Ornithopter formation flight energy saving method and device

Abstract

The application provides a flapping-wing aircraft formation flight energy-saving method and device, the method comprising: inputting geometric parameters of a required control flapping-wing aircraft; calculating a required relative flight distance to be kept when the flapping-wing aircraft flies in formation according to the input geometric parameters of the flapping-wing aircraft; determining a lead aircraft and wingman according to an evaluation function selection to form a formation flight; detecting a residual power of a current lead aircraft, and replacing the lead aircraft when the current lead aircraft consumes energy exceeding a set value; and continuously replacing the lead aircraft before the end of a flight task, and selecting a new lead aircraft according to the evaluation function. The method can keep the energy distribution of the flapping-wing aircraft group balanced when the flapping-wing aircraft flies in formation, effectively saves the energy of the flapping-wing aircraft, and improves the endurance of the flapping-wing aircraft.

Description

Technical Field

[0001] This invention belongs to the field of ornithopter formation flight technology, specifically, it relates to an energy-saving method and device for ornithopter formation flight that mimics the pelican. Background Technology

[0002] An ornithopter is a biomimetic robot that achieves flight by flapping its wings. The difference between an ornithopter and a fixed-wing or quadcopter is that the ornithopter generates lift through low-frequency flapping of its flexible wings, while fixed-wing and quadcopters primarily achieve flight through the reaction force of the jet stream generated by the high-frequency rotation of its blades. The flapping frequency of an ornithopter is typically between a few hertz and tens of hertz, and its wings are flexible, a significant difference from the rigid wings of fixed-wing drones.

[0003] The flapping power of the two wings and the power to adjust the direction and angle of the tail fin are provided by electric motors and servos, respectively. The wing drive motors reduce speed and increase torque through gear reducers, and the rotation of the motors is converted into the reciprocating motion of the wings through a linkage mechanism, thereby generating lift. The two servos on the tail fin are symmetrically arranged. By the difference in the output angle of the two servos, the tail linkage mechanism drives the tail fin to sway left and right or up and down, thereby changing the flight direction and altitude of the flapping fin.

[0004] Currently, most existing technologies for fixed-wing, quadcopter, and ornithopter aircraft focus on reducing the energy consumption of individual robots. However, few address the energy consumption reduction of groups of robots during formation flight, especially ornithopter aircraft, where energy-saving flight methods are even rarer. Therefore, this paper proposes an energy-saving method for ornithopter formation flight, focusing on energy conservation in such applications. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an energy-saving method and device for ornithopter formation flight that features simple algorithm design and long endurance.

[0006] To solve the above problems, the technical solution of the present invention is as follows:

[0007] An energy-saving method for ornithopter formation flying includes the following steps:

[0008] Input the geometric parameters of the flapping-wing aircraft to be controlled;

[0009] Based on the input geometric parameters of the ornithopter, calculate the relative flight distance that the ornithopter formations need to maintain.

[0010] The lead aircraft and wingman are selected based on the evaluation function to form a flight formation.

[0011] Detect the remaining battery power of the current lead aircraft. When the energy consumed by the current lead aircraft exceeds the set value, the formation will switch lead aircraft.

[0012] The lead aircraft is continuously changed before the end of the flight mission, and a new lead aircraft is selected based on the evaluation function.

[0013] Preferably, the step of inputting the geometric parameters of the flapping-wing aircraft to be controlled specifically includes: the user inputting the geometric parameters of the flapping-wing aircraft to be controlled, including wingspan and aspect ratio.

[0014] Preferably, the step of calculating the relative flight distance that the ornithopter aircraft need to maintain during formation flying based on the input geometric parameters of the ornithopter specifically includes:

[0015] Based on the input geometric parameters of the ornithopter, the relative flight distance required for formation flight is calculated by solving the Biot-Savert equation using the Lagrange multiplier method.

[0016] Based on the relative flight distance, each ornithopter calculates its target position in the formation, and each individual ornithopter reaches its position in the formation to perform formation flight.

