Aerocar air attitude control method and device

Abstract

The invention discloses a hovercar air attitude control method and device, and relates to the technical field of hovercars. The method comprises the following steps: according to a rolling-pitching-yaw Euler angle convention model, constructing a kinetic model of the hovercar in a flight state; discretizing the linear state space equation with continuous time to obtain a state space expression form after linear discretization; the method comprises the following steps: acquiring current attitude data of an aerocar through an inertial measurement unit, and converting the attitude data into attitude data under a world coordinate system; and a model predictive control algorithm is utilized to control the vehicle body attitude of the flying vehicle in a plurality of time steps in the future. According to the technical scheme, the control method can effectively process system nonlinearity, external disturbance and multi-constraint conditions, high-precision tracking and dynamic stable control over the attitude of the hovercar are achieved, and meanwhile the calculation complexity is reduced to meet the real-time control requirement.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of flying cars, and in particular to a method and device for controlling the aerial attitude of a flying car. Background Art

[0002] With the acceleration of global urbanization and the increase in population density, the ground transportation system is facing unprecedented pressure. Flying cars, as a revolutionary way of air travel, have gradually entered the public eye and are seen as one of the key technologies to ease ground transportation pressure and realize future urban three-dimensional transportation.

[0003] The flight control technology of flying cars mainly involves seamless switching between vertical take-off and landing (VTOL) and horizontal cruise mode, which requires precise attitude control and dynamic modeling. Existing air attitude control systems mainly include proportional-integral-differential control, linear quadratic regulator control, nonlinear control (such as backstepping and sliding mode control) and model predictive control.

[0004] Among them, proportional-integral-differential control is still widely used in actual aircraft due to its simple structure and easy implementation, but it has a slow response in strongly nonlinear systems and cannot effectively handle external disturbances; linear quadratic regulator control is based on the design of linear quadratic regulators and has good effects on linear systems, but performs poorly when dealing with highly nonlinear and constrained systems. Nonlinear control methods such as backstepping can handle the nonlinear characteristics of the system, but rely on accurate system modeling and have limited anti-disturbance capabilities; although sliding mode control has good robustness, it is prone to jitter problems, which affects practical applications. Model predictive control provides higher flexibility and accuracy for air attitude control through online optimization and constraint processing, but the computational complexity is high and it is difficult to apply in real time in resource-constrained embedded systems, and further optimization and improvement are urgently needed. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method and device for controlling the aerial attitude of a flying car, so as to achieve high-precision tracking and dynamic stability control of the attitude of the flying car, while reducing the computational complexity to meet real-time control requirements.

[0006] In a first aspect, the present invention provides a method for controlling the aerial attitude of a flying car, which is applied to a flying car using six ducted fans as a flying power, wherein the flying car comprises a ducted fan 1 located at the left front of the flying car, a ducted fan 2 located at the right front of the flying car, a ducted fan 3 located at the right side of the top of the flying car, a ducted fan 4 located at the right rear of the flying car, a ducted fan 5 located at the left rear of the flying car, and a ducted fan 6 located at the left side of the top of the flying car, including:

[0007] S1. Construct a dynamic model of the flying car in flight based on the roll-pitch-yaw Euler angle convention model;

[0008] S2, discretizing the time-continuous linear state space equation to obtain a linear discretized state space expression;

[0009] S3, obtaining the current attitude data of the flying car, and converting the attitude data into attitude data in the world coordinate system using the dynamic model in S1;

[0010] S4. Use the model predictive control algorithm to control the body posture of the flying car in several future time steps.

[0011] Optionally, the method further includes:

[0012] S5. Obtain the positioning data and attitude data of the flying car as feedback information, and repeat S3 and S4 to ensure the stability of the flying car's attitude in the air.

[0013] Optionally, the S1 specifically includes:

[0014] According to the layout of the ducted fans, the relationship between the lift and torque provided by each ducted fan is calculated;

[0015] The control parameters in the relational expression are simplified according to the symmetry between the six ducted fans;

[0016] The flying car body torque is converted into angle information in the object coordinate system to obtain the Euler angle convention information in the world coordinate system.

