An event-triggered unmanned airship trajectory tracking control method and system

Abstract

The application provides an unmanned airship trajectory tracking control method and system based on event triggering, and belongs to the field of airship control. The method comprises the following steps: based on the mathematical model of the unmanned airship, according to the current trajectory, the current speed and the actual control input at the previous moment, a fixed-time disturbance observer is used to determine the unknown disturbance estimation value; according to the current trajectory, the expected trajectory, the current speed, the expected speed constraint and the trajectory tracking error constraint, the kinematic loop tracking error, the actual expected speed and the compensation speed tracking error are determined; according to the trajectory tracking error constraint, the compensation speed tracking error, the kinematic loop tracking error, the actual expected speed and the unknown disturbance estimation value, the virtual control input is determined; and based on the event triggering mechanism, the actual control input at the current moment is determined to control the running trajectory of the unmanned airship. The application improves the efficiency of the unmanned airship converging to the preset trajectory, and reduces the loss of the actuator.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of airship control, in particular to an unmanned airship trajectory tracking control method and system based on event triggering. BACKGROUND

[0002] In recent years, with the rise of the concept of high-altitude platform communication system, airships have once again become a research hotspot in the military field and the industry due to their ability to stay in the stratosphere for a long time. As a lighter-than-air unmanned aircraft, unlike general high-altitude balloons, airships are equipped with a propeller propulsion system and have the ability to maneuver along a preset trajectory. For the flight control of unmanned airships, there are mainly two control strategies: trajectory tracking and path tracking. Currently, the trajectory tracking control method of unmanned airships can only guarantee the asymptotic stability of the system, which means that it takes a long time for the unmanned airship to converge to the preset trajectory, and the convergence speed of the algorithm needs to be improved. In addition, in the fine task scenario, the state of the unmanned airship needs to meet certain constraints during tracking the preset trajectory to better meet the task requirements. At the same time, the traditional method of periodically updating the control signal will cause the actuator to move frequently, affecting its service life and being not conducive to the long-time stay of the unmanned airship. SUMMARY

[0003] The purpose of the present application is to provide an unmanned airship trajectory tracking control method and system based on event triggering, which can improve the efficiency of the unmanned airship converging to the preset trajectory and reduce the action frequency of the actuator, thereby reducing the wear and tear of the actuator.

[0004] To achieve the above purpose, the present application provides the following solutions:

[0005] An unmanned airship trajectory tracking control method based on event triggering, comprising:

[0006] establishing a mathematical model of the unmanned airship, wherein the mathematical model of the unmanned airship includes a kinematic model and a dynamic model;

[0007] for any time, obtaining a current trajectory vector, a current speed vector, an expected trajectory vector, an expected speed constraint vector, a trajectory tracking error constraint vector, and a control input constraint vector of the unmanned airship;

[0008] based on the mathematical model of the unmanned airship, according to the current trajectory vector, the current speed vector, and the actual control input vector at the previous time, using a fixed-time disturbance observer to determine an unknown disturbance estimate value; the actual control input vector at the initial time is preset;

[0009] determining a kinematic loop tracking error vector, an actual desired velocity vector and a compensated velocity tracking error vector according to the current trajectory vector, the desired trajectory vector, the current velocity vector, the desired velocity constraint vector and the trajectory tracking error constraint vector;

[0010] determining a virtual control input vector according to the trajectory tracking error constraint vector, the compensated velocity tracking error vector, the kinematic loop tracking error vector, the actual desired velocity vector and the unknown disturbance estimation value;

[0011] determining an actual control input vector at the current time based on an event-triggered mechanism according to the virtual control input vector, the compensated velocity tracking error vector and the control input constraint vector;

[0012] controlling the operation trajectory of the unmanned airship according to the actual control input vector at the current time.

