CN115327906A - Design method and system of fault-tolerant controller of quad-rotor unmanned aerial vehicle - Google Patents

Abstract

The method comprises the steps of constructing a target motion model for reflecting the flight condition of the unmanned aerial vehicle by combining the fault distribution condition and the rotor rotating speed of the unmanned aerial vehicle under the condition that the influence of faults on a rotor is considered; setting a relative threshold value and a fixed threshold value which synchronously change along with the change of the control input of the model; by combining with the event triggering characteristic, the flight track of the unmanned aerial vehicle approaches to a preset target flight track through the relative threshold and the control input of the fixed threshold adjusting model; in the adjusting process, a corresponding virtual control law and an actual control law are designed in a recursion mode by adopting a backstepping method, so that the model approaches asymptotically stable. The implementation of the method can ensure the accurate tracking control when multiple faults of the quad-rotor unmanned aerial vehicle occur simultaneously.

Description

Design method and system for a fault-tolerant controller of a quadrotor UAV

technical field

The present application relates to the field of unmanned aerial vehicle control technology, in particular, to a design method and system for a fault-tolerant controller of a quadrotor unmanned aerial vehicle.

Background technique

In recent years, with the rapid development of technologies in the fields of communication, computer, and network, the related topics of quadrotor drones have become a new research direction in the field of automatic control. Quadrotor drones can complete various tasks in a wide range of complex environments with low cost and high flexibility, which makes quadrotor drones continue to improve their status in the military and civilian fields. Therefore, in order to make better use of quadrotor UAVs to assist in completing various tasks, the control of quadrotor UAVs has attracted more and more attention from researchers.

The current mainstream attitude stabilization or tracking methods for quadrotor UAVs mainly include control structures, backstepping, theory-based control methods, and adaptive control. Although the existing control methods can improve the stability of the UAV during flight; however, these control methods are all based on the control method when the quadrotor UAV system is fault-free, and because the UAV is at high speed During the operation process, with the aging of components or the occurrence of damage to the drive motor and propeller, it is easy to cause the drive motor-propeller system to fail, resulting in the failure of the quadrotor UAV to complete the set tasks, and even out of control to cause safety problems, which makes While discussing the control problem of quadrotor UAV, it is necessary to ensure that it can achieve ideal performance under normal conditions and under fault conditions.

Currently, the traditional FDA architecture usually employs a fault detection, isolation, and evaluation (FDIE algorithm) mechanism to provide diagnostic information on faults that have occurred. Early on, fault detection and isolation may help avoid more severe failures, and the detailed fault information generated during fault diagnosis is valuable for condition-based maintenance and redundancy management. However, the overall performance of this type of fault-tolerant control method is directly affected by the time delay between fault occurrence and fault isolation, and the accuracy of the FDIE algorithm. When multiple faults occur at the same time, the accuracy of the FDIE algorithm will be difficult to guarantee. There is a problem of low control accuracy.

Contents of the invention

The purpose of the embodiments of the present application is to provide a design method and system for a fault-tolerant controller of a quadrotor UAV, which can ensure accurate tracking control of the quadrotor UAV when multiple faults occur simultaneously.

The embodiment of the present application also provides a design method for a fault-tolerant controller of a quadrotor UAV, including the following steps:

S1. In the case of considering the impact of faults on the rotor, combined with the distribution of faults and the rotor speed of the UAV, construct a target motion model for reflecting the flight status of the UAV;

S2. Setting a relative threshold that changes synchronously with changes in the control input of the model, and a fixed threshold;

S3. In combination with the event trigger feature, adjust the control input of the model through the relative threshold and the fixed threshold, so that the flight trajectory of the drone approaches the preset target flight trajectory;

S4. During the adjustment process, the corresponding virtual control law and actual control law are recursively designed by using the backstepping method, so that the model tends to be asymptotically stable.

In the second aspect, the embodiment of the present application also provides a design system for a fault-tolerant controller of a quadrotor UAV, which is characterized in that the system includes a motion model building module, a threshold setting module, a control input adjustment module and a feedback Step-by-step recursive design module, in which:

The motion model construction module is used to construct a target motion model for reflecting the flight status of the UAV in consideration of the impact of the fault on the rotor, in combination with the distribution of the fault and the rotor speed of the UAV;

The threshold setting module is used to set a relative threshold that changes synchronously with changes in the control input of the model, and a fixed threshold;

The control input adjustment module is configured to adjust the control input of the model through the relative threshold and the fixed threshold in combination with the event triggering characteristics, so that the flight trajectory of the drone approaches a preset target flight trajectory;

The backstepping recursive design module is used to recursively design the corresponding virtual control law and actual control law by using the backstepping method during the adjustment process, so that the model tends to be asymptotically stable.

