically adjusts the equipment actions through the sub-controllers to achieve closed-loop correction. In this way, even under environmental disturbances such as turbulence, the cooperative control commands can still be adjusted in real time, improving the accuracy and success rate of tasks in complex environments.

[0053] This application embodiment can collect multi-source status data from the tanker aircraft, receiver aircraft, and refueling boom in real time through multiple navigation subsystems, laying a data foundation for coordinated control. Then, it generates desired docking trajectories including multiple control nodes and corresponding safety constraints for each trajectory, achieving a balance between optimal path and flight safety, and dynamically adapting to multiple scenarios. Next, through coordinated control laws and sub-command calculations, it ensures the coordination of the actions of the tanker aircraft, receiver aircraft, and refueling boom, reducing docking deviations and improving docking accuracy. Simultaneously, embedding safety constraints during the calculation process reduces the possibility of control commands exceeding safe limits. Thus, through global acquisition of multi-source data, trajectory planning with safety constraints, coordinated control law calculation of coordinated control commands, and separate control of the tanker aircraft, receiver aircraft, and refueling boom to execute sub-control commands, it is possible to improve the docking accuracy and efficiency of rigid aerial refueling while ensuring its safety.

[0054] In step 201, the first attitude data of the refueling pump, as well as the first relative position and first relative velocity between the refueling pump and the receiving pump, can be acquired through the first navigation subsystem to obtain first state data. Furthermore, the second attitude data of the receiving pump can be acquired through the second navigation subsystem to obtain second state data. The third state data can also be obtained by acquiring the boom parameters of the refueling boom, as well as the second relative position and second relative velocity between the boom and the receiving port of the receiving pump, through the third navigation subsystem.

[0055] The first pose data is a set of position and attitude parameters of the refueling aircraft in three-dimensional space, which may include the position data and attitude data of the refueling aircraft. The first relative position and the first relative velocity represent the spatial positional and kinematic relationship between the refueling aircraft and the receiving aircraft, and may include longitudinal distance, lateral offset, vertical offset, longitudinal velocity difference, and lateral or vertical velocity components. The first state data is a dataset integrating the first pose data, the first relative position, and the first relative velocity, reflecting the state of the refueling aircraft and the relationship between the refueling aircraft and the receiving aircraft. It can reflect the state of the refueling aircraft itself and its relative state with the receiving aircraft.

[0056] As an example, the first navigation subsystem can obtain the absolute position of the tanker aircraft through a differential GNSS / INS integrated navigation system, and output pitch, roll, and yaw angles via a fiber optic INS to obtain the first attitude data. Simultaneously, the longitudinal, lateral, and vertical distances between the tanker aircraft and the receiver aircraft are measured by a millimeter-wave radar mounted on the tail of the tanker aircraft. Combined with the GNSS velocity data of the tanker and receiver aircraft, the relative velocity is calculated to obtain the first relative velocity. Finally, the above data is time-aligned to form the first state data, which is then output to the main controller.

[0057] The second pose data is a set of position and attitude parameters of the receiver aircraft in three-dimensional space, which may include the position of the receiver aircraft's refueling port. The second state data is state data based on the second pose data, which may include motion parameters such as the receiver aircraft's airspeed and acceleration, as well as the position information of the refueling port, to reflect the receiver aircraft's real-time state.

[0058] As an example, the second navigation subsystem can obtain the absolute position, attitude, and acceleration of the receiving aircraft through its own differential GNSS / INS integrated navigation system, and acquire airspeed through an atmospheric data computer. Then, by using reference markers near the refueling port, the position of the refueling port is transformed from the airframe coordinate system to the global coordinate system, integrated into the second pose data, and finally combined into second state data, which is then output to the main controller.

[0059] The refueling boom is mounted on the fuel dispenser, so its positional data can be obtained from the dispenser. Based on this, the boom's body parameters and its second relative position and second relative velocity relative to the fuel inlet of the receiving machine can be acquired. The boom's body parameters are its physical state parameters, which may include extension length, joint angles, and boom stress. The second relative position and second relative velocity represent the precise relative relationship between the boom tip and the fuel inlet, and may include linear distance, offset, approach velocity, and velocity components in each direction within three-dimensional space. The third state data is an integration of the boom's body parameters, second relative position, and second relative velocity, reflecting the boom's own state and the precise relative dynamics of the fuel inlet.

[0060] As an example, the third navigation subsystem can measure the telescopic length using the travel encoder of the telescopic boom, and collect pitch and roll angles using angle sensors at the joints to obtain boom parameters. It then measures the second relative position with the fuel inlet using a lidar and binocular vision camera at the boom head, calculates the second relative velocity using speed sensors between the fuel inlet and the fuel inlet, and finally integrates this into third state data, which is output to the main controller at high frequency.

[0061] The embodiments of this application can employ a multi-sensor redundancy fusion architecture to ensure continuous, stable and high-precision measurement results under any flight phase and specific conditions (such as insufficient light, low visibility, sudden changes in air pressure, etc.).

[0062] In one example, a high-precision differential GNSS receiver and an INS can be installed at the tail of the tanker aircraft and near the nose or refueling port of the receiver aircraft, respectively. Through real-time dynamic differential technology, common errors in satellite navigation are eliminated, providing centimeter-level relative position information between the tanker and receiver aircraft. The INS provides high-frequency attitude and angular velocity information and is deeply fused with the differential GNSS data, providing high-precision short-term navigation capabilities during brief GNSS signal interruptions. This combination can serve as the primary attitude source for medium- to long-range (e.g., greater than 30 meters) formation flying and the initial phase of docking.

