Multi-UUV cluster formation control method based on asynchronous discontinuous event triggering

Abstract

The invention relates to the technical field of unmanned underwater navigation, and discloses a multi-UUV cluster formation control method based on asynchronous discontinuous event triggering, which is used for adjusting a control strategy of a UUV and ensuring the dynamic stability of a cluster by designing distributed discontinuous control input and updating control input at a discontinuous event triggering moment. Whether control updating needs to be triggered or not is judged through setting of a time triggering function, through cooperation of a cooperative positioning module and a control strategy module and in combination with a closed-loop system, it is ensured that the UUV cluster can effectively cope with various environment changes when executing tasks, stability adjustment can be deduced through the property of a Laplacian matrix L and an inequality formula, and the stability of the UUV cluster is improved. By introducing the mechanism of the event trigger function, the updating frequency of the control input can be reduced, and the communication burden is relieved.

Description

Technical Field

[0001] The present invention relates to the field of unmanned underwater navigation technology, and in particular to a multi-UUV cluster formation control method based on asynchronous non-continuous event triggering. Background Art

[0002] The so-called underwater unmanned swarm refers to a group of underwater unmanned platforms that have certain autonomous decision-making capabilities, command control and communication relationships between each other, and jointly undertake given mission tasks. The underwater unmanned platform swarm collaboration represented by UUV has attracted widespread attention due to its high operating efficiency, good concealment, low cost, and few casualties. It is widely used in underwater military confrontation tactics, deep-sea area retrieval and detection, target tracking, ocean data observation and other underwater tasks. Collaborative formation control is an important part of group collaboration. By designing interactive control strategies based on local information, a group of autonomous intelligent agents can form and stably maintain a specific formation shape.

[0003] One of the key issues in multi-UUV formation control is the state information exchange between UUVs. However, unlike in the air and on land, electromagnetic waves have high energy loss when propagating underwater, which makes radio, satellite and other communication equipment unusable. The commonly used underwater hydroacoustic communication equipment also has the characteristics of low propagation speed, limited bandwidth, and fast acoustic energy attenuation. The data transmission rate between UUVs is very low. Summary of the invention

[0004] The purpose of the present invention is to provide a multi-UUV cluster formation control method based on asynchronous non-continuous event triggering. In actual engineering applications, each UUV can directly measure the distance and azimuth instead of the position state, and convert the distance and azimuth measurement values ​​into the relative position information between each neighbor UUV through a collaborative positioning strategy, and then design a control strategy with low communication burden to realize the rigid control of the UUV cluster formation.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solutions: a multi-UUV cluster formation control method based on asynchronous non-continuous event triggering, comprising a collaborative positioning module and a control strategy module;

[0006] The hybrid constraints of each UUV cluster are measured under non-continuous time conditions, and the control input is updated;

[0007] The collaborative positioning module determines the relative positions between adjacent UUVs by a collaborative positioning method based on a mixed measurement of orientation and distance in a local coordinate system;

[0008] The control strategy module needs time and computing resources to reconstruct the relative position from the mixed measurement data, and underwater communication is limited by communication bandwidth and signal propagation speed. Consider introducing an event trigger mechanism based on discontinuous communication to design a control strategy to replace the continuous-time formation control;

[0009] The collaborative positioning module includes perception map division, orientation and distance measurement, and collaborative positioning strategy, wherein the perception map division includes the perception map G S , the perception graph G S Divide into several subgraphs according to the adjacent relationship, namely Define the m=1,…,M subgraphs as The number of nodes in the mth subgraph is r m , that is, |V m |=r m ; The position and distance measurements can be directly obtained by the sensors configured by the UUV; The collaborative positioning strategy is characterized by:

[0010] If the sensor subgraph of the system The constraint matrix satisfies the formula:

[0011] rank(R(p m ))=2r m -2, then in the subgraph On the structure p m It is relatively locatable.