In the third aspect, the application provides a readable storage medium, the readable storage medium includes the design method program of the fault-tolerant controller of the quadrotor UAV, and the design of the fault-tolerant controller of the quadrotor UAV When the method program is executed by the processor, the steps of any one of the methods described above are realized.

It can be seen from the above that the design method, system and readable storage medium of a fault-tolerant controller for a quadrotor UAV provided by the embodiment of the present application consider the influence of the fault on the rotor, simulate the fault through fault parameters, and use Compared with the traditional control method, the event trigger mechanism of comprehensive relative threshold control and fixed threshold control can minimize the number of event triggers, and can save communication resources while ensuring the control effect. In the case of ensuring the event trigger mechanism, the corresponding virtual control law and actual control law are recursively designed by using the backstepping method, which can make the system asymptotically stable and ensure the precise tracking control of the quadrotor UAV when multiple faults occur simultaneously. .

Other features and advantages of the present application will be set forth in the ensuing description and, in part, will be apparent from the description, or can be learned by practicing the embodiments of the present application. The objectives and other advantages of the application may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings that need to be used in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, so It should not be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings according to these drawings without creative work.

Fig. 1 is the flow chart of the design method of a kind of quadrotor unmanned aerial vehicle fault-tolerant controller that the embodiment of the present application provides;

Figure 2 is a schematic diagram of the results of simulation debugging based on the design method of the fault-tolerant controller of the quadrotor UAV;

FIG. 3 is a schematic structural diagram of a design system for a fault-tolerant controller of a quadrotor UAV provided in an embodiment of the present application.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all of them. The components of the embodiments of the application generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations. Accordingly, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present application.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures. Meanwhile, in the description of the present application, the terms "first", "second" and the like are only used to distinguish descriptions, and cannot be understood as indicating or implying relative importance.

Please refer to FIG. 1 . FIG. 1 is a flow chart of a design method of a fault-tolerant controller for a quadrotor UAV in some embodiments of the present application. The method includes the following steps:

Step S1, considering the impact of the fault on the rotor, combined with the distribution of faults and the rotor speed of the UAV, construct a target motion model to reflect the flight status of the UAV.

Step S2, setting a relative threshold that changes synchronously with changes in the control input of the model, and a fixed threshold.

Step S3, in combination with the event-triggered characteristics, adjust the control input of the model through the relative threshold and the fixed threshold, so that the flight trajectory of the UAV approaches the preset target flight trajectory.

Step S4, during the adjustment process, the corresponding virtual control law and the actual control law are recursively designed by using the backstepping method, so that the model tends to be asymptotically stable.

It can be seen from the above that the design method of a fault-tolerant controller for a quadrotor UAV disclosed in this application considers the influence of faults on the rotor, simulates faults through fault parameters, and adopts comprehensive relative threshold control and fixed threshold control Compared with the traditional control method, the unique event trigger mechanism can minimize the number of event triggers, and can save communication resources while ensuring the control effect. In the case of ensuring the event trigger mechanism, the corresponding virtual control law and actual control law are recursively designed by using the backstepping method, which can make the system asymptotically stable and ensure the precise tracking control of the quadrotor UAV when multiple faults occur simultaneously. .

In one of the embodiments, in step S1, considering the impact of the fault on the rotor, combining the fault distribution and the rotor speed of the UAV, constructing a target motion model for reflecting the flight status of the UAV, include:

Step S11, in combination with the impact of the fault on the rotor, define corresponding fault parameters, wherein the definition of the fault parameters includes:

为定义的故障参数。Among them, α _s represents the fault degree,

is the defined fault parameter.

时表示当前转子是正常运转的；其他情况下，则表示转子在运转的过程中产生了故障，且会产生对应程度的推力损失。Specifically, when

When , it means that the current rotor is operating normally; in other cases, it means that the rotor has a fault during operation, and a corresponding degree of thrust loss will occur.

Step S12, according to the fault parameters, fault distribution and rotor speed of the UAV, determine the synchronously generated thrust and torque, wherein the definition of the thrust and torque includes:

Among them, U represents the thrust, which is the control input of the model; τ _φ , τ _θ , τ _ψ represent the angular acceleration generated by the UAV in the three directions of yaw, pitch and roll respectively, and I ₄ represents the unit of 4×4 matrix, M represents the mapping matrix between thrust and torque and rotational speed, Λ _s represents the preset fault distribution matrix, and Ω _i (i=1,2,3,4) is the rotational speed of the four rotors of the UAV.