[0017] Preferably, the step of calculating the relative flight distance required for formation flying based on the input geometric parameters of the ornithopter and solving the Biot-Savert equation using the Lagrange multiplier method specifically includes: calculating the relative position of the wingman to the lead aircraft, taking into account the impact of the relative distance between the lead and wingmen on the increase in drag and lift, wherein the formula for calculating the increase in lift is:

[0018]

[0019] In the formula, ΔC L C represents the increase in lift. L It is the lift coefficient, a W The rate of change of the wing's lift curve is represented by μ, which is a constant related to eddies. R y' represents the aspect ratio, z' represents the lateral relative distance, and z' represents the vertical relative distance.

[0020] The formula for calculating the increase in resistance is:

[0021]

[0022] The net increase in lift is obtained from the formulas for calculating drag and lift increment: ΔC L -ΔC D The relative flight distance that the formation flight needs to maintain is calculated based on the Biot-Savert law.

[0023] Preferably, in the step of calculating the target position of each ornithopter in the formation based on the relative flight distance, and each ornithopter reaching its own position in the formation for formation flight, an optimal interactive collision avoidance algorithm is used to enable each ornithopter to reach its target position in the formation without collision and to perform formation flight.

[0024] Preferably, in the step of selecting and determining the lead aircraft and wingman based on the evaluation function to form a formation flight, the evaluation function is: Where rate is the percentage of remaining battery power, N is the number of times the wingman has acted as the lead aircraft, and nums is the number of ornithopters.

[0025] Preferably, the step of detecting the remaining battery power of the current lead aircraft and replacing the lead aircraft in the formation when the energy consumed by the current lead aircraft exceeds a set value specifically includes: after setting the energy consumed by the current lead aircraft to exceed 30% of the total battery energy, the formation replaces the lead aircraft. The replacement process is as follows: the original lead aircraft obtains the wingman number of the new lead aircraft, the new lead aircraft obtains the lead aircraft number of the original lead aircraft, and the original lead aircraft and wingman exchange positions and become the new wingman and lead aircraft.

[0026] Preferably, the step of continuously changing the lead aircraft before the end of the flight mission and selecting a new lead aircraft based on the evaluation function specifically includes: when it is necessary to change the lead aircraft, each wingman will execute the evaluation function, broadcast its own value, and receive the values ​​broadcast by other ornithopters. The wingman with the highest value becomes the new lead aircraft, and the N value of this new lead aircraft is incremented by 1.

[0027] Furthermore, the present invention also provides an energy-saving device for ornithopter formation flight, the device including a processor and a memory for storing executable instructions of the processor, the processor being configured to perform the energy-saving method for ornithopter formation flight as described above by executing the executable instructions.

[0028] Compared with the prior art, the energy-saving method for ornithopter formation flight of the present invention can maintain a balanced energy distribution among ornithopter groups during formation flight. Furthermore, since the ornithopter formation makes full use of the net lift generated by the vortex of the lead aircraft, it can effectively save energy of the ornithopter and improve the endurance of the ornithopter. Attached Figure Description

[0029] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0030] Figure 1 This is a flowchart of an energy-saving method for formation flight of ornithopter aircraft provided in an embodiment of the present invention;

[0031] Figure 2 A flowchart for determining the target position in a formation of ornithopter aircraft provided in an embodiment of the present invention;

[0032] Figure 3a , 3b Figures 3c and 3d are schematic diagrams of replacing the lead engine provided in the embodiments of the present invention. Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0034] Specifically, Figure 1 The flowchart of the energy-saving method for formation flight of ornithopter aircraft provided in the embodiments of the present invention is as follows: Figure 1 As shown, the method includes the following steps:

[0035] S1: Input the geometric parameters of the flapping-wing aircraft to be controlled;

[0036] Specifically, the user inputs the geometric parameters of the ornithopter to be controlled, mainly the wingspan b and the aspect ratio A. R All other parameters involved in the Biot-Savert law have default values, and users can also input the relative safety distance in the x-direction to replace the default values.

[0037] S2: Based on the input geometric parameters of the ornithopter, calculate the relative flight distance that the ornithopter needs to maintain when flying in formation;

[0038] Based on the input geometric parameters of the ornithopter, the relative flight distance required for formation flight is calculated by solving the Biot-Savert equation using the Lagrange multiplier method.