[0063] In another example, visual marking cameras can be positioned at the tip of the refueling pump and around the refueling port of the receiving unit. For instance, a set of high-brightness, geometrically specific markers composed of infrared light-emitting diodes (LEDs) can be installed around the refueling port. At least two high-resolution, high-frame-rate infrared cameras can be installed at the tip of the refueling pump to form a stereo vision system. Alternatively, a high-contrast special pattern can be sprayed around the refueling port. A high-performance visible light camera can be installed at the tip of the refueling pump, and machine vision algorithms can be used to identify and calculate the pose of the pattern in real time. This combination can serve as the data required for extremely high-precision relative pose measurement at close range (e.g., less than or equal to 30 meters), and for fine-tuning and final insertion confirmation at the end of the refueling process.

[0064] In another example, a small 3D lidar can be installed at a suitable location at the tip of the refueling pump or the tail of the refueling machine. This lidar actively emits a laser beam to acquire high-precision 3D point cloud data of the tail of the receiving machine and the refueling port area. This combination offers extremely high ranging accuracy and is unaffected by ambient light, effectively compensating for the limitations of the vision system in strong light, low light, or cloud cover. Together with the vision measurement system, it forms a near-range primary sensor redundancy.

[0065] Additionally, millimeter-wave radar or ultra-wideband radio ranging modules can be configured as supplements and backups to the aforementioned main sensors. This provides reliable relative distance and approach rate information under extreme weather conditions (such as dense fog and heavy rain), enhancing the system's robustness under all operating conditions.

[0066] This application embodiment collects the status of the refueling machine, the receiving machine, and the refueling boom, as well as their relative relationships, through three navigation subsystems. This reduces the perception blind spots of a single platform and provides a complete data foundation for subsequent fusion.

[0067] Next, a Kalman filter is used to fuse the first state data, the second state data, and the third state data to obtain the six-degree-of-freedom relative pose estimate at the current moment.

[0068] The data processing of the navigation subsystem can be integrated into a unified main controller, handled by a dedicated core in the main controller's multi-core processor, or it can exist as a separate navigation computer. Based on this, a centralized Kalman filter or an extended Kalman filter is used to fuse multi-source data. The Kalman filter is an estimator based on a recursive algorithm. Through closed-loop processing of prediction and updating, it fuses noisy multi-source state data, outputs the optimal estimate of the system state, suppresses noise interference, and is suitable for real-time pose estimation in dynamic control refueling.

[0069] The Kalman filter receives first-state, second-state, and third-state data as inputs. Based on the system's dynamic model, the Kalman filter predicts the current state and performs weighted corrections based on observations from each sensor. The sensor confidence weights can be dynamically adjusted according to preset accuracy indicators and real-time signal-to-noise ratio. This outputs a unique, continuous, smooth, and optimally accurate six-DOF relative pose estimate, which is then transmitted to the main controller at a high speed. The six-DOF relative pose estimate represents the six-DOF relative pose of the refueling boom tip relative to the refueling port and its rate of change, indicating a high-precision state quantity of the refueling boom tip relative to the refueling port, which may include three-dimensional position and three-dimensional attitude.

[0070] In one example, the pose estimation prediction model of the fuel dispenser, receiver, and fuel pump can be used to predict the current state of the fuel pump relative to the receiving port. This pose estimation prediction model is a mathematical model that considers the kinematic coupling relationship between the fuel dispenser, receiver, and fuel pump. Its core is to describe the chain relationship between the movement of the fuel dispenser, the pose change of the fuel pump, the movement of the receiver, and the position change of the receiving port.

[0071] In one example, the main controller can retrieve historical state data, including the refueling unit's attitude change rate, the receiver's speed change, the extension and retraction speed of the refueling boom, and the joint angle change rate. Then, it calculates the coupling effects using the model's built-in kinematic equations. For example, based on the refueling unit's pitch angle change and boom length, it calculates the vertical offset of the boom tip caused by the refueling unit's attitude change. Based on the receiver's roll angle change and the refueling nozzle height, it calculates the refueling nozzle's lateral offset. Combining the boom's extension and retraction with joint deflection, it calculates the positional changes caused by the boom tip's active movement. Finally, the coupling effects are superimposed onto the previous moment's actual state to obtain the predicted state for the current moment.

[0072] Then, the first, second, and third state data are used as observations. The prediction deviation between the observed values ​​and the predicted state is calculated, and the confidence weight of the observed values ​​is dynamically adjusted according to a preset accuracy index and real-time signal-to-noise ratio. Observed values ​​refer to parameters directly related to the pose of the refueling boom relative to the refueling port, extracted from the first, second, and third state data. The prediction deviation is the difference between the observed values ​​and the parameters corresponding to the predicted state, used to quantify the inconsistency between model prediction and actual observation. In one example, the main controller extracts parameters consistent with the dimensions of the predicted state, ensuring that the units and coordinate system are consistent to obtain the observed values. Then, the deviation is calculated for each of the six degrees of freedom pose and motion parameters. For example, position deviation, attitude deviation, and velocity deviation can be calculated.

