Multi-actuator tail seat type unmanned aerial vehicle hovering vector attitude control method

Abstract

The present application relates to the technical field of unmanned aerial vehicle control, and specifically provides a multi-actuator tail stand type unmanned aerial vehicle hovering vector attitude control method, comprising the following steps: S1: establishing a moment model and a rotation model of a tail stand type unmanned aerial vehicle under a body coordinate system, and introducing a deflection angle of a motor in the moment model; S2: respectively designing adaptive controllers of a roll channel, a pitch channel and a yaw channel of the unmanned aerial vehicle based on the moment model and the rotation model; and respectively calculating roll moment, pitch moment and yaw moment of the unmanned aerial vehicle according to the roll channel adaptive controller, the pitch channel adaptive controller and the yaw channel adaptive controller; S3: the roll moment, the pitch moment and the yaw moment are used to calculate the output of the four motors through control distribution. In the present application, the control quality of the roll channel, the pitch channel and the yaw channel of the unmanned aerial vehicle is high during vertical descent, the problem of loss of control and disturbance is solved, and the safety hazard of the unmanned aerial vehicle is reduced.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) control technology, and specifically provides a hovering vector attitude control method for a multi-actuator tail-mounted UAV. Background Technology

[0002] Vertical takeoff and landing (VTOL) drones combine the advantages of fixed-wing and rotary-wing aircraft, enabling rapid takeoff and landing in confined areas, and possessing hovering and cruise capabilities. VTOL drones are mainly classified into compound, tilt-pivot, and tail-seat types. Compared to compound or tilt-pivot VTOL drones, tail-seat VTOL drones can switch flight modes without complex conversion mechanisms, resulting in lighter weights and wider applications. However, the aerodynamic characteristics of tail-seat VTOL drones present significant challenges to attitude controller design, especially in achieving precise attitude control during the hovering phase.

[0003] During the vertical takeoff and landing of a tail-sitting VTOL UAV, the airflow speed over the control surfaces is low due to the low vertical speed, resulting in low control surface effectiveness. Especially during vertical descent, when the descent speed is too fast, the airflow on the control surfaces reverses, and the slipstream generated by the propeller is no longer effective for the control surfaces. Therefore, the control surfaces have poor stability in controlling the yaw attitude of the aircraft. Yaw stability can only be achieved during slow descent and in light wind conditions. During rapid descent or in strong wind conditions, the yaw attitude of the UAV may become uncontrollable.

[0004] In the prior art, the following patents relate to attitude control methods for drones or aircraft: 1. The invention patent with application number "201711268895.7" and patent name "Dual Fuzzy Control System and Method for Longitudinal Attitude of Tail-mounted UAV" includes two fuzzy controllers. Fuzzy controller I is designed with the concept of variable domain fractal, and fuzzy controller II takes flight speed and system error as input, so that the parameters of the PID controller not only change with the change of system error, but also solves the oscillation problem of pitch attitude loop caused by the influence of flight speed change.

[0005] 2. The invention patent application with application number "201810945463.3" and patent title "Robust Attitude Control Method, Device and Electronic Equipment for Unmanned Aerial Vehicles" obtains the current state data and current desired attitude angle of the unmanned aerial vehicle, and determines the attitude control input of the unmanned aerial vehicle based on the current state data, current desired attitude angle and pre-designed robust attitude controller. Its robust attitude controller includes a feedforward controller, an H controller and a robust compensator designed based on an attitude error model represented by quaternions; and controls the flight attitude of the unmanned aerial vehicle according to the attitude control input.

[0006] None of the above solutions have a clear disturbance compensation mechanism, and they rely solely on the robustness of the controller itself to overcome disturbances; moreover, they do not effectively control the motor deflection angle, and when the drone is hovering, especially during the descent, it is very easy to lose control and experience disturbances, resulting in weak yaw control.

[0007] In summary, designing a hovering vector attitude control method for multi-actuator tail-mounted UAVs that can solve the problems of loss of control and disturbance during vertical descent and reduce the safety hazards of UAVs is an urgent problem to be solved. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a hovering vector attitude control method for a multi-actuator tail-mounted UAV, which can enhance the control torque of the tail-mounted VTOL UAV during the vertical take-off and landing phase, avoid loss of control and disturbance during the vertical descent of the UAV, and improve the safety performance of the UAV.

