CN113515066B - Nonlinear multi-intelligent system dynamic event trigger control method - Google Patents
Nonlinear multi-intelligent system dynamic event trigger control method Download PDFInfo
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Abstract
The invention discloses a nonlinear multi-intelligent system dynamic event trigger control method, which comprises the following steps: each intelligent agent synchronously samples state information and periodically monitors an event trigger function, and each intelligent agent broadcasts own state only when the event trigger function is triggered; dynamically updating parameters in the event triggering function; and verifying the validity of the control strategy through numerical simulation. The invention researches the formation control problem of a nonlinear high-order multi-agent system, adopts a dynamic event trigger mechanism based on sampling data, converts the formation problem into the stability problem of a subsystem, then constructs the subsystem into a time delay system, obtains a sufficient condition of system stability by utilizing a linear matrix inequality, and finally realizes formation control.
Description
Technical Field
The invention relates to the technical field of dynamic event trigger control, in particular to a nonlinear multi-agent system dynamic event trigger control method based on sampling data.
Background
In recent years, distributed control of multi-agent systems has received increasing attention due to their wide application in the fields of power grids, sensor networks, transportation and robots, etc. Distributed cooperative control includes numerous branches, such as: congestion, consistency, formation and surrounding, etc. The formation control aims to enable a group of intelligent agents to realize a specified geometric formation, and the formation control method is widely applied to the scenes such as military fields, satellite networking, unmanned aerial vehicle performance and the like.
In a real system, the controller runs on an embedded microprocessor and executes periodically. Therefore, discrete control strategies are receiving increasing attention. The y.p.gao et al studied the problem of consistency of the second order system in a time-varying directed communication topology, each agent could only obtain neighbor position and velocity information at the sampling instant, and the sampling period of each agent was different. The g.h.wen et al proposed a delay input strategy for multi-agent systems with nonlinear dynamics by which a discrete system can be converted to a nonlinear system with a time-varying delay and the maximum sampling period allowed by the system can be estimated. In addition, there are more research works on multi-agent distributed cooperative control based on sampled data, which are not described here.
Considering the limited communication and computing resources of practical systems, how to reduce the use of communication bandwidth and transmission energy is of paramount importance. The event-triggered strategy can well solve this problem. The event-triggered strategy provides a natural way to accomplish the control task, and whether the control strategy is executed depends on a pre-set trigger spring rather than periodically executing the control strategy. When the trigger condition is satisfied, an event is triggered at this time, and the controller is updated. There have been some studies on the problem of multi-agent system consistency, but few studies have been made on the use of event-triggered control based on sampled data, and the present invention has been made based on this.
Disclosure of Invention
The invention aims to provide a nonlinear multi-intelligent system dynamic event triggering control method, which adopts a dynamic event triggering mechanism based on sampling data, converts formation problems into stability problems of subsystems, constructs the subsystems into time delay systems, obtains sufficient conditions of system stability by utilizing linear matrix inequality, and finally realizes formation control.
In order to solve the technical problems, the embodiment of the invention provides the following scheme:
a nonlinear multi-intelligent system dynamic event trigger control method comprises the following steps:
s1, each intelligent agent synchronously samples state information and periodically monitors an event trigger function, and each intelligent agent broadcasts own state only when the event trigger function is triggered;
s2, dynamically updating parameters in the event triggering function;
s3, verifying the effectiveness of the control strategy through numerical simulation.
