Structural Angle Design and Performance Analysis Method and System of Inclined Thrust Quadrotor

Abstract

The present invention relates to the technical field of aircraft performance analysis, and specifically discloses a structural angle design and performance analysis method and system for an inclined thrust quadrotor. First, the angular parameters of the two degrees of freedom of the inclined thrust quadrotor are set, and the three-axis thrust equation in the body coordinate system is constructed. Then, the components of the x-axis and y-axis in the three-axis thrust equation are set to zero, and the self-stabilization boundary of the quadrotor is calculated to obtain the self-stabilization domain. Next, the lift coefficient and yaw moment coefficient are calculated according to the three-axis thrust equation. After discretizing the angular parameters within the self-stabilization domain, the lift coefficient values and yaw moment coefficient values at each discrete point are calculated. Finally, the desired lift efficiency and desired yaw control efficiency are set, and the values of the angular parameters that satisfy the desired efficiency are solved respectively. The present invention explores the coupling relationship and sensitivity between flight performance and two structural angles from both quantitative and qualitative levels, providing a guiding direction for the structural optimization of aircraft.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft performance analysis, and in particular, to a structural angle design and performance analysis method and system for an inclined thrust quadrotor. Background Art

[0002] Due to the ability to achieve vertical takeoff and landing and long-term hovering in narrow and variable areas, rotor UAVs show strong development potential and application value, and have begun to receive more and more attention and research. Multi-rotor aircraft achieve attitude motion control by adjusting the magnitude and direction of thrust in different ducts. However, ordinary multi-rotor UAVs usually show poor yaw maneuverability and wind resistance. To address this problem, methods for optimizing the performance of the airframe based on vector thrust have gradually attracted attention, but there are many difficulties in the engineering implementation of this design. Therefore, scholars have considered using structural design to achieve passive thrust inclination to avoid complex mechanical structure design and control. For example, non-planar multi-rotor design schemes can achieve full controllability by adjusting the inclination angle, significantly improving the yaw control efficiency. Most of the inclination angles in these studies are single-degree-of-freedom rotation angles. Another scholar proposed a two-layer optimization method for large multi-rotor aircraft, which involves rotation angles of two degrees of freedom and successfully improves the maneuverability while ensuring high endurance.

[0003] Obviously, thrust inclination will cause a loss of lift efficiency while improving yaw maneuverability. Therefore, it is necessary to consider the balance between lift efficiency and maneuverability during the structural parameter design process. Most existing studies focus on single-degree-of-freedom inclination configurations, especially for two-degree-of-freedom inclinations, and a complete design system has not yet been formed. Therefore, based on this problem, how to construct a two-degree-of-freedom inclination model and analyze its performance is an urgent problem to be solved. Summary of the Invention

[0004] In view of the technical problems in the prior art, the present invention provides a structural angle design and performance analysis method and system for an inclined thrust quadrotor.

[0005] In a first aspect of the present invention, there is provided a structural angle design and performance analysis method for an inclined thrust quadrotor, including:

[0006] Setting the angle parameters of two degrees of freedom of the inclined thrust quadrotor, and constructing a three-axis thrust equation in the body coordinate system according to the angle parameters; the three-axis thrust equation includes the component force equations of the x-axis, y-axis, and z-axis in the body coordinate system;

[0007] Making the component forces of the x-axis and y-axis in the three-axis thrust equation equal to zero, calculating the self-stabilization boundary of the quadrotor, and obtaining the self-stabilization domain;

[0008] Calculate the lift coefficient according to the z-axis component force equation in the three-axis thrust equation, and calculate the yaw moment coefficient according to the x-axis and y-axis component force equations in the three-axis thrust equation;

[0009] Within the self-stabilizing domain, discretize the angle parameters according to the set grid step size, and calculate the lift coefficient value and yaw moment coefficient value at each discrete point;

[0010] Set the desired lift efficiency and desired yaw control efficiency, and respectively solve for the values of the angle parameters that satisfy the desired lift efficiency and desired yaw control efficiency;

[0011] Calculate the values of the angle parameters that simultaneously satisfy the desired lift efficiency and desired yaw control efficiency. If there is no solution, change the settings of the desired lift efficiency and desired yaw control efficiency, and re-execute the previous step until the values of the angle parameters that simultaneously satisfy the desired lift efficiency and desired yaw control efficiency are obtained.