[0017] Alternatively, a simplified expression for the relationship between lift and torque is:

[0018]

[0019] Among them, τ x , τ y , τ z They are the torques of the flying car on the x-axis, y-axis, and z-axis respectively. l a , l b , l c are the distances between ducted fan 1 and ducted fan 2, the distance between ducted fan 2 and ducted fan 4, and the distance between ducted fan 3 and ducted fan 6, μ is the drag coefficient, They are the distributed lift adjustment amounts of ducted fan 1, ducted fan 2, and ducted fan 3 respectively.

[0020] Optionally, the state space expression after linear discretization in S2 is:

[0021] X d (k+1)=A d X d (k)+B d U d (k)+D d (k)

[0022] Where k is the time step, is the discretized state quantity, is the discretized input quantity, D d (k) is the discretized external disturbance vector, A d and B d is the discretized system matrix.

[0023] Optionally, the S4 specifically includes:

[0024] Constraining the lift provided by each ducted fan to obtain constraints on the working space of each ducted fan;

[0025] The state quantity and the input quantity are stacked to obtain a stacked state sequence, an input sequence, and an input increment sequence;

[0026] An optimization function is constructed according to the state sequence, the input sequence, and the input increment sequence, and the body posture of the flying car in a number of future time steps is controlled by the optimization function.

[0027] Optionally, the constraints of the ducted fan working space are:

[0028] u min ≤u j (k)≤u max

[0029] Among them, u j (k), j = 1, 2, ..., 6 is the lift provided by each ducted fan, u max and u min They are the upper and lower limits of the lift of the ducted fan respectively.

[0030] Optionally, the stacked state sequence, input sequence, and input increment sequence are:

[0031]

[0032] Np represents the time step.

[0033] Optionally, the optimization function is:

[0034]

[0035] and Among them, P, Q, and R are three diagonal matrices respectively.

[0036] In a second aspect, the present invention further provides a flying car air attitude control device, which is configured in a flying car using six ducted fans as a flying power, wherein the flying car comprises a ducted fan 1 located at the left front of the vehicle, a ducted fan 2 located at the right front of the vehicle, a ducted fan 3 located at the right side of the top of the vehicle, a ducted fan 4 located at the right rear of the vehicle, a ducted fan 5 located at the left rear of the vehicle, and a ducted fan 6 located at the left side of the top of the vehicle, including:

[0037] A model building module is used to build a dynamic model of the flying car in flight according to the roll-pitch-yaw Euler angle convention model;

[0038] Discretization module, used to discretize the time-continuous linear state space equation to obtain the linear discretized state space expression;

[0039] A coordinate conversion module, used to obtain the current attitude data of the flying car through the inertial measurement unit, and convert the attitude data into attitude data in the world coordinate system using the dynamic model in S1;

[0040] The attitude control module is used to control the body attitude of the flying car in the future several time steps by using the model predictive control algorithm.

[0041] The present invention provides a method and device for controlling the attitude of a flying car in the air. By accurately modeling the dynamic model and using the symmetry of the ducted fan to simplify the control parameters to three, the computational complexity is significantly reduced and the real-time control performance is improved. In addition, the present invention combines the model predictive control algorithm and state feedback, and the system can effectively handle nonlinearity, external disturbances and multiple constraints, achieving high-precision tracking and stable control of the attitude of the flying car, providing technical support for the efficient and stable operation of the flying car. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram of the structure of a six-duct flying car provided by an embodiment of the present invention;

[0043] Figure 2 The present invention provides a flowchart of a method for controlling the aerial attitude of a flying car according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0045] Example

[0046] See also Figure 1 The flying car used in this embodiment uses six ducted fans as the flying power, wherein two ducted fans are deployed at the front and rear ends of the vehicle, and the four ducted fans are all located in the same horizontal plane. There are two ducted fans on the roof, which are respectively distributed on the left and right sides of the roof, and the six ducted fans are distributed on a circle in a vertical perspective. Specifically, the flying car includes a ducted fan 1 located at the left front of the vehicle, a ducted fan 2 located at the right front of the vehicle, a ducted fan 3 located at the right side of the top of the vehicle, a ducted fan 4 located at the right rear of the vehicle, a ducted fan 5 located at the left rear of the vehicle, and a ducted fan 6 located at the left side of the top of the vehicle.