Specifically, since the thrust and torque of the rotor are proportional to the square of the rotational speed, in the current embodiment, the thrust and torque of the quadrotor UAV will be further determined in combination with the definition of the above fault parameters.

In one of the embodiments, Λ _s represents the fault distribution matrix, and s=1...4 represents the number of rotors that have faults. Exemplarily, when s=1, then there is Λ ₁ =diag{1,0,0,0}; when s=2, then there is Λ ₂ =diag{0,1,0,0}, in other cases It can be deduced by analogy, which is not limited in this embodiment of the present application.

In step S13, the determined thrust and torque are substituted into the dynamic model of the UAV for model conversion to obtain a target motion model for reflecting flight conditions.

Specifically, the definition of the dynamic model of the UAV includes:

It should be noted that since the various parameters in the above formula have been defined later, no further explanation will be given at present.

The above-mentioned embodiment considers the influence of the fault on the rotor, simulates the fault through the fault parameters, and needs to adopt adaptive control to eliminate the influence of the fault, so as to ensure the precise tracking control when multiple faults of the UAV occur at the same time, and further improve the control Effect.

In one of the embodiments, in step S13, the definition method of the target motion model includes:

x₁＝[p_z,φ,θ,ψ]^T,x₂＝[v_z,p,q,r]^T，[φ,θ,ψ]分别表示产生的偏航角、俯仰角以及滚转角，[p,q,r]分别对应表示上述三个角的角加速度；p_z表示惯性垂直位置，v_z表示惯性垂直速度；R_η(φ,ψ)表示将产生的角速度和欧拉角速度关联起来的关联矩阵，m表示无人机的机体重量，g表示产生的重力加速度；J＝diag{J_x,J_y,J_z}表示机体的惯性矩阵，c_d表示机体的阻力系数；

为参数x₁的导数，

为参数x₂的导数。in,

x ₁ ＝[p _z ,φ,θ,ψ] ^T , x ₂ ＝[v _z ,p,q,r] ^T , [φ,θ,ψ] represent the yaw angle, pitch angle and roll angle generated respectively , [p, q, r] respectively correspond to the angular accelerations of the above three angles; p _z represents the inertial vertical position, v _z represents the inertial vertical velocity; R _η (φ, ψ) represents the relationship between the angular velocity and the Euler angular velocity The resulting correlation matrix, m represents the body weight of the UAV, g represents the gravitational acceleration generated; J=diag{J _x , J _y , J _z } represents the inertia matrix of the body, and c _d represents the drag coefficient of the body;

is the derivative of the parameter x ₁ ,

is the derivative of the parameter _x2 .

In the above embodiment, the second-order Newton-Lagrangian model is used to construct the dynamic model of the UAV, wherein the rotation of the quadrotor UAV is represented by the rotation matrix, which can better describe the attitude of the UAV, and is more concise The realization of UAV control input to the solution of each rotor speed of UAV.

In one of the embodiments, in step S3, adjusting the control input of the model through the relative threshold and the fixed threshold so that the flight trajectory of the drone approaches the preset target flight trajectory includes:

In step S31, the actual control input of the model is obtained, and the actual control input is compared with a preset switching threshold control parameter.

与预设的切换阈值控制参数D进行比较，以确定何时切换控制策略。In the current embodiment, the actual control of the model will be further input into

It is compared with the preset switching threshold control parameter D to determine when to switch the control strategy.

时，当前将切换到相对阈值策略，通过将无人机的控制输入与相对阈值进行关联，当确定无人机的控制输入比较大时，则说明无人机离目标轨迹较远，由于此时的主要任务是使无人机先追到目标飞行轨迹附近，所以不需要精细控制。For example, after determining

When , it will switch to the relative threshold strategy at present. By associating the control input of the UAV with the relative threshold, when it is determined that the control input of the UAV is relatively large, it means that the UAV is far away from the target trajectory. The main task of the drone is to make the UAV catch up to the target flight track first, so fine control is not required.

It should be noted that because the value of the control input is relatively large, the value of the corresponding relative threshold is relatively large. At this time, the trigger threshold is relatively high and the number of triggers is relatively small. In this way, no one The machine can track the target at a faster tracking speed.