[0073] Confidence weights are coefficients that measure the reliability of each observation; a higher weight indicates a greater impact of the observation on the final fusion result. Preset accuracy indicators are accuracy thresholds obtained from sensor manufacturing or calibration, used to determine whether observations are within the normal error range. Real-time signal-to-noise ratio (SNR) is the ratio of useful signal to noise in the sensor output signal, reflecting the quality of real-time status data. The main controller obtains the real-time SNR from each navigation subsystem, compares the observations with the predicted accuracy indicators, and calculates the accuracy matching degree. Then, the SNR is normalized and weighted with the accuracy matching degree to obtain the confidence weights. The confidence weights are then normalized again to ensure that the sum of the weights for each observation is 1. In this way, abnormal data can be automatically filtered out in complex environments through weight adjustment, ensuring the stability of the fusion result and reducing the interference of low-quality data on the fusion result, thus improving data quality.

[0074] Finally, based on the predicted state, prediction bias, and confidence weights, the predicted state is corrected, and the estimated six-degree-of-freedom relative pose at the current moment is calculated. Specifically, the main controller uses a Kalman filter, taking the predicted state as a prior estimate and correcting it by combining the prediction bias and confidence weights. For example, the correction can be the product of the confidence weights and the prediction bias. The final estimate is the sum of the prior estimate and the correction. Next, the above corrections are applied to the six-degree-of-freedom parameters, such as the X, Y, and Z axes of the coordinate system, pitch angle, roll angle, and yaw angle, ensuring that the estimated value for each dimension incorporates the effective information from the corresponding observations. Finally, the six-degree-of-freedom relative pose at the current moment is output, and the current value is used as the historical input for the prediction model in the next cycle. The output six-degree-of-freedom relative pose exhibits both high accuracy and high stability, providing core data support for subsequent trajectory planning and cooperative control, and forming the foundation for achieving fully automatic high-precision docking.

[0075] In step 202, the current environmental information and performance constraints of the tanker, receiver, and refueling boom are acquired. Environmental information refers to external environmental parameters affecting aerial refueling, reflecting environmental interference and limitations during the docking process, and may include meteorological parameters and airspace restrictions. Performance constraints may include the physical performance limits and operational limitations of the tanker, receiver, and refueling boom themselves. In one example, the main controller can acquire real-time meteorological data through the weather radar and atmospheric data computer onboard the tanker, and receive airspace restriction information from the ground command center via an onboard micro-communication link. Then, it retrieves the performance parameters of the tanker, receiver, and refueling boom models involved in the current mission from pre-stored equipment parameter data, and dynamically adjusts the constraint thresholds in conjunction with real-time equipment status data. Performance constraints can be stored in the form of a mapping table, which may include name, threshold, and unit.

[0076] Then, based on the refueling task instructions, environmental information, and performance constraints, a desired docking trajectory including multiple control nodes is generated. Control nodes are target points that discretize the refueling process into key stages, with each control node corresponding to a specific task stage. Multiple control nodes can include stable formation points, pre-docking positions, docking start points, docking completion points, oil delivery completion points, and docking release points. A stable formation point is the control node where the receiver and refueling aircraft form a stable relative array, preparing for subsequent approach. A pre-docking position is the control node where the receiver aircraft approaches further below and behind the refueling aircraft, with the refueling boom slightly extended. A docking start point is the control node where the receiver aircraft arrives below and behind the refueling aircraft, and the refueling boom continues to extend, minimizing the relative positional deviation between the boom tip and the refueling port, preparing for precise docking. A docking completion point is the control node where the refueling boom tip inserts into and locks into the refueling port. An oil delivery completion point is the control node where, after reaching the target oil volume, the docking state remains stable. A docking release point is the control node where the refueling boom unlocks and retracts to a small extent, and the receiver aircraft begins to detach, preparing to leave the formation.

[0077] The desired docking trajectory is a continuous path connecting multiple control nodes, which can include the desired position, speed, and attitude of the refueling aircraft, receiving aircraft, and refueling boom at each control node. Key parameters are extracted from the refueling mission instructions to determine the trajectory's time constraints. Combined with environmental information and performance constraints, specific parameters are set for each control node, and a smooth trajectory is generated based on these control nodes. This approach divides the complex entire process into multiple clearly defined stages, reducing the complexity of trajectory planning and facilitating real-time monitoring and adjustments.

[0078] Next, using each control node as the center of the desired location, and combining performance constraints and environmental information, a safety boundary range is defined for the control node. The safety boundary range is a defined allowable fluctuation range in three-dimensional space, ensuring that each device operates within this range without collisions or exceeding limits. For example, it can include position boundaries, velocity boundaries, and attitude boundaries. Then, the safety boundary range is used as a local safety corridor for the control node. The local safety corridor is a small three-dimensional space formed by the safety boundary range of each control node, representing the safe operating area for that control node. The local safety corridor clearly defines the safety range of each control node; even if a small disturbance causes a slight deviation, subsequent steps can still be performed as long as the node remains within the local safety corridor, reducing the possibility of mission interruption due to minor deviations. Since different control nodes have different risk levels, the local safety corridor allows for differentiated setting of the safety range for each control node, achieving a balance between safety and efficiency for the desired docking trajectory.

[0079] Finally, the local safety corridors of each control node are connected by a smooth curve transition, forming a tubular three-dimensional safety corridor around the desired docking trajectory, serving as a safety constraint for the docking trajectory. The tubular three-dimensional safety corridor, formed by connecting the local safety corridors of each control node with a smooth curve, constitutes a three-dimensional pipeline around the desired docking trajectory, representing the global safety boundary of the entire docking process. Its cross-sectional size can dynamically change with the trajectory. For example, the pipeline diameter is smaller during the docking phase and larger during the disengagement phase. In one example, a bicubic interpolation algorithm can be used to smoothly connect adjacent local safety corridors, extract the boundary points of the local safety corridors of adjacent nodes, and perform interpolation calculations on these boundary points to generate continuous pipeline wall curves. The boundary parameters of the pipeline safety corridor are stored as a constraint array, which can serve as the safety constraint range for subsequent control commands. The pipeline three-dimensional safety corridor reserves a certain amount of fluctuation space for the trajectory, improving the continuity of task execution and the system's anti-interference capability.

