CN110825122A - Active anti-jamming tracking control method for circular trajectory of quadrotor UAV - Google Patents

Abstract

The invention discloses an active anti-interference tracking control method for a four-rotor unmanned aerial vehicle on a circular track. Establishing a four-rotor unmanned aerial vehicle position system model, and converting the track tracking problem of the four-rotor unmanned aerial vehicle into the stabilization problem of the tracking error of a position ring; introducing virtual control quantity, and establishing a high-order sliding mode disturbance observer of a position subsystem of the quad-rotor unmanned aerial vehicle; establishing a composite nonlinear dynamic inverse controller of the quad-rotor unmanned aerial vehicle, and ensuring that a disturbed quad-rotor unmanned aerial vehicle position system dynamically and gradually tracks a reference track of the disturbed quad-rotor unmanned aerial vehicle; through algebraic conversion, turn into the real controlled variable of four rotor unmanned aerial vehicle with virtual controlled variable. The invention can observe the lumped interference of the system in a limited time and dynamically compensate the lumped interference, so that the quad-rotor unmanned aerial vehicle has better anti-interference performance and robustness.

Description

Active anti-jamming tracking control method for circular trajectory of quadrotor UAV

technical field

The invention belongs to the technical field of flight control, and particularly relates to a control method of a quadrotor unmanned aerial vehicle.

Background technique

Quadrotor UAV is a kind of UAV that can take off and land vertically and hover in the air. Due to its simple structure, convenient control, strong flight environment versatility and low maintenance cost, it has been widely used in aerial reconnaissance, high-altitude It has important research significance and application prospects in the fields of photography, environmental disaster monitoring, and disaster rescue. In the field of control theory research, quadrotor UAV system control is a typical benchmarking problem with multiple inputs and multiple outputs, obvious nonlinear characteristics and serious state coupling. In addition, the flight process of the quadrotor UAV is also affected by the unmodeled dynamic external gust interference such as internal aerodynamic parameter perturbation, friction and other multi-source interference, as well as environmental uncertainty factors. The key problems that need to be solved urgently in the design of UAV control system.

At present, for the anti-jamming control problem of quadrotor UAV, scholars at home and abroad have given a variety of anti-jamming control strategies, including the robust control strategy that relies on the robustness of the system to passively eliminate the interference and the expansion state observer to control the interference. Active anti-jamming control strategy with real-time observation and feed-forward compensation. However, the anti-jamming performance of the existing robust control strategy is obtained at the expense of the nominal performance of the system, while the active anti-jamming control strategy based on the extended state observer can achieve good control effects, but its impact on the disturbance is limited. The assumptions are too harsh, which greatly limits its engineering application. Therefore, there is an urgent need to propose an active anti-jamming control method for quadrotor UAVs that can handle multiple disturbances.

SUMMARY OF THE INVENTION

In order to solve the technical problems mentioned in the above-mentioned background art, the present invention proposes an active anti-jamming tracking control method for a circular trajectory of a quadrotor UAV.

In order to realize the above-mentioned technical purpose, the technical scheme of the present invention is:

An active anti-jamming tracking control method for a circular trajectory of a quadrotor unmanned aerial vehicle, comprising the following steps:

(1) Establish a quadrotor UAV position system model, and transform the quadrotor UAV trajectory tracking problem into the stabilization problem of the position loop tracking error;

(2) Introduce virtual control variables and establish a high-order sliding mode interference observer for the position subsystem of the quadrotor UAV;

(3) Establish a composite nonlinear dynamic inverse controller of the quadrotor UAV to ensure that the disturbed quadrotor UAV position system dynamically and progressively tracks its reference trajectory;

(4) Through algebraic transformation, the virtual control quantity is converted into the real control quantity of the quadrotor UAV.