[0009] To achieve the above objectives, the present invention proposes the following technical solution: a hovering vector attitude control method for a multi-actuator tail-mounted unmanned aerial vehicle, comprising the following steps: S1: Establish the tail-sitting UAV in the body coordinate system Torque model and rotation model under; S2: Based on the torque model and rotation model, adaptive controllers for the roll, pitch, and yaw channels of the UAV are designed respectively; and the roll torque, pitch torque, and yaw torque of the UAV are calculated according to the adaptive controllers for the roll, pitch, and yaw channels respectively. S3: Rolling torque, pitching torque, and yaw torque are calculated and distributed across the four motors via control.

[0010] Preferably, the torque model of the UAV in S1 is established using formula (1.1): (1.1) in, For motor thrust, This represents the deflection angle of the motor. From the center of mass of the motor to the aircraft Distance between planes, These are the rolling moment, pitching moment, and yaw moment, respectively.

[0011] Preferably, the rotation model of the UAV in S1 is established using formula (1.2): (1.2) in, For rotational inertia, These are the airframe roll rate, pitch rate, and yaw rate, respectively.

[0012] Preferably, the design of the adaptive controller for the roll path of the UAV in S2 includes the following steps: S21a: Establish the spatial equations for the state of the open-loop system in the roll channel: (1.3a) in, This refers to the mismatch uncertainty, specifically the coupling interference between the roll, pitch, and yaw channels. Φ This refers to the roll angle; Once the roll channel reaches the desired closed-loop pole, equation (1.3a) becomes: (1.4a) Among them, through The desired closed-loop poles are configured as follows: ; (1.4a) can be abbreviated as: (1.5a) in, , , To control interference within the channel; S22a, Establish the state estimator using equation (1.6a): (1.6a) in, For design parameters; up This is the control input to the system, namely the rolling torque; S23a, the adaptive law of the roll channel is shown in equation (1.7a): (1.7a) in, They are respectively The estimate, For the controller's call cycle, This is the estimation error correction term; S24a, Roll Channel Control Law, i.e., Roll Torque: (1.8a) in, , , For the desired roll angle, These are design parameters.

[0013] Preferably, the design of the pitch channel adaptive controller for the UAV in S2 includes the following steps: S21b: Establish the spatial equations for the open-loop system state of the pitch channel: (1.3b) in, This refers to the mismatch uncertainty, specifically the coupling interference between the roll, pitch, and yaw channels. Φ The pitch angle; Once the pitch channel reaches the desired closed-loop poles, equation (1.3b) becomes: (1.4b) Among them, through The desired closed-loop poles are configured as follows: ; (1.4b) can be abbreviated as: (1.5b) in, , , To control interference within the channel; S22b, Establish the state estimator using equation (1.6b): (1.6b) in, For design parameters; uq This is the control input for the system, namely the pitch torque; S23b, the pitch channel adaptive law is shown in equation (1.7b): (1.7b) in, They are respectively The estimate, For the controller's call cycle, To estimate the error, This is the estimation error correction term; S24b, Pitch Channel Control Law, i.e., Pitch Moment: (1.8b) in, , , For the desired pitch angle, These are design parameters.

[0014] Preferably, the design of the yaw channel adaptive controller for the UAV in S2 includes the following steps: S21c, Calculate the desired airframe yaw rate: For the yaw loop, the desired airframe yaw rate is: (1.9) in, For the desired pitch angle, These are the desired pitch Euler rate and yaw Euler rate, respectively. Obtained by mapping from the aircraft's yaw stick; The calculation formula is as follows: (1.10) in, For design parameters, The difference between the expected pitch angles of adjacent cycles. The maximum permissible pitch Euler angle acceleration; S22c. Establish the state-space equations for the yaw channel: (1.11) Incorporating the desired closed-loop pole dynamics, equation (1.11) becomes: (1.12) in, The location of the closed-loop poles in the left half-plane of the complex plane; Equation (1.12) can be simplified as follows: (1.13) in, , , ur This is the control input to the system, namely the yaw moment; S23c, Establish the state estimator using equation (1.14): (1.14) in, To prevent interference with the control channel The estimate, For design parameters; S24c, the yaw channel adaptive law is shown in equation (1.15): (1.15) in, For the controller's call cycle, This is the estimation error correction term; S25c, the yaw channel control law, i.e., the yaw moment is: (1.16) in, For design parameters, .