[0013] To achieve the above object, the present application further provides the following scheme:

[0014] An event-triggered unmanned airship trajectory tracking control system, comprising:

[0015] a model establishing unit for establishing a mathematical model of the unmanned airship; the mathematical model of the unmanned airship comprises a kinematic model and a dynamic model;

[0016] a data acquisition unit for acquiring a current trajectory vector, a current velocity vector, a desired trajectory vector, a desired velocity constraint vector, a trajectory tracking error constraint vector and a control input constraint vector of the unmanned airship at any time;

[0017] a disturbance estimation unit connected with the model establishing unit and the data acquisition unit respectively, for determining an unknown disturbance estimation value based on the mathematical model of the unmanned airship according to the current trajectory vector, the current velocity vector and an actual control input vector at the previous time by using a fixed-time disturbance observer; the actual control input vector at the initial time is preset;

[0018] an error determining unit connected with the disturbance estimation unit, for determining a kinematic loop tracking error vector, an actual desired velocity vector and a compensated velocity tracking error vector according to the current trajectory vector, the desired trajectory vector, the current velocity vector, the desired velocity constraint vector and the trajectory tracking error constraint vector;

[0019] a virtual input determining unit connected with the error determining unit, for determining a virtual control input vector according to the trajectory tracking error constraint vector, the compensated velocity tracking error vector, the kinematic loop tracking error vector, the actual desired velocity vector and the unknown disturbance estimation value.

[0020] An actual input determining unit, connected with the virtual input determining unit, is configured to determine an actual control input vector at a current time based on the virtual control input vector, the compensation speed tracking error vector and the control input constraint vector according to an event-triggered mechanism.

[0021] A trajectory control unit, connected with the actual input determining unit, is configured to control a running trajectory of the unmanned airship according to the actual control input vector at the current time.

[0022] According to the embodiments of the present application, the following technical effects are provided.

[0023] Based on the mathematical model of the unmanned airship, the fixed-time disturbance observer is adopted to determine the unknown disturbance estimation value, and then the virtual control input vector is determined according to the current trajectory vector, the expected trajectory vector, the current speed vector, the expected speed constraint vector, the trajectory tracking error constraint vector and the unknown disturbance estimation value, and the actual control input vector at the current time is determined based on the event-triggered mechanism according to the last virtual control input vector, the compensation speed tracking error vector and the control input constraint vector, so as to control the running trajectory of the unmanned airship. Based on the theory of fixed-time stability, the unmanned airship can converge to the preset trajectory within a fixed time, the efficiency of the unmanned airship converging to the preset trajectory is improved, the event-triggered mechanism is introduced, the updating frequency of the control input is greatly reduced, and then the loss of the actuator is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0025] Figure 1 A flow chart of the unmanned airship trajectory tracking control method based on the event triggering provided by the present application;

[0026] Figure 2 A frame diagram of the unmanned airship trajectory tracking control;

[0027] Figure 3 A schematic diagram of the unmanned airship trajectory tracking control system based on the event triggering provided by the present application.

[0028] Symbol explanation:

[0029] 1 - model building unit, 2 - data acquisition unit, 3 - interference estimation unit, 4 - error determination unit, 5 - virtual input determination unit, 6 - actual input determination unit, 7 - trajectory control unit. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0031] The object of the present application is to provide an event-triggered unmanned airship trajectory tracking control method and system, which introduces an event-triggering mechanism to greatly reduce the update frequency of control input and further reduce the wear of the actuator.

[0032] In order to make the above-mentioned objects, features and advantages of the present application more apparent and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0033] Embodiment one

[0034] As shown in the figure, the present embodiment provides an event-triggered unmanned airship trajectory tracking control method, which comprises: Figure 1

[0035] Step 100: Establishing a mathematical model of the unmanned airship. The mathematical model of the unmanned airship includes a kinematic model and a dynamic model.

