Flapping-rotor composite flight control system and control method

Abstract

The invention discloses a flapping-rotor composite flight control system, and belongs to the field of unmanned aerial vehicle control, and the system comprises a vehicle body supporting member which is connected with a four-flapping-wing driving mechanism and a double-rotor driving mechanism; the four-flapping-wing driving mechanism and the double-rotor-wing driving mechanism are provided with a control unit; the control unit comprises a sensor module and a central controller; the sensor module comprises an encoder, an inertial measurement sensor and a barometer; and the flapping wing motor and the two rotor motors are controlled by the central controller. The invention further discloses a flapping-rotor composite flight control method, and a closed-loop control system and a control method suitable for the flapping-rotor composite platform are constructed through disturbance modeling, parameter identification, compensation generation, power distribution, energy consumption optimization, mode management, fault-tolerant control and the like by taking a flapping-wing motion phase as a reference. Periodic disturbance caused by flapping wing movement can be effectively restrained, and meanwhile self-adaptive switching and energy consumption optimization of flight modes are achieved.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) control, and more specifically to a control system and control method for a flapping-wing and rotor hybrid aircraft. Background Technology

[0002] Ornithoptering aircraft, due to their biomimetic characteristics, possess advantages such as low noise, high maneuverability, high aerodynamic efficiency, and strong stealth capabilities, and have shown broad application prospects in fields such as military reconnaissance and environmental monitoring. However, the unsteady aerodynamic characteristics generated by flapping motion are complex, especially under low Reynolds number conditions, where the lift, thrust, and yaw moment of the flapping wing exhibit significant nonlinear and periodic disturbances, making modeling and control extremely challenging. Existing ornithoptering aircraft have shortcomings in attitude stabilization and heading control: on the one hand, relying solely on flapping motion to provide lift and control force is difficult to maintain stability in complex environments, easily resulting in undesirable yaw and roll; on the other hand, traditional control methods are mostly designed for fixed-wing or rotary-wing aircraft and are difficult to apply directly to ornithoptering aircraft, leading to limitations in flight performance and control accuracy. Rotary-wing aircraft have mature control methods for hovering and attitude control, but they suffer from high energy consumption and low cruise efficiency.

[0003] Therefore, how to effectively combine flapping wings and rotors, using flapping wings to provide the main lift and forward propulsion, and rotors to be responsible for attitude stabilization and yaw compensation, is a technical problem that urgently needs to be solved in order to balance energy efficiency and stability. Summary of the Invention

[0004] In view of at least one of the above-mentioned technical problems, this invention provides a flapping rotor hybrid flight control system and method. Using the flapping rotor motion phase as a reference, through disturbance modeling, parameter identification, compensation generation, power allocation, energy consumption optimization, mode management, and fault-tolerant control, a closed-loop control system and method suitable for flapping rotor hybrid platforms are constructed. This system can effectively suppress periodic disturbances caused by flapping rotor motion, while simultaneously achieving adaptive switching of flight modes and energy consumption optimization. The specific technical solution is as follows: A flapping rotor composite flight control system includes a fuselage support component. The upper part of the fuselage support component is connected to a four-flapping rotor drive mechanism, which includes a vertically arranged flapping rotor motor and four centrally symmetrically distributed flapping rotor assemblies with the rotor axis of the flapping rotor motor as the central axis. The lower part of the fuselage support component is equipped with a dual-rotor drive mechanism, which includes two centrally symmetrically distributed rotor assemblies with the rotor axis of the flapping rotor motor as the central axis. Each rotor assembly includes a rotor motor, and the rotor motor drives the rotor body. The four-flapping rotor drive mechanism and the dual-rotor drive mechanism are equipped with control units. The control units include a sensor module and a central controller. The sensor module includes an encoder, an inertial measurement sensor, and a barometer. The central controller controls the flapping rotor motor and the two rotor motors.

[0005] In some embodiments of this disclosure, the fuselage support is an inverted T-shaped support, with a device compartment vertically connected to the upper part of the fuselage support, and the control unit is placed inside the device compartment; the flapping wing assembly includes a flapping wing body, the flapping wing body includes a support rod, and the device compartment is provided with a clearance window for the support rod to extend out.