In other cases, it will switch to a fixed threshold strategy. When it is determined that the UAV is approaching the target flight trajectory, as the control input decreases, the fixed threshold will be used to achieve high-precision control by increasing the number of controls to ensure the improvement of the control effect. .

It should be noted that the fixed threshold may be a positive constant. In the current embodiment, its specific value is not limited. In different embodiments, it can be determined through simulation and debugging in combination with specific practical situations. The purpose is to ensure that the UAV is on the target flight path. Nearby control effects, while reducing the number of triggers and saving communication resources.

Step S32, when it is determined that the flight trajectory of the UAV is far from the target trajectory, and the actual control input is greater than or equal to the preset switching threshold control parameter, based on the relative threshold, the actual control input The interval difference between the control input and the control input set at different times is used to determine whether the first triggering time is reached.

大于、或等于预设的切换阈值控制参数D时，将进一步比较相对阈值、与所述实际控制输入与不同时刻中设置的控制输入之间的间隔差值即

之间的大小。Specifically, in determining the actual control input of the model

When it is greater than or equal to the preset switching threshold control parameter D, the relative threshold will be further compared with the interval difference between the actual control input and the control input set at different times, that is,

size between.

时，将该第一目标时刻作为第一触发时刻，后续将基于该第一触发时刻设置的设计控制输入调整模型的实际控制输入。In one of the embodiments, when judging whether the first trigger moment is reached, the implementation that can be referred to includes: the relative threshold obtained in determining the first target moment is greater than or equal to the interval difference existing at this moment

, the first target time is used as the first trigger time, and the design control input set based on the first trigger time is subsequently used to adjust the actual control input of the model.

Step S33, when it is determined that the first trigger moment is reached, based on the control input set at the first trigger moment, the actual control input of the model is adjusted so that the UAV quickly approaches the target trajectory.

的更新，即使得

其中，在非触发时刻中即t∈[t,t_k+1)，实际控制输入将保持不变即不做更新，直到达到触发时刻t_k+1即t＝t_k+1时，才基于该触发时刻t_k+1中设置的设计控制输入Ω进行更新。Specifically, when it is determined that the first trigger time t _k+1 is reached, the design control input Ω set at this time t _k+1 will be further determined. Afterwards, the actual control input to the model is realized based on the design control input Ω

update, that is,

Among them, in the non-triggering moment, that is, t∈[t,t _k+1 ), the actual control input will remain unchanged, that is, no update will be made, until the triggering moment t _k+1 is reached, that is, t=t _k+1 , based on The programmed control input Ω set at this trigger instant t _k+1 is updated.

Step S34, when it is determined that the UAV is near the target trajectory, and the actual control input is less than the preset switching threshold control parameter, based on the fixed threshold, the actual control input and the control input set at different times The difference between the intervals is determined to determine whether the second trigger moment has been reached.

小于预设的切换阈值控制参数D时，将进一步比较固定阈值、与所述实际控制输入与不同时刻中设置的控制输入之间的间隔差值即

之间的大小。Specifically, in determining the actual control input of the model

When it is less than the preset switching threshold control parameter D, the fixed threshold will be further compared with the interval difference between the actual control input and the control input set at different times, that is,

size between.

时，将该第二目标时刻作为第二触发时刻。In one of the embodiments, when judging whether the second trigger moment is reached, the implementation that can be referred to includes: the fixed threshold obtained in determining the second target moment is greater than or equal to the interval difference existing at this moment

, use the second target moment as the second trigger moment.

Step S35, when it is determined that the second trigger moment is reached, the actual control input of the model is adjusted based on the control input set at the second trigger moment.

Specifically, when it is determined that the second trigger moment is reached, the adjustment manner of the actual control input of the model may refer to the foregoing implementation manners, and no further description is given in the current embodiment.

In the current embodiment, the advantages of relative threshold control and fixed threshold control are integrated, so that the controller will only make changes, that is, update, when the corresponding threshold conditions are met. Compared with the traditional control method, the controller will follow It changes in real time as the system changes, which can minimize the number of event triggers and improve the control effect at the same time.