[0015] Preferably, when calculating the output of each motor in the UAV using roll torque, pitch torque, and yaw torque in S3, equation (1.17) should be satisfied: (1.17) in, This represents the thrust output in the vertical direction, which is a pre-designed, known parameter. This represents the deflection angle of the motor.

[0016] Preferably, in equation (1.17) Error in yaw body angular rate | |Related, From equation (1.18), we get: (1.18) in, These are design parameters, and are directly proportional to the speed of motor deflection.

[0017] Compared with the prior art, the present invention can achieve the following beneficial effects: The present invention introduces the deflection angle of the motor into the torque model of the UAV. Simultaneously, adaptive controllers for the roll, pitch, and yaw channels were designed. The output of each motor in the UAV was calculated using the obtained roll, pitch, and yaw torques. The control of the UAV was then distributed based on the motor outputs. This enhanced the control torque of the tail-mounted VTOL UAV during the vertical takeoff and landing phase, improved the control quality of the roll, pitch, and yaw channels, especially the yaw channel, and prevented loss of control and disturbances during the vertical descent of the UAV, thus avoiding potential safety hazards. Attached Figure Description

[0018] Figure 1 This is a coordinate diagram of a vector tail-mounted vertical takeoff and landing unmanned aerial vehicle (UAV) according to an embodiment of the present invention.

[0019] Figure 2 This is a flowchart of attitude control for a vector tail-mounted vertical takeoff and landing unmanned aerial vehicle (UAV) according to an embodiment of the present invention.

[0020] Figure 3 This is a curve comparing the control effects of a vector tail-mounted vertical takeoff and landing UAV provided according to an embodiment of the present invention with those of a UAV that relies solely on yaw rate control via control surfaces.

[0021] Figure 1 In the diagram, 1 is the propeller, 2 is the motor, 3 is the vectoring mechanism, 4 is the aileron, 5 is the wing, and 6 is the landing gear.

[0022] Figure 2In the diagram, point A is the roll channel adaptive controller, point B is the pitch channel adaptive controller, and point C is the yaw channel adaptive controller. Detailed Implementation

[0023] The appendix will be referenced below. Figure 1-3 Embodiments of the present invention are described below. In the following description, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 1-3 The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute a limitation thereof.

[0025] A hovering vector attitude control method for a multi-actuator tail-mounted unmanned aerial vehicle (UAV) includes the following steps: S1: Establishing a tail-mounted UAV in Figure 1 The machine coordinate system shown The torque and rotation models are as follows: First, establish the torque model of the UAV in S1 using formula (1.1): (1.1) in, For motor thrust, This represents the deflection angle of the motor. From the center of mass of the motor to the aircraft Distance between planes, These are the rolling moment, pitching moment, and yaw moment, respectively.

[0026] Then, the rotation model of the UAV in S1 is established using formula (1.2): (1.2) in, For rotational inertia, These are the airframe roll rate, pitch rate, and yaw rate, respectively.

[0027] S2: Based on the torque model and rotation model, adaptive controllers for the roll, pitch, and yaw channels of the UAV are designed respectively; and the roll torque, pitch torque, and yaw torque of the UAV are calculated according to the adaptive controllers for the roll, pitch, and yaw channels respectively.

[0028] The design of an adaptive controller for the roll path of a UAV includes the following steps: S21a: Establish the spatial equations for the state of the open-loop system in the roll channel: (1.3a) in, This refers to the mismatch uncertainty, specifically the coupling interference between the roll, pitch, and yaw channels. Φ This refers to the roll angle; Once the roll channel reaches the desired closed-loop pole, equation (1.3a) becomes: (1.4a) Among them, through The desired closed-loop poles are configured as follows: ; (1.4a) can be abbreviated as: (1.5a) in, , , To control interference within the channel.

[0029] S22a, Establish the state estimator using equation (1.6a): (1.6a) in, For design parameters, it is possible to increase damping while accelerating the estimation of errors. The convergence speed; up This is the control input to the system, namely the rolling torque.

[0030] S23a, the adaptive law of the roll channel is shown in equation (1.7a): (1.7a) in, They are respectively The estimate, For the controller's call cycle, This is the estimation error correction term.

[0031] S24a, Roll Channel Control Law, i.e., Roll Torque: (1.8a) in, , , For the desired roll angle, These are design parameters.