Preferably, the method further comprises, prior to step S1:
giving a theory, definitions of dynamics and formation problems of each agent, and follow-up assumptions and quotations;
the graph theory includes:
consider an undirected graph G with N nodes, denoted g= { V, E, W }, where v= { V 1 ,v 2 ,...,v N The number of nodes represents the set of nodes,representing a collection of edges, w= [ W ] ij ]∈R N×N Representing an adjacency matrix; for the adjacency matrix W, if (v i ,v j ) E, w is ij > 0, where v i And v j Are neighbors of each other; otherwise w ij =0;N i Representing a set of neighbors of the intelligent agent i;
the laplacian matrix l= [ L ] of graph G ij ]∈R N×N Is defined asWhen a connection path exists between any two nodes in the graph, the undirected graph G is fully connected;
the problem is described as follows:
consider a multi-agent system with a communication topology G, comprising N agents, each of which has a kinetic model described as:
wherein x is i (t)∈R n ,u i (t)∈R m ,f(x i (t),t)∈R n Respectively represent the state, input and nonlinear dynamics of the intelligent agent i, and has A and B are each a component having a corresponding dimensionA constant matrix of numbers;
definition 1: the multi-agent system is said to be capable of achieving time-varying state formation h if, for any given bounded initial condition, the following requirements are met:
wherein h is i ∈R n Representing state x i Offset of (t) and hasr (t) is a formation location function;
definition 2: if a controller u is used i (t) (i=1, 2,., N.) the multi-agent system is able to achieve formation h, then it is said that formation h is viable;
the hypothesis and quotation are as follows:
suppose 1: graph G is undirected graph and fully connected;
suppose 2: for any x, y ε R n Nonlinear dynamics f (x i (t), t) satisfies the following Li Puxi z condition:
lemma 1: the Laplacian matrix of the undirected graph G is L epsilon R N×N Then:
l has at least one zero eigenvalue, and the eigenvalue corresponds to an eigenvector of 1 N I.e. L1 N =0 N ;
If G is fully connected, 0 is a single eigenvalue of L, the remaining N-1 eigenvalues all have positive real parts, i.e. 0 = λ 1 <λ 2 ≤...≤λ N ;
And (4) lemma 2: if the matrix R > 0, then for any matrix X and scalar ρ > 0, the following is satisfied:
-XR -1 X≤ρ 2 R-2ρX
and (3) lemma 3: for symmetric matrix A 11 ,A 12 ,A 22 The following properties are equivalent:
preferably, the step S1 specifically includes:
designing an event triggering mechanism:
the formation error is defined as:
δ i (t)=x i (t)-h i (i=1,2,...,N)
Defining the measurement error as:
Defining a combined measurement as:
The nonlinear term f (x i (t), t), the state estimate of the obtained agent i is:
wherein KT is the sampling time and hasEstimated for the state of agent i at time KT, and there is +.>
Then, the state estimation error is obtained as:
The event-triggered queuing control strategy based on the sampled data is designed as follows:
Dynamic event trigger function g of agent i i (t) is defined as:
wherein sigma i (KT) is a dynamic parameter, and θ > 0 is a positive constant.
Preferably, the agent checks the dynamic event trigger function g only at each sampling instant KT i (t);
First, according to
Updating dynamic parameter sigma i (KT);
Then, substituting the sampled value into
If and only if g i When (KT) is not less than 0, the system triggers and updates the controller u i (t);
The trigger time is expressed as:
and 4, lemma: for a given initial condition sigma i (0) E [0, 1) and θ > 0, with the adoption of
Parameter update is performed, then sigma i (KT) satisfying the following constraint at any time:
preferably, the demonstration is performed using mathematical induction:
when k=1, we get:
indicating 0.ltoreq.sigma i (T)≤σ i (0)<1;
Thus, sigma i (KT) monotonically decreases with increasing K, proving 0.ltoreq.sigma i ((K+1)T)≤σ i (KT) < 1, thereby obtaining, for any of Inequality 0 +.sigma i (KT)≤σ i (0)<1,/>This is true.
Preferably, a control strategy is employedAnd t.epsilon.KT, (K+1) T,the multi-agent system has the following form:
delta of the formula i (t)=x i (t)-h i (i=1, 2,) N) substituted into the above formula, further resulting in:
let lambda get i (i=1, 2,., N) represents the eigenvalues of the laplace matrix L, J is about the right standard type of L, then there is presentAnd U -1 =U T Satisfies the following formula:
U -1 LU=U T LU=J=diag{λ 1 ,λ 2 ,...,λ N }
Defining a time delay function tau (t) =t-KT, t epsilon [ KT ], and [ ]K+1) T), 0.ltoreq.τ (T) < T is piecewise linear and hasAt this time, a method for solving the time delay problem is adopted to solve the formation problem;
The writing is as follows:
system and method for controlling a system
Conversion of formation control problems into systems
Stability problems of (2);
and (5) lemma: for multiple intelligent systemsUsing a controllerAnd dynamic event trigger function based on sampling data
A formation h can be implemented if and only if:
the proving process is as follows:
if and only if the following formula is satisfied:
the method comprises the following steps:
due toIs nonsingular, < >>Description->Thus, when and only whenWhen the state formation h is realized;
and (3) lemma 6: for event triggering functions
Given an initial condition σ (0) =diag { σ } 1 (0),σ 2 (0),...,σ N (0) ' and sigma N-1 (0)=diag{σ 2 (0),...,σ N (0) } $ gives the following inequality:
The following was demonstrated:
the method comprises the following steps of:
this gives:
from the definition of η (t), it is known that:
substituting the two formulas into one
The method comprises the following steps:
and (5) finishing the verification.
