CN110908288A - Unmanned aerial vehicle ground speed constraint disturbance rejection control method based on obstacle Lyapunov function - Google Patents

Abstract

The invention discloses a ground speed constraint anti-disturbance control method for an unmanned aerial vehicle based on an obstacle Lyapunov function. The method mainly includes: first, establishing a dynamic model of a nonlinear subsystem of the ground speed of the aircraft, and processing it into an affine nonlinear form ; On this basis, for the ground velocity affine nonlinear model, a finite-time high-order sliding-mode disturbance observer is designed to estimate the uncertain disturbance caused by the perturbation of system parameters; then, the estimated unknown disturbance is used as feedforward compensation , the nonlinear constrained anti-disturbance tracking controller of the ground speed subsystem is designed to achieve accurate tracking of the desired ground speed under the given ground speed constraints. The invention can be used for ground speed constrained and precise control in the fields of aircraft aerial refueling and docking, space-based recovery and docking, ultra-low-altitude airdrop, and obstacle avoidance in complex terrain, and can effectively improve the aircraft ground speed flight control accuracy and flight safety.

Description

A ground-speed-constrained anti-disturbance control method for unmanned aerial vehicles based on obstacle Lyapunov function

technical field

The invention relates to a ground speed restraint anti-disturbance control method for an unmanned aerial vehicle based on an obstacle Lyapunov function, and belongs to the technical field of unmanned aerial vehicle navigation, guidance and control.

Background technique

UAVs have been widely used and developed in many fields due to their advantages of low loss, low cost, zero casualties, reusability and high maneuverability. Aircraft ground speed is a very important motion parameter, which is the premise of UAV stability and track control. Fixed-wing UAVs generally fly at a certain altitude according to the designed cruise speed, but when performing complex tasks, the flight speed often needs to be changed. With the rapid development of UAVs, many application scenarios have put forward new and higher requirements for UAV ground speed control. UAVs automatically track moving targets, automatic formation flying, automatic aerial refueling, automatic aerial recovery, and automatic landing. and ultra-low-altitude airdrops, etc.

In the above-mentioned special application scenarios, the aircraft ground speed controller often not only has high control accuracy, but also requires excellent anti-interference ability and ground speed constrained control ability. Existing aircraft ground speed control methods, such as PID control, adaptive control, robust control, and synovial control, are rarely considered from the perspective of anti-interference and constrained control capability at the same time. How to ensure that the ground speed control of the aircraft has sufficient anti-interference ability at the same time, and at the same time can make the ground speed be strictly constrained and controlled within the expected range, is a problem that must be solved to make it adapt to some tasks with special requirements for ground speed control. , which can significantly improve the mission execution capability and flight safety of fixed-wing UAVs.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is: to provide a ground speed restraint anti-disturbance control method based on the obstacle Lyapunov function, which can effectively improve the ground speed of the aircraft on the premise of ensuring that the ground speed is strictly constrained and controlled within a desired range. The control accuracy and anti-interference ability of the speed controller can provide technical support for improving the UAV mission execution ability and flight safety.

The present invention adopts the following technical solutions for solving the above-mentioned technical problems:

A ground-speed-constrained anti-disturbance control method for unmanned aerial vehicles based on the obstacle Lyapunov function, comprising the following steps:

地速指令上界

和下界

以及地速约束范围K_c；Step 1, set the aircraft ground speed command

Ground speed command upper bound

and the Nether

and the ground speed constraint range K _c ;

Step 2, establish a dynamic model of the aircraft ground speed nonlinear subsystem to describe the ground speed motion state;

Step 3, converting the dynamic model of the aircraft ground speed nonlinear subsystem established in step 2 into an aircraft ground speed affine nonlinear model;

Step 4: The term in the aircraft ground speed affine nonlinear model that is linearly independent of the throttle opening _δT of the control variable is regarded as the system lumped disturbance term, and a finite-time convergence high-order sliding mode disturbance observer is designed to observe the lumped disturbance. estimate;

In step 5, the aggregate disturbance obtained by the observation and estimation in step 4 is used as the feedforward compensation term, and combined with the ground speed constraint condition, a ground speed constrained anti-jamming controller based on the obstacle Lyapunov function is designed; the specific process is as follows:

V_k为飞机地速，

为飞机地速指令，并定义常数A₀＞0使得则

Step 51, define ground speed tracking error

V _k is the ground speed of the aircraft,

is the ground speed command of the aircraft, and defines the constant A ₀ > 0 so that the