[0080] The cooperative control commands in this embodiment can be determined using Model Predictive Control (MPC). Specifically, in step 203, the motion state evolution trend of the refueling unit, receiving unit, and refueling boom under the control commands can be predicted first based on the motion state prediction model of the coupled refueling unit, receiving unit, and refueling boom after a set time. The set time is the size of the prediction time window with rolling optimization, balancing prediction accuracy and real-time performance. The motion state evolution trend is the change law of the position, velocity, and attitude of the refueling unit, receiving unit, and refueling boom over time within the set future time. The main controller extracts the real-time positions of the refueling unit, receiving unit, and refueling boom from the six-degree-of-freedom relative pose estimation values, generates a set of candidate control commands to be verified, covering the possible range of motion. Then, based on the built-in kinematic equations, the coupling effect under the candidate control commands is calculated, and finally the predicted state of the refueling unit, receiving unit, and refueling boom is obtained.

[0081] Then, a multi-objective optimization function is constructed by balancing the weighting coefficients of the refueling aircraft, receiving aircraft, and refueling boom. Safety constraints are then incorporated as boundary conditions into this multi-objective optimization function, creating a constrained rolling optimization problem. The weighting coefficients, which balance the priorities of the refueling aircraft, receiving aircraft, and refueling boom in the objective optimization function, can be dynamically adjusted according to the mission phase. The multi-objective optimization function is a comprehensive evaluation function aimed at minimizing trajectory tracking error, minimizing energy consumption, and minimizing motion fluctuations. Safety constraints include at least safe distance constraints, flight performance constraints, and the motion limit constraints of the refueling boom. Transforming safety constraints into mathematical inequalities and using them as boundary conditions for the optimization problem, incorporated into the multi-objective optimization function, ensures the compliance of the optimized coordinated control commands. This solves the problem of traditional optimization requiring finding the optimal solution before verifying safety, which may lead to invalid solutions and improves safety redundancy.

[0082] Finally, a rolling solution is performed on the constrained rolling optimization problem based on the docking trajectory to obtain the cooperative control command after a set time. Specifically, a time window is first initialized, and then the expected state at each moment within the time window is extracted from the desired docking trajectory as the benchmark for the trajectory tracking error term of the optimization function. Next, a constrained quadratic programming algorithm is used to solve the constrained multi-objective optimization function within the time window. Then, the first command of the optimal control sequence is used as the cooperative control command for the current moment. Rolling optimization reduces the computational load, enabling devices with limited computing power to operate in real time, balancing accuracy and real-time performance.

[0083] In step 203, the execution characteristic constraints of multiple sub-controllers are obtained, and multi-body coupled dynamic constraints of the refueling pump, receiving pump, and refueling boom are extracted based on the motion state prediction model. Execution characteristic constraints represent the physical execution limits of the sub-controllers controlling the refueling pump, receiving pump, and refueling boom, reflecting the action boundaries that the actuators can perform, such as response speed constraints, output range constraints, and accuracy constraints. Multi-body coupled dynamic constraints are the constraint relationships formed by the mechanical interactions between the refueling pump, receiving pump, and refueling boom, reflecting the constraint relationships between their respective actions. The main controller can read the real-time state parameters of each sub-controller to obtain the execution characteristic constraints. Then, based on the motion state prediction model, the multi-body coupled dynamic constraints are derived through dynamic equations.

[0084] Then, based on multibody coupling dynamics constraints, the cooperative control command is solved into multiple initial sub-control commands. These initial sub-control commands can include the first sub-control command for the refueling unit, the second sub-control command for the receiving unit, and the third sub-control command for the refueling boom. As an example, the first sub-control command can include the first throttle increment command and the first control surface deflection command; the second sub-control command can include the second throttle increment command and the second control surface deflection command; and the third sub-control command can include the control surface deflection commands for each segment of the refueling boom and the travel command for the telescopic motor. Decomposing the system control command into multiple target actions according to different devices yields multiple initial sub-control commands. These initial sub-control commands are preliminary commands obtained by decomposing the cooperative control command by device and have not undergone execution feasibility verification. Therefore, it is necessary to verify the initial sub-control commands based on execution characteristic constraints, and determine the verified initial sub-control commands as sub-control commands. This reduces the possibility of commands exceeding the capabilities of the actuators, and minimizes equipment overload or hardware failures. Multibody coupling dynamics constraints can also ensure that the initial sub-control commands will not cause danger due to the mechanical interaction between devices, eliminating the problem of individual devices being compliant but the whole system being dangerous from the root, and reducing the probability of collisions.