[0039] The onboard computer of the ornithopter calculates the relative flight distance required for formation flight by solving the Biot-Savert equation using the Lagrange multiplier method, and obtains the relative distance between the wingman and the lead aircraft. This relative distance is the constraint condition for the wingman to obtain the maximum net lift from the vortex generated by the wing flapping of the lead aircraft.

[0040] Specifically, according to the Biot-Savert law, the impact of the relative distance between the lead and wingman aircraft on the increase in drag and lift needs to be considered holistically. The formula for calculating the increase in lift simplifies to:

[0041]

[0042] Where, ΔC L C represents the increase in lift. L It is the lift coefficient, a WThe rate of change of the wing's lift curve is represented by μ, which is a constant related to eddies. R Let y' represent the aspect ratio, y' represent the lateral relative distance, and z' represent the vertical relative distance. The formula for calculating the drag increment is simplified to:

[0043]

[0044] Based on the formulas for drag and lift increment, the net lift increment, ΔC, can be obtained. L -ΔC D At this point, the condition for maximizing the net lift increment can be obtained using the Lagrange multiplier method, namely the values ​​of the relative distances y' and z' in the y and z directions. By calculating the relative positions, the target positions y and z in each flapping-wing formation can be obtained. It can also be seen from the above formula that the relative distance x' in the x direction has no effect on lift; therefore, it is only necessary to maintain a safe distance between the wingman and the lead aircraft in the x direction.

[0045] like Figure 2 As shown, the process by which the ornithopter determines its relative position and calculates its target position within the formation in this embodiment is as follows: The wingman's onboard controller reads its relevant parameters. Based on these parameters and default parameters, it solves the Biot-Savert equation using the Lagrange multiplier method to calculate the conditions required for maximizing the net lift provided by the lead aircraft's vortex, i.e., the wingman's relative positions y' and z' relative to the lead aircraft. Since the relative distance x' in the x-direction has no effect on the lift and drag caused by the vortex, the controller's control strategy for the relative distance in the x-direction is to ensure a safe distance between the wingman and the lead aircraft. If the user inputs the relative distance x' in the x-direction in advance, the controller will control the relative distance between the wingman and the lead aircraft to x' while ensuring safety. Finally, the controller calculates the target positions x, y, and z of the ornithopter within the formation using the relative distance.

[0046] Secondly, based on the relative flight distance, each ornithopter calculates its target position in the formation, and each individual ornithopter reaches its position in the formation to carry out formation flight.

[0047] Specifically, the ornithopter's controller obtains its position within the formation. The next step is to reach that position without collisions. This is achieved using a readily available and mature dynamic path planning algorithm, specifically an optimal interactive collision avoidance algorithm. Its core principle is to establish a feasible velocity domain in each iteration and select a velocity within that domain to avoid collisions in the next iteration. This algorithm is executed when all ornithopters have reached their positions within the formation, thus ensuring that each ornithopter reaches its target position without collisions.

[0048] S3: Select and determine the lead aircraft and wingman based on the evaluation function to form a formation flight;

[0049] Specifically, a lead aircraft is selected based on an evaluation function. Once the lead aircraft is confirmed, all other ornithopters become wingmen. At this point, the number and target position of each ornithopter within the formation are also determined. They then proceed to their target positions within the formation using the optimal interactive collision avoidance method, forming a V-formation. In this V-formation, the wingmen benefit from the lift generated by the vortices created by the lead aircraft's flapping wings, significantly conserving energy and achieving energy efficiency. Conversely, the lead aircraft lacks the vortices generated by the flapping wings in front of it and therefore cannot benefit from the lift generated by the vortices, resulting in increased energy consumption.

[0050] An evaluation function is designed to select the lead aircraft. Throughout the flight mission, after a predetermined energy consumption period, a new lead aircraft is continuously selected using the evaluation function to maintain a balanced energy distribution across the group. The evaluation function is as follows: Where rate is the percentage of remaining battery power, N is the number of times the wingman has acted as the lead aircraft, and nums is the number of ornithopters.

[0051] S4: Detect the remaining power of the current lead aircraft. When the current lead aircraft consumes more energy than the set value, the formation will switch to a new lead aircraft.