[0036] Establishing the kinematic equation of the unmanned airship: defining the position ζ = [x, y, z] of the unmanned airship in the inertial system T and the attitude γ = [φ, θ, ψ] of the unmanned airship T , as well as the velocity v = [u, v, w] of the unmanned airship in the body axis system T and the angular velocity ω = [p, q, r] T , φ is the roll angle, θ is the pitch angle, and ψ is the yaw angle, and the kinematic model can be expressed as:

[0037]

[0038]

[0039]

[0040] wherein, is the derivative of ζ, is the derivative of γ, O 3×3 is a 3x3 zero matrix.​

[0041] The dynamic equation of the unmanned airship is established, and the dynamic model can be expressed as:

[0042]

[0043]

[0044]

[0045]

[0046] wherein, is the derivative of v, is the derivative of ω, τ is the actual control input vector, δ is the unknown disturbance, m is the mass, I 3×3 is the identity matrix, M' is the added mass matrix, r' C is the vector from the center of mass to the center of the unmanned airship, S() represents the skew-symmetric matrix, I O is the inertia matrix, I' O is the added inertia matrix, f g is the gravity, f b is the buoyancy, f a is the aerodynamic force, m g is the gravity moment, m b is the buoyancy moment, m a is the aerodynamic moment.

[0047] The formula (1) and the formula (4) can be written in the following compact form:

[0048]

[0049] wherein, y = [ζ T , γ T ] T , x = [v T , ω T ] T , R = diag{R ζ , R γ}. Further, R can be decomposed as R = R0 + ΔR, R0 is composed of the diagonal elements of R, and ΔR is the coupling matrix of R. Similarly, B = M -1 , B can be decomposed as B = B0 + ΔB, B0 is composed of the diagonal elements of B, and ΔB is the coupling matrix of B.

[0050] Further, the formula (8) can be converted into the following form:

[0051]

[0052] wherein, δ x= ΔRx, f = M -1 (F-N), δ * = M -1 δ + ΔBτ, δ * represents unknown lumped disturbance.

[0053] Step 200: for any time, obtaining a current trajectory vector, a current speed vector, an expected trajectory vector, an expected speed constraint vector, a trajectory tracking error constraint vector and a control input constraint vector of the unmanned airship.

[0054] Step 300: based on a mathematical model of the unmanned airship, according to the current trajectory vector, the current speed vector and an actual control input vector at a previous time, using a fixed-time disturbance observer to determine an unknown disturbance estimation value. The actual control input vector at the initial time is preset.

[0055] Specifically, based on the mathematical model of the unmanned airship, according to the current trajectory vector, the current speed vector and the actual control input vector at the previous time, an intermediate vector is determined, such as f in formula (9). According to the intermediate vector and the current speed vector, using a fixed-time disturbance observer to determine an unknown disturbance estimation value.

[0056] First, for a scalar x, its fractional order representation is sig r (x) = sgn(x) |x| r , where Similarly, for a vector sig r (x) = [sig r (x1),..., sig r (x n )] T .

[0057] Secondly, the second formula in formula (9) is rewritten as:

[0058]

[0059] where

[0060] Then the fixed-time disturbance observer is:

[0061]

[0062] where is an unknown disturbance estimation value, l1, l2, l3, l4, l5 are design parameters, and {l1, l2, l3, l4, l5} > 0, x is a current speed vector, f is an intermediate vector, is an estimation value of x, is an estimated value of z1, is an estimated error, is a derivative of , z2 = l2z1, is a derivative of z2, β1 and β2 are positive even numbers, and β1 < β2, sig() represents a fractional order,

[0063] Step 400: determining a kinematic loop tracking error vector, a nominal desired velocity vector, and a compensated velocity tracking error vector according to the current trajectory vector, the desired trajectory vector, the current velocity vector, the desired velocity constraint vector, and the trajectory tracking error constraint vector.

[0064] Further, step 400 includes:

[0065] Step 401: determining a kinematic loop tracking error vector y according to the current trajectory vector y and the desired trajectory vector y

[0066] y e = y - y d (12)

[0067] wherein y e is the kinematic loop tracking error vector, y is the current trajectory vector, y d is the desired trajectory vector, ζ d is the desired position, γ d is the desired attitude.