Preferably, for a multiple intelligent systemIf a controller is usedBased on the dynamic event trigger function of the sampled data, when hypothesis 1 and hypothesis 2 are satisfied, formation h is possible when the following conditions are satisfied:
(A+BK 2 )(h i -h j )=0
B. there is a real matrix And sigma (sigma) i (0) E [0, 1), θ > 0, ρ > 0 satisfies the following inequality:
In addition, the controller gain matrix K 1 And K is equal to 3 From the following componentsAnd->Obtained.
Preferably, the proving process is as follows:
the following lyapunov function was constructed:
wherein p=p T ,Q=Q T And r=r T Is a positive definite matrix;
when the condition A is satisfied, the following steps are obtained:
opposite typeBoth sides are multiplied by +.>Because of->The method further comprises the following steps: />
According to the quotation mark 1,is non-singular; will->Both sides are multiplied by +.>The method comprises the following steps of:
then
The writing is as follows:
according to the above formula, the derivative of V (t) is given by:
applying lemma 1, obtaining:
wherein χ is 1 =ε(t-τ(t))-ε(t),χ 2 ε (T-T) - ε (T- τ (T)) and S is a real matrix;
Substituted formula
The derivative of V (t) is written as:
wherein, xi= [ xi ] p,q ] 6×6 Is a symmetrical matrix and has
Ξ 2,4 =Ω 2 ,
Ξ 2,5 =Ξ 2,6 =0 (N-1)n×Nn ,
Ξ 3,4 =Ξ 3,5 =Ξ 3,6 =0 (N-1)n×Nn ,
Ξ 4,4 =Ω 3 ,
Ξ 4,5 =Ξ 4,6 =Ξ 5,5 =Ξ 5,6 =Ξ 6,6 =0 Nn×Nn ,
Wherein the method comprises the steps of
Multiplying the two sides simultaneously
the method further comprises the following steps:
consider the conditions
And the Shu Er's theorem, get:
combining the above formulas yields:
equivalent to inequality
At the same time satisfy inequality
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
compared with the prior art, the invention has the advantages that: firstly, a dynamic event triggering strategy based on sampling data is provided, and the strategy can effectively avoid continuous communication and sampling; the formation problem is converted into the stability problem of the time delay system by introducing a time delay function, and then the stability problem can be solved by a linear matrix inequality and a Leeleapunov function; then, the dynamic event triggering strategy is a distributed control strategy, and parameters in the triggering conditions are dynamically changed, so that the event triggering times can be effectively reduced; secondly, the nonlinear multi-agent system is considered, the state estimation error is used for representing the influence of nonlinear dynamics on the system, and the state estimation error is introduced into the controller, so that the influence of nonlinearity can be effectively restrained.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for controlling dynamic event triggering of a nonlinear multi-intelligent system based on sampling data provided by an embodiment of the invention;
FIG. 2 is a diagram of a state x of each agent according to an embodiment of the present invention i (t) a time-dependent curve;
FIGS. 3 a-3 c illustrate the formation error delta for each agent provided by embodiments of the present invention i (t) schematic;
FIGS. 4 a-4 c illustrate combined measurement q of individual agents provided by embodiments of the present invention i (t) a profile;
FIGS. 5 a-5 c illustrate the measured error e of each agent provided by embodiments of the present invention i A variation curve of (t);
FIG. 6 is a graph showing the dynamic trigger function parameter σ of each agent according to an embodiment of the present invention i (KT) time-dependent curve.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the embodiments of the present invention will be described in further detail with reference to the accompanying drawings.