的不对称障碍Lyapunov函数；具体如下：Step 52, select based on

The asymmetric barrier Lyapunov function of ; as follows:

p为正整数，p≥1，

where L represents the asymmetric barrier Lyapunov function,

p is a positive integer, p≥1,

Step 53, design the aircraft ground speed constrained tracking controller; the details are as follows:

T_max为发动机最大推力，σ为发动机安装角，α和β分别为迎角和侧滑角，m为飞机质量，

为集总扰动项，

为地速反馈控制增益；in,

T _max is the maximum thrust of the engine, σ is the engine installation angle, α and β are the angle of attack and sideslip angle, respectively, m is the mass of the aircraft,

is the lumped disturbance term,

is the ground speed feedback control gain;

代替步骤53式中中的

得到飞机地速受约束抗扰动跟踪控制器，完成控制器设计；具体如下：Step 54, use the estimated value of aggregated interference observations obtained by the observer in step 4

Substitute for step 53 in the formula

The aircraft ground speed constrained anti-disturbance tracking controller is obtained, and the controller design is completed; the details are as follows:

As a preferred solution of the present invention, the dynamic model of the aircraft ground speed nonlinear subsystem described in step 2 is:

Among them, V _k is the ground speed of the aircraft, m is the mass of the aircraft, g is the acceleration of gravity, T is the thrust of the engine, D, L, and C are the aerodynamic drag, lift, and side force, respectively, σ is the engine installation angle, and γ is the track inclination angle. , α and β are the angle of attack and sideslip angle, respectively, and _αw and _βw are the additional quantities of the angle of attack and sideslip angle caused by airflow disturbance, respectively.

As a preferred solution of the present invention, the specific process of the step 3 is:

Step 31, separate the dynamic model of the aircraft ground speed nonlinear subsystem established in step 2 into two parts:

Among them, V _k is the ground speed of the aircraft, m is the mass of the aircraft, g is the acceleration of gravity, T _max is the maximum thrust of the engine, D, L, and C are the aerodynamic drag, lift, and side force, respectively, σ is the engine installation angle, and γ is the air force. track inclination, α and β are the angle of attack and sideslip angle, respectively, _αw and _βw are the additional amounts of the angle of attack and sideslip angle caused by airflow disturbance, respectively, _δT is the engine accelerator opening;

Step 32, convert the model of step 31 into an affine nonlinear model of aircraft ground speed:

in,

As a preferred solution of the present invention, the specific process of the step 4 is:

视为系统集总扰动项，对飞机地速仿射非线性模型进行增广，得到地速增广系统：Step 41, the term in the aircraft ground speed affine nonlinear model that is linearly independent of the throttle opening δT of the control _variable

As the lumped disturbance term of the system, the ground speed affine nonlinear model of the aircraft is augmented, and the ground speed augmented system is obtained:

是

的导数，

T_max为发动机最大推力，σ为发动机安装角，α和β分别为迎角和侧滑角，m为飞机质量，δ_T为发动机油门开度；where V _k is the ground speed of the aircraft,

Yes

the derivative of ,

T _max is the maximum thrust of the engine, σ is the engine installation angle, α and β are the angle of attack and sideslip angle, respectively, m is the mass of the aircraft, and δ _T is the throttle opening of the engine;

Step 42, for the ground speed augmentation system, design a finite-time convergence high-order sliding mode interference observer; the details are as follows:

为V_k的估计值，

为待设计的观测器参数；

为对集总扰动项

的观测估计值。in,

is the estimated value of V _k ,

is the observer parameter to be designed;

is the lumped perturbation term

The observed estimate of .

Compared with the prior art, the present invention adopts the above technical scheme, and has the following technical effects:

1. A ground-speed-constrained anti-disturbance control method for unmanned aerial vehicles based on the obstacle Lyapunov function of the present invention can realize accurate observation and estimation of unmeasurable lumped disturbances induced by uncertainties including parameter perturbations.

2. The present invention is an anti-disturbance control method for UAV ground speed constraint based on obstacle Lyapunov function, which can significantly ensure that the ground speed of the aircraft is strictly constrained and controlled within a desired range.

3. The present invention is a ground-speed-constrained anti-disturbance control method for UAV based on the obstacle Lyapunov function, which can realize the restrained anti-disturbance precise control of ground speed under certain parameter perturbation, and significantly improve the control accuracy.

Description of drawings

FIG. 1 is a block diagram of a ground speed constraint anti-disturbance control method for UAV based on the obstacle Lyapunov function of the present invention.