[0085] In step 204, an initial refueling formation is formed based on multi-source state data and the desired docking trajectory, and the target parameters of the initial refueling formation are determined. The initial refueling formation is the baseline coordinated position of the tanker and receiver aircraft before entering the docking process, serving as the starting point for subsequent approach and docking, and meeting the characteristics of relative stability and sufficient safety distance. The target parameters are the quantitative standards that the initial refueling formation needs to achieve, and may include relative position parameters, relative velocity parameters, and attitude parameters. Specifically, the main controller fuses multi-source state data, calculates the actual relative position of the tanker and receiver aircraft, and then compares it with the initial formation point of the desired docking trajectory to determine the deviation between the current position and the target. If the current position deviates from the target, an adjustment command is generated to fine-tune the receiver aircraft until it reaches the target position, and the relative velocity and attitude deviations meet the target parameters. Once this is achieved, the initial refueling formation is confirmed to be formed, and the target parameters are stored as baseline data for subsequent stages. As an example, when the tanker and receiver aircraft enter the pre-docking position, system initialization can be performed according to the pilot's authorized instructions. The main controller performs a power-on self-test, loads the corresponding receiver aircraft model parameters, and begins filter initialization. Navigation data is continuously input to the main controller, generating high-precision real-time state estimates. These state estimates are then fed into a unified cooperative control law module, which generates cooperative control commands in real time and decomposes them into multiple sub-control commands to control the actions of the refueling pump, receiving pump, and refueling boom at different stages.

[0086] In this embodiment, the first set distance is a threshold distinguishing between the long-range formation phase and the mid-range docking phase. When the relative position of the tanker and the receiver aircraft is greater than or equal to the first set distance, it indicates that the tanker and receiver aircraft are at a safe and controllable long distance, and their main task is to stabilize the formation and approach slowly. Therefore, the actual parameters of the actual refueling formation of the tanker and receiver aircraft can be monitored in real time, and when the deviation between the actual parameters and the target is greater than the first set deviation, the throttle and control surfaces of both the tanker and receiver aircraft are fine-tuned. The first set deviation is the maximum allowable deviation during the long-range formation phase. During fine-tuning, the relative speed of the tanker and receiver aircraft is controlled to be slow, such as below a small set speed, to reduce attitude instability caused by rapid approach.

[0087] In this embodiment, the second set distance is a threshold distinguishing between the mid-range pre-docking phase and the close-range docking phase, typically a longitudinal distance. At this point, the refueling aircraft and the receiving aircraft are relatively close, requiring increased control precision and preparation for the refueling boom operation. Therefore, when the relative position of the refueling aircraft and the receiving aircraft is less than the first set distance but greater than or equal to the second set distance, the refueling aircraft and the receiving aircraft are controlled to approach based on sub-control commands. During the approach, actual parameters are monitored in real time. When the actual parameters deviate from the target parameters beyond the second set deviation, the throttle and control surfaces of both the refueling aircraft and the receiving aircraft are fine-tuned, and the refueling boom extension and joint deflection are controlled. The second set deviation is the maximum allowable deviation in the mid-range phase. Since the precision requirements in the approach phase are greater than in the formation phase, the second set deviation is less than the first set deviation. By introducing the refueling boom operation, the approach of the two aircraft and the pre-alignment of the refueling boom are synchronized, reducing subsequent docking time.

[0088] When the relative distance between the refueling pump and the receiving pump is detected to be less than a second preset distance, it indicates that the fine-tuning and locking stage has begun. Therefore, based on measurement data from visual sensors or lidar, the position and orientation of the refueling pump can be controlled and corrected to complete the locking and connection between the pump's tip and the receiving port of the receiving pump. Through high-precision measurement and refueling pump correction using visual sensors or lidar, the alignment deviation between the pump tip and the receiving port can be minimized, meeting the rigid docking requirements of rigid refueling systems.

[0089] In this way, through the phased control logic of initial formation establishment, long-distance coarse adjustment, medium-distance medium adjustment, and close-distance fine adjustment, a smooth transition from long-distance coordination between the two engines to fine docking of the refueling boom and the refueling port can be achieved, improving control accuracy and reducing the situation of low efficiency or insufficient accuracy caused by unified control throughout the entire process.

[0090] In this application, the main controller can also monitor the performance data of each device in the application scenario of the system control method in real time, and issue timely alarms when abnormal information is detected.

[0091] In one example, the operating status of the refueling pump and receiving pump, the boom status, and the effectiveness of each sensor can be monitored in real time. If any sensor malfunctions, the system switches to a pre-defined redundant sensor. The redundant sensor is a backup sensor configured for critical measurement tasks, employing a different principle or installation location than the primary sensor to ensure data collection continues even if a single sensor fails. For example, the primary sensor might be a LiDAR, and the redundant sensor might be a binocular vision camera. Based on the pre-defined switching logic between the primary and redundant sensors, clearly defining trigger conditions, priorities, and data fusion methods, the overall process can continue unaffected even with a faulty sensor, ensuring the stability of the docking process.

[0092] In another example, a safety disengagement procedure is triggered when any of the following conditions are met: the number of attempts to connect the refueling boom to the receiving port exceeds a set threshold, or the refueling machine, receiving machine, and refueling boom exceed safety constraints. This triggers the refueling boom to stop docking and retract, fine-tunes the attitude of the refueling machine and receiving machine to maintain a safe distance, and sends an alarm signal to the operator until the distance between the refueling machine and receiving machine exceeds the safe distance. The set threshold is the maximum number of times the refueling boom is allowed to attempt to connect to the receiving port; exceeding this threshold indicates docking failure. Safety constraints can be global safety boundaries, such as distance constraints, performance constraints, and structural constraints. When a hazardous condition is triggered, the docking process can be aborted and the refueling boom retracted, while simultaneously increasing the distance between the refueling machine and receiving machine and issuing an alarm. Thus, when docking fails or safety constraints are exceeded, the safety disengagement procedure can be automatically triggered, reducing the risk of collisions or equipment damage.