[0068] Step 402: determining a nominal desired velocity vector x cd according to the kinematic loop tracking error vector y, the desired trajectory vector y, and the trajectory tracking error constraint vector

[0069]

[0070]

[0071] wherein x i,cd is an i-th element value of the nominal desired velocity vector, R i,0 is an i-th element value of R0, k i,1 is a value greater than 0, y i,e is an i-th element value of the kinematic loop tracking error vector y e , y i,d is an i-th element value of the desired trajectory vector y d , is a compensated trajectory tracking error The value of the i-th element, s i,1 and s i,2 For design parameters, s i,1 >0, s i,2 >0, μ s >1, k i,b Let k be the trajectory tracking error constraint vector. b The value of the i-th element, For a small constant, δ i,x For the vector δ in formula (9) x The i-th element.

[0072] Step 403: Determine the actual expected speed vector based on the expected speed constraint vector and the nominal expected speed vector. Specifically, the actual expected speed vector x is determined using the following formula. c :

[0073]

[0074] Where, x i,c Let x be the value of the i-th element of the actual desired velocity vector. i,cd Let x be the value of the i-th element of the nominal desired velocity vector. i,max Let i be the value of the i-th element of the desired velocity constraint vector, and sign() be the sign function, where i = 1, ..., 6.

[0075] Step 404: Determine the dynamic loop tracking error vector based on the current velocity vector and the actual expected velocity vector.

[0076] x e =xx c (16)

[0077] Where, x e Let x be the tracking error vector of the dynamic loop, and x be the current velocity vector. c This represents the actual desired velocity vector.

[0078] Step 405: Determine auxiliary variables based on the nominal expected velocity vector and the actual expected velocity vector.

[0079] To eliminate the impact of the difference between the nominal and actual expected speeds caused by the expected speed constraint, the following auxiliary system is introduced:

[0080]

[0081] Where ξ1 and ξ2 are auxiliary variables in the auxiliary system, and k1 and k2 are design parameter matrices. And satisfy {k i,1 >0,ki,2 > 0.5}.

[0082] Step 406: determining a compensated velocity tracking error vector according to the auxiliary variable and the dynamics loop tracking error vector. The present application also calculates a compensated trajectory tracking error vector. Specifically, the compensated velocity tracking error vector and the compensated trajectory tracking error vector are determined by using the following formulas:

[0083]

[0084] wherein, is the compensated trajectory tracking error, is the compensated velocity tracking error vector.

[0085] Specifically, in step 400, firstly, an initial nominal desired velocity vector is obtained; an actual desired velocity vector is determined according to the desired velocity constraint vector and the initial nominal desired velocity vector; a dynamics loop tracking error vector is determined according to the current velocity vector and the actual desired velocity vector; an auxiliary variable is determined according to the initial nominal desired velocity vector and the actual desired velocity vector; a compensated trajectory tracking error vector and a compensated velocity tracking error vector are determined according to the auxiliary variable and the dynamics loop tracking error vector; a nominal desired velocity vector is determined according to the kinematics loop tracking error vector, the desired trajectory vector, the compensated trajectory tracking error vector and the trajectory tracking error constraint vector; an actual desired velocity vector is determined according to the desired velocity constraint vector and the nominal desired velocity vector; a dynamics loop tracking error vector is determined according to the current velocity vector and the actual desired velocity vector; an auxiliary variable is determined according to the nominal desired velocity vector and the actual desired velocity vector; a compensated velocity tracking error vector is determined according to the auxiliary variable and the dynamics loop tracking error vector.