FIG. 2 is the ground speed tracking result of the aircraft with and without aerodynamic parameter perturbation in the embodiment of the present invention.

FIG. 3 shows the results of ground speed tracking error of the aircraft with and without aerodynamic parameters perturbed in the embodiment of the present invention.

FIG. 4 is the result of perturbing the throttle opening of the aircraft engine with and without aerodynamic parameters in the embodiment of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but not to be construed as a limitation of the present invention.

The present invention is a ground-speed-constrained anti-disturbance control method for unmanned aerial vehicles based on the obstacle Lyapunov function. First, a dynamic model of the aircraft ground-speed nonlinear subsystem is established, and it is processed into an affine nonlinear form; An affine nonlinear model is used to design a finite-time high-order sliding mode disturbance observer to estimate the uncertain disturbance caused by the perturbation of system parameters; on this basis, the estimated unknown disturbance is used as feedforward compensation to design the ground velocity subsystem Nonlinear constrained anti-disturbance tracking controller to achieve accurate tracking of desired ground speed under given ground speed constraints.

In this embodiment, the flight altitude of the aircraft is set to be 7010m.

As shown in Figure 1, a UAV ground speed constraint anti-disturbance control method based on the obstacle Lyapunov function specifically includes the following steps:

地速指令上下界

和

以及地速约束范围S＝{V_k||V_k|≤K_c}。Step 1. Set the aircraft ground speed command

Ground speed command upper and lower bounds

and

And the ground speed constraint range S={V _k ||V _k |≤K _c }.

则地速指令上下边界为

和

同时，本步骤中选取地速约束范围K_c＝202.2m/s。In this step, select the aircraft ground speed command

Then the upper and lower boundaries of the ground speed command are

and

Meanwhile, the ground speed constraint range K _c =202.2m/s is selected in this step.

Step 2: Establish a dynamic model of the aircraft ground speed nonlinear subsystem to describe the ground speed motion state.

In the formula, c ₍ · ₎ = cos ( · ), s ₍ · ₎ = sin ( · ), m is the mass of the aircraft, g is the acceleration of gravity, T is the engine thrust, D, L and C are aerodynamic drag, lift and side force, σ is the engine installation angle, γ is the track inclination angle, α and β are the angle of attack and sideslip angle, and _αw and _βw are the additional quantities of the angle of attack and sideslip angle caused by airflow disturbance.

In this step:

T=T _max δ _T , ρ=ρ ₀ e ^-k|z| , Q=0.5ρV ²

ρ、V和Q分别为大气密度、空速和动压，ρ₀为基准大气密度，k为大气密度计算参数，z为飞行高度，S为气动截面积，

为气动弦长，q为俯仰角速率，δ_e为升降舵偏角，δ_r为方向舵偏角。In the formula,

ρ, V and Q are atmospheric density, airspeed and dynamic pressure, respectively, ρ ₀ is the reference atmospheric density, k is the calculation parameter of atmospheric density, z is the flight height, S is the aerodynamic cross-sectional area,

is the aerodynamic chord length, q is the pitch rate, δ _e is the elevator deflection angle, and δ _r is the rudder deflection angle.

c_D,0＝0.028、

c_C,0＝0、

The physical and aerodynamic parameters of the aircraft are selected as follows: T _max 244647.2N, m=88380kg, S=226.03m ² , c _L,0 = 0,

c _D,0 = 0.028,

c _C,0 = 0,

Step 3: Convert the dynamic model of the ground speed subsystem established in Step 2 into an affine nonlinear form, so as to facilitate the design of a nonlinear controller.

Specific steps are as follows:

Step 31. Separate the ground velocity subsystem dynamic model established in step 2 into: the ground velocity subsystem dynamic model established in step 2 and other items; the details are as follows:

In the formula, δ _T is the throttle opening of the engine, unit: %; T _max is the maximum thrust of the engine.

Step 32, write formula (2) in step 31 into the affine nonlinear form described by formula (3); the details are as follows:

In the formula,

视为系统集总扰动，设计有限时间收敛高阶滑模干扰观测器对其进行准确观测估计。Step 4. The term in the affine nonlinear model of the aircraft ground speed that is linearly independent of the throttle opening δT of the control _variable

Considering the system lumped disturbance, a finite-time convergent high-order sliding-mode disturbance observer is designed to accurately observe and estimate it.