The embodiment of the invention provides a nonlinear multi-intelligent system dynamic event trigger control method, as shown in fig. 1, comprising the following steps:
s1, each intelligent agent synchronously samples state information and periodically monitors an event trigger function, and each intelligent agent broadcasts own state only when the event trigger function is triggered;
s2, dynamically updating parameters in the event triggering function;
s3, verifying the effectiveness of the control strategy through numerical simulation.
The embodiment of the invention researches the distributed formation control problem of the multi-agent system with nonlinear dynamics, and researches a dynamic event trigger control strategy based on sampling data by considering an actual digital processor and limited network resources. Firstly, each intelligent agent synchronously samples state information and periodically monitors event triggering functions, and each intelligent agent only broadcasts own state when the functions are triggered, so that the communication times can be greatly reduced. Meanwhile, the Zeno behavior can be avoided due to the periodic sampling mechanism. Further, parameters in the event triggering function are dynamically updated, so that the balance between communication frequency and formation performance can be realized. The invention converts the formation problem into the stability problem of the time delay system. Finally, the effectiveness of the control strategy provided by the invention is verified by numerical simulation.
Specifically, before the step S1, the method further includes: definition of the theory, dynamics and formation problem of each agent, and the assumption and quotation used later are given. Wherein the following symbols are used: 0 N Matrix representing all elements 0,1 N A matrix representing all elements as 1, the superscript T representing the matrixIs to be used in the present invention,representing Cronecker product, metropolyl>Representing a non-negative set of integers.
The graph theory includes:
consider an undirected graph G with N nodes, which can be expressed as g= { V, E, W }, where v= { V 1 ,v 2 ,...,v N And represents a collection of nodes,representing a collection of edges, w= [ W ] ij ]∈R N×N Representing the adjacency matrix. For the neighbor matrix W, if (v i ,v j ) E, w is ij > 0, where v i And v j Are neighbors of each other; otherwise w ij =0。N i Representing a set of neighbors of agent i.
The laplacian matrix l= [ L ] of graph G ij ]∈R N×N Is defined asThe undirected graph G is fully connected when there is a connection path between any two nodes in the graph.
The problem is described as follows:
considering a multi-agent system with a communication topology G, comprising N agents, the kinetic model of each agent can be described as:
wherein x is i (t)∈R n ,u i (t)∈R m ,f(x i (t),t)∈R n Respectively represent the state, input and nonlinear dynamics of the intelligent agent i, and has A and B are constant matrices having corresponding dimensions.
Definition 1: the multi-intelligent system (1) is said to be able to implement a time-varying state formation h if, for any given bounded initial condition, the following requirements are met:
wherein h is i ∈R n Representing state x i Offset of (t) and hasr (t) is a formation location function.
Definition 2: if a controller u is used i (t) (i=1, 2,., n.), the multi-agent system may implement formation h, then it is possible to call formation h.
The assumptions and quotations include:
suppose 1: graph G is undirected and fully connected.
Suppose 2: for any x, y ε R n Nonlinear dynamics f (x i (t), t) satisfies the following Li Puxi z condition:
lemma 1: the Laplacian matrix of the undirected graph G is L epsilon R N×N Then
(1) L has at least one zero eigenvalue, and the eigenvalue corresponds to an eigenvector of 1 N I.e. L1 N =0 N ;
(2) If G is fully connected, 0 is a single eigenvalue of L, the remaining N-1 eigenvalues all have a positive real part, i.e. 0 = λ 1 <λ 2 ≤...≤λ N 。
And (4) lemma 2: if the matrix R > 0, then for any matrix X and scalar ρ > 0, the following is satisfied:
-XR -1 X≤ρ 2 R-2ρX (2)
and (3) lemma 3: for symmetric matrix A 11 ,A 12 ,A 22 The following properties are equivalent:
furthermore, the invention designs a dynamic event trigger formation control strategy based on the sampling data and provides conditions for realizing formation control.