[0086] Step 500: determining a virtual control input vector according to the trajectory tracking error constraint vector, the compensated velocity tracking error vector, the kinematics loop tracking error vector, the actual desired velocity vector and the unknown disturbance estimate value Specifically, the i-th element value a i,u of the virtual control input vector is determined by using the following formula:

[0087]

[0088]

[0089] wherein, B i,0 is the i-th element value of B0, k i,2 is a value greater than 0, is the i-th element value of the compensated velocity tracking error vector s i,3 and s i,4s is a design parameter, i,3 > 0, s i,4 > 0, h i,1 and h i,2 is a small constant, h i,1 > 0, h i,2 > 0, f i is the ith element value of the intermediate vector f, is the ith element value of the unknown disturbance estimate is the ith element value of the auxiliary variable ξ2, R i,2 is the ith element value of the auxiliary variable ξ2, R i,0 is the ith element value of R0, y i,e is the kinematic loop tracking error vector y e is the ith element value of the actual desired velocity vector x i,c is the actual desired velocity vector x c is the ith element value of the actual desired velocity vector x

[0090] Step 600: determining the actual control input vector at the current time instant based on the event-triggered mechanism according to the virtual control input vector, the compensated velocity tracking error vector and the control input constraint vector.

[0091] Further, step 600 comprises:

[0092] Step 601: determining the design control input vector at the current time instant according to the virtual control input vector and the compensated velocity tracking error vector. Specifically, the design control input vector at time t is determined by the following formula:

[0093]

[0094] wherein, is the ith element value of the design control input vector at time t, 0 < η i,u < 1, a i,u is the ith element value of the virtual control input vector, is the ith element value of the compensated velocity tracking error vector, B i,0 is the ith element value of the vector B0, B0 consisting of the diagonal elements of the inverse of the mass matrix, and ε i,u is a design parameter affecting the time-triggered frequency, {ε i,u , d i} > 0, satisfies

[0095] Step 602: determining the preliminary control input vector at the current time instant based on the event-triggered mechanism according to the design control input vector at the current time instant. Specifically, the preliminary control input vector at time t is determined by the following formula, i.e. the triggering event:

[0096]

[0097] t k+1 =inf{t>t k ||e i,u |≥η i,u |u i (t)|+d i},t1=0 (23)

[0098] Among them, u i (t) represents the value of the i-th element of the initial control input vector u at time t. For t k The timing design controls the value of the i-th element of the input vector. This represents the error between the actual control input and the design control input, 0 < η i,u <1, This refers to the moment the event is triggered.

[0099] Specifically, the event triggering mechanism can be described as: initially controlling the value u of the i-th element of the input vector. i (t) at t=t k Update the value of the i-th element of the design control input vector at each step. In the interval [t] k ,t k+1 )superior, Remain unchanged; when u i (t) and error e i,u The absolute value exceeds the threshold η i,u |u i When (t)|+d, it is the time t when the next event is triggered. k+1 Actual control input u i (t) at t=t k+1 The design control input is updated to the current time.

[0100] Step 603: Based on the preliminary control input vector at the current moment and the control input constraint vector, determine the actual control input vector at the current moment. Specifically, considering input saturation, the actual control input vector is determined using the following formula:

[0101]

[0102] Where, τ i (u i ) represents the value of the i-th element of the actual control input vector, u i To initially control the value of the i-th element of the input vector, τ i,maxThe sign() function is used to control the value of the i-th element of the input constraint vector.

[0103] Step 700: Control the trajectory of the unmanned airship according to the actual control input vector at the current moment.

[0104] In summary, this invention can be decomposed into four parts: model establishment, design of a fixed-time interference observer, design of a fixed-time controller, and design of an event triggering mechanism. The algorithm framework is as follows: Figure 2 As shown, the main process is as follows: First, a kinematic and dynamic model of the airship is established. Then, a fixed-time disturbance observer is designed based on the dynamic model to obtain an estimate of the unknown disturbance. Next, based on the given desired trajectory, state constraints, and disturbance estimate, a virtual control input is designed. Finally, an event-triggered mechanism is designed based on the virtual control input to obtain the actual control input. In practical applications, the position, attitude, velocity, angle, and other state variables of the unmanned airship can be measured by sensors on the airship. The actual control input calculated by this method is sent to actuators such as the propeller to achieve the unmanned airship's tracking effect on the preset trajectory.