[0047] See also Figure 2 , Figure 2 A flowchart of a method for controlling the aerial attitude of a flying car provided by an embodiment of the present invention, the method specifically includes:

[0048] S1. Based on the roll-pitch-yaw Euler angle conventional model, a dynamic model of the flying car in flight state is constructed.

[0049] When constructing the power model of the flying car, this embodiment uses the roll-pitch-yaw Euler discrete angle convention model to obtain the relationship between fan thrust and torque, torque and angle, torque and angular velocity, and torque and angular acceleration.

[0050] Specifically, firstly, according to the layout of the ducted fans, the relationship between the lift and torque provided by each ducted fan can be calculated:

[0051]

[0052] Among them, τ x , τ y , τ z are the torques of the flying car on the x-axis, y-axis, and z-axis respectively. u1, u2, u3, u4, u5, and u6 are the lifts provided by the six ducted fans respectively. a , l b , l c are the distances between ducted fans 1 and 2, ducted fans 2 and 4, and ducted fans 3 and 6, respectively. μ is the drag coefficient. Assuming that the total lift that each ducted fan needs to provide is 6η in order to maintain the normal flight of the flying car, the above formula can be rewritten as:

[0053]

[0054] Since ducted fans 1 and 4, 2 and 5, and 3 and 6 all generate opposite body torques in all directions, the lift forces of the six ducted fans are related as follows:

[0055]

[0056] If:

[0057]

[0058] Then we have:

[0059]

[0060] By using the above method, the control parameters can be simplified from 6 to 3, thereby improving the calculation efficiency.

[0061] Furthermore, in order to convert the flying car body torque into angle information in the object coordinate system, the classic Euler equation of the relationship between torque and angular acceleration can be used. Transformation is performed, where I = diag (I x ,I y ,I z ) is the inertia matrix, which represents the inertia of the object rotating along the x, y, and z axes, respectively. are the angular velocity and angular acceleration vectors in the body coordinate system, respectively, ω=[pqr] T and Since these angle information is information in the body coordinate system, and the control of the body posture needs to be performed in the world coordinate system, it is necessary to convert it into an angular velocity vector in the world coordinate system during the control process. and the angular acceleration vector The conversion equation is as follows:

[0062]

[0063] At this point, we can get the Euler angle convention information in the world coordinate system, where Represent the roll angular velocity, pitch angular velocity and yaw angular velocity respectively, They represent roll angular acceleration, pitch angular acceleration and yaw angular acceleration respectively.

[0064] This embodiment realizes the merging of control signals by utilizing the symmetry of the ducted fan, thereby significantly reducing the complexity of calculation.

[0065] S2. Discretize the time-continuous linear state space equation to obtain a linearly discretized state space expression.

[0066] Specifically, let the state vector be represented as The input vector is represented as Then there is a state space equation in continuous time:

[0067]

[0068] in is the derivative of the state quantity, A and B are both system matrices, D is the external disturbance vector, and:

[0069]

[0070] After performing Euler discretization on the above state space equation, the linear discrete state space equation can be obtained:

[0071] X d (k+1)=A d X d (k)+B d U d (k)+D d (k)

[0072] Where k is the time step, is the discretized state quantity, is the discretized input quantity, D d (k) is the discretized external disturbance vector. This embodiment does not take the yaw angle ψ(k) into consideration because the driver often gives the yaw angle by himself and does not need to be specially controlled. It only needs to optimize the yaw angle velocity. The output vector can be expressed as This will be used later to optimize the roll, pitch and yaw rates.

[0073] S3, obtaining the current posture data of the flying car, and using the dynamic model in S1 to convert the posture data into posture data in the world coordinate system.

[0074] Optionally, this embodiment uses an inertial measurement unit to obtain the current attitude data of the flying car. An inertial measurement unit is a device that can be used to measure the acceleration, angular velocity and direction of an object in space, and is usually composed of an accelerometer, a gyroscope and a magnetometer. The device can measure the angular velocity information ω in the body coordinate system, and the angular velocity and angular acceleration information in the world coordinate system can be obtained through the above S1.

[0075] S4. Use the model predictive control algorithm to control the body posture of the flying car in several future time steps.