First, an event trigger mechanism is designed:
the formation error is defined as:
δ i (t)=x i (t)-h i (i=1,2,...,N) (3)
Defining the measurement error as:
where T is the sampling period and where,is the latest triggering moment of the intelligent agent i and has
Defining a combined measurement as:
According to equation (1), the nonlinear term f (x i (t), t) can be estimated as the state of agent i:
wherein KT is the sampling time and hasEstimated for the state of agent i at time KT, and there is +.>
Then, the state estimation error can be obtained as:
Nonlinear term f (x) in system (1) i (t), t) is difficult to model or to obtain accurate values. Thus, the state estimation errorFor representing non-linear terms f (x i (t), influence of t) on the system, and use +.>To eliminate the effect of nonlinear terms, the method is inspired by a model-based event-triggered strategy.
The event-triggered queuing control strategy based on the sampled data is designed as follows:
Inspired by a dynamic event trigger strategy, the dynamic event trigger function g of the intelligent agent i i (t) is defined as:
wherein sigma i (KT) is a dynamic parameter, θ > 0 is a positive constant, ψ=ψ T > 0 and Φ=Φ T > 0 will be calculated below.
The agent checks the dynamic event trigger function g only at each sampling instant KT i (t). First, the dynamic parameter σ is updated according to equation (10) i (KT); then substituting the sampled value into formula (9); if and only if g i When (KT) is not less than 0, the system triggers and updates the controller u i (t). The trigger time can be expressed as:
The dynamic parameter in the prior art is designed as σ (KT), which requires global information. In contrast, the dynamic parameter sigma of the inventive design i (KT) is distributed, requiring only neighbor information.
And 4, lemma: for a given initial condition sigma i (0) E [0,1 ] and θ > 0, and updating parameters by using formula (10), σ i (KT) satisfying the following constraint at any time:
the proving process is as follows:
the mathematical induction method is adopted for proving;
when k=1, it is possible to obtain:
indicating 0.ltoreq.sigma i (T)≤σ i (0)<1。
and hasTherefore, it is easy to know σ i (KT) monotonically decreases with increasing K, proving 0.ltoreq.sigma i ((K+1)T)≤σ i (KT) < 1, whereby,for arbitrary +.>The inequality (12) holds.
And (5) finishing the verification.
Adopts a control strategy (8), and T is [ KT, (K+1) T),the multi-agent system has the following form:
substituting formula (3) into formula (15) can further yield:
let lambda get i (i=1, 2,., N) represents the eigenvalues of the laplace matrix L, J is about the right standard type of L, then there is presentAnd U -1 =U T Satisfies the following formula:
U -1 LU=U T LU=J=diag{λ 1 ,λ 2 ,...,λ N } (17)
lambda is known from the quotation 1 1 =0, and its corresponding feature vector isDefinition of the definitionAnd->The multi-agent system (16) may be written as: />
Defining a time delay function tau (T) =t-KT, T e [ KT, (k+1) T). As can be readily seen, 0.ltoreq.τ (T) < T is piecewise linear and hasAt this time, a method for solving the latency problem may be adopted to solve the formation problem.
next, the formation control problem of the system (15) is converted into a stability problem of the system (20).
And (5) lemma: for multi-agent systems (1), formation h can be achieved using a controller (8) and a dynamic event trigger function (9), (10) based on sampled data, if and only if:
the following was demonstrated:
if and only if the following formula is satisfied:
at this time, the expression (22) can be obtained:
due toIs nonsingular, < >>Description->Thus, when and only whenAt that time, state formation h may be implemented.
And (5) finishing the verification.
E (t) and epsilon (t) represent the formation subspace and the formation complement subspace respectively, when delta i (t) when fully in the formation subspace, formation may be achieved.
And (3) lemma 6: for event-triggered functions (9) and (10), and given an initial condition σ (0) =diag { σ 1 (0),σ 2 (0),...,σ N (0) ' and sigma N-1 (0)=diag{σ 2 (0),...,σ N (0) The following inequality can be obtained:
The following was demonstrated: from the event trigger functions (9) and (10), it is possible to obtain:
From delta i (t) and e i The definition of (t) can be given by:
substituting formula (27) into formula (26) can give:
thus, it is possible to obtain:
from the definition of η (t), it is known that:
substituting the formula (30) and the formula (31) into the formula (29) can obtain:
and (5) finishing the verification.