[0105] This invention proposes an event-triggered trajectory tracking control method with fixed-time stability for constrained six-DOF unmanned airships. This method combines the obstacle Lyapunov function method, backstepping control, and an event-triggered mechanism to ensure the unmanned airship's state remains within the constraints. Unlike conventional periodically triggered control input updates, this method introduces an event-triggered mechanism, significantly reducing the update frequency of control inputs and minimizing actuator wear. Furthermore, based on fixed-time stability theory, it allows the unmanned airship to converge to a preset trajectory within a fixed time, improving control performance and providing an effective engineering design tool for long-endurance maneuvering flight of unmanned airships.

[0106] Example 2

[0107] In order to implement the method corresponding to Embodiment 1 above and achieve the corresponding functions and technical effects, an event-triggered unmanned airship trajectory tracking and control system is provided below.

[0108] like Figure 3 As shown, the event-triggered unmanned airship trajectory tracking control system provided in this embodiment includes: a model building unit 1, a data acquisition unit 2, an interference estimation unit 3, an error determination unit 4, a virtual input determination unit 5, an actual input determination unit 6, and a trajectory control unit 7.

[0109] The model building unit 1 is used to build a mathematical model of the unmanned airship; the mathematical model of the unmanned airship includes a kinematic model and a dynamic model.

[0110] The data acquisition unit 2 is configured to acquire, for any time instant, a current trajectory vector, a current velocity vector, a desired trajectory vector, a desired velocity constraint vector, a trajectory tracking error constraint vector and a control input constraint vector of the unmanned airship.

[0111] The disturbance estimation unit 3 is connected with the model establishment unit 1 and the data acquisition unit 2 respectively, and is configured to determine an unknown disturbance estimation value based on the mathematical model of the unmanned airship, according to the current trajectory vector, the current velocity vector and an actual control input vector of a previous time instant, by using a fixed-time disturbance observer. The actual control input vector of the initial time instant is preset.

[0112] The error determination unit 4 is connected with the disturbance estimation unit 3, and is configured to determine a kinematic loop tracking error vector, an actual desired velocity vector and a compensated velocity tracking error vector according to the current trajectory vector, the desired trajectory vector, the current velocity vector, the desired velocity constraint vector and the trajectory tracking error constraint vector.

[0113] The virtual input determination unit 5 is connected with the error determination unit 4, and is configured to determine a virtual control input vector according to the trajectory tracking error constraint vector, the compensated velocity tracking error vector, the kinematic loop tracking error vector, the actual desired velocity vector and the unknown disturbance estimation value.

[0114] The actual input determination unit 6 is connected with the virtual input determination unit 5, and is configured to determine an actual control input vector of the current time instant based on an event-triggered mechanism according to the virtual control input vector, the compensated velocity tracking error vector and the control input constraint vector.

[0115] The trajectory control unit 7 is connected with the actual input determination unit 6, and is configured to control the running trajectory of the unmanned airship according to the actual control input vector of the current time instant.

[0116] Compared with the prior art, the unmanned airship trajectory tracking control system based on event triggering provided by the embodiment has the same beneficial effects as the unmanned airship trajectory tracking control method based on event triggering provided by the first embodiment, and thus the repeated description is omitted here.

[0117] Embodiment Three

[0118] The embodiment provides an electronic device, including a memory and a processor, the memory is used for storing a computer program, and the processor runs the computer program to make the electronic device execute the unmanned airship trajectory tracking control method based on event triggering of the first embodiment.

[0119] Optionally, the electronic device can be a server.

[0120] In addition, the embodiment of the present application further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the event-triggered unmanned airship trajectory tracking control method of the embodiment one.