[0012] Furthermore, set the angle parameters of the tilt-thrust quadrotor with two degrees of freedom, and construct the three-axis thrust equation in the body coordinate system according to the angle parameters, including:

[0013] Set the angle parameters of the tilt-thrust quadrotor with two degrees of freedom to be the angle of the rotor motor rotating around the arm and the angle between the arm and the horizontal plane of the frame ;

[0014] Obtain the thrust of a single motor according to the rotation angle of each motor The component forces on the x-axis, y-axis, and z-axis in the body coordinate system 、 、 。

[0015] Furthermore, make the component forces on the x-axis and y-axis in the three-axis thrust equation 、 equal to zero, calculate the self-stabilizing boundary of the quadrotor, and obtain the self-stabilizing domain, including:

[0016] Set the angle parameters to satisfy and when holds;

[0017] Let and , calculate the functional relationship between and , as the self-stabilizing boundary of the quadrotor;

[0018] Calculate the necessary and sufficient conditions for the functional relationship to have real solutions. The necessary and sufficient conditions are for The first value range;

[0019] Define the self-stabilizing domain as: and and respectively satisfy and the first value range.

[0020] Furthermore, calculate the lift coefficient according to the z-axis component equation in the three-axis thrust equation, including: The lift coefficient is: .

[0021] Furthermore, calculate the yaw moment coefficient according to the x-axis and y-axis component equations in the three-axis thrust equation, including:

[0022] Calculate the yaw moment generated by the thrust of a single motor ;

[0023] Consider the thrust increment generated by the rotational speed difference , and calculate the yaw moment coefficient according to the x-axis and y-axis component equations in the three-axis thrust equation and the yaw moment generated by the thrust of a single motor Calculate the yaw moment coefficient .

[0024] Furthermore, within the self-stabilizing domain, discretize the angle parameter according to the set grid step size, and calculate the lift coefficient value and yaw moment coefficient value at each discrete point, including:

[0025] Discretize and with according to the grid spacing;

[0026] Calculate the lift coefficient value and yaw moment coefficient value at each discrete point according to the lift coefficient and the yaw moment coefficient .

[0027] Furthermore, it also includes:

[0028] Make a three-dimensional surface plot of the angle parameter and the lift coefficient with the lift coefficient value as the vertical axis and the discrete grid of the angle parameter as the horizontal and vertical axes;

[0029] With as the horizontal axis coordinate and the yaw moment coefficient value as the vertical axis coordinate, make a curve plot of the angle parameter and the yaw moment coefficient;

[0030] Conduct quantitative analysis on the three-dimensional surface plot and the curve plot.

[0031] Further, set the expected lift efficiency and the expected yaw control efficiency, and solve for the values of the angular parameters that satisfy the expected lift efficiency and the expected yaw control efficiency, including:

[0032] Design the expected lift efficiency , let the number axis coordinate value be , which generates an intersection line L with the three-dimensional surface diagram; L is the relationship that the structural angles under the expected lift efficiency and need to satisfy;

[0033] Design the expected yaw control efficiency , let the yaw moment coefficient , and solve for the structural angles that satisfy the expected yaw control efficiency .

[0034] Further, calculate the values of the angular parameters that simultaneously satisfy the expected lift efficiency and the expected yaw control efficiency. If there is no solution, then change the settings of the expected lift efficiency and the expected yaw control efficiency, including:

[0035] If the angular value range corresponding to the intersection line L is , , then determine whether the structural angle satisfies . If so, the intersection point of the intersection line L and is the design value of the angle ; if not, then change the expected lift efficiency and the expected yaw control efficiency and .

[0036] In the second aspect of the present invention, there is provided a structural angle design and performance analysis system for an inclined thrust quadrotor. The system includes a thrust equation construction module, a self-stabilizing domain calculation module, a lift coefficient calculation module, a yaw moment coefficient calculation module, and an expected value calculation module, wherein:

[0037] The thrust equation construction module is connected to the self-stabilizing domain calculation module, the lift coefficient calculation module, and the yaw moment coefficient calculation module. The thrust equation construction module is used to set the angular parameters of the two degrees of freedom of the inclined thrust quadrotor and construct a three-axis thrust equation in the body coordinate system according to the angular parameters; the three-axis thrust equation includes the component force equations of the x-axis, y-axis, and z-axis in the body coordinate system;

[0038] The self-stabilizing domain calculation module is connected to the thrust equation construction module, the lift coefficient calculation module, and the yaw moment coefficient calculation module. The self-stabilizing domain calculation module is used to make the x-axis and y-axis component forces in the three-axis thrust equation equal to zero, calculate the self-stabilizing boundary of the quadrotor, and obtain the self-stabilizing domain;