[0093] The following describes the process steps of rigid aerial refueling using a specific embodiment.

[0094] Phase 1: Task initiation and initialization.

[0095] Establish communication and enter the pre-docking position. The tanker and receiver aircraft establish secure communication via data link. Under the control of the pilot or autopilot, the receiver aircraft flies to the pre-docking position (pre-contact position) below and behind the tanker. This is the preparatory work.

[0096] Phase Two: Automated docking.

[0097] 1. Issue the "Start Docking" command. After confirmation by the pilot or higher-level system, issue a command to the unified main controller to initiate the fully automated docking process.

[0098] 2. Generate the desired trajectory. Based on the current states of the two machines, calculate and generate an optimal, smooth desired docking trajectory and a safe corridor, and send it to the collaborative control layer.

[0099] 3. Run cooperative algorithms. Multi-agent cooperative algorithms (such as MPC) calculate the optimal control commands in a rolling manner based on the desired trajectory and the real-time feedback of the three platform states.

[0100] 4. The three platforms work together to drive the execution of instructions on the three platforms.

[0101] Tanker aircraft: Make slight adjustments to throttle and control surfaces to maintain stable flight or actively create a better docking environment.

[0102] Receiving aircraft: The autopilot executes precise instructions to accurately control attitude and speed and track trajectory.

[0103] Refueling boom: The telescopic boom extends actively and adjusts its posture to "welcome" the refueling port.

[0104] Docking Result Judgment: The system determines whether the oil receiving port and the refueling rod have been successfully docked and locked. This is a key decision point in the process.

[0105] If successful: the process proceeds to the next stage.

[0106] If it fails: The system records the number of failures and determines whether it is less than the preset maximum number of attempts (e.g., 3 times).

[0107] If the limit is not exceeded: Return to step 3 to readjust the strategy and try connecting again.

[0108] If the limit has been exceeded: it is judged as a serious fault, triggers the safety mode, terminates the task and controls the two machines to safely detach to avoid danger.

[0109] Phase 3: Fueling and Stability Maintenance.

[0110] 1. Switch to "Stable Maintenance" mode. After successful docking, the control objective of the collaborative control layer switches from "Precise Docking" to "Stable Maintenance." Algorithm parameters are adjusted to suppress interference such as turbulence and maintain a stable refueling formation posture for both aircraft.

[0111] 2. Refueling begins. Once the flow stabilizes, the fuel dispenser will begin pumping fuel.

[0112] 3. Refueling Completion Detection. The system continuously monitors the fuel level until refueling is complete or an external termination command is received (such as pilot abort). This is a cyclical waiting process until the conditions are met.

[0113] Phase Four: Safe Escape and Mission Completion

[0114] 1. Issue a "Disengage" command. After refueling is completed, the collaborative control layer will automatically or after receiving an instruction to issue a disengage command.

[0115] 2. Coordinated Disengagement. The actuator controls the receiving port to unlock first, then retracts the refueling boom. Under the coordinated control of the two controllers, the receiving unit smoothly decelerates and descends, disengaging from the refueling unit and returning to a safe distance.

[0116] The autonomous collaborative control method for rigid aerial refueling in this application is fully automated, greatly reducing reliance on manual operation and alleviating the workload of pilots and operators. Secondly, it boasts high precision and a high success rate. Through multi-sensor fusion and advanced control algorithms, the docking accuracy far surpasses that of manual human operation, especially in turbulent environments, significantly improving docking success rate and efficiency. Simultaneously, it offers high safety, reducing the risk of human error. The unified control law ensures that the motion of the three aircraft remains within a safe envelope, greatly reducing the risk of collision. Furthermore, by treating the three as a whole for collaborative optimization, it achieves system-level performance optimization, rather than optimization of a single platform.

[0117] Figure 3 This is a schematic diagram of the structure of an autonomous cooperative control device for rigid aerial refueling provided in an embodiment of this application. Figure 3 As shown, the autonomous collaborative control device 300 for rigid aerial refueling may include a data acquisition module 301, a planning module 302, a calculation module 303, and a control module 304.

[0118] The data acquisition module 301 is used to respond to the received refueling task instruction by acquiring multi-source status data of the refueling machine, receiving machine and refueling boom in real time through multiple navigation subsystems.

[0119] The planning module 302 is used to generate the desired docking trajectory, which includes multiple control nodes, and the safety constraints corresponding to each desired docking trajectory.

[0120] The calculation module 303 is used to calculate the cooperative control command based on the docking trajectory, safety constraints and multi-source state data through a preset cooperative control law, and to solve the cooperative control command to obtain multiple sub-control commands, including refueling machine command, receiving machine command and refueling boom command.

[0121] The control module 304 is used to send sub-control commands to the sub-controllers corresponding to the sub-control commands, so as to control the fuel dispenser, the receiving machine and the fuel pump to work together to perform the refueling task.

[0122] The acquisition module 301, planning module 302, calculation module 303 and control module 304 can be used to execute steps 201-204 in the embodiments of the above-mentioned autonomous cooperative control method for rigid aerial refueling. For the specific implementation of these modules and more details, please refer to the corresponding method section, which will not be elaborated here.

[0123] This application also provides a computer-readable storage medium storing a program that can be loaded by a processor and executed by any of the autonomous cooperative control methods for hard-core aerial refueling in this application.