Further, in step (1), the four-rotor unmanned aerial vehicle position system model is as follows:

Among them, x represents the x-axis displacement of the quad-rotor drone, y represents the y-axis displacement of the quad-rotor drone, z represents the z-axis displacement of the quad-rotor drone, the point above the letter represents its first-order differential, and the two points above the letter The point represents its second-order differential; the positive x-axis is defined as the tangential direction along the local longitude, pointing to the north; the positive y-axis is defined as the tangential direction along the local latitude, pointing to the east; the positive z-axis is defined as perpendicular to the The local horizontal plane, pointing to the center of the earth; D _x , D _y , D _z represent the aggregated interference in three axial directions; φ represents the roll angle of the quadrotor UAV, θ represents the pitch angle of the quadrotor UAV, ψ represents The yaw angle of the quad-rotor drone; m represents the mass of the quad-rotor drone, g represents the acceleration of gravity, U _P represents the total lift generated by the quad-rotor drone, and k _d represents the air damping coefficient;

Define the position tracking error:

e _x =xx _d , e _y =yy _d , e _z =zz _d

Among them, e _x , e _y , and e _z are the three-axis position tracking errors, and x _d , y _d , and z _d are the three-axis trajectory reference signals;

Build the position loop tracking error subsystem:

Then the control inputs of the position loop tracking error subsystem are φ, θ, ψ and U _P .

Further, in step (2), a three-axis virtual control quantity is introduced:

Create an x-axis high-order sliding mode observer:

v ₂ =-1.5L ^1/2 |z ₂ -v ₁ | ^1/2 sign(z ₂ -v ₁ )+z ₃

Create a higher-order sliding-mode observer in the y-axis:

v ₂ =-1.5L ^1/2 |z ₂ -v ₁ | ^1/2 sign(z ₂ -v ₁ )+z ₃

Create a higher-order sliding mode observer in the z-axis:

v ₂ =-1.5L ^1/2 |z ₂ -v ₁ | ^1/2 sign(z ₂ -v ₁ )+z ₃

表示三轴向集总干扰的估计值；L为高阶滑模观测器增益；sign表示符号函数。Among them, z ₁ , z ₂ , z ₃ are high-order sliding mode observer dynamics;

represents the estimated value of the three-axis lumped interference; L is the gain of the high-order sliding mode observer; sign represents the sign function.

Further, in step (3), a composite nonlinear dynamic inverse controller is established for the three axial directions respectively:

Among them, K _XP , K _XD , K _YP , K _YD , K _ZP , and K _ZD are controller parameters, and they are all positive constants.

Further, in step (4), the yaw angle command ψ ^d is directly set to 0, the roll angle command φ ^d , the pitch angle command θ ^d and the total lift command U _P ^d are obtained according to the inverse solution of the virtual control quantity:

The beneficial effects brought by the above technical solutions:

(1) the present invention adopts the high-order sliding mode interference observer to estimate the multi-source interference in the quadrotor unmanned aerial vehicle position system, which significantly expands the types of interference that the controller can suppress, and ensures that the interference can be accurately estimated within a limited time;

(2) The present invention makes full use of the nonlinear characteristics of the system, cancels the nominal nonlinearity in the form of feedback in the feedback channel, greatly reduces the adjustment pressure of the error-based feedback part in the controller, and significantly reduces the difficulty of adjusting the parameters of the controller;

(3) The present invention incorporates the multi-source interference estimation information into the design of the nonlinear dynamic inverse controller, reconstructs it into a composite dynamic inverse controller, and significantly improves the anti-interference of the system by performing dynamic real-time feedforward compensation for the multi-source interference. performance and robustness;

(4) The present invention can not only significantly improve the tracking accuracy in the control system of the quadrotor UAV, but also the anti-jamming control method proposed can be applied to the high-precision control of other aircraft, and has a broad application prospect.