[0039] The lift coefficient calculation module is connected to the thrust equation construction module, the self-stabilizing domain calculation module, and the expected value calculation module. The lift coefficient calculation module is used to calculate the lift coefficient according to the z-axis component force equation in the three-axis thrust equation, and, within the self-stabilizing domain, discretize the angle parameter according to the set grid step size, and calculate the lift coefficient value at each discrete point;

[0040] The yaw moment coefficient calculation module is connected to the thrust equation construction module, the self-stabilizing domain calculation module, and the expected value calculation module. The yaw moment coefficient calculation module is used to calculate the yaw moment coefficient according to the x-axis and y-axis component force equations in the three-axis thrust equation, and, within the self-stabilizing domain, discretize the angle parameter according to the set grid step size, and calculate the yaw moment coefficient value at each discrete point;

[0041] The expected value calculation module is connected to the lift coefficient calculation module and the yaw moment coefficient calculation module. The expected value calculation module is used to set the expected lift efficiency and the expected yaw control efficiency, and respectively solve the values of the angle parameter that satisfy the expected lift efficiency and the expected yaw control efficiency; and calculate the values of the angle parameter that simultaneously satisfy the expected lift efficiency and the expected yaw control efficiency. If there is no solution, change the settings of the expected lift efficiency and the expected yaw control efficiency, and re-solve until the values of the angle parameter that simultaneously satisfy the expected lift efficiency and the expected yaw control efficiency are obtained.

[0042] A structural angle design and performance analysis method and system for an inclined thrust quadrotor. First, set the angle parameters of the two degrees of freedom of the inclined thrust quadrotor and construct the three-axis thrust equation in the body coordinate system. Then, make the component forces on the x-axis and y-axis in the three-axis thrust equation equal to zero, calculate the self-stabilization boundary of the quadrotor to obtain the self-stabilization domain. Next, calculate the lift coefficient and yaw moment coefficient according to the three-axis thrust equation. After discretizing the angle parameters at a set grid step within the self-stabilization domain, calculate the lift coefficient values and yaw moment coefficient values at each discrete point. Finally, set the desired lift efficiency and desired yaw control efficiency, and respectively solve for the values of the angle parameters that satisfy the desired lift efficiency and desired yaw control efficiency. By establishing the functional relationship between the two degrees of freedom of the inclination angle and the force / moment coefficient, this invention explores the coupling relationship and sensitivity between flight performance and the two structural angles from both quantitative and qualitative levels, thus obtaining an optimization scheme for the structural parameters of an inclined thrust quadrotor aircraft, providing a guiding direction for aircraft structure optimization and also having a certain degree of generality. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0044] Figure 1 It is a flow chart of the steps of a structural angle design and performance analysis method for an inclined thrust quadrotor according to an embodiment of the present invention;

[0045] Figure 2 It is a schematic diagram of the structural angles (I) in a structural angle design and performance analysis method for an inclined thrust quadrotor according to an embodiment of the present invention;

[0046] Figure 3 It is a schematic diagram of the structural angles (II) in a structural angle design and performance analysis method for an inclined thrust quadrotor according to an embodiment of the present invention;

[0047] Figure 4 It is a schematic diagram of the body of an inclined thrust quadrotor unmanned aerial vehicle in a structural angle design and performance analysis method according to an embodiment of the present invention;

[0048] Figure 5 It is a schematic diagram of the self-stabilization boundary in a structural angle design and performance analysis method for an inclined thrust quadrotor according to an embodiment of the present invention;

[0049] Figure 6 It is a three-dimensional surface diagram of the lift coefficient in a structural angle design and performance analysis method for an inclined thrust quadrotor according to an embodiment of the present invention;

[0050] Figure 7 For the three - dimensional surface diagram projection diagram (1) in the structural angle design and performance analysis method of an inclined - thrust quadrotor according to an embodiment of the present invention;

[0051] Figure 8 For the three - dimensional surface diagram projection diagram (2) in the structural angle design and performance analysis method of an inclined - thrust quadrotor according to an embodiment of the present invention;

[0052] Figure 9 For the yaw moment coefficient curve diagram in the structural angle design and performance analysis method of an inclined - thrust quadrotor according to an embodiment of the present invention;

[0053] Figure 10 For the lift efficiency parameter diagram in the structural angle design and performance analysis method of an inclined - thrust quadrotor according to an embodiment of the present invention;

[0054] Figure 11 For the structural composition diagram of the structural angle design and performance analysis system of an inclined - thrust quadrotor according to an embodiment of the present invention. Specific embodiments

[0055] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0056] A structural angle design and performance analysis method of an inclined - thrust quadrotor according to an embodiment of the present invention, as Figure 1 shown, includes the following steps:

[0057] Step S10: Set the angle parameters of the two degrees of freedom of the inclined - thrust quadrotor, and construct the three - axis thrust equation in the body coordinate system according to the angle parameters.