Theorem 1: for multi-agent system (1), if a controller (8) is employed, dynamic event trigger functions (9) and (10) based on sampled data, satisfying hypothesis 1 and hypothesis 2, then formation h is possible when the following conditions are satisfied:
(A+BK 2 )(h i -h j )=0 (33)
(2) There is a real matrix And sigma (sigma) i (0) E [0, 1), θ > 0, ρ > 0 satisfies the following inequality:
The following was demonstrated:
constructing a Lyapunov function:
wherein p=p T ,Q=Q T And r=r T Is a positive definite matrix.
When the condition (1) is satisfied, it is obtained that:
according to the quotation mark 1,is non-singular. Multiplying both sides of formula (38) by +.>The method can obtain the following steps:
then, the formula (20) can be written as:
from equation (40), the derivative of V (t) can be obtained in the form:
applying lemma 1, one can get:
wherein χ is 1 =ε(t-τ(t))-ε(t),χ 2 ε (T-T) - ε (T- τ (T)) and S is a real matrix.
order theAnd->Multiplying both sides of formula (43) by +.>The inequality (43) can be found to be equivalent to:
Zeta (T) =col { epsilon (T), epsilon (T-tau (T)), epsilon (T-T), e (T-tau (T)),substituting equations (25), (40), (42) into equation (41), the derivative of V (t) can be written as:
wherein, xi= [ xi ] p,q ] 6×6 Is a symmetrical matrix and has
Ξ 2,4 =Ω 2 ,
Ξ 2,5 =Ξ 2,6 =0 (N-1)n×Nn ,
Ξ 3,4 =Ξ 3,5 =Ξ 3,6 =0 (N-1)n×Nn ,
Ξ 4,4 =Ω 3 ,
Ξ 4,5 =Ξ 4,6 =Ξ 5,5 =Ξ 5,6 =Ξ 6,6 =0 Nn×Nn ,
Wherein the method comprises the steps of
Multiplying both sides of formula (45) simultaneously:
Applying lemma 2 may result in:
it is further possible to obtain:
taking into account the condition (35) and the schulb theorem, one can obtain:
combining formula (47) with formula (48) can obtain:
And (5) finishing the verification.
By fully utilizing the properties of the undirected graph, the invention obtains the lemma 6, which can effectively avoid using the pseudo-inverse of the matrix compared with the lemma 2.
The numerical simulation process of the embodiment of the invention is as follows:
the control strategy is verified by a system consisting of six agents, the laplace matrix L is as follows:
the kinetic parameters for each agent are shown below:
the formation is in the form ofParameter sigma i (0) The initial value is sigma 1 (0)=σ 2 (0)=σ 3 (0)=σ 4 (0)=σ 5 (0)=σ 6 (0) =0.99 and θ=10 -7 The sampling period is t=0.001 s. K can be selected according to equation (33) 2 =-B -1 A, can be obtained by: k (K) 2 =[-1 3 1;-1 2 0;2 -3 -1]。
Using the LMI tool in MATLAB, let ρ=0.08, the parameters in condition (2) can be calculated:
status x of each agent i (t) time-dependent curves as shown in FIG. 2, it can be seen that the system state eventually tends to a specified formation.
Formation error delta for each agent i And (t) as shown in fig. 3 a-3 c, it can be seen from the graph that the formation error of the intelligent agent tends to be consistent, and the formation definition can be seen from the formation definition, and the formation control can be effectively realized by adopting a dynamic event triggering strategy based on the sampling data.
FIGS. 4 a-4 c show the combined measurement q for each agent i (t) change curve, q i (t) converges and approaches zero over time. Due to non-linear term f i (x i (t), the presence of t), combined measurement q i (t) eventually converging into a domain around zero.
FIGS. 5 a-5 c show the measured error e of each agent i From the graph, it can be seen that e i (t) gradually converges and approaches zero.
Dynamic trigger function parameter sigma for each agent i As shown in FIG. 6, the time-dependent curve of (KT) is shown as σ i (KT) decreases monotonically with time, which will help to reduce the event trigger function g i The number of triggers of (t).