Specific steps are as follows:

增广为该系统的一个新状态，得到地速增广系统；具体如下：Step 41, put step 32 in formula (3)

Augmentation is a new state of the system, and the ground-speed augmentation system is obtained; the details are as follows:

是

的导数；In the formula,

Yes

the derivative of ;

Step 42: Design a finite-time convergent high-order sliding-mode interference observer for the ground speed augmentation system described by equation (4) in step 41; the details are as follows:

为待设计的观测器参数；

即为对集总扰动项

的观测估计值。In the formula,

is the observer parameter to be designed;

is the lumped perturbation term

The observed estimate of .

In this step, the parameters of the finite-time convergent high-order sliding mode observer are selected as:

Step 5: Taking the disturbance estimated in step 4 as a feedforward compensation term, and combining the ground speed constraint condition, a ground speed constrained anti-jamming controller based on the obstacle Lyapunov function is designed.

Specific steps are as follows:

并定义常数A₀＞0，则

Step 51, define ground speed tracking error

And define the constant A ₀ > 0, then

的不对称障碍Lyapunov函数；具体如下：Step 52, select based on

The asymmetric barrier Lyapunov function of ; as follows:

p≥1为正整数，

In the formula,

p≥1 is a positive integer,

Step 53, design the aircraft ground speed constrained tracking controller; the details are as follows:

为地速反馈控制增益。In the formula,

Control gain for ground speed feedback.

代替步骤53中式(7)中的

得到飞机地速受约束抗扰动跟踪控制器，完成控制器设计；具体如下：Step 54, use the aggregated interference estimate obtained by the observer in step 4

Substitute for step 53 in formula (7)

The aircraft ground speed constrained anti-disturbance tracking controller is obtained, and the controller design is completed; the details are as follows:

p＝2。In this step, the selected control parameters are:

p=2.

Using the ground speed constraint anti-disturbance control method of the UAV based on the obstacle Lyapunov function of the present invention, combined with the above-mentioned given flight and ground speed constraints, respectively, in the absence of the above aerodynamic parameter perturbation, -20% aerodynamic parameter perturbation and +20% % Under the perturbation of aerodynamic parameters, the result graph of the ground speed, ground speed error and throttle opening of the aircraft obtained by simulation.

As shown in FIG. 2 , it is the result of ground speed tracking of the aircraft without perturbation of aerodynamic parameters, -20% perturbation of aerodynamic parameters and +20% perturbation of aerodynamic parameters in this embodiment. It can be seen that with or without the perturbation of aerodynamic parameters, the ground speed controller of the method of the present invention can well control the ground speed and accurately track the command, and the ground speed tracking results in the three cases tend to coincide, which fully shows that The aircraft ground speed controller proposed by the present invention has excellent anti-interference ability and can better resist the perturbation effect of ±20% aerodynamic parameters; on the other hand, the ground speed tracking results in the three cases do not exceed the given ground speed The speed constraint range K _C =202.2m/s, which shows that the method of the present invention can accurately constrain the ground speed within the given constraint range.

As shown in FIG. 3 , it is the result of the ground speed tracking error of the aircraft with no aerodynamic parameter perturbation, -20% aerodynamic parameter perturbation and +20% aerodynamic parameter perturbation in this embodiment. It can be seen that with or without the perturbation of aerodynamic parameters, the tracking error is slightly different at the beginning, but it tends to coincide soon, and the controller can better resist the influence of ±20% perturbation of aerodynamic parameters, thus Keep a high tracking accuracy; on the other hand, the ground speed tracking error results in the three cases do not exceed the given ground speed error constraint range [-0.20.2]m/s, which also confirms that the method of the present invention can be accurate ground speed restraint control capability.

As shown in Figure 4, it is the result graph of the throttle opening without perturbation of aerodynamic parameters, -20% perturbation of aerodynamic parameters and +20% perturbation of aerodynamic parameters. It can be seen that with the introduction of aerodynamic parameter perturbation, the throttle opening has obvious differences in amplitude, but the overall change trend tends to be consistent. When the aerodynamic parameter perturbation increases (such as +20%), a larger throttle opening is required to achieve the desired ground speed constrained anti-disturbance control effect; conversely, when the aerodynamic parameter perturbation decreases (such as -20%) , a smaller throttle opening is required to achieve the desired ground speed constrained anti-disturbance control effect.

Based on the above analysis and simulation verification, the effectiveness of the ground speed constrained anti-disturbance control method of the UAV based on the obstacle Lyapunov function of the present invention is fully proved in the precise control of the ground speed constrained anti-disturbance of the aircraft.