[0058] In this embodiment, the three - axis thrust equation in this step includes the component force equations of the x - axis, y - axis, and z - axis in the body coordinate system. Specifically, step S10 includes:

[0059] Step S101: Set the angle parameters of the two degrees of freedom of the inclined - thrust quadrotor to be the angle of the rotor motor rotating around the arm and the angle between the arm and the horizontal plane of the frame. As Figure 2 and Figure 3 shown, they are respectively the schematic diagrams of the structural angle and the structural angle .

[0060] Step S102: Obtain the thrust of a single motor based on the rotation angle of each motor The component forces on the x-axis, y-axis, and z-axis in the body coordinate system 、 、 。The body coordinate system of the quadrotor UAV and the rotation angle directions of each motor are as shown in Figure 4 . By force decomposition, the component force magnitudes of the thrust of a single motor in the body coordinate system can be obtained. Taking the No. 1 motor as an example, its corresponding component forces 、 、 、 are respectively:

[0061] (1)

[0062] (2)

[0063] (3).

[0064] The component forces of other motors 、 、 can be obtained according to their positions in the body coordinate system, which will not be elaborated in the embodiments of the present invention. The calculation methods in subsequent steps are common for each motor.

[0065] Step S20: Set the component forces on the x-axis and y-axis in the three-axis thrust equation to zero, calculate the self-stabilization boundary of the quadrotor, and obtain the self-stabilization domain.

[0066] When the component forces of the thrust on the x-axis and y-axis point to the inside of the fuselage, the restoring moment generated under the oncoming flow disturbance is beneficial to the self-stabilization of the fuselage. It can be seen that the self-stability of the fuselage depends on the directions of the component forces of the thrust on the x-axis and y-axis in the body coordinate system. Therefore, set the component forces 、 on the x-axis and y-axis in the three-axis thrust equation obtained in Step S10 to zero, that is and , solve the functional relationship between the structural angles and , derive the self-stabilization boundary constraint based on the condition that the fuselage generates a restoring moment under the oncoming flow disturbance, and thus calculate the self-stabilization boundary of the quadrotor to obtain the self-stabilization domain Ω.

[0067] Specifically, Step S20 includes:

[0068] Step S201: Set the angle parameters to satisfy and when holds.

[0069] Combined with the setting of the structural angle in this embodiment and , the value range of the known structural angle is and . Taking the No. 1 motor as an example again, from Equation (1), it can be obtained that holds, that is, the component force of the thrust on the x-axis always points to the inside of the fuselage.

[0070] Step S202: Let , and , calculate the functional relationship and as , which is used as the self-stabilization boundary of the quadrotor.

[0071] Considering Equation (2), let , and , then when the component force on the y-axis is 0, the functional relationship that the structural angles and need to satisfy is (4).

[0072] Step S203: Calculate the necessary and sufficient conditions for the existence of real solutions of the functional relationship . The necessary and sufficient conditions are the first value range for .

[0073] This step is to calculate the necessary and sufficient conditions for the existence of real solutions of Equation (4). The first value range for is:[[]] (5).

[0074] Step S204: Define the self-stabilization domain as: , and and respectively satisfy , the first value range.

[0075] In summary, the self-stabilization boundary of the quadrotor is defined as:

[0076] (6).

[0077] Taking and as the ordinate and abscissa respectively, the self-stabilization boundary shown in Equation (4) is as shown by the red solid line in Figure 5 . The angle value range that satisfies the self-stabilization boundary constraint of Equation (6) is called the self-stabilization domain Ω, as shown by the blue shaded part in Figure 5 .

[0078] Step S30: Calculate the lift coefficient according to the component force equation of the z-axis in the three-axis thrust equation, and calculate the yaw moment coefficient according to the component force equations of the x-axis and y-axis in the three-axis thrust equation.

[0079] If the lift generated at different structural angles under the same rotor speed is used as an index, according to Equation (3), the lift magnitudes corresponding to different and can be obtained, and thus the lift efficiency of the airframe structure can be evaluated.