Description of drawings

Fig. 1 is the control strategy block diagram of the present invention;

Fig. 2 is a four-rotor UAV tracking space three-dimensional circular trajectory effect diagram under the action of the traditional benchmark nonlinear controller and the composite controller of the present invention;

Fig. 3 is the four-rotor UAV position three-channel trajectory response curve diagram under the action of the traditional benchmark nonlinear controller and the composite controller of the present invention;

Fig. 4 is a four-rotor unmanned aerial vehicle position three-channel trajectory tracking error curve diagram under the action of the traditional benchmark nonlinear controller and the composite controller of the present invention;

FIG. 5 is a graph of the control input response curve of the quadrotor UAV under the action of the traditional benchmark nonlinear controller and the composite controller of the present invention.

Detailed ways

The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings.

The present invention designs an active anti-jamming tracking control method for a circular trajectory of a quadrotor UAV, as shown in Figure 1, and the basic steps are as follows:

Step 1: Establish a quad-rotor UAV position system model, and convert the quad-rotor UAV's trajectory tracking problem into a stabilization problem of position loop tracking error;

Step 2: Introduce virtual control variables and establish a high-order sliding mode interference observer for the position subsystem of the quadrotor UAV;

Step 3: Establish a composite nonlinear dynamic inverse controller of the quadrotor UAV to ensure that the disturbed quadrotor UAV position system dynamically and progressively tracks its reference trajectory;

Step 4: Convert the virtual control amount to the real control amount of the quadrotor UAV through algebraic transformation.

In the present embodiment, adopt the following preferred scheme to realize step 1:

In step (1), the four-rotor UAV position system model is as follows:

Among them, x represents the x-axis displacement of the quad-rotor drone, y represents the y-axis displacement of the quad-rotor drone, z represents the z-axis displacement of the quad-rotor drone, the point above the letter represents its first-order differential, and the two points above the letter The point represents its second-order differential; the positive x-axis is defined as the tangential direction along the local longitude, pointing to the north; the positive y-axis is defined as the tangential direction along the local latitude, pointing to the east; the positive z-axis is defined as perpendicular to the The local horizontal plane, pointing to the center of the earth; D _x , D _y , D _z represent the aggregated interference in three axial directions; φ represents the roll angle of the quadrotor UAV, θ represents the pitch angle of the quadrotor UAV, ψ represents The yaw angle of the quad-rotor drone; m represents the mass of the quad-rotor drone, g represents the acceleration of gravity, U _P represents the total lift generated by the quad-rotor drone, and k _d represents the air damping coefficient. In this embodiment, m=0.8, and the air damping coefficient k _d =0.09.

Define the position tracking error:

e _x =xx _d , e _y =yy _d , e _z =zz _d

Among them, ed , _{ed , and ed are the three-axis position tracking errors, and x d , y d , and z d are} the three-axis trajectory reference signals;

Build the position loop tracking error subsystem:

Since the outer loop of the quadrotor UAV control system is a position loop and the inner loop is an attitude loop, and the control of the position loop is realized by changing the attitude angle, the control input of the position tracking subsystem is the three-axis attitude angle φ, θ , ψ and the total lift U _P .

In the present embodiment, adopt the following preferred scheme to realize step 2:

For the quadrotor UAV position system (1), a high-order sliding-mode observer is designed to achieve finite-time estimation of the aggregate interference of the three position channels.

For the position subsystem model of the quadrotor UAV in system (1), in order to facilitate the controller design, the following virtual control quantities are introduced:

Create an x-axis high-order sliding mode observer:

Create a higher-order sliding-mode observer in the y-axis:

Create a higher-order sliding mode observer in the z-axis:

表示三轴向集总干扰的估计值；L为高阶滑模观测器增益；sign表示符号函数。在本实施例中，L取值0.1。Among them, z ₁ , z ₂ , z ₃ are high-order sliding mode observer dynamics;

represents the estimated value of the three-axis lumped interference; L is the gain of the high-order sliding mode observer; sign represents the sign function. In this embodiment, L takes a value of 0.1.