[0006] In some embodiments of this disclosure, the flapping wing motor is equipped with an active bevel gear, which drives four flapping wing assemblies; the flapping wing assembly also includes a passive bevel gear that meshes with the active bevel gear, the passive bevel gear drives the flapping wing wheel assembly, and the flapping wing wheel assembly drives the flapping wing body.

[0007] In some embodiments of this disclosure, the flapping wing wheel assembly includes a drive gear meshing with a passive bevel gear and a push rod wheel connected to the flapping wing body; the spokes of the drive gear are eccentrically connected to an eccentric push rod, and the other end of the eccentric push rod is eccentrically connected to the spokes of the push rod wheel.

[0008] A flapping rotor composite flight control method is provided for controlling any of the above-mentioned flapping rotor composite flight control systems.

[0009] In some embodiments of this disclosure, the flapping rotor compound flight control method mainly includes the following steps: S1 collects flight status data of the flapping rotor composite flight control system through the sensor module; S2, a harmonic model of yaw moment is constructed based on the flapping wing phase, wherein the yaw moment is composed of DC component, fundamental frequency component and harmonic frequency component; S3 uses an adaptive identification algorithm to estimate the amplitude and phase of the yaw moment in real time; S4, Generate the differential compensation thrust of the dual rotors based on the estimation results. The differential compensation includes DC trim, fundamental frequency feedforward and bandpass feedback. S5, combining the differential compensation thrust with attitude control requirements, and configuring the rotational speeds of the two rotor motors respectively through the central controller.

[0010] In some embodiments of this disclosure, energy consumption optimization control is also performed during cruise mode.

[0011] In some embodiments of this disclosure, the energy consumption optimization control employs an extreme value search algorithm, using energy consumption per unit mileage (P / V) as an indicator, and adjusts the flapping frequency and amplitude through periodic perturbations.

[0012] In some embodiments of this disclosure, the adaptive identification algorithm in step S3 employs either the constrained least mean square algorithm or the recursive least squares algorithm.

[0013] In some embodiments of this disclosure, the calculation of the differential compensation thrust in step S4 is performed analytically using the following formula 3: <Formula 3>; in, For DC balancing, f w For flapping frequency, Let b be the fundamental frequency phase, δ be the rotor torque arm, and r be the phase compensation of the actuation / measurement stage. BP (t) represents the yaw rate r(t) after passing through a point f w The bandpass filter output centered on K bp K bd This represents the proportional / differential gain of the bandpass channel.

[0014] Compared with existing technologies, the above-mentioned flapping rotor composite flight control system and control method have the following advantages: 1. This invention achieves both efficient propulsion and stable hovering through the coordinated design of flapping wings and rotors; by adopting a differential compensation strategy that combines DC trim, fundamental frequency feedforward and bandpass feedback, it can effectively suppress the periodic disturbances caused by flapping wing motion and improve the stability of flight attitude. 2. This invention introduces an extreme value optimization algorithm in cruise mode, using the energy consumption per unit distance J=P / V as the optimization objective, to optimize the flapping frequency f. w With the amplitude of the flapping A w By performing perturbation and gradient estimation and dynamically adjusting control parameters, the system achieves optimal overall energy efficiency, extends flight endurance, and improves energy efficiency during cruise. The system also has the ability to switch between multiple modes such as hovering, cruise, and turning, adapting to complex mission environments. Attached Figure Description

[0015] Figure 1 This is a schematic block diagram of the flapping rotor composite flight control system in this invention; Figure 2 This is a schematic diagram of the flapping rotor composite flight control system in this invention; Figure 3This is a schematic diagram of the flapping wing motor, flapping wing assembly, and active bevel gear meshing structure in this invention; Figure 4 This is a schematic diagram of the flapping wing body structure in this invention; Figure 5 This is a structural schematic diagram showing the engagement positions of the four passive bevel gears and the active bevel gear in this invention; Figure 6 This is a flowchart illustrating the flapping rotor composite flight control method of the present invention; The following are the labels in the diagram: 1. Airframe support component; 2. Four-wing flapping drive mechanism; 21. Flapping wing motor; 22. Flapping wing assembly; 221. Support rod; 222. Passive bevel gear; 223. Flapping wing wheel assembly; 2231. Drive gear; 2232. Push rod wheel; 2233. Eccentric push rod; 224. Flapping wing shaft frame; 23. Active bevel gear; 3. Dual rotor drive mechanism; 31. Rotor assembly; 311. Rotor motor; 312. Rotor body; 4. Component compartment. Detailed Implementation