[0080] Specifically, in step S30, the lift coefficient is calculated according to the z-axis component force equation in the three-axis thrust equation, including: the lift coefficient is: . From Equation (3), it can be seen that the function of the lift coefficient with respect to the parameters and is: (7). It can be seen that both the parameters and will affect the lift efficiency of the aircraft.

[0081] The yaw moment of the UAV is composed of the component forces of the thrust of each nozzle in the x-axis and y-axis and the motor counter-torque. Given that the motor installation angle remains unchanged, the magnitude of the counter-torque generated by a single motor with the same rotational speed difference is the same. Therefore, at the same motor speed, the yaw moment coefficient is only related to the magnitude of the component force of the thrust.

[0082] Specifically, in step S30, the yaw moment coefficient is calculated according to the x-axis and y-axis component force equations in the three-axis thrust equation, including:

[0083] First, calculate the yaw moment generated by the thrust of a single motor, which is (8), where is the distance between the motor and the center of mass of the aircraft.

[0084] If there is a thrust increment generated due to the rotational speed difference, then according to the x-axis and y-axis component force equations in the three-axis thrust equation, and the yaw moment generated by the thrust of a single motor, calculate the yaw moment coefficient , that is, substituting Equation (2) and Equation (3) into Equation (8) and expanding, the yaw moment coefficient generated by the thrust component force can be obtained as (9). It can be seen that the yaw moment generated by the rotational speed change is only related to the angle .

[0085] Qualitatively analyze the influence of the structural angle on the flight performance based on the lift coefficient and yaw moment coefficient calculated above.

[0086] Step S40: Within the self-stabilization domain, discretize the angle parameters according to the set grid step size, and calculate the lift coefficient value and yaw moment coefficient value at each discrete point.

[0087] This step specifically includes:

[0088] Step S401: Design the grid spacing within the self-stabilizing domain , and discretize the angle parameters and with respect to the grid spacing . Then the self-stabilizing domain can be represented as a set composed of discrete points. In this embodiment, the value of the grid spacing is not specifically limited. Taking as an example, the lift coefficient values at each discrete point can be calculated from Equation (7), and the normalized results are as shown in Figure 6 . Figure 6 is a three-dimensional surface plot of the angle parameter and the lift coefficient, with the lift coefficient value as the vertical axis and the discrete grid of the angle parameter as the horizontal axis and the vertical axis in the plane. Figure 7 is the projection of the three-dimensional surface plot on the vertical axis - vertical axis plane, Figure 8 is the projection of the three-dimensional surface plot on the horizontal axis - vertical axis plane. It can be seen from Figures 6 to 8 that the angle parameter and the lift coefficient show a monotonically decreasing trend. The angle parameter is the main factor affecting the lift efficiency. If the given parameter is given, then changing has an impact on the lift coefficient of no more than 13.2%. From the surface curvature, it can be known that in the range of angle values from [0°, 25°], the sensitivity of the lift coefficient to the parameter is small, and the lift efficiency is above 80% at this time; when the angle is greater than 25°, the lift coefficient drops sharply as the angle increases.

[0089] Step S402: Calculate the lift coefficient value and the yaw moment coefficient value at each discrete point according to the lift coefficient and the yaw moment coefficient .

[0090] According to Equation (9), the specific numerical correspondence between the angle parameter and the yaw moment coefficient can be solved, and the normalized results are as shown in Figure 9 . Figure 9 is a curve graph of the angle parameter and the yaw moment coefficient, with as the horizontal axis coordinate and the yaw moment coefficient value as the vertical axis coordinate. It can be seen that the parameter within the self-stabilizing domain has an approximately linear relationship with the yaw efficiency.

[0091] Combined with the above content regarding Step S40, quantitative analysis is performed on the three-dimensional surface plot and the curve graph.

[0092] Step S50: Set the desired lift efficiency and the desired yaw control efficiency, and respectively solve for the values of the angular parameters that satisfy the desired lift efficiency and the desired yaw control efficiency.

[0093] Specifically, this step includes:

[0094] Step S501: Design the desired lift efficiency , let the number axis coordinate value be , which generates an intersection line L with the three-dimensional surface plot; L is the relationship that the structural angles and need to satisfy under the desired lift efficiency .

[0095] Step S502: Design the desired yaw control efficiency , let the yaw moment coefficient , and solve for the structural angles that satisfy the desired yaw control efficiency.

[0096] Considering the actual engineering constraints, the throttle control of the UAV is more likely to saturate under large angular parameters, and even the situation of being unable to hover may occur. Therefore, preferably, in this embodiment, the desired lift efficiency is designed to be , that is, the purple plane in Figure 6 . The projection of the intersection line of this plane and the original surface on the horizontal axis - vertical axis plane is the functional relationship that and need to satisfy at this lift efficiency, as shown by the black solid line in Figure 10 .