[0012] The control strategy module includes a design control input, a distributed discontinuous control input and a closed-loop system.

[0013] Preferably, the formula for the design control input is:

[0014] The parameter w ij is a positive real number.

[0015] Preferably, the formula of the distributed discontinuous control input is:

[0016] Indicates UUV- i At the event triggering moment, the distributed non-continuous control input is brought into the original system, and the formula can be obtained:

[0017] By and Simplified representation and The compact formula of the closed-loop system is:

[0018] Where L represents a positive real Laplace matrix.

[0019] Preferably, the formula of the event trigger function is:

[0020] in, And η>|N i |.

[0021] Preferably, the Lyapunov function formula of the closed-loop system is: in, Taking the derivative, we get the formula:

[0022] for Simplified form, introducing a 2×n auxiliary vector, Known Each column vector in represents the relative position information between the corresponding agent and its neighbors at the triggering moment, that is, the formula:

[0023]

[0024] Preferably, according to the properties and inequalities of the Laplace matrix L:

[0025] |ab|≤(η / 2)a 2 +(1 / 2η)b 2 (η>0), we get the equation:

[0026] Where |N i | represents UUV- i The number of neighbors of , for all agents i∈v, the parameter η is a positive real number and satisfies η>|N i |, when δ i ∈(0,1), if there is an inequality:

[0027] If established,

[0028] Preferably, when the event trigger function meets the following conditions:

[0029]

[0030] Among them, δ i ∈(0,1), the event can be triggered, and the trigger condition is designed as: f(e i )≥0, the event trigger function depends on the state at the last trigger time, ensuring that the UUV will not miss any trigger event.

[0031] Preferably, for i∈{1,…,n}, let δ max =maxδ i , we can get the formula:

[0032]

[0033] in:

[0034] At this time, the derivation formula of V is:

[0035]

[0036] According to formula 1:

[0037]

[0038] And formula 2:

[0039]

[0040] in:

[0041] Preferably, by substituting the formula 1 and the formula 2 into the formula of V, the formula can be derived:

[0042]

[0043] Thus the formula is established:

[0044] To be more intuitive, According to the comparison theorem, V(p(t))≤V(p(0))e -Ct , t ≥ 0, indicating that all UUVs can converge exponentially to the desired formation, ensuring the dynamic stability of the cluster.

[0045] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0046] First, the present invention shows how to adjust the control input according to the position difference between UUVs to maintain the stability of the cluster through the formula of the control input updated continuously at each moment, where p i (t) and p j (t) represent UUV- i and UUV- j The position vector, w ij is a positive real number weight, which is used to measure the interaction strength between two UUVs. Through the formula of distributed discontinuous control input, the control input updated at the discontinuous moment of the event triggering moment is used to adjust the control strategy of UUV to ensure the dynamic stability of the cluster. Indicates UUV-i The event triggering time, and the closed-loop system formula Indicates UUV- i The rate of change of the position vector over time, and L in the compact formula of the closed-loop system represents the positive real Laplace matrix. The time trigger function is set to determine whether the control update needs to be triggered. Through the cooperation of the collaborative positioning module and the control strategy module, combined with the closed-loop system, it is ensured that the UUV cluster can effectively respond to various environmental changes when performing tasks and maintain the stability and efficiency of the cluster. The stability regulation can be derived through the properties of the Laplace matrix L and the inequality formula. By introducing the mechanism of the event trigger function, the update frequency of the control input can be reduced and the communication burden can be reduced.