[0032] Designing an adaptive pitch channel controller for a UAV includes the following steps: S21b: Establish the spatial equations for the open-loop system state of the pitch channel: (1.3b) in, This refers to the mismatch uncertainty, specifically the coupling interference between the roll, pitch, and yaw channels. Φ The pitch angle; Once the pitch channel reaches the desired closed-loop poles, equation (1.3b) becomes: (1.4b) Among them, through The desired closed-loop poles are configured as follows: ; (1.4b) can be abbreviated as: (1.5b) in, , , To control interference within the channel; S22b, Establish the state estimator using equation (1.6b): (1.6b) in, For design parameters; uq This is the control input for the system, namely the pitch torque; S23b, the pitch channel adaptive law is shown in equation (1.7b): (1.7b) in, They are respectively The estimate, For the controller's call cycle, To estimate the error, This is the estimation error correction term; S24b, Pitch Channel Control Law, i.e., Pitch Moment: (1.8b) in, , , For the desired pitch angle, These are design parameters.

[0033] The design of an adaptive yaw channel controller for a UAV includes the following steps: S21c, Calculate the desired airframe yaw rate: For the yaw loop, the desired airframe yaw rate is: (1.9) in, For the desired pitch angle, These are the desired pitch Euler rate and yaw Euler rate, respectively. Obtained by mapping from the aircraft's yaw stick; The calculation formula is as follows: (1.10) in, For design parameters, The difference between the expected pitch angles of adjacent cycles. The maximum allowable pitch Euler angle acceleration.

[0034] S22c. Establish the state-space equations for the yaw channel: (1.11) Incorporating the desired closed-loop pole dynamics, equation (1.11) becomes: (1.12) in, The location of the closed-loop poles in the left half-plane of the complex plane; Equation (1.12) can be simplified as follows: (1.13) in, , , ur This is the control input to the system, namely the yaw torque.

[0035] S23c, Establish the state estimator using equation (1.14): (1.14) in, To prevent interference with the control channel The estimate, These are design parameters.

[0036] S24c, the yaw channel adaptive law is shown in equation (1.15): (1.15) in, For the controller's call cycle, This is the estimation error correction term.

[0038] S25c, the yaw channel control law, i.e., the yaw moment is: (1.16) in, For design parameters, .

[0039] S3: Roll torque, pitch torque, and yaw torque are calculated and distributed across the four motors via control. Equation (1.17) should be satisfied: (1.17) in, This represents the thrust output in the vertical direction, which is a pre-designed, known parameter. This represents the deflection angle of the motor.

[0040] in, Error in yaw body angular rate | |Related, From equation (1.18), we get: (1.18) in, These are design parameters, and are directly proportional to the speed of motor deflection.

[0041] Figure 3 The simulation diagram shows a comparison of the control performance of a UAV with motor vector control and a UAV relying solely on yaw rate control via control surfaces during vertical descent. Line 1 represents the desired yaw rate, line 3 represents the actual yaw rate with motor vector control, and line 2 represents the actual yaw rate with control surface control. The tracking curves for the desired yaw rate clearly show, as shown by line 3, that the control quality of the yaw channel with motor vector control is significantly better than that relying solely on control surface yaw rate control.

[0042] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0043] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A hovering vector attitude control method for a multi-actuator tail-mounted unmanned aerial vehicle (UAV), characterized in that, Includes the following steps: S1: Establish the tail-sitting UAV in the body coordinate system Torque model and rotation model under; S2: Based on the torque model and rotation model, adaptive controllers for the roll, pitch, and yaw channels of the UAV are designed respectively; and the roll torque, pitch torque, and yaw torque of the UAV are calculated according to the adaptive controllers for the roll, pitch, and yaw channels respectively. The design of the adaptive controller for the roll path of the UAV in S2 includes the following steps: S21a: Establish the spatial equations for the state of the open-loop system in the roll channel: （1.3a） in, This refers to the mismatch uncertainty, specifically the coupling interference between the roll, pitch, and yaw channels. Φ For roll angle, Indicates rolling torque. and Both represent the moment of inertia. These are the airframe roll rate, pitch rate, and yaw rate, respectively. Once the roll channel reaches the desired closed-loop pole, equation (1.3a) becomes: （1.4a） Among them, through design parameters The desired closed-loop poles are configured as follows: ;in, ; (1.4a) can be abbreviated as: （1.5a） in, , To control interference within the channel; S22a, Establish the state estimator using equation (1.6a): （1.6a） in, up The control input for the system is the rolling torque. For design parameters; S23a, the adaptive law of the roll channel is shown in equation (1.7a): （1.7a） in, They are respectively The estimate, For the controller's call cycle, To estimate the error, This is the estimation error correction term; S24a, Roll Channel Control Law, i.e., Roll Torque: （1.8a） in, , , For the desired roll angle, For design parameters; S3: Rolling torque, pitching torque, and yaw torque are calculated and distributed across the four motors via control.