[0097] As an example, select the desired yaw efficiency to be , then from Equation (9), can be solved.

[0098] Step S60: Calculate the values of the angular parameters that simultaneously satisfy the desired lift efficiency and the desired yaw control efficiency. If there is no solution, change the settings of the desired lift efficiency and the desired yaw control efficiency, and re - execute Step S50 until the values of the angular parameters that simultaneously satisfy the desired lift efficiency and the desired yaw control efficiency are obtained.

[0099] Specifically: If the angular value range corresponding to the intersection line L is , , then determine whether the structural angle satisfies . If so, the intersection point of the intersection line L and is the design value of the angle ; if not, change the desired lift efficiency and the desired yaw control efficiency .

[0100] Combined with the example in step S50, the corresponding angular range is: 、 , within the range of parameter values. According to Figure 10 the intersection point of the black solid line in it is possible to determine the value of . If there is no solution during the solution process, the settings of the expected lift efficiency and the expected yaw control efficiency are changed, and step S50 is executed again to solve again until the values of the angular parameters that simultaneously satisfy the expected lift efficiency and the expected yaw control efficiency are obtained.

[0101] A structural angle design and performance analysis system for an inclined thrust quadrotor according to another embodiment of the present invention, as Figure 11 shown, the system includes a thrust equation construction module 101, a self-stabilization domain calculation module 102, a lift coefficient calculation module 103, a yaw moment coefficient calculation module 104, and an expected value calculation module 105, wherein:

[0102] The thrust equation construction module 101 is connected to the self-stabilization domain calculation module 102, the lift coefficient calculation module 103, and the yaw moment coefficient calculation module 104. The thrust equation construction module 101 is used to set the angular parameters of the two degrees of freedom of the inclined thrust quadrotor and construct a three-axis thrust equation in the body coordinate system; the three-axis thrust equation includes the component force equations of the x-axis, y-axis, and z-axis in the body coordinate system;

[0103] The self-stabilization domain calculation module 102 is connected to the thrust equation construction module 101, the lift coefficient calculation module 103, and the yaw moment coefficient calculation module 104. The self-stabilization domain calculation module 102 is used to make the component forces of the x-axis and y-axis in the three-axis thrust equation equal to zero, calculate the self-stabilization boundary of the quadrotor, and obtain the self-stabilization domain;

[0104] The lift coefficient calculation module 103 is connected to the thrust equation construction module 101, the self-stabilization domain calculation module 102, and the expected value calculation module 105. The lift coefficient calculation module 103 is used to calculate the lift coefficient according to the component force equation of the z-axis in the three-axis thrust equation, and, within the self-stabilization domain, discretize the angular parameters according to the set grid step size and calculate the lift coefficient values at each discrete point;

[0105] The yaw moment coefficient calculation module 104 is connected to the thrust equation construction module 101, the self-stabilization domain calculation module 102, and the expected value calculation module 105. The yaw moment coefficient calculation module 104 is used to calculate the yaw moment coefficient according to the component force equations of the x-axis and y-axis in the three-axis thrust equation, and, within the self-stabilization domain, discretize the angular parameters according to the set grid step size, and calculate the yaw moment coefficient values at each discrete point;

[0106] The expected value calculation module 105 is connected to the lift coefficient calculation module 103 and the yaw moment coefficient calculation module 104. The expected value calculation module 105 is used to set the expected lift efficiency and the expected yaw control efficiency, and respectively solve the values of the angular parameters that satisfy the expected lift efficiency and the expected yaw control efficiency; and calculate the values of the angular parameters that simultaneously satisfy the expected lift efficiency and the expected yaw control efficiency. If there is no solution, then change the settings of the expected lift efficiency and the expected yaw control efficiency, and re-solve until the values of the angular parameters that simultaneously satisfy the expected lift efficiency and the expected yaw control efficiency are obtained.

[0107] The implementation manner of the above structure angle design and performance analysis system for the tilt-thrust quadrotor can refer to the relevant steps of the foregoing method embodiment, and will not be elaborated here.