[0076] The model predictive control algorithm in this embodiment mainly includes two parts, namely the state constraint part and the optimization function part. The first is the state constraint part, which includes the constraints of the ducted fan working space. Assuming that the upper and lower limits of the lift of the ducted fan are umax and umin respectively, the lift u provided by each ducted fan is j (k),j=1,2,...,6, all have inequality constraints:

[0077] u min ≤u j (k)≤u max

[0078] In addition, since model predictive control includes a prediction part, the state quantity and the input quantity need to be stacked before building the optimization function.

[0079] Assume that from X d (k) After a series of control inputs, the vehicle body state will evolve to X after the Npth time step. d (k+Np), then the stacked state sequence, input sequence, and input increment sequence are:

[0080]

[0081] The relationship between the stacked state sequence and the input increment sequence can be obtained:

[0082]

[0083] in:

[0084]

[0085] Then, for the above state sequence, input sequence, and input increment sequence, an optimization function can be constructed:

[0086]

[0087] and Among them, P, Q, and R are three diagonal matrices, representing the weights of different vectors in the optimization process, which can be defined according to actual conditions.

[0088] S5. Obtain the positioning data and attitude data of the flying car as feedback information, and repeat S3 and S4 to ensure the stability of the flying car's attitude in the air.

[0089] On the basis of the above embodiments, the present invention further provides a flying car air attitude control device, which is configured in a flying car using six ducted fans as a flying power, wherein the flying car comprises a ducted fan 1 located at the left front of the vehicle, a ducted fan 2 located at the right front of the vehicle, a ducted fan 3 located at the right side of the top of the vehicle, a ducted fan 4 located at the right rear of the vehicle, a ducted fan 5 located at the left rear of the vehicle, and a ducted fan 6 located at the left side of the top of the vehicle, including:

[0090] A model building module is used to build a dynamic model of the flying car in flight according to the roll-pitch-yaw Euler angle convention model;

[0091] Discretization module, used to discretize the time-continuous linear state space equation to obtain the linear discretized state space expression;

[0092] A coordinate conversion module is used to obtain the current posture data of the flying car and convert the posture data into posture data in the world coordinate system using the dynamic model in S1;

[0093] The attitude control module is used to control the body attitude of the flying car in the future several time steps by using the model predictive control algorithm.

[0094] The feedback module is used to obtain the positioning data and attitude data of the flying car as feedback information, and repeatedly execute S3 and S4 to ensure the stability of the flying car's attitude in the air.

[0095] The model building module is specifically used to perform:

[0096] According to the layout of the ducted fans, the relationship between the lift and torque provided by each ducted fan is calculated;

[0097] The control parameters in the relational expression are simplified according to the symmetry between the six ducted fans;

[0098] The flying car body torque is converted into angle information in the object coordinate system to obtain the Euler angle convention information in the world coordinate system.

[0099] Specifically, the state space expression after the above linear discretization is:

[0100] X d (k+1)=A d X d (k)+B d U d (k)+D d (k)

[0101] Where k is the time step, is the discretized state quantity, is the discretized input quantity, D d (k) is the discretized external disturbance vector, A d and B d is the discretized system matrix.

[0102] The above-mentioned attitude control module is specifically used to perform:

[0103] Constraining the lift provided by each ducted fan to obtain constraints on the working space of each ducted fan;

[0104] The state quantity and the input quantity are stacked to obtain a stacked state sequence, an input sequence, and an input increment sequence;

[0105] An optimization function is constructed according to the state sequence, the input sequence, and the input increment sequence, and the body posture of the flying car in a number of future time steps is controlled by the optimization function.

[0106] Among them, the constraints of the ducted fan working space are:

[0107] u min ≤u j (k)≤u max

[0108] Among them, u j (k), j = 1, 2, ..., 6 is the lift provided by each ducted fan, u max and u min They are the upper and lower limits of the lift of the ducted fan respectively.

[0109] The stacked state sequence, input sequence, and input increment sequence are:

[0110]

[0111] The optimization function is:

[0112]

[0113] and Among them, P, Q, and R are three diagonal matrices respectively.

[0114] A flying car air attitude control device provided in an embodiment of the present invention can execute a flying car air attitude control method provided in any embodiment of the present invention, and has corresponding functional modules and beneficial effects of the execution method, which will not be described in detail.