In the present embodiment, adopt the following preferred scheme to realize step 3:

For the quadrotor UAV position loop tracking error system (2), a nonlinear dynamic inverse controller is designed, and combined with the lumped disturbance estimation information of the high-order sliding mode observer, a composite nonlinear dynamic inverse controller is designed. The stability analysis of the attitude error system is carried out by using the VF function, and the specific steps of its design include:

Design a composite dynamic inverse controller for the X-axis channel of the quadrotor UAV position system:

Design a composite dynamic inverse controller for the Y-axis channel of the quadrotor UAV position system:

Design a composite dynamic inverse controller for the Z-axis channel of the quadrotor UAV position system:

Among them, K _XP , K _XD , K _YP , K _YD , K _ZP , and K _ZD are controller parameters, and they are all normal numbers. Its stability is analyzed and explained as follows:

Substitute the X-axis dynamic inverse controller into the position loop tracking error system (2) to obtain:

在有限时间T_e内收敛其真实值D_x，所以当t＞T_e时，X轴向跟踪误差闭环系统转化为如下动态：Since the higher-order sliding mode observer (4) guarantees the interference estimation

Convergence its true value D _x within a finite time _{Te, so when t>T e ,} the X-axis tracking error closed-loop system is transformed into the following dynamics:

Define the following Lyapunov function:

Taking into account equation (10), derivation of the Lyapunov function can be obtained:

Therefore, the closed-loop system (10) converges asymptotically, that is, under the action of the composite dynamic inverse controller (7), the x-axis disturbed error tracking system gradually converges. Similarly, it can be proved that the composite dynamic inverse controllers (8) and (9) guarantee The tracking errors in the y and z axes converge asymptotically. That is, the composite dynamic inverse controllers (7)-(9) ensure that the disturbed quadrotor UAV position system (1) dynamically and progressively tracks its reference trajectory.

The virtual control quantity is analyzed, and the virtual control quantity is converted into the real control quantity of the quadrotor UAV through algebraic transformation. Considering that the inner ring of the quadrotor UAV is an attitude ring, and its position control is coordinated by changing the attitude angle and lift.

In the actual flying process of the quadrotor UAV, in order to facilitate the system control, it is always hoped that its yaw angle is kept at zero, that is, ψ ^d =0, and the remaining roll angle command φ ^d , pitch angle command θ ^d and total lift command U _P ^d is obtained according to the inverse solution of the virtual control variable:

In order to verify the superior anti-interference performance of the present invention, the algorithm of the present invention and the traditional nonlinear dynamic inverse algorithm are compared and verified by the simulation of the quadrotor UAV based on the MATLAB simulation environment under the condition of fully considering the existence of external interference. The initial value of the position in the simulation process is set as x(0)=0, y(0)=1, z(0)=0, and the desired position is set as follows:

The external interference settings during the simulation process are as follows:

_Dx =-1.6,Dy=-1.84, _{Dx =} -1.6

The parameters of the composite nonlinear dynamic inverse controller (CNDIC) designed by the present invention are as follows:

K _XP = 9, K _XD = 6, K _YP = 9, K _YD = 6, K _ZP = 9, K _ZD = 6.

The Baseline Nonlinear Dynamic Inverse Controller (BNDIC) used as a simulation comparison is designed as follows:

ψ ^d = 0

The controller parameters take the following values:

K _XP = 9, K _XD = 6, K _YP = 9, K _YD = 6, K _ZP = 9, K _ZD = 6.

Figures 2 to 4 are respectively the effect diagrams of trajectory tracking of disturbed quadrotor UAV using CNDIC and BNDIC. It can be seen that the anti-interference performance of the composite control method proposed by the present invention is obviously better than that of the traditional dynamic inverse control method. Figure 5 shows the control input response curve, including (a), (b), (c), (d) four sub-graphs, corresponding to the roll angle, pitch angle, yaw angle and total lift respectively, it can be seen that the present invention The method controls the inputs (attitude angle and total lift) within certain limits. To sum up, the present invention can ensure that the quadrotor UAV has faster trajectory tracking speed and stronger anti-interference performance.