[0108] A method and system for structure angle design and performance analysis of a tilt-thrust quadrotor according to the present invention first sets the angular parameters of the two degrees of freedom of the tilt-thrust quadrotor and constructs a three-axis thrust equation in the body coordinate system, then makes the component forces of the x-axis and y-axis in the three-axis thrust equation equal to zero, calculates the self-stabilization boundary of the quadrotor to obtain the self-stabilization domain, and then calculates the lift coefficient and the yaw moment coefficient according to the three-axis thrust equation. After discretizing the angular parameters according to the set grid step size within the self-stabilization domain, calculate the lift coefficient values and the yaw moment coefficient values at each discrete point. Finally, set the expected lift efficiency and the expected yaw control efficiency, and respectively solve the values of the angular parameters that satisfy the expected lift efficiency and the expected yaw control efficiency. The present invention explores the coupling relationship and sensitivity between flight performance and two structural angles from both quantitative and qualitative levels by establishing a functional relationship between the two-degree-of-freedom tilt angle and the force / moment coefficient, thereby obtaining an optimization scheme for the structural parameters of a tilt-thrust quadrotor aircraft, providing a guiding direction for aircraft structure optimization, and also having a certain degree of generality.

[0109] The above further describes the present invention with the aid of specific embodiments. However, it should be understood that this specific description should not be construed as a limitation on the essence and scope of the present invention. Various modifications made by those of ordinary skill in the art to the above embodiments after reading this specification all fall within the scope protected by the present invention.

Claims

1. A structural angle design and performance analysis method for an inclined thrust quadrotor, characterized in that Including: Setting the angle parameters of the tilt-thrust quadrotor with two degrees of freedom, and constructing a three-axis thrust equation in the body coordinate system according to the angle parameters; the three-axis thrust equation includes the component force equations of the x-axis, y-axis, and z-axis in the body coordinate system; Making the component forces of the x-axis and y-axis in the three-axis thrust equation equal to zero, calculating the self-stabilization boundary of the quadrotor, and obtaining the self-stabilization domain; Calculating the lift coefficient according to the component force equation of the z-axis in the three-axis thrust equation, and calculating the yaw moment coefficient according to the component force equations of the x-axis and y-axis in the three-axis thrust equation; Within the self-stabilization domain, discretizing the angle parameters according to the set grid step size, and calculating the lift coefficient value and yaw moment coefficient value at each discrete point; Setting the desired lift efficiency and desired yaw control efficiency, and respectively solving the values of the angle parameters that satisfy the desired lift efficiency and desired yaw control efficiency; Calculating the values of the angle parameters that simultaneously satisfy the desired lift efficiency and desired yaw control efficiency. If there is no solution, change the settings of the desired lift efficiency and desired yaw control efficiency, and re-execute the previous step until the values of the angle parameters that simultaneously satisfy the desired lift efficiency and desired yaw control efficiency are obtained; Setting the angle parameters of the tilt-thrust quadrotor with two degrees of freedom, and constructing a three-axis thrust equation in the body coordinate system, including: Set the angle parameters of the tilt-thrust quadrotor with two degrees of freedom as the angles of the rotor motors rotating around the arm and the angle between the arm and the horizontal plane of the frame ; According to the angle of rotation of the rotor motor of each motor around the arm , and the angle between the arm and the horizontal plane of the frame The thrust of a single motor is obtained The component forces on the x-axis, y-axis and z-axis in the body coordinate system , , ; Set the x-axis and y-axis component forces in the three-axis thrust equation and equal to zero, calculate the self-stabilization boundary of the quadrotor, and obtain the self-stabilization domain, including: The set angle parameter satisfies and When holds; Let and Calculate and The functional relationship as the self-stabilizing boundary of the quadrotor; Calculation functional relation The necessary and sufficient condition for the existence of real solutions, and the necessary and sufficient condition is about The first value range of Define the self-stabilizing domain as: and and respectively satisfy the first value range.

2. The structural angle design and performance analysis method of an inclined thrust quadrotor as claimed in claim 1, characterized in that, Calculating the lift coefficient according to the z-axis component force equation in the three-axis thrust equation, including: the lift coefficient is as follows: .

3. The structural angle design and performance analysis method of an inclined thrust quadrotor as claimed in claim 2, wherein Calculating the yaw moment coefficient according to the component force equations of the x-axis and y-axis in the three-axis thrust equation, including: Calculate the thrust of a single motor The yaw moment generated ; Consider the existence of a thrust increment caused by a rotational speed difference , and calculate the yaw moment coefficient according to the component force equations of the x-axis and y-axis in the three-axis thrust equation and the yaw moment generated by the thrust of a single motor . .