[0052] Specifically, because the wingman gains the largest net energy increment from the vortex generated by the lead aircraft's flapping motion, and the lead aircraft lacks the vortex generated by the flapping motion of other flapping aircraft, it cannot obtain the lift boost from the vortex, resulting in increased energy consumption. This leads to the lead aircraft consuming more energy for the same flight distance. To enable the formation to fly longer distances, it is necessary to continuously replace the lead aircraft. Specifically, after the lead aircraft at the V-shaped nose flies for a period of time, its energy consumption reaches the set value for replacement. At this point, the lead aircraft needs to be replaced, that is, the current lead aircraft exchanges positions with the wingman at the rear of the V-shape within the formation. Typically, the formation replaces the lead aircraft when its energy consumption exceeds 30% of the total battery energy. Similarly, at this time, each flapping aircraft broadcasts its remaining battery power value calculated based on the aforementioned evaluation function. The flapping aircraft with the largest remaining battery power value becomes the lead aircraft, and the original lead aircraft becomes the wingman. Likewise, the optimal interactive collision avoidance algorithm is still used when replacing the lead aircraft.

[0053] The logic behind changing the lead aircraft is to change the target position within the formation of the ornithopter. Specifically, the original lead aircraft acquires the wingman number of the new lead aircraft, and the new lead aircraft acquires the lead aircraft number of the original lead aircraft. The original lead and wingman switch roles, becoming the new wingman and lead aircraft. By changing the numbers and roles in this way, the formation adjustments caused by changing the lead aircraft are minimized as much as possible.

[0054] For simplicity, the lead aircraft is changed by altering its serial number. That is, if the lead aircraft is numbered 1, and the new lead aircraft is numbered 2 (still the wingman), when the lead aircraft changes, the lead aircraft inherits the wingman's serial number, and the wingman inherits the lead aircraft's serial number. The advantage of this approach is that the amount of data that needs to be changed for the entire formation is minimal; only two ornithopters need to exchange positions, thus avoiding the energy loss caused by large-scale position changes and achieving energy conservation. Specifically... Figure 3a , 3b As shown in 3c and 3d, Figure 3a For the current formation of ornithopter aircraft, Figure 3a When the formation changes for the first time, such as Figure 3b As shown, ornithopters No. 2 and No. 4 accelerate, while ornithopters No. 1, 3, and 5 decelerate. Simultaneously, the lateral distance between the corresponding ornithopters remains unchanged. The formation change is achieved solely by altering the distance between the ornithopters through acceleration and deceleration. Figure 3c As shown, Unit 2 becomes the new lead unit. This formation change minimizes the extra distance the group moves during the formation change, making it the most energy-efficient formation replacement scheme. The final new formation is as follows: Figure 3d As shown.

[0055] S5: Continuously change the lead aircraft before the end of the flight mission, and select a new lead aircraft based on the evaluation function.

[0056] Specifically, for longer flights, simply changing the lead aircraft once cannot fully cover the energy consumption averaging throughout the entire flight. Therefore, it is necessary to continuously change the lead aircraft before the end of the flight mission, selecting the lead aircraft based on the aforementioned evaluation function, so that the entire formation is always in the positive gain of vortex-induced lift, thereby saving energy. That is, for every set energy value consumed by the current lead aircraft, the formation changes the lead aircraft once, and this process is repeated continuously, thereby achieving energy saving and balanced energy distribution for the entire formation.

[0057] Changing the lead aircraft requires certain evaluation criteria. The more battery power a wingman has and the fewer times it has served as the lead aircraft, the greater its likelihood of becoming the lead aircraft. When a lead aircraft replacement is needed, each wingman will execute an evaluation function: Where rate is the percentage of remaining battery power, N is the number of times the wingman has served as the lead aircraft, and nums is the number of ornithopters. The wingman broadcasts its own value and receives values ​​broadcast by other ornithopters. The wingman with the highest value becomes the new lead aircraft, and the N value of this new lead aircraft is incremented by 1. This process is repeated until the mission ends.