The embodiment is only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any changes made on the basis of the technical idea proposed by the present invention all fall within the protection scope of the present invention. .

Claims (5)

1. a four-rotor unmanned aerial vehicle circular trajectory active anti-jamming tracking control method, is characterized in that, comprises the following steps: (1) Establish a quadrotor UAV position system model, and transform the quadrotor UAV trajectory tracking problem into the stabilization problem of the position loop tracking error; (2) Introduce virtual control variables and establish a high-order sliding mode interference observer for the position subsystem of the quadrotor UAV; (3) Establish a composite nonlinear dynamic inverse controller of the quadrotor UAV to ensure that the disturbed quadrotor UAV position system dynamically and progressively tracks its reference trajectory; (4) Through algebraic transformation, the virtual control quantity is converted into the real control quantity of the quadrotor UAV. 2. according to the described quadrotor unmanned aerial vehicle circular trajectory active anti-jamming tracking control method, it is characterized in that, in step (1), described quadrotor unmanned aerial vehicle position system model is as follows: Among them, x represents the x-axis displacement of the quad-rotor drone, y represents the y-axis displacement of the quad-rotor drone, z represents the z-axis displacement of the quad-rotor drone, the point above the letter represents its first-order differential, and the two points above the letter The point represents its second-order differential; the positive x-axis is defined as the tangential direction along the local longitude, pointing to the north; the positive y-axis is defined as the tangential direction along the local latitude, pointing to the east; the positive z-axis is defined as perpendicular to the The local horizontal plane, pointing to the center of the earth; D _x , D _y , D _z represent the aggregated interference in three axial directions; φ represents the roll angle of the quadrotor UAV, θ represents the pitch angle of the quadrotor UAV, ψ represents The yaw angle of the quad-rotor drone; m represents the mass of the quad-rotor drone, g represents the acceleration of gravity, U _P represents the total lift generated by the quad-rotor drone, and k _d represents the air damping coefficient; Define the position tracking error: e _x =xx _d , e _y =yy _d , e _z =zz _d Among them, ed , _{ed , and ed are the three-axis position tracking errors, and x d , y d , and z d are} the three-axis trajectory reference signals; Build the position loop tracking error subsystem:

Then the control inputs of the position loop tracking error subsystem are φ, θ, ψ and U _P . 3. according to the described quadrotor unmanned aerial vehicle circular track active anti-jamming tracking control method of claim 2, it is characterized in that, in step (2), introduce three-axis virtual control quantity:

Create an x-axis high-order sliding mode observer:

v ₂ =-1.5L ^1/2 |z ₂ -v ₁ | ^1/2 sign(z ₂ -v ₁ )+z ₃ Create a higher-order sliding-mode observer in the y-axis:

v ₂ =-1.5L ^1/2 |z ₂ -v ₁ | ^1/2 sign(z ₂ -v ₁ )+z ₃ Create a higher-order sliding mode observer in the z-axis:

v ₂ =-1.5L ^1/2 |z ₂ -v ₁ | ^1/2 sign(z ₂ -v ₁ )+z ₃ Among them, z ₁ , z ₂ , z ₃ are high-order sliding mode observer dynamics;

represents the estimated value of the three-axis lumped interference; L is the gain of the high-order sliding mode observer; sign represents the sign function. 4. according to the described four-rotor unmanned aerial vehicle circular trajectory active anti-jamming tracking control method of claim 3, it is characterized in that, in step (3), establish compound nonlinear dynamic inverse controller respectively for three axial directions:

Among them, K _XP , K _XD , K _YP , K _YD , K _ZP , and K _ZD are controller parameters, and they are all positive constants. 5. according to the described quadrotor unmanned aerial vehicle circular trajectory active anti-jamming tracking control method according to claim 4, it is characterized in that, in step (4), yaw angle command ψ ^d is directly set to 0, roll angle command φ ^d , the pitch angle command θ ^d and the total lift command U _P ^d are obtained according to the inverse solution of the virtual control variable:

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