In one embodiment, in step S32, the judging whether the first triggering moment is reached based on the relative threshold, the interval difference between the actual control input and the control input set at different times includes:

Step S321, when it is determined that the interval difference is greater than or equal to the relative threshold, judge whether the first trigger moment is reached by the following formula:

表示所述实际控制输入，Ω表示在时刻t中设置的控制输入，m₁、m₂分别表示预设的常数，“m₁Ω+m₂”表示随Ω变化而同步发生变化的相对阈值。Among them, t _k+1 represents the first trigger moment reached, t represents the time, R represents the preset real number set,

represents the actual control input, Ω represents the control input set at time t, m ₁ and m ₂ represent preset constants respectively, and “m ₁ Ω+m ₂ ” represents a relative threshold that changes synchronously with Ω.

In one embodiment, in step S34, the determining whether the second triggering moment is reached based on the fixed threshold, the interval difference between the actual control input and the control input set at different times, includes:

Step S341, when it is determined that the interval difference is greater than or equal to the fixed threshold, judge whether the second trigger moment is reached by the following formula:

where m represents a fixed threshold.

In one of the embodiments, in step S4, in the adjustment process, the corresponding virtual control law is recursively designed by using the backstepping method, including:

Step S41, performing coordinate changes based on the target motion model to obtain:

Among them, z1 represents the coordinate transformation form _of the state variable x1, _z2 represents the coordinate transformation form _of the state variable _x2 , c1 represents the preset proportional gain, _c2 represents the preset integral gain, and _x1 represents the system _of the model state, x _d represents the achieved target state, and α represents the virtual control law.

Specifically, the reason for the current coordinate change is to facilitate the design and processing of the subsequent backstepping method. In the current embodiment, an appropriate Lyapunov function will be selected based on the principle of adaptive control, and then its derivative will be derived, and a corresponding virtual control law will be designed.

Step S42, based on the principle of adaptive control, select the corresponding first Lyapunov function V ₁ :

表示故障参数的参数估计。Among them, σ _s represents the adaptive parameter,

represents the parameter estimate of the failure parameter.

Step S43, solving the first-order derivative for the first Lyapunov function V ₁ to obtain the corresponding first-order derivative

的第一限定条件，设计出相应的虚拟控制律，以使得系统趋近渐近稳定，其中：Step S44, based on making the first order derivative negative definite

The first limiting condition of , the corresponding virtual control law is designed to make the system approach to asymptotically stable, where:

Among them, α ₁ represents the virtual control law at the design site, a>0, b>0, 0<δ<1 are all preset positive numbers, and k ₁ represents the preset error gain.

进行化简。之后，在此基础上，再进行虚拟控制律的设计，并在确定所选取的虚拟控制律能够可以使一阶导数负定时，即认为当前所设计的虚拟控制律能使得无人机系统实现渐近稳定。Specifically, after solving the first-order derivative of the first Lyapunov function V ₁ , in order to reduce the amount of calculation, the obtained first-order derivative

Simplify. Afterwards, on this basis, the virtual control law is designed, and after confirming that the selected virtual control law can make the first-order derivative negative timing, it is considered that the currently designed virtual control law can make the UAV system realize gradual nearly stable.

In the above embodiments, various system control requirements are integrated, and a virtual control law is recursively designed by using the backstepping method, so that the UAV system can achieve asymptotic stability and improve the control effect.

In one of the embodiments, in step S4, in the adjustment process, the corresponding actual control law is recursively designed by using the backstepping method, including:

Step S45, based on the principle of adaptive control, select the corresponding second Lyapunov function V ₂ , namely:

Specifically, the various parameters in the above formula have been explained above, and will not be explained too much at present.

Step S46, solving the first-order derivative for the second Lyapunov function V ₂ to obtain the corresponding first-order derivative

进行化简，之后再此基础上，再基于事件触发特性、以及使得一阶导数负定的限定条件，进行实际控制律的设计。Specifically, before designing the corresponding actual control law, the obtained first derivative

After simplification, on this basis, the design of the actual control law is carried out based on the event-triggered characteristics and the limiting conditions that make the first-order derivative negative.

的第二限定条件，设计出相应的实际控制律，以使得在故障条件下也能够完成对目标的渐近跟踪，其中：Step S47, based on the event-triggered characteristics, making the first-order derivative negative definite, that is,

The second limiting condition of , the corresponding actual control law is designed so that the asymptotic tracking of the target can also be completed under fault conditions, where:

或

其中，λ_i(t),i＝1,...,3表示连续时变参数，其满足λ_i(t_k)＝0,λ_i(t_k+1)＝±1且|λ_i|≤1；δ表示预设的正参数，m₁表示相对阈值控制输入增益。

or

Among them, λ _i (t), i=1,...,3 represent continuous time-varying parameters, which satisfy λ _i (t _k )=0, λ _i (t _k+1 )=±1 and |λ _i | ≤1; δ represents the preset positive parameter, and m ₁ represents the relative threshold control input gain.