[0016] To better understand the purpose, structure, and function of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit this application. The terms "comprising" and "equipped with," and any variations thereof, are open-ended and intended to cover non-exclusive inclusion. It should be understood that directional terms such as "upper" and "lower" indicate directional or positional relationships based on the directional or positional relationships of the aircraft during flight, and are only for ease of description, not indicating or implying that the device or unit referred to must have a specific directional orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0017] As shown in the attached diagram. Figures 1 to 6 As shown, a flapping rotor composite flight control system is designed, including a fuselage support 1. In this embodiment, the fuselage support 1 is an inverted T-shaped support body, which can be a lightweight sheet metal. The upper part of the fuselage support 1 is vertically connected to a device compartment 4 along the coaxial line to keep the center of gravity on the central axis as much as possible. The control unit is placed inside the device compartment 4. The flapping wing assembly 22 includes a flapping wing body, which includes a support rod 221. The device compartment 4 is provided with a clearance window for the support rod 221 to extend out, which can avoid mechanical interference when the flapping wing body moves.

[0018] The upper part of the body support 1 is connected to the four flapping wing drive mechanism 2. The four flapping wing drive mechanism 2 includes a vertically arranged flapping wing motor 21, and four flapping wing components 22 arranged in a centrally symmetrical manner with the rotor axis of the flapping wing motor 21 as the central axis. The flapping wing motor 21 is equipped with an active bevel gear 23, which drives the four flapping wing components 22. The flapping wing component 22 also includes a passive bevel gear 222 that meshes with the active bevel gear 23. The meshing passive bevel gear 222 drives the flapping wing wheel assembly 223, which in turn drives the flapping wing body.

[0019] The flapping wing wheel assembly 223 includes a drive gear 2231 that meshes with a passive bevel gear 222 and a push rod wheel 2232 that is connected to the flapping wing body; the spokes of the drive gear 2231 are eccentrically connected to an eccentric push rod 2233, and the other end of the eccentric push rod 2233 is eccentrically connected to the spokes of the push rod wheel 2232.

[0020] like Figure 3 As shown, the passive bevel gear 222 is a stepped bevel gear. The bevel end of the passive bevel gear 222 meshes with the driving bevel gear 23, and the other end of the passive bevel gear 222 is a spur gear, which meshes with the driving gear 2231. The outer end of the gear shaft of the passive bevel gear 222 is fixedly connected to the inner wall of the device compartment 4, and the connection method can be a pin connection. The outer end of the gear shaft of the driving gear 2231 is also fixedly connected to the inner wall of the device compartment 4, and the connection method can also be a pin connection.

[0021] like Figure 4 As shown, the flapping wing body is movably connected to the inner wall of the device compartment 4 via the flapping wing shaft bracket 224. The clearance window is a vertically set elongated hole. When the push rod wheel 2232 rotates, the flapping wing body realizes the flapping wing action.

[0022] The lower part of the fuselage support 1 is equipped with a dual-rotor drive mechanism 3. The dual-rotor drive mechanism 3 includes two rotor assemblies 31 arranged symmetrically around the rotor axis of the flapping wing motor 21. The rotor assembly 31 includes a rotor motor 311, which is connected to the rotor body 312. The four-flapping wing drive mechanism 2 and the dual-rotor drive mechanism 3 are equipped with a control unit. The control unit includes a sensor module and a central controller. The sensor module includes an encoder, an inertial measurement sensor, and a barometer. The central controller controls the flapping wing motor 21 and the two rotor motors 311.

[0023] A method for controlling the aforementioned flapping rotor composite flight control system is also disclosed. This method operates on a central controller and is designed for UAV systems with an "upper four flapping wing drive mechanism + lower symmetrical dual rotor mechanism." It employs a hierarchical system of "phase reference, harmonic identification, differential compensation, force / torque distribution, energy consumption extremum optimization, and mode management / fault tolerance." Through disturbance modeling, parameter identification, compensation generation, power distribution, energy consumption optimization, and mode management and fault-tolerant control, a closed-loop control method suitable for flapping rotor composite platforms is constructed. The main steps include: S1 collects flight status data of the flapping rotor composite flight control system through the sensor module; The flapping wing beat frequency and phase information are obtained through an encoder, and the attitude angular velocity and acceleration are obtained through an inertial measurement unit. Specifically, the flapping wing angle signal is processed through a phase-locked loop or a central mode generator to obtain the real-time flapping wing frequency and phase, providing a reference benchmark for subsequent disturbance modeling. The machine system is: x forward, y right, z down. The flapping wing motion is approximately a periodic vibration, which can be analyzed using the following equation 1: <Formula 1>; Where, θ w (t) is the flapping angle, A w f is the amplitude of the flapping motion. w For flapping wing frequency, The initial phase is t, and the time is in seconds (s).