[0047] Second, in the present invention, when the event trigger function meets certain conditions, that is, where δ i ∈(0,1), the event can be triggered, and the trigger condition is designed as: f(e i )≥0, the event trigger function depends on the state of the previous trigger time, ensuring that the UUV will not miss any trigger event. i )<0, UUV- i The control input remains unchanged, and its error e i Will grow discontinuously and gradually, at any triggering moment The trigger condition is met, the error e i will be reset to zero, so it can be inferred that when δ i ∈(0,1), When certain conditions are met, the derivative of the Lyapunov function of the closed-loop system is negative, thus ensuring the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a schematic diagram of the motion change trajectory structure of the UUV of the present invention;

[0049] Figure 2 This is a schematic diagram of the relative distance error structure of UUV-1 and UUV-2 of the present invention;

[0050] Figure 3 It is a schematic diagram of the relative distance error between UUV-2 and UUV-3 and the relative distance error between UUVs of the present invention;

[0051] Figure 4 This is a schematic diagram of the event triggering moment structure of the UUV-1 of the present invention;

[0052] Figure 5 It is a schematic diagram of the asynchronous triggering moment structure of the UUV-3 of the present invention when the event is triggered. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The present invention provides the following technical solutions:

[0055] Embodiment 1

[0056] See also Figure 1-5 , a multi-UUV cluster formation control method based on asynchronous non-continuous event triggering, including a collaborative positioning module and a control strategy module;

[0057] The collaborative positioning module includes perception map division, orientation and distance measurement, and collaborative positioning strategy. The perception map division includes the perception map G S , the perception graph G S Divide into several subgraphs according to the adjacent relationship, namely Define the m=1,…,M subgraphs as The number of nodes in the mth subgraph is r m , that is, |V m |=r m ; The orientation and distance measurements can be directly obtained through the sensors configured on the UUV; The collaborative positioning strategy is: if the sensor sub-map of the system The constraint matrix satisfies the formula:

[0058] rank(R(p m ))=2r m -2, then in the subgraph On the structure p m It is relatively locatable.

[0059] The control strategy module includes continuously updated control input, distributed discontinuous control input and closed-loop system.

[0060] By perceiving the graph G S The definition of the perception graph G S Divide into several subgraphs, each of which Represents a group of UUVs in a specific area and their interconnected relationships. The number of nodes in the mth subgraph is r m , design the sensor subgraph of the system The constraint matrix rank(R(p m ))=2r m -2, ensure that the structure p mIt is relatively locatable, and the control strategy module is responsible for formulating control strategies to ensure the stability and efficiency of the cluster.

[0061] The formula for designing the control input is:

[0062] The parameter w ij is a positive real number.

[0063] The control input formula shows how to adjust the control input according to the position difference between UUVs to maintain the stability of the cluster, where p i (t) and p j (t) represent UUV- i and UUV- j The position vector, w ij is a positive real number weight used to measure the interaction strength between two UUVs.

[0064] The formula for distributed non-continuous control input is:

[0065]

[0066] Indicates UUV- i At the event triggering moment, the distributed non-continuous control input is brought into the original system, and the formula can be obtained:

[0067] By and Simplified representation and The compact formula for the closed-loop system is:

[0068] Where L represents a positive real Laplace matrix.

[0069] Through the formula of distributed discontinuous control input, the control input updated at the discontinuous moment of the event triggering moment is used to adjust the control strategy of the UUV to ensure the dynamic stability of the cluster. Indicates UUV- i The event triggering time, and the closed-loop system formula represents the rate of change of the position vector of UUV-i with time, and L in the compact formula of the closed-loop system represents the positive real Laplace matrix.

[0070] The formula for the event trigger function is:

[0071] in, And η>|Ν i |.