[0124] Since the instructions stored in the autonomous cooperative control device and computer-readable storage medium for rigid aerial refueling can execute the steps in any of the autonomous cooperative control methods for rigid aerial refueling provided in the embodiments of this application, the beneficial effects that any of the autonomous cooperative control methods for rigid aerial refueling provided in the embodiments of this application can achieve can be realized. For details, please refer to the previous embodiments, which will not be repeated here.

[0125] Those skilled in the art will understand that all or part of the functions of the various methods in the above embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, which may include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to achieve the above functions. For example, the program can be stored in the memory of a device, and when the program in the memory is executed by the processor, all or part of the above functions can be achieved. In addition, when all or part of the functions in the above embodiments are implemented by computer programs, the program can also be stored in a server, another computer, disk, optical disk, flash drive, or external hard drive, etc., and can be downloaded or copied to the memory of a local device, or the system of the local device can be updated. When the program in the memory is executed by the processor, all or part of the functions in the above embodiments can be achieved.

[0126] The above examples illustrate this application only to aid understanding and are not intended to limit its scope. Those skilled in the art to which this application pertains can make various simple deductions, modifications, or substitutions based on the ideas presented.

Claims

1. An autonomous cooperative control method for rigid aerial refueling, characterized in that, The autonomous collaborative control method is applied to a main controller, which communicates with multiple navigation subsystems and multiple sub-controllers, and the multiple navigation subsystems and multiple sub-controllers communicate with a refueling machine, a receiving machine, and a refueling boom, respectively. The autonomous collaborative control method includes: In response to receiving a refueling task instruction, the system collects multi-source status data of the refueling machine, the receiving machine, and the refueling boom in real time through multiple navigation subsystems. Generate a desired docking trajectory that includes multiple control nodes and a safety constraint corresponding to each desired docking trajectory; Based on the motion state prediction model of the fuel dispenser, the receiving machine, and the fuel pump, the evolution trend of the motion state of the fuel dispenser, the receiving machine, and the fuel pump under the action of control commands is predicted after a set time. A multi-objective optimization function is constructed by balancing the weighting coefficients of the refueling aircraft, the receiving aircraft, and the refueling boom. The safety constraints are then incorporated as boundary conditions into the multi-objective optimization function to construct a constrained rolling optimization problem. The safety constraints include at least safety distance constraints, flight performance constraints, and motion limit constraints of the refueling boom. Based on the docking trajectory, the constrained rolling optimization problem is solved in a rolling manner to obtain the cooperative control command after the set time. The execution characteristic constraints of multiple sub-controllers are obtained, and the multi-body coupling dynamic constraints of the refueling machine, the receiving machine and the refueling boom are extracted based on the motion state prediction model. Based on the multibody coupling dynamics constraints, the cooperative control command is solved into multiple initial sub-control commands, which include the first sub-control command of the refueling machine, the second sub-control command of the receiving machine, and the third sub-control command of the refueling boom. The initial sub-control instruction is verified based on the execution characteristic constraints, and the initial sub-control instruction that passes the verification is determined as the sub-control instruction. The sub-control commands are sent to the sub-controllers corresponding to the sub-control commands respectively, so as to control the fuel dispenser, the receiving machine and the fuel pump to work together to perform the refueling task; The first sub-control command includes a first throttle increment command and a first control surface deflection command; the second sub-control command includes a second throttle increment command and a second control surface deflection command; and the third sub-control command includes control surface deflection commands for each segment of the fuel filler lever and travel commands for the telescopic motor.

2. The autonomous cooperative control method according to claim 1, characterized in that, The navigation subsystem includes a first navigation subsystem installed on the refueling machine, a second navigation subsystem installed on the receiving machine, and a third navigation subsystem installed on the refueling boom. The real-time acquisition of multi-source status data from the refueling machine, the receiving machine, and the refueling boom through these multiple navigation subsystems includes: The first navigation subsystem collects the first attitude data of the refueling machine, as well as the first relative position and first relative velocity between the refueling machine and the receiving machine, to obtain the first state data. The second navigation subsystem collects the second pose data of the receiver aircraft to obtain the second state data; The third navigation subsystem collects the rod parameters of the refueling boom, as well as the second relative position and second relative velocity between the refueling boom and the oil receiving port of the receiving machine, to obtain third state data; A Kalman filter is used to fuse the first state data, the second state data, and the third state data to obtain the six-degree-of-freedom relative pose estimate at the current moment.

3. The autonomous cooperative control method according to claim 2, characterized in that, The process of fusing the first state data, the second state data, and the third state data using a Kalman filter to obtain the six-degree-of-freedom relative pose estimate at the current moment includes: Based on the pose estimation and prediction model coupled with the refueling pump, the receiving pump and the refueling boom, the predicted state of the refueling boom relative to the receiving port at the current moment is predicted. The pose parameters of the refueling rod relative to the refueling port are extracted from the first state data, the second state data and the third state data as observation values. The deviation of the pose of the six degrees of freedom is calculated one by one to obtain the prediction deviation between the observation value and the prediction state. The confidence weight of the observation value is dynamically adjusted according to the preset accuracy index and the real-time signal-to-noise ratio. The prediction deviation includes position deviation and attitude deviation. Based on the predicted state, the predicted deviation, and the confidence weight, the predicted state is corrected, and the estimated value of the six degrees of freedom relative pose at the current moment is calculated.