能够使得

时，则说明当前所提出的事件触发机制仍能使系统实现渐近稳定。在其中一个实施例中，还可以利用拉格朗日中值定理，验证事件触发机制能够避免芝诺现象，以保证控制精准度。Specifically, in the actual control law designed

able to make

, it shows that the proposed event-triggered mechanism can still make the system asymptotically stable. In one of the embodiments, the Lagrangian median value theorem can also be used to verify that the event trigger mechanism can avoid the Zeno phenomenon, so as to ensure control accuracy.

进行系统仿真。In one of the embodiments, please refer to Fig. 2, in order to verify that the controller designed by the present application can make the system, its states follow the given reference signal changes, the following parameters will be selected: M=1kg, g=9.8m/ s ² , and the reference signal:

Perform system simulation.

Among them, it can be seen from Figure 2(d) that the event-triggered adaptive fault-tolerant control can quickly and accurately make the UAV system track the target estimate (ie, the target trajectory). It should be noted that the solid line in Figure 2(a)-Figure 2(d) is the actual trajectory of the UAV system, and the dotted line is the target trajectory. It can be seen from the figure that the adaptive control based on event triggering can quickly and accurately make the UAV system track the target trajectory, and the tracking error is small, and the tracking effect is very good. It can be seen from the following table 1 that the trigger mode is the switch threshold event trigger mechanism, which can greatly reduce the number of triggers compared with the traditional time trigger mechanism, thus ensuring accurate tracking control when multiple faults of the drone occur simultaneously, and also It can effectively reduce the control times and save communication resources.

Table 1 Comparison of trigger times

trigger method Trigger times traditional time trigger 10000 Toggle Threshold Event Trigger 326

Please refer to FIG. 3 , which is a design system 300 of a fault-tolerant controller for a quadrotor UAV disclosed in the present application. Step recursive design module 304, wherein:

The motion model construction module 301 is used to construct a target motion model for reflecting the flight status of the UAV in consideration of the influence of the fault on the rotor, combined with the distribution of the fault and the rotor speed of the UAV.

The threshold setting module 302 is configured to set a relative threshold that changes synchronously with changes in the control input of the model, and a fixed threshold.

The control input adjustment module 303 is configured to adjust the control input of the model through the relative threshold and the fixed threshold in combination with event triggering characteristics, so that the flight trajectory of the UAV approaches a preset target flight trajectory.

The backstepping recursive design module 304 is used to recursively design the corresponding virtual control law and actual control law by using the backstepping method during the adjustment process, so that the model tends to be asymptotically stable.

In one of the embodiments, each module in the system is also used to implement the method in any optional implementation manner of the embodiment, which will not be described too much in the current embodiment.

It can be seen from the above that the design system of a fault-tolerant controller for a quadrotor UAV disclosed in this application considers the impact of faults on the rotor, simulates faults through fault parameters, and adopts comprehensive relative threshold control and fixed threshold control Compared with the traditional control method, the unique event trigger mechanism can minimize the number of event triggers, and can save communication resources while ensuring the control effect. In the case of ensuring the event trigger mechanism, the corresponding virtual control law and actual control law are recursively designed by using the backstepping method, which can make the system asymptotically stable and ensure the precise tracking control of the quadrotor UAV when multiple faults occur simultaneously. .

An embodiment of the present application provides a readable storage medium. When the computer program is executed by a processor, the method in any optional implementation manner of the foregoing embodiments is executed. Wherein, the storage medium can be realized by any type of volatile or non-volatile storage device or their combination, such as Static Random Access Memory (Static Random Access Memory, referred to as SRAM), Electrically Erasable Programmable Read-Only Memory (EPROM) Electrically Erasable Programmable Read-Only Memory, referred to as EEPROM), Erasable Programmable Read-Only Memory (Erasable Programmable Read Only Memory, referred to as EPROM), Programmable Read-Only Memory (Programmable Red-Only Memory, referred to as PROM), Read-only memory (Read -Only Memory, referred to as ROM), magnetic memory, flash memory, magnetic disk or optical disk.

The above-mentioned readable storage medium considers the impact of faults on the rotor, simulates faults through fault parameters, and adopts the event trigger mechanism of comprehensive relative threshold control and fixed threshold control. Compared with traditional control methods, it can maximize the Reduce the number of event triggers, while ensuring the control effect, it can also save communication resources. In the case of ensuring the event trigger mechanism, the corresponding virtual control law and actual control law are recursively designed by using the backstepping method, which can make the system asymptotically stable and ensure the precise tracking control of the quadrotor UAV when multiple faults occur simultaneously. .