4. The structural angle design and performance analysis method of an inclined thrust quadrotor according to claim 3, characterized in that, Within the self-stabilization domain, discretizing the angle parameters according to the set grid step size, and calculating the lift coefficient value and yaw moment coefficient value at each discrete point, including: According to the grid spacing discretize and perform discretization; According to the lift coefficient and the yaw moment coefficient calculate the lift coefficient value and the yaw moment coefficient value at each discrete point.

5. The structural angle design and performance analysis method of an inclined thrust quadrotor according to claim 4, characterized in that, Further including: Taking the lift coefficient value as the vertical axis, and using the discrete grid of the angle parameters as the plane where the horizontal axis and the vertical axis are located, to make a three-dimensional surface plot of the angle parameters and the lift coefficient; Taking as the horizontal axis coordinate and the yaw moment coefficient value as the vertical axis coordinate, a curve graph of the angle parameter and the yaw moment coefficient is made; Performing quantitative analysis on the three-dimensional surface plot and the curve plot.

6. The structural angle design and performance analysis method of an inclined thrust quadrotor as described in claim 5, characterized in that Setting the desired lift efficiency and desired yaw control efficiency, and respectively solving the values of the angle parameters that satisfy the desired lift efficiency and desired yaw control efficiency, including: Designed expected lift efficiency , let the coordinate value on the number axis be , which generates an intersection line L with the three-dimensional surface diagram; L is the structural angle under the condition of satisfying the expected lift efficiency and the relationship that needs to be satisfied; Designed expected yaw control efficiency , let the yaw moment coefficient , and solve for the structural angle that meets the expected yaw control efficiency .

7. The structural angle design and performance analysis method of an inclined thrust quadrotor according to claim 6, characterized in that, Calculating the values of the angle parameters that simultaneously satisfy the desired lift efficiency and desired yaw control efficiency. If there is no solution, change the settings of the desired lift efficiency and desired yaw control efficiency, including: If the angle value range corresponding to the intersection line L is , , then determine whether the structural angle meets . If so, the intersection point of the intersection line L and is the design value of the angle ; if not, then change the expected lift efficiency and the expected yaw control efficiency .

8. A structural angle design and performance analysis system for an inclined thrust quadrotor, characterized in that, Implementing the method according to any one of claims 1 to 7. The system includes a thrust equation construction module, a self-stabilization domain calculation module, a lift coefficient calculation module, a yaw moment coefficient calculation module, and an expected value calculation module, wherein: The thrust equation construction module is connected to the self-stabilization domain calculation module, the lift coefficient calculation module, and the yaw moment coefficient calculation module. The thrust equation construction module is used to set the angle parameters of the tilt-thrust quadrotor with two degrees of freedom, and construct a three-axis thrust equation in the body coordinate system; the three-axis thrust equation includes the component force equations of the x-axis, y-axis, and z-axis in the body coordinate system; The self-stabilizing domain calculation module is connected to the thrust equation construction module, the lift coefficient calculation module, and the yaw moment coefficient calculation module. The self-stabilizing domain calculation module is used to make the x-axis and y-axis component forces in the three-axis thrust equation equal to zero, calculate the self-stabilizing boundary of the quadrotor, and obtain the self-stabilizing domain; The lift coefficient calculation module is connected to the thrust equation construction module, the self-stabilizing domain calculation module, and the expected value calculation module. The lift coefficient calculation module is used to calculate the lift coefficient according to the z-axis component force equation in the three-axis thrust equation, and, within the self-stabilizing domain, discretize the angle parameter according to the set grid step size, and calculate the lift coefficient value at each discrete point; The yaw moment coefficient calculation module is connected to the thrust equation construction module, the self-stabilizing domain calculation module, and the expected value calculation module. The yaw moment coefficient calculation module is used to calculate the yaw moment coefficient according to the x-axis and y-axis component force equations in the three-axis thrust equation, and, within the self-stabilizing domain, discretize the angle parameter according to the set grid step size, and calculate the yaw moment coefficient value at each discrete point; The expected value calculation module is connected to the lift coefficient calculation module and the yaw moment coefficient calculation module. The expected value calculation module is used to set the expected lift efficiency and the expected yaw control efficiency, and respectively solve the values of the angle parameter that satisfy the expected lift efficiency and the expected yaw control efficiency; and calculate the values of the angle parameter that simultaneously satisfy the expected lift efficiency and the expected yaw control efficiency. If there is no solution, then change the settings of the expected lift efficiency and the expected yaw control efficiency, and re-solve until the values of the angle parameter that simultaneously satisfy the expected lift efficiency and the expected yaw control efficiency are obtained.

Images