[0072] Through the above technical solution, the control input formula is used to express how to adjust the control input according to the position difference between UUVs to maintain the stability of the cluster, where p i (t) and p j (t) represent the position vectors of UUV-i and UUV-j respectively, p(t) is the target position vector, w ij is a positive real number weight, which is used to measure the interaction strength between two UUVs. Through the formula of distributed discontinuous control input, the control input updated at the discontinuous moment of the event triggering moment is used to adjust the control strategy of UUV to ensure the dynamic stability of the cluster. Indicates UUV- i The event triggering time, and the closed-loop system formula Indicates UUV- i The rate of change of the position vector with time, and L in the compact formula of the closed-loop system represents the positive real Laplace matrix. The time trigger function is set to determine whether the control update needs to be triggered. The coordination of the collaborative positioning module and the control strategy module, combined with the closed-loop system, ensures that the UUV cluster can effectively respond to various environmental changes when performing tasks and maintain the stability and efficiency of the cluster. The communication pressure and formation control problems of the UUV cluster are solved through the collaborative formation and collaborative positioning method based on hybrid constraints and asynchronous event triggering. The underwater unmanned platform cluster collaboration represented by UUV proves its advantages such as high operating efficiency, good concealment, low cost and few casualties.

[0073] Embodiment 2

[0074] See also Figure 1-5 , based on the multi-UUV cluster formation control method triggered by asynchronous non-continuous events, the Lyapunov function formula of the closed-loop system is: in, Taking the derivative, we get the formula:

[0075] To simplify In the form of , a 2×n auxiliary vector is introduced Known Each column vector in represents the relative position information between the corresponding agent and its neighbors at the triggering moment, that is, the formula:

[0076]

[0077] By introducing the auxiliary vector To simplify The form of Represents the relative position information between the agent and its neighbors corresponding to the trigger moment.

[0078] According to the properties of the Laplace matrix L and the inequality formula:

[0079] |ab|≤(η / 2)a 2 +(1 / 2η)b 2 (η>0), the equation is obtained:

[0080]

[0081] Where |N i | represents UUV- i The number of neighbors of , for all agents i∈v, the parameter η is a positive real number and satisfies η>|N i |, when δ i ∈(0,1), if there is an inequality:

[0082] If established,

[0083] The purpose of introducing the event trigger mechanism is to reduce the update frequency of the control input and reduce the communication burden. In the form of The formula It represents the relative position information between the intelligent agent and its neighbors corresponding to the trigger moment. The stability regulation can be derived through the properties of the Laplace matrix L and the inequality formula. By introducing the mechanism of event trigger function, the update frequency of control input can be reduced and the communication burden can be reduced.

[0084] Embodiment 3

[0085] See also Figure 1-5 , a multi-UUV cluster formation control method based on asynchronous non-continuous event triggering, when the event trigger function meets the following conditions:

[0086] Among them, δ i ∈(0,1), the event can be triggered, and the trigger condition is designed as: f(e i )≥0, the event trigger function depends on the state at the last trigger time, ensuring that the UUV will not miss any trigger event.

[0087] For i∈{1,…,n}, let δ max =maxδ i , we can get the formula:

[0088]

[0089] in:

[0090] At this time, the derivation formula of V is:

[0091]

[0092] According to formula 1:

[0093]

[0094] And formula 2:

[0095]

[0096] in:

[0097] Substituting formula 1 and formula 2 into the formula of V, we can derive the formula:

[0098]

[0099] Thus the formula is established:

[0100] To be more intuitive, According to the comparison theorem, V(p(t))≤V(p(0))e -Ct , t ≥ 0, indicating that all UUVs can converge exponentially to the desired formation, ensuring the dynamic stability of the cluster.

[0101] Through the above technical solution, when the event trigger function meets specific conditions, that is, where δ i ∈(0,1), the event can be triggered, and the trigger condition is designed as: f(e i )≥0, the event trigger function depends on the state of the previous trigger time, ensuring that the UUV will not miss any trigger event. i )<0, UUV- i The control input remains unchanged, and its error e i Will grow discontinuously and gradually, at any triggering moment The trigger condition is met, the error e i will be reset to zero, so it can be inferred that δ i ∈(0,1), When certain conditions are met, the derivative of the Lyapunov function of the closed-loop system is negative, thus ensuring the stability of the system.