[0024] To obtain an accurate phase reference in control, this invention utilizes a phase-locked loop (PLL) to input the actual encoder output θ. m (t) is filtered and tracked to obtain the estimated phase. With frequency : ; in, , , To estimate the phase and angular frequency, The mechanistic phase measured by the encoder. , For PLL gain (>0) For phase winding to The operator.

[0025] S2, a harmonic model of yaw moment is constructed based on the flapping wing phase, wherein the yaw moment is composed of DC component, fundamental frequency component and harmonic frequency component; The aerodynamic forces caused by flapping wing motion manifest as periodic disturbances in the yaw direction, mainly consisting of DC components, fundamental frequency components, and harmonic components. A torque model is established, which can be analyzed using the following equation 2: <Formula 2>; Where, τ z Let τ represent the yaw moment, τ0 represent the average yaw moment, and τ1 and τ2 represent the amplitudes of the fundamental frequency and second harmonic components, respectively. , This corresponds to the phase.

[0026] S3 uses an adaptive identification algorithm to estimate the amplitude and phase of the yaw moment in real time; The adaptive identification algorithm employs either the constrained least mean square algorithm or the recursive least squares algorithm.

[0027] To estimate the disturbance torque parameters in real time, this invention employs the recursive least squares (RLS) algorithm: ; Input the regression vector; ; The update law is: ; ; ; Where λ is the forgetting factor, P(t) is the covariance matrix used to control the convergence rate, and K(t) is the gain vector, which determines the contribution of the current sample to the parameter update.

[0028] S4, Generate the differential compensation thrust of the dual rotors based on the estimation results. The differential compensation includes DC trim, fundamental frequency feedforward and bandpass feedback. Based on the identification results, the differential compensation thrust for the left and right rotors is generated, and the differential compensation thrust is analyzed using the following equation 3: <Formula 3>; in, For DC balancing, f w For flapping frequency, Let b be the fundamental frequency phase, δ be the rotor torque arm, and r be the phase compensation of the actuation / measurement stage. BP (t) represents the yaw rate, and r(t) represents the distance traveled after f. w The bandpass filter output centered on K bp K bd This represents the proportional / differential gain of the bandpass channel.

[0029] The thrust distribution between the left and right rotors is analyzed using the following equation 4: <Formula 4>; Among them, T L For the thrust of the left rotor, T R The thrust T of the right rotorbase The basic thrust ΔT required to maintain hovering is the differential compensation obtained from Equation 3.

[0030] S5, combining the differential compensation thrust with attitude control requirements, and configuring the rotational speed of the two rotor motors 311 respectively through the central controller; To avoid power overload and improve energy efficiency, a power-constrained optimization model is established and analyzed using the following equation (5): <Formula 5>; The constraints are: ; in, B is the control variable; P is the energy efficiency matrix; r P f These are the power consumption of the rotor and flapping wing, respectively. (Expected resultant force / resultant moment), W is the weighted matrix. This is the power penalty coefficient.

[0031] Further optimization is possible by including energy consumption optimization control during cruise mode.

[0032] The energy consumption optimization control adopts an extreme value search algorithm, using energy consumption per unit mileage P / V as the index, and adjusts the flapping frequency and amplitude through periodic perturbations.

[0033] In cruise mode, to reduce energy consumption per unit distance J=P / V, an extreme value optimization algorithm is used, which is analyzed as follows: Equation 6: <Formula 6>; Where P is the total electric power, V is the ground speed or air speed, and k is the ground speed or air speed. f k A To find the optimal step length, , This is for online estimation using the perturbation method.

[0034] Furthermore, this method can also achieve mode switching based on flight speed V and mission status using a hysteresis threshold: ; Among them, V h2c V c2h These are the upper and lower thresholds for hysteresis, and the source of V (airspeed sensor / visual odometry / VIO fusion).