[0121] The various embodiments are described in a progressive manner in the specification, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0122] The principles and implementation manners of the present application are described by using specific examples in the specification. The above description of the embodiments is only used to help understand the method of the present application and its core idea. Meanwhile, for the general technical personnel in the field, the specific implementation manners and application ranges will be changed according to the idea of the present application. In conclusion, the content of the specification should not be understood as the limitation of the present application.

Claims

1. An event-triggered unmanned airship trajectory tracking control method, characterized in that, The event-triggered unmanned airship trajectory tracking control method comprises the following steps: A mathematical model of the unmanned airship is established; the mathematical model of the unmanned airship comprises a kinematic model and a dynamic model; For any time, a current trajectory vector, a current speed vector, an expected trajectory vector, an expected speed constraint vector, a trajectory tracking error constraint vector and a control input constraint vector of the unmanned airship are obtained; Based on the mathematical model of the unmanned airship, an unknown disturbance estimation value is determined by using a fixed-time disturbance observer according to the current trajectory vector, the current speed vector and an actual control input vector at a previous time; the actual control input vector at an initial time is preset; A kinematic loop tracking error vector, an actual expected speed vector and a compensation speed tracking error vector are determined according to the current trajectory vector, the expected trajectory vector, the current speed vector, the expected speed constraint vector and the trajectory tracking error constraint vector; A virtual control input vector is determined according to the trajectory tracking error constraint vector, the compensation speed tracking error vector, the kinematic loop tracking error vector, the actual expected speed vector and the unknown disturbance estimation value; An actual control input vector at the current time is determined based on an event-triggering mechanism according to the virtual control input vector, the compensation speed tracking error vector and the control input constraint vector; The running trajectory of the unmanned airship is controlled according to the actual control input vector at the current time.

2. The event-triggered trajectory tracking control method for unmanned airships according to claim 1, wherein, Based on the mathematical model of the unmanned airship, an unknown disturbance estimation value is determined by using a fixed-time disturbance observer according to the current trajectory vector, the current speed vector and an actual control input vector at a previous time, and specifically comprises the following steps: Based on the mathematical model of the unmanned airship, an intermediate vector is determined according to the current trajectory vector, the current speed vector and an actual control input vector at a previous time; The unknown disturbance estimation value is determined by using a fixed-time disturbance observer according to the intermediate vector and the current speed vector.

3. The event-triggered trajectory tracking control method for unmanned airships according to claim 2, characterized in that, The fixed-time disturbance observer is as follows: wherein is an unknown disturbance estimate, li, l2, l3, l4, l5 are design parameters, and {li, l2, l3, l4, l5} > 0, x is a current velocity vector, f is an intermediate vector, is an estimate of x, is an estimate of zl, is an estimation error, is a derivative of z2 = l2z1, is a derivative of z2, β1 and β2 are positive even numbers, and β1 < β2, sig() denotes a fractional order.

4. The event-triggered trajectory tracking control method for unmanned airships according to claim 1, wherein, The kinematic loop tracking error vector, the actual expected speed vector and the compensation speed tracking error vector are determined according to the current trajectory vector, the expected trajectory vector, the current speed vector, the expected speed constraint vector and the trajectory tracking error constraint vector, and specifically comprises the following steps: The kinematic loop tracking error vector is determined according to the current trajectory vector and the expected trajectory vector; The nominal expected speed vector is determined according to the kinematic loop tracking error vector, the expected trajectory vector and the trajectory tracking error constraint vector; The actual expected speed vector is determined according to the expected speed constraint vector and the nominal expected speed vector; The dynamic loop tracking error vector is determined according to the current speed vector and the actual expected speed vector; The auxiliary variable is determined according to the nominal expected speed vector and the actual expected speed vector; The compensation speed tracking error vector is determined according to the auxiliary variable and the dynamic loop tracking error vector.