In the embodiments provided in this application, it should be understood that the disclosed devices and methods may be implemented in other ways. The device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or May be integrated into another system, or some features may be ignored, or not implemented. In another point, the mutual coupling or direct coupling or communication connection shown or discussed may be through some communication interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.

In addition, a unit described as a separate component may or may not be physically separated, and a component displayed as a unit may or may not be a physical unit, that is, it may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

Furthermore, each functional module in each embodiment of the present application may be integrated to form an independent part, each module may exist independently, or two or more modules may be integrated to form an independent part.

In this document, relational terms such as first and second etc. are used only to distinguish one entity or operation from another without necessarily requiring or implying any such relationship between these entities or operations. Actual relationship or sequence.

The above descriptions are only examples of the present application, and are not intended to limit the scope of protection of the present application. For those skilled in the art, various modifications and changes may be made to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims (10)

1. a design method of a quadrotor unmanned aerial vehicle fault-tolerant controller, is characterized in that, comprises the following steps: S1. In the case of considering the impact of faults on the rotor, combined with the distribution of faults and the rotor speed of the UAV, construct a target motion model for reflecting the flight status of the UAV; S2. Setting a relative threshold that changes synchronously with changes in the control input of the model, and a fixed threshold; S3. In combination with the event trigger feature, adjust the control input of the model through the relative threshold and the fixed threshold, so that the flight trajectory of the drone approaches the preset target flight trajectory; S4. During the adjustment process, the corresponding virtual control law and actual control law are recursively designed by using the backstepping method, so that the model tends to be asymptotically stable. 2. The method according to claim 1, characterized in that in step S1, in consideration of the impact of the fault on the rotor, combined with the distribution of faults and the rotor speed of the UAV, the construction for reflecting the UAV The target motion model of aircraft flight conditions, including: S11. Combining with the impact of the fault on the rotor, define corresponding fault parameters, wherein the definition of the fault parameters includes:

Among them, α _s represents the fault degree,

is the defined fault parameter; S12. Determine synchronously generated thrust and torque according to the fault parameters, fault distribution and rotor speed of the UAV, wherein the definition of the thrust and torque includes:

Among them, U represents the thrust, which is the control input of the model; τ _φ , τ _θ , τ _ψ represent the angular acceleration generated by the UAV in the three directions of yaw, pitch and roll respectively, and I ₄ represents the unit of 4×4 Matrix, M represents the mapping matrix between thrust and torque and rotational speed, Λ _s represents the preset fault distribution matrix, Ω _i (i=1,2,3,4) is the rotational speed of the four rotors of the drone; S13. Substituting the determined thrust and torque into the dynamics model of the UAV to perform model conversion to obtain a target motion model for reflecting flight conditions. 3. The method according to claim 2, characterized in that, in step S13, the definition of the target motion model comprises:

in,

x ₁ ＝[p _z ,φ,θ,ψ] ^T , x ₂ ＝[v _z ,p,q,r] ^T , [φ,θ,ψ] represent the yaw angle, pitch angle and roll angle generated respectively , [p, q, r] respectively correspond to the angular accelerations of the above three angles; p _z represents the inertial vertical position, v _z represents the inertial vertical velocity; R _η (φ, ψ) represents the relationship between the angular velocity and the Euler angular velocity The resulting correlation matrix, m represents the body weight of the UAV, g represents the gravitational acceleration generated; J=diag{J _x , J _y , J _z } represents the inertia matrix of the body, and c _d represents the drag coefficient of the body;