In summary, the invention researches the formation control problem of the nonlinear high-order multi-agent system, adopts a dynamic event triggering mechanism based on sampling data, converts the formation problem into the stability problem of the subsystem, then constructs the subsystem into a time delay system, obtains the sufficient condition of system stability by utilizing the inequality of a linear matrix, and finally realizes the formation control.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (7)
1. The nonlinear multi-intelligent system dynamic event triggering control method is characterized by comprising the following steps of:
s1, each agent synchronously samples state information and periodically monitors an event triggering function, and each agent only broadcasts own state when the function is triggered;
s2, dynamically updating parameters in the event triggering function;
s3, verifying the effectiveness of the control strategy through numerical simulation;
the method further comprises, prior to step S1:
giving a theory, definitions of dynamics and formation problems of each agent, and assumptions and quotations used subsequently;
the graph theory includes:
consider an undirected graph G with N nodes, denoted g= { V, E, W }, where v= { V 1 ,v 2 ,...,v N And represents a collection of nodes,representing a collection of edges, w= [ W ] ij ]∈R N×N Representing an adjacency matrix; for the adjacency matrix W, if (v i ,v j ) E, w is ij > 0, where v i And v j Are neighbors of each other; otherwise w ij =0;N i Representing a set of neighbors of agent i;
the laplacian matrix l= [ L ] of graph G ij ]∈R N×N Is defined asWhen a connection path exists between any two nodes in the graph, the undirected graph G is fully connected;
the problem is described as follows:
consider a multi-agent system with a communication topology G, comprising N agents, each of which has a kinetic model described as:
wherein x is i (t)∈R n ,u i (t)∈R m ,f(x i (t),t)∈R n Respectively represent the state, input and nonlinear dynamics of the intelligent agent i, and has A and B are constant matrices having corresponding dimensions;
definition 1: the multi-agent system is said to be capable of achieving time-varying state formation h if, for any given bounded initial condition, the following requirements are met:
wherein h is i ∈R n Representing state x i Offset of (t) and hasr (t) is a formation location function;
definition 2: if a controller u is used i (t) (i=1, 2,., N.) the multi-agent system is able to achieve formation h, then it is said that formation h is viable;
the hypothesis and quotation are as follows:
suppose 1: graph G is undirected graph and fully connected;
suppose 2: for any x, y ε R n Nonlinear dynamics f (x i (t), t) satisfies the following Li Puxi z condition:
lemma 1: the Laplacian matrix of the undirected graph G is L epsilon R N×N Then:
l has at least one zero eigenvalue, and the eigenvalue corresponds to an eigenvector of 1 N I.e. L1 N =0 N ;
If G is fully connected, 0 is a single eigenvalue of L, the remaining N-1 eigenvalues all have a positive real part, i.e. 0 = λ 1 <λ 2 ≤...≤λ N ;
And (4) lemma 2: if the matrix R > 0, then for any matrix X and scalar ρ > 0, the following is satisfied:
-XR -1 X≤ρ 2 R-2ρX
and (3) lemma 3: for symmetric matrix A 11 ,A 12 ,A 22 The following properties are equivalent:
2. the method for controlling dynamic event triggering of a nonlinear multi-intelligent system according to claim 1, wherein the step S1 specifically comprises:
designing an event triggering mechanism:
the formation error is defined as:
δ i (t)=x i (t)-h i (i=1,2,...,N)
Defining the measurement error as:
Defining a combined measurement as:
wherein the method comprises the steps ofIs the latest trigger time of agent j and has +.>The nonlinear term f (x i (t), t), the state estimate of the obtained agent i is:
Then, the state estimation error is obtained as:
The event-triggered queuing control strategy based on the sampled data is designed as follows:
Dynamic event trigger function g of agent i i (t) is defined as:
wherein sigma i (KT) is a dynamic parameter, and θ > 0 is a positive constant.