[0035] Fault detection is determined by monitoring motor current, yaw residual and temperature anomalies. When a subsystem fails, the system enters conservative mode and another subsystem takes over the main control tasks.

[0036] It is understood that the above description is only for illustrating specific implementation methods of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the scope of disclosure of this application.

Claims

1. A compound flight control system for a rotary wing aircraft comprising a body support member (1) characterised in that: The upper part of the body support (1) is connected with a four-flapping-wing driving mechanism (2), which includes a vertically arranged flapping-wing motor (21), and four flapping-wing assemblies (22) are symmetrically arranged around the rotor axis of the flapping-wing motor (21); the lower part of the body support (1) is provided with a double-rotor driving mechanism (3), which includes two rotor assemblies (31) symmetrically arranged around the rotor axis of the flapping-wing motor (21), and the rotor assembly (31) includes a rotor motor (311) and a rotor body (312); the four-flapping-wing driving mechanism (2) and the double-rotor driving mechanism (3) are provided with a control unit; the control unit includes a sensor module and a central controller; the sensor module includes an encoder, an inertial measurement sensor and a barometer; the flapping-wing motor (21) and the two rotor motors (311) are controlled by the central controller.

2. The compound flight control system of claim 1, wherein, The body support (1) is an inverted T-shaped support, and the upper part of the body support (1) is vertically connected with a device bin (4), and the control unit is arranged in the device bin (4); the flapping-wing assembly (22) includes a flapping-wing body, and the flapping-wing body includes a support rod (221), and the device bin (4) is provided with a position-avoiding window for the support rod (221) to extend out.

3. The compound flight control system of claim 2, wherein, The flapping-wing motor (21) is provided with a driving bevel gear (23), and the four flapping-wing assemblies (22) are connected through the driving bevel gear (23); the flapping-wing assembly (22) further includes a driven bevel gear (222) engaged with the driving bevel gear (23), the driven bevel gear (222) is connected with a flapping-wing wheel set (223), and the flapping-wing wheel set (223) is connected with the flapping-wing body.

4. The compound flight control system of claim 3, wherein, The flapping-wing wheel set (223) includes a driving gear (2231) engaged with the driven bevel gear (222) and a push rod wheel (2232) connected with the flapping-wing body; the spoke of the driving gear (2231) is eccentrically connected with an eccentric push rod (2233), and the other end of the eccentric push rod (2233) is eccentrically connected with the spoke of the push rod wheel (2232).

5. A compound flight control method for a multicopter, characterized by, A flapping-rotor composite flight control system according to any one of claims 1-4.

6. The compound flight control method of claim 5, wherein, The method comprises the following steps: S1, collecting flight state data of the flapping-rotor composite flight control system through the sensor module; S2, constructing a yaw moment harmonic model based on the flapping-wing phase, wherein the yaw moment is composed of a direct current component, a fundamental frequency component and a multiple frequency component; S3, using an adaptive identification algorithm to estimate the amplitude and phase of the yaw moment in real time; S4, generating a differential compensation thrust for the double rotors according to the estimation result, wherein the differential compensation includes direct current trimming, fundamental frequency feedforward and bandpass feedback; S5, combining the differential compensation thrust with the attitude control demand, and configuring the rotation speed of the two rotor motors (311) through the central controller.

7. The compound flight control method of claim 6, wherein, The method further comprises performing energy consumption optimization control in a cruising state.

8. The compound flight control method of claim 7, wherein, The energy consumption optimization control adopts an extremum seeking algorithm, takes the unit mileage energy consumption P / V as an index, and adjusts the flapping-wing frequency and amplitude through periodic perturbation.

9. The compound flight control method of claim 6, wherein, In step S3, the adaptive identification algorithm adopts a constrained least mean square algorithm or a recursive least square algorithm.

10. The compound flight control method of claim 6, wherein, In step S4, the calculation of the differential compensation thrust is resolved by the following equation 3: < Formula 3 >; in, For DC balancing, f w For flapping frequency, Let b be the fundamental frequency phase, δ be the rotor torque arm, and r be the phase compensation of the actuation / measurement stage. BP (t) represents the yaw rate. After f w The bandpass filter output centered on K bp K bd This represents the proportional / differential gain of the bandpass channel.

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