is the derivative of the parameter x ₁ ,

is the derivative of the parameter _x2 . 4. The method according to claim 3, characterized in that, in step S3, the control input of the model is adjusted by the relative threshold and the fixed threshold, so that the flight track of the unmanned aerial vehicle approaches a predetermined The set target flight trajectory, including: S31. Obtain an actual control input of the model, and compare the actual control input with a preset switching threshold control parameter; S32. When it is determined that the flight trajectory of the UAV is far from the target trajectory, and the actual control input is greater than or equal to the preset switching threshold control parameter, based on the relative threshold, the actual control input and the The interval difference between the control inputs set at different times is used to determine whether the first triggering time is reached; S33. When it is determined that the first trigger moment is reached, based on the control input set at the first trigger moment, adjust the actual control input of the model so that the UAV quickly approaches the target trajectory; S34. When it is determined that the UAV is near the target trajectory, and the actual control input is less than the preset switching threshold control parameter, based on the fixed threshold, the actual control input and the control input set at different times. Interval difference, judging whether the second trigger moment is reached; S35. When it is determined that the second trigger moment is reached, based on the control input set at the second trigger moment, adjust the actual control input of the model. 5. The method according to claim 4, characterized in that, in step S32, it is judged based on the relative threshold, the interval difference between the actual control input and the control input set at different times, whether to reach The first trigger moment, including: S321. When it is determined that the interval difference is greater than or equal to the relative threshold, judge whether the first trigger moment is reached by using the following formula:

Among them, t _k+1 represents the first trigger moment reached, t represents the time, R represents the preset real number set,

represents the actual control input, Ω represents the control input set at time t, m ₁ and m ₂ represent preset constants respectively, and “m ₁ Ω+m ₂ ” represents a relative threshold that changes synchronously with Ω. 6. The method according to claim 5, characterized in that, in step S34, it is judged based on the fixed threshold, the interval difference between the actual control input and the control input set at different times, whether to reach The second trigger moment, including: S341. When it is determined that the interval difference is greater than or equal to the fixed threshold, judge whether the second trigger moment is reached by using the following formula:

where m represents a fixed threshold. 7. The method according to claim 6, characterized in that, in step S4, in the adjustment process, a corresponding virtual control law is recursively designed by backstepping method, including: S41. Perform coordinate change based on the target motion model to obtain:

Among them, z1 represents the coordinate transformation form _of the state variable x1, _z2 represents the coordinate transformation form _of the state variable _x2 , c1 represents the preset proportional gain, _c2 represents the preset integral gain, and _x1 represents the system _of the model state, x _d represents the achieved target state, and α represents the virtual control law; S42. Based on the adaptive control principle, select the corresponding first Lyapunov function V ₁ :

Among them, σ _s represents the adaptive parameter,

represents the parameter estimate of the fault parameter; S43. Solving the _first -order derivative for the first Lyapunov function V1 to obtain the corresponding first-order derivative

S44, based on making the first order derivative negative definite

The first limiting condition of , the corresponding virtual control law is designed to make the system approach to asymptotically stable, where:

Among them, α ₁ represents the virtual control law at the design site, a>0, b>0, 0<δ<1 are all preset positive numbers, and k ₁ represents the preset error gain. 8. The method according to claim 7, characterized in that, in step S4, in the adjustment process, a corresponding actual control law is recursively designed by backstepping method, including: S45. Based on the adaptive control principle, select the corresponding second Lyapunov function V ₂ , namely:

S46. Solving the first-order derivative for the _second Lyapunov function V2 to obtain the corresponding first-order derivative

S47, based on the event-triggered characteristic, making the first-order derivative negative definite

The second limiting condition of , the corresponding actual control law is designed so that the asymptotic tracking of the target can also be completed under fault conditions, where:

or

Among them, λ _i (t), i=1,...,3 represent continuous time-varying parameters, which satisfy λ _i (t _k )=0, λ _i (t _k+1 )=±1 and |λ _i | ≤1; δ represents the preset positive parameter, and m ₁ represents the relative threshold control input gain. 9. A design system of a quadrotor unmanned aerial vehicle fault-tolerant controller, it is characterized in that, the system includes a motion model building block, a threshold setting module, a control input adjustment module and a backstepping recursive design module, wherein: The motion model construction module is used to construct a target motion model for reflecting the flight status of the UAV in consideration of the impact of the fault on the rotor, in combination with the distribution of the fault and the rotor speed of the UAV; The threshold setting module is used to set a relative threshold that changes synchronously with changes in the control input of the model, and a fixed threshold; The control input adjustment module is configured to adjust the control input of the model through the relative threshold and the fixed threshold in combination with the event triggering characteristics, so that the flight trajectory of the drone approaches a preset target flight trajectory; The backstepping recursive design module is used to recursively design the corresponding virtual control law and actual control law by using the backstepping method during the adjustment process, so that the model tends to be asymptotically stable. 10. A readable storage medium, characterized in that, the readable storage medium includes a design method program of a quadrotor UAV fault-tolerant controller, and a design method program of a quadrotor UAV fault-tolerant controller When executed by a processor, the steps of the method according to any one of claims 1 to 8 are realized.

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