[0115] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for controlling the aerial attitude of a flying car, applied to a flying car using six ducted fans as a flying power, wherein the flying car comprises a ducted fan 1 located at the left front of the flying car, a ducted fan 2 located at the right front of the flying car, a ducted fan 3 located at the right side of the top of the flying car, a ducted fan 4 located at the right rear of the flying car, a ducted fan 5 located at the left rear of the flying car, and a ducted fan 6 located at the left side of the top of the flying car, characterized in that: include: S1. Construct a dynamic model of the flying car in flight based on the roll-pitch-yaw Euler angle convention model; S2, discretizing the time-continuous linear state space equation to obtain a linear discretized state space expression; S3, obtaining the current attitude data of the flying car, and converting the attitude data into attitude data in the world coordinate system using the dynamic model in S1; S4. Use the model predictive control algorithm to control the body posture of the flying car in several future time steps.

2. The method according to claim 1, characterized in that The method further comprises: S5. Obtain the positioning data and attitude data of the flying car as feedback information, and repeat S3 and S4 to ensure the stability of the flying car's attitude in the air.

3. The method according to claim 1, characterized in that The S1 specifically includes: According to the layout of the ducted fans, the relationship between the lift and torque provided by each ducted fan is calculated; The control parameters in the relational expression are simplified according to the symmetry between the six ducted fans; The flying car body torque is converted into angle information in the object coordinate system to obtain the Euler angle convention information in the world coordinate system.

4. The method according to claim 2, characterized in that: The simplified expression of the relationship between lift and torque is: Among them, τ x , τ y , τ z They are the torques of the flying car on the x-axis, y-axis, and z-axis respectively. l a , l b , l c are the distances between ducted fan 1 and ducted fan 2, the distance between ducted fan 2 and ducted fan 4, and the distance between ducted fan 3 and ducted fan 6, μ is the drag coefficient, The adjustment amount of lift compared to the average lift is allocated to ducted fan 1, ducted fan 2, and ducted fan 3 respectively.

5. The method according to claim 1, characterized in that The state space expression after linear discretization in S2 is: X d (k+1)=A d X d (k)+B d U d (k)+D d (k) Where k is the time step, is the discretized state quantity, is the discretized input quantity, D d (k) is the discretized external disturbance vector, A d and B d is the discretized system matrix.

6. The method according to claim 1, characterized in that The S4 specifically includes: Constraining the lift provided by each ducted fan to obtain constraints on the working space of each ducted fan; The state quantity and the input quantity are stacked to obtain a stacked state sequence, an input sequence, and an input increment sequence; An optimization function is constructed according to the state sequence, the input sequence, and the input increment sequence, and the body posture of the flying car in a number of future time steps is controlled by the optimization function.

7. The method according to claim 6, characterized in that The constraints of the ducted fan working space are: in min in j (k)≤u max Among them, u j (k), j = 1, 2, ..., 6 is the lift provided by each ducted fan, u max and u min They are the upper and lower limits of the lift of the ducted fan respectively.

8. The method according to claim 6, characterized in that The stacked state sequence, input sequence, and input increment sequence are: Np represents the time step.

9. The method according to claim 8, characterized in that The optimization function is: and Among them, P, Q, and R are three diagonal matrices respectively.

10. A flying car air attitude control device, the device is configured in a flying car using six ducted fans as a flying power, the flying car comprises a ducted fan 1 located at the left front of the vehicle, a ducted fan 2 located at the right front of the vehicle, a ducted fan 3 located at the right side of the top of the vehicle, a ducted fan 4 located at the right rear of the vehicle, a ducted fan 5 located at the left rear of the vehicle, and a ducted fan 6 located at the left side of the top of the vehicle, characterized in that: include: A model building module is used to build a dynamic model of the flying car in flight according to the roll-pitch-yaw Euler angle convention model; Discretization module, used to discretize the time-continuous linear state space equation to obtain the linear discretized state space expression; A coordinate conversion module is used to obtain the current posture data of the flying car and convert the posture data into posture data in the world coordinate system using the dynamic model in S1; The attitude control module is used to control the body attitude of the flying car in the future several time steps by using the model predictive control algorithm.

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