4. The autonomous cooperative control method according to claim 1, characterized in that, The generation includes a desired docking trajectory for multiple control nodes and corresponding safety constraints, including: Obtain the current environmental information and the performance constraints of the fuel dispenser, the receiving machine, and the fuel pump; Based on the refueling task instruction, the environmental information, and the performance constraints, a desired docking trajectory is generated, including multiple control nodes. The multiple control nodes include a stable formation point, a pre-docking position, a docking start point, a docking completion point, an oil delivery completion point, and a docking release point. The desired docking trajectory includes the desired position, desired speed, and desired attitude of the refueling machine, the receiving machine, and the refueling boom at each control node. Taking each control node as the center of the desired location, and combining the performance constraints and environmental information, a safety boundary range is set for the control node as a local safety corridor for the control node; Each control node's local safety corridor is connected by a smooth curve transition to form a tubular three-dimensional safety corridor surrounding the desired docking trajectory, serving as a safety constraint on the docking trajectory.

5. The autonomous cooperative control method according to claim 1, characterized in that, The step of sending the sub-control commands to the corresponding sub-controllers to control the refueling machine, the receiving machine, and the refueling boom to coordinately perform the refueling task includes: An initial refueling formation is formed based on the multi-source state data and the desired docking trajectory, and the target parameters of the initial refueling formation are determined. When the relative position between the refueling aircraft and the receiving aircraft is greater than or equal to a first set distance, the actual parameters of the actual refueling formation of the refueling aircraft and the receiving aircraft are monitored in real time, and when the deviation between the actual parameters and the target is greater than the first set deviation, the throttle and control surfaces of the refueling aircraft and the receiving aircraft are finely adjusted. When the relative position between the refueling pump and the receiving pump is less than the first set distance but greater than or equal to the second set distance, the refueling pump is controlled to approach the receiving pump based on the sub-control command. When the actual parameter and the target parameter are greater than the second set deviation, the throttle and control surface of the refueling pump and the throttle and control surface of the receiving pump are finely adjusted, and the refueling boom is extended and the joint is deflected. The second set deviation is less than the first set deviation. When the relative distance between the refueling pump and the receiving pump is detected to be less than a second preset distance, the position and posture of the refueling pump are controlled and corrected based on the measurement data of the vision sensor or lidar, so as to complete the insertion and locking between the head end of the refueling pump and the receiving port of the receiving pump.

6. The autonomous cooperative control method according to claim 1, characterized in that, The autonomous collaborative control method also includes: Real-time monitoring of the operating status of the fuel dispenser and the receiving machine, the status of the fuel pump, and the effectiveness of each sensor; If any of the sensors malfunctions, the system switches to a preset redundant sensor. If the number of attempts to connect the refueling boom to the receiving port of the receiving machine exceeds a set threshold, and / or the refueling machine, the receiving machine, and the refueling boom exceed the safety constraints, a safety disengagement procedure is triggered. The refueling boom is controlled to stop docking and retract, the attitudes of the refueling machine and the receiving machine are finely adjusted to maintain a safe distance, and an alarm signal is sent to the operator until the distance between the refueling machine and the receiving machine exceeds the safe distance.

7. An autonomous cooperative control device for rigid aerial refueling, characterized in that, The autonomous collaborative control device is applied to a main controller, which communicates with multiple navigation subsystems and multiple sub-controllers, and the multiple navigation subsystems and multiple sub-controllers communicate with a refueling machine, a receiving machine, and a refueling boom, respectively. The autonomous collaborative control device includes: The data acquisition module is used to collect multi-source status data of the fuel dispenser, the receiving machine, and the fuel pump in real time through multiple navigation subsystems in response to receiving a refueling task instruction. The planning module is used to generate a desired docking trajectory including multiple control nodes and a safety constraint corresponding to each desired docking trajectory; The calculation module is used to predict the evolution trend of the motion state of the refueling aircraft, the receiving aircraft, and the refueling boom under control commands after a set time, based on the coupled motion state prediction model of the refueling aircraft, the receiving aircraft, and the refueling boom; construct a multi-objective optimization function by balancing the weighting coefficients of the refueling aircraft, the receiving aircraft, and the refueling boom, and embed the safety constraints as boundary conditions into the multi-objective optimization function to construct a constrained rolling optimization problem, wherein the safety constraints include at least safety distance constraints, flight performance constraints, and motion limit constraints of the refueling boom; perform rolling solution on the constrained rolling optimization problem based on the docking trajectory to obtain the cooperative control command after the set time; obtain the execution characteristic constraints of multiple sub-controllers, and based on the motion state prediction... The test model extracts the multi-body coupled dynamic constraints of the refueling machine, the receiving machine, and the refueling boom. Based on the multi-body coupled dynamic constraints, the cooperative control command is calculated into multiple initial sub-control commands. The initial sub-control commands include a first sub-control command for the refueling machine, a second sub-control command for the receiving machine, and a third sub-control command for the refueling boom. The initial sub-control commands are verified based on the execution characteristic constraints. The initial sub-control commands that pass the verification are determined as the sub-control commands. The first sub-control command includes a first throttle increment command and a first control surface deflection command. The second sub-control command includes a second throttle increment command and a second control surface deflection command. The third sub-control command includes control surface deflection commands for each segment of the refueling boom and stroke commands for the telescopic motor. The control module is used to send the sub-control commands to the sub-controllers corresponding to the sub-control commands, so as to control the refueling machine, the receiving machine and the refueling boom to work together to perform the refueling task.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a program that can be loaded by a processor and executed as described in any one of claims 1 to 6 for autonomous cooperative control of rigid aerial refueling.

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