2. The hovering vector attitude control method for a multi-actuator tail-mounted UAV according to claim 1, characterized in that, The torque model of the UAV in S1 is established using formula (1.1): (1.1) in, For motor thrust, This represents the deflection angle of the motor. From the center of mass of the motor to the aircraft Distance between planes, These are the rolling moment, pitching moment, and yaw moment, respectively.

3. The hovering vector attitude control method for a multi-actuator tail-mounted UAV according to claim 2, characterized in that, The rotation model of the UAV in S1 is established using formula (1.2): (1.2) in, For rotational inertia, These are the airframe roll rate, pitch rate, and yaw rate, respectively.

4. The hovering vector attitude control method for a multi-actuator tail-mounted UAV according to claim 3, characterized in that, The design of the pitch channel adaptive controller for the UAV in S2 includes the following steps: S21b: Establish the spatial equations for the open-loop system state of the pitch channel: （1.3b） in, This refers to the mismatch uncertainty, specifically the coupling interference between the roll, pitch, and yaw channels. The pitch angle; Once the pitch channel reaches the desired closed-loop poles, equation (1.3b) becomes: （1.4b） Among them, through design parameters The desired closed-loop poles are configured as follows: ;in, ; (1.4b) can be abbreviated as: （1.5b） in, , , To control interference within the channel; S22b, Establish the state estimator using equation (1.6b): （1.6b） in, For design parameters; uq This is the control input for the system, namely the pitch torque; S23b, the pitch channel adaptive law is shown in equation (1.7b): （1.7b） in, They are respectively The estimate, For the controller's call cycle, To estimate the error, This is the estimation error correction term; S24b, Pitch Channel Control Law, i.e., Pitch Moment: （1.8b） in, , , For the desired pitch angle, These are design parameters.

5. The hovering vector attitude control method for a multi-actuator tail-mounted UAV according to claim 4, characterized in that, The design of the yaw channel adaptive controller for the UAV in S2 includes the following steps: S21c, Calculate the desired airframe yaw rate: For the yaw loop, the desired airframe yaw rate is: (1.9) in, For the desired roll angle, These are the desired pitch Euler rate and yaw Euler rate, respectively. Obtained by mapping from the aircraft's yaw stick; The calculation formula is as follows: (1.10) in, For design parameters, The difference between the expected pitch angles of adjacent cycles. The maximum permissible pitch Euler angle acceleration; S22c. Establish the state-space equations for the yaw channel: (1.11) Incorporating the desired closed-loop pole dynamics, equation (1.11) becomes: (1.12) in, The location of the closed-loop poles in the left half-plane of the complex plane; Equation (1.12) can be simplified as follows: (1.13) in, Indicates the yaw rate. , , ur This is the control input to the system, namely the yaw moment; S23c, Establish the state estimator using equation (1.14): (1.14) in, To prevent interference with the control channel The estimate, For design parameters; S24c, the yaw channel adaptive law is shown in equation (1.15): (1.15) in, For the controller's call cycle, To estimate the error, This is the estimation error correction term; S25c, the yaw channel control law, i.e., the yaw moment is: (1.16) in, Indicates design parameters, , The desired yaw rate.

6. The hovering vector attitude control method for a multi-actuator tail-mounted UAV according to claim 5, characterized in that, When calculating the output of each motor in the UAV using roll torque, pitch torque, and yaw torque in S3, equation (1.17) should be satisfied: (1.17) in, This indicates the total thrust output in the vertical direction. This represents the deflection angle of the motor.

7. The hovering vector attitude control method for a multi-actuator tail-mounted UAV according to claim 6, characterized in that, In equation (1.17) Error of yaw body angular rate Related, From equation (1.18), we get: (1.18) in, These are design parameters, and are directly proportional to the speed of motor deflection.

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