[0058] In summary, this invention proposes an energy-saving method for ornithopter formation flight. This method can maintain a balanced energy distribution among ornithopter groups during formation flight. Furthermore, because the ornithopter formation fully utilizes the net lift generated by the vortex of the lead aircraft, it can effectively save energy and improve the endurance of the ornithopter.

[0059] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for energy-saving formation flight of ornithopter aircraft, characterized in that, The method includes the following steps: Input the geometric parameters of the flapping-wing aircraft to be controlled; Based on the input geometric parameters of the ornithopter, the relative flight distance that the ornithopter formations need to maintain is calculated, specifically including: Based on the input geometric parameters of the ornithopter, the relative flight distance required for formation flight is calculated by solving the Biot-Savert equation using the Lagrange multiplier method. Based on the relative flight distance, each ornithopter calculates its target position in the formation, and each ornithopter reaches its position in the formation and then flies in formation. The lead aircraft and wingman are selected based on an evaluation function to form a flight formation. The evaluation function is: Where rate is the percentage of remaining battery power, N is the number of times the wingman has acted as the lead aircraft, and nums is the number of ornithopters; Detect the remaining battery power of the current lead aircraft. When the current lead aircraft consumes more energy than the set value, the formation will switch lead aircraft. The lead aircraft is continuously changed before the end of the flight mission, and a new lead aircraft is selected based on the evaluation function.

2. The energy-saving method for ornithopter formation flight according to claim 1, characterized in that, The step of inputting the geometric parameters of the flapping-wing aircraft to be controlled specifically includes: the user inputting the geometric parameters of the flapping-wing aircraft to be controlled, including wingspan and aspect ratio.

3. The energy-saving method for ornithopter formation flight according to claim 1, characterized in that, The step of calculating the relative flight distance required for formation flying based on the input geometric parameters of the ornithopter and solving the Biot-Savert equation using the Lagrange multiplier method specifically includes: calculating the relative position of the wingman to the lead aircraft, which requires comprehensive consideration of the impact of the relative distance between the lead and wingmen on the increase in drag and lift. The formula for calculating the increase in lift is as follows: In the formula, Indicates the increase in lift. It is the lift coefficient. This represents the rate of change of the wing's lift curve. It is a constant term related to eddies. Indicates the aspect ratio. Indicates the relative horizontal distance. Indicates relative height; The formula for calculating the increase in resistance is: The net increase in lift is obtained using the formulas for calculating drag and lift increment: - The relative flight distance that the formation flight needs to maintain is calculated based on the Biot-Savert law.

4. The energy-saving method for ornithopter formation flight according to claim 1, characterized in that, In the step of calculating the target position of each ornithopter in the formation based on the relative flight distance, and each ornithopter reaching its own position in the formation for formation flight, the optimal interactive collision avoidance algorithm is used to enable each ornithopter to reach its target position in the formation without collision and to perform formation flight.

5. The energy-saving method for ornithopter formation flight according to claim 1, characterized in that, The process of detecting the remaining battery power of the current lead aircraft and replacing the lead aircraft in the formation when the energy consumed by the current lead aircraft exceeds a set value specifically includes: after setting the energy consumed by the current lead aircraft to exceed 30% of the total battery energy, the formation replaces the lead aircraft. The replacement process is as follows: the original lead aircraft obtains the wingman number of the new lead aircraft, the new lead aircraft obtains the lead aircraft number of the original lead aircraft, and the original lead aircraft and wingman switch positions and become the new wingman and lead aircraft.

6. The energy-saving method for formation flight of ornithopter aircraft according to claim 1, characterized in that, The steps of continuously changing the lead aircraft before the end of the flight mission and selecting a new lead aircraft based on the evaluation function specifically include: when it is necessary to change the lead aircraft, each wingman will execute the evaluation function, broadcast its own value, and receive the values ​​broadcast by other ornithopters. The wingman with the highest value becomes the new lead aircraft, and the N value of this new lead aircraft is incremented by 1.

7. An energy-saving device for ornithopter formation flight, characterized in that, The device includes a processor and a memory for storing executable instructions of the processor, the processor being configured to perform the energy-saving method for ornithopter formation flight as described in any one of claims 1 to 6 by executing the executable instructions.

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