[0102] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit thereof, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-UUV cluster formation control method based on asynchronous non-continuous event triggering, characterized by: Includes collaborative positioning module and control strategy module; The hybrid constraints of each UUV cluster are measured under non-continuous time conditions, and the control input is updated; The collaborative positioning module determines the relative positions between adjacent UUVs by a collaborative positioning method based on a mixed measurement of orientation and distance in a local coordinate system; The control strategy module needs time and computing resources to reconstruct the relative position from the mixed measurement data, and underwater communication is limited by communication bandwidth and signal propagation speed. Consider introducing a control strategy based on discontinuous communication event trigger mechanism to replace continuous time formation control; The collaborative positioning module includes perception map division, orientation and distance measurement, and collaborative positioning strategy, wherein the perception map division includes a perception map, the perception map G S Divide into several subgraphs according to the adjacent relationship, namely Define the m=1,…,M subgraphs as The number of nodes in the mth subgraph is r m , that is, V m =r m ; The position and distance measurements can be directly obtained by the sensors configured by the UUV; The collaborative positioning strategy is characterized by: If the sensor subgraph of the system The constraint matrix satisfies the formula: rank(R(p m ))=2r m -2, then in the subgraph On the structure p m is relatively locatable; The control strategy module includes a design control input, a distributed discontinuous control input and a closed-loop system.

2. The multi-UUV cluster formation control method based on asynchronous non-continuous event triggering according to claim 1 is characterized by: The formula for the design control input is: The parameter w ij is a positive real number.

3. The multi-UUV cluster formation control method based on asynchronous non-continuous event triggering according to claim 1 is characterized by: The formula for the distributed discontinuous control input is: Indicates UUV- i At the event triggering moment, the distributed non-continuous control input is brought into the original system, and the formula can be obtained: By and Simplified representation and The compact formula of the closed-loop system is: Where L represents a positive real Laplace matrix.

4. The multi-UUV cluster formation control method based on asynchronous non-continuous event triggering according to claim 1 is characterized by: The formula of the event trigger function is: in, And η>N i .

5. The multi-UUV cluster formation control method based on asynchronous non-continuous event triggering according to claim 3 is characterized by: The Lyapunov function formula of the closed-loop system is: in, By taking the derivative, we can get the formula: To simplify In the form of , a 2×n auxiliary vector is introduced Known Each column vector in represents the relative position information between the corresponding agent and its neighbors at the triggering moment, that is, the formula:

6. The multi-UUV cluster formation control method based on asynchronous non-continuous event triggering according to claim 3 is characterized by: By the properties and inequalities of the Laplace matrix L: ab≤(η2)a 2 +(12η)b 2 (η>0), we get the equation: Where N i Indicates the UUV- i The number of neighbors of the agent i∈v, for all agents i∈v, the parameter η is a positive real number and satisfies η>N i , when δ i ∈(0,1), if there is an inequality: If established, 7. The multi-UUV cluster formation control method based on asynchronous non-continuous event triggering according to claim 3 is characterized by: When the event trigger function meets the following conditions: Among them, δ i ∈(0,1), the event can be triggered, and the trigger condition is designed as: f(e i )≥0, the event trigger function depends on the state at the last trigger time, ensuring that the UUV will not miss any trigger event.

8. The multi-UUV cluster formation control method based on asynchronous non-continuous event triggering according to claim 5 is characterized by: For i∈{1,…,n}, let δ max =maxδ i , we can get the formula: in: At this time, the derivation formula of V is: According to formula 1: And formula 2: in:

9. The multi-UUV cluster formation control method based on asynchronous non-continuous event triggering according to claim 7 is characterized by: Substituting Formula 1 and Formula 2 into the formula of V, the formula can be derived: Thus the formula is established: To be more intuitive, According to the comparison theorem, V(p(t))≤V(p(0))e -Ct , t ≥ 0, indicating that all UUVs can converge exponentially to the desired formation, ensuring the dynamic stability of the cluster.

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