The above embodiments are only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the present invention. Inside.

Claims (4)

1. an unmanned aerial vehicle ground speed constraint anti-disturbance control method based on obstacle Lyapunov function, is characterized in that, comprises the steps: Step 1, set the aircraft ground speed command

Ground speed command upper bound

and the Nether

and the ground speed constraint range K _c ; Step 2, establish a dynamic model of the aircraft ground speed nonlinear subsystem to describe the ground speed motion state; Step 3, converting the dynamic model of the aircraft ground speed nonlinear subsystem established in step 2 into an aircraft ground speed affine nonlinear model; Step 4: The term in the aircraft ground speed affine nonlinear model that is linearly independent of the throttle opening _δT of the control variable is regarded as the system lumped disturbance term, and a finite-time convergence high-order sliding mode disturbance observer is designed to observe the lumped disturbance. estimate; In step 5, the aggregate disturbance obtained by the observation and estimation in step 4 is used as the feedforward compensation term, and combined with the ground speed constraint condition, a ground speed constrained anti-jamming controller based on the obstacle Lyapunov function is designed; the specific process is as follows: Step 51, define ground speed tracking error

V _k is the ground speed of the aircraft,

is the aircraft ground speed command, and defines the constant A ₀ > 0 such that

Step 52, select based on

The asymmetric barrier Lyapunov function of ; as follows:

where L represents the asymmetric barrier Lyapunov function,

p is a positive integer, p≥1,

Step 53, design the aircraft ground speed constrained tracking controller; the details are as follows:

in,

T _max is the maximum thrust of the engine, σ is the engine installation angle, α and β are the angle of attack and sideslip angle, respectively, m is the mass of the aircraft,

is the lumped disturbance term,

is the ground speed feedback control gain; Step 54, use the estimated value of aggregated interference observations obtained by the observer in step 4

Substitute for step 53 in the formula

The aircraft ground speed constrained anti-disturbance tracking controller is obtained, and the controller design is completed; the details are as follows:

2. the unmanned aerial vehicle ground speed constraint anti-disturbance control method based on obstacle Lyapunov function according to claim 1, is characterized in that, described in step 2, the aircraft ground speed nonlinear subsystem dynamic model is:

Among them, V _k is the ground speed of the aircraft, m is the mass of the aircraft, g is the acceleration of gravity, T is the thrust of the engine, D, L, and C are the aerodynamic drag, lift, and side force, respectively, σ is the engine installation angle, and γ is the track inclination angle. , α and β are the angle of attack and sideslip angle, respectively, and _αw and _βw are the additional quantities of the angle of attack and sideslip angle caused by airflow disturbance, respectively. 3. the unmanned aerial vehicle ground speed restraint anti-disturbance control method based on obstacle Lyapunov function according to claim 1 is characterized in that, the concrete process of described step 3 is: Step 31, separate the dynamic model of the aircraft ground speed nonlinear subsystem established in step 2 into two parts:

Among them, V _k is the ground speed of the aircraft, m is the mass of the aircraft, g is the acceleration of gravity, T _max is the maximum thrust of the engine, D, L, and C are the aerodynamic drag, lift, and side force, respectively, σ is the engine installation angle, and γ is the air force. track inclination, α and β are the angle of attack and sideslip angle, respectively, _αw and _βw are the additional amounts of the angle of attack and sideslip angle caused by airflow disturbance, respectively, _δT is the engine accelerator opening; Step 32, convert the model of step 31 into an affine nonlinear model of aircraft ground speed:

in,

4. the unmanned aerial vehicle ground speed restraint anti-disturbance control method based on obstacle Lyapunov function according to claim 1, is characterized in that, the concrete process of described step 4 is: Step 41, the term in the aircraft ground speed affine nonlinear model that is linearly independent of the throttle opening δT of the control _variable

As the lumped disturbance term of the system, the ground speed affine nonlinear model of the aircraft is augmented, and the ground speed augmented system is obtained:

where V _k is the ground speed of the aircraft,

Yes

the derivative of ,

T _max is the maximum thrust of the engine, σ is the engine installation angle, α and β are the angle of attack and sideslip angle, respectively, m is the mass of the aircraft, and δ _T is the throttle opening of the engine; Step 42, for the ground speed augmentation system, design a finite-time convergence high-order sliding mode interference observer; the details are as follows:

in,

is the estimated value of V _k ,

is the observer parameter to be designed;

is the lumped perturbation term

The observed estimate of .

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