5. The event-triggered trajectory tracking control method for unmanned airships according to claim 4, characterized in that, The actual expected speed vector is determined by using the following formula: where x i,c is the value of the i-th element of the actual desired velocity vector, x i,cd is the value of the i-th element of the nominal desired velocity vector, x i,max is the value of the i-th element of the desired velocity constraint vector, and sign() is the sign function.

6. The event-triggered trajectory tracking control method for unmanned airships according to claim 1, wherein, According to the virtual control input vector, the compensation speed tracking error vector and the control input constraint vector, an actual control input vector at a current time is determined based on an event-triggered mechanism, specifically comprising: According to the virtual control input vector and the compensation speed tracking error vector, a design control input vector at the current time is determined; According to the design control input vector at the current time, a preliminary control input vector at the current time is determined based on the event-triggered mechanism; According to the preliminary control input vector at the current time and the control input constraint vector, the actual control input vector at the current time is determined.

7. The event-triggered trajectory tracking control method for unmanned airships according to claim 6, characterized in that, The design control input vector at time t is determined by using the following formula: wherein, is the value of the i-th element of the design control input vector at time t, 0 < η i,u < 1, a i,u is the value of the i-th element of the virtual control input vector, is the value of the i-th element of the compensation velocity tracking error vector, B i,0 is the value of the i-th element of the vector B0, B0is composed of the diagonal elements of the inverse of the mass matrix, and ε i,u is a design parameter that influences the time-triggered frequency.

8. The event-triggered trajectory tracking control method for unmanned airships according to claim 6, wherein, The preliminary control input vector at time t is determined by using the following formula: Among them, u i (t) represents the value of the i-th element of the initial control input vector at time t. For t k The timing design controls the value of the i-th element of the input vector.

9. The event-triggered unmanned airship trajectory tracking control method according to claim 6, characterized in that, The actual control input vector is determined by using the following formula: where τ i (u i ) is the value of the i-th element of the actual control input vector, u i is the value of the i-th element of the preliminary control input vector, τ i,max is the value of the i-th element of the control input constraint vector, and sign() is the sign function.

10. An event-triggered unmanned airship trajectory tracking control system, applied to the event-triggered unmanned airship trajectory tracking control method of any one of claims 1 to 9, characterized in that, The unmanned airship trajectory tracking control system based on the event-triggered mechanism comprises: A model establishing unit is configured to establish a mathematical model of the unmanned airship, wherein the mathematical model of the unmanned airship comprises a kinematic model and a dynamic model; A data acquisition unit is configured to acquire, for any time, a current trajectory vector, a current speed vector, an expected trajectory vector, an expected speed constraint vector, a trajectory tracking error constraint vector and a control input constraint vector of the unmanned airship; An interference estimation unit is connected with the model establishing unit and the data acquisition unit, and is configured to determine an unknown interference estimation value by using a fixed-time disturbance observer based on the mathematical model of the unmanned airship, according to the current trajectory vector, the current speed vector and an actual control input vector at a previous time; the actual control input vector at an initial time is preset; An error determination unit is connected with the interference estimation unit, and is configured to determine a kinematic loop tracking error vector, an actual expected speed vector and a compensation speed tracking error vector according to the current trajectory vector, the expected trajectory vector, the current speed vector, the expected speed constraint vector and the trajectory tracking error constraint vector; A virtual input determination unit is connected with the error determination unit, and is configured to determine a virtual control input vector according to the trajectory tracking error constraint vector, the compensation speed tracking error vector, the kinematic loop tracking error vector, the actual expected speed vector and the unknown interference estimation value; An actual input determination unit is connected with the virtual input determination unit, and is configured to determine an actual control input vector at a current time according to the virtual control input vector, the compensation speed tracking error vector and the control input constraint vector based on an event-triggered mechanism; A trajectory control unit is connected with the actual input determination unit, and is configured to control a running trajectory of the unmanned airship according to the actual control input vector at the current time.

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