3. According to claim 2The nonlinear multi-agent system dynamic event trigger control method is characterized in that an agent only checks a dynamic event trigger function g at each sampling moment KT i (t);
First, according to
Updating dynamic parameter sigma i (KT);
Then, substituting the sampled value into
If and only if g i When (KT) is not less than 0, the system triggers and updates the controller u i (t);
The trigger time is expressed as:
and 4, lemma: for a given initial condition sigma i (0) E [0, 1) and θ > 0, with the adoption of
Parameter update is performed, then sigma i (KT) satisfying the following constraint at any time:
4. the nonlinear multi-intelligent system dynamic event trigger control method according to claim 3, wherein the proving is performed by adopting a mathematical induction method:
when k=1, we get:
indicating 0.ltoreq.sigma i (T)≤σ i (0)<1;
5. The method for dynamic event triggering control of a non-linear multi-intelligent system according to claim 4, wherein a control strategy is adoptedAnd t.epsilon.KT, (K+1) T) and->The multi-agent system has the following form:
delta of the formula i (t)=x i (t)-h i (i=1, 2,) N) substituted into the above formula, further resulting in:
let lambda get i (i=1, 2,., N) represents the eigenvalue of the laplace matrix L, J is about the right standard type of L, then there isAnd U -1 =U T Satisfies the following formula:
U -1 LU=U T LU=J=diag{λ 1 ,λ 2 ,...,λ N }
defining a time delay function tau (T) =t-KT, t.epsilon.KT, (K+1) T, 0.ltoreq.tau (T) < T being piecewise linear, and havingAt this time, a method for solving the time delay problem is adopted to solve the formation problem;
The writing is as follows:
system and method for controlling a system
Conversion of formation control problems into systems
Stability problems of (2);
and (5) lemma: for multiple intelligent systemsUsing a controllerAnd dynamic event trigger function based on sampling data
A formation h can be implemented if and only if:
the proving process is as follows:
if and only if the following formula is satisfied:
the method comprises the following steps:
and (3) lemma 6: for event triggering functions
Given an initial condition σ (0) =diag { σ } 1 (0),σ 2 (0),...,σ N (0) ' and sigma N-1 (0)=diag{σ 2 (0),...,σ N (0) } $ gives the following inequality:
The following was demonstrated:
the method comprises the following steps of:
from delta i (t) and e i Definition of (t) gives:
this gives:
from the definition of η (t), it is known that:
substituting the two formulas into one
The method comprises the following steps:
and (5) finishing the verification.
6. The method for dynamic event-triggered control of a non-linear multi-intelligent system of claim 5, wherein for a multi-intelligent systemIf a controller is used->Based on the dynamic event trigger function of the sampled data, when hypothesis 1 and hypothesis 2 are satisfied, formation h is possible when the following conditions are satisfied:
(A+BK 2 )(h i -h j )=0
B. there is a real matrix And sigma (sigma) i (0) E [0, 1), θ > 0, ρ > 0 satisfies the following inequality:
7. The method for controlling dynamic event triggering of a nonlinear multi-intelligent system according to claim 6, wherein the proving process is as follows:
the following lyapunov function was constructed:
wherein p=p T ,Q=Q T And r=r T Is a positive definite matrix;
when the condition A is satisfied, the following steps are obtained:
opposite typeBoth sides are multiplied by +.>Because of->The method further comprises the following steps:
according to the quotation mark 1,is non-singular; will->Both sides are multiplied by +.>The method comprises the following steps:
then
The writing is as follows:
according to the above formula, the derivative of V (t) is given by:
applying lemma 1, obtaining:
wherein χ is 1 =ε(t-τ(t))-ε(t),χ 2 ε (T-T) - ε (T- τ (T)) and S is a real matrix;
Substituted formula
The derivative of V (t) is written as:
wherein, xi= [ xi ] p,q ] 6×6 Is a symmetrical matrix and has
Ξ 2,4 =Ω 2 ,
Ξ 2,5 =Ξ 2,6 =0 (N-1)n×Nn ,
Ξ 3,4 =Ξ 3,5 =Ξ 3,6 =0 (N-1)n×Nn ,
Ξ 4,4 =Ω 3 ,
Ξ 4,5 =Ξ 4,6 =Ξ 5,5 =Ξ 5,6 =Ξ 6,6 =0 Nn×Nn ,
Wherein the method comprises the steps of
consider the conditions
And the Shu Er's theorem, get:
combining the above formulas yields:
equivalent to inequality
At the same time satisfy inequality
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