CN111435230A

CN111435230A - Intra-cavity structure sound integrated control technology based on smart structure

Info

Publication number: CN111435230A
Application number: CN201910028911.8A
Authority: CN
Inventors: 崔怀峰
Original assignee: Ningbo University of Technology
Current assignee: Ningbo University of Technology
Priority date: 2019-01-12
Filing date: 2019-01-12
Publication date: 2020-07-21

Abstract

The invention provides an active structure sound control system with an agile structure. Noise in a closed cavity containing multiple elastic walls is controlled by a smart structure. The smart structure has functions of starting, combining, global optimization and the like. Collaboration between the agile structures is addressed by the coordination structure. The coordination structure has three functions of starting judgment, activation decision and cooperation, wherein the cooperation function is realized by distributing control factors. The difference in control factor depends on the position of the PZT actuator. And extracting the control factors from the smart structure to the coordination structure. Whether or not control factors are assigned to smart structures depends on real-time changes in the sound field. The processing method not only ensures the consistency of the design of the smart structures and is beneficial to realizing centralized control, but also solves the coupling problem between the smart structures. Meanwhile, the system has the characteristics of high reliability, openness and the like of distributed control and has the advantage of high control performance of centralized control due to the modularized design of the comprehensive smart structure.

Description

Intra-cavity structure sound integrated control technology based on smart structure

Technical Field

The invention belongs to the technical field of vibration noise active control, and particularly relates to an integrated control method for a rectangular intracavity noise active acoustic structure with two elastic walls.

Background

The active structure sound control is difficult to popularize in practice, and is mainly attributed to the defects of low reliability, difficult installation and maintenance and the like of most control systems. The active structure sound control has the distributed characteristic, and the control mode mainly comprises distributed, centralized and distributed control. The distributed control is made up of a plurality of controllers, each of which receives system local sensor signals and generates local control signals therefrom. The decentralized control also comprises a plurality of controllers, each of which receives only one sensor signal and generates a control signal in response thereto. The centralized control has only one controller for receiving the signals of all sensors and generating all control signals through it. The centralized control is beneficial to realizing the integral optimization and has better control performance than the distributed control under the same control condition. However, the centralized control has poor expandability, and the distributed control has the advantages of strong expandability, high reliability, easy execution and maintenance, and the like. The integrated control adopted by the application comprises a plurality of controllers, each controller receives all sensor signals and outputs a control signal according to the sensor signals, and the aim of the integrated control is to integrate the advantages of centralized control and decentralized control.

Through long-term practice, it has been found that the problem of active structure acoustic control of complex systems must be solved by high-dimensional coupled systems. However, a completely continuous distributed control mechanism is used for complex large systems, which is expensive if not impossible. Therefore, there is a need to develop a more rational control framework. The limited discrete distributed control of the intelligent control unit is certainly one of the solutions, but this creates a coordination problem between the overall control framework and the intelligent control unit.

The ultimate goal of active noise control is intelligent control. Currently, intelligent control is far from being realized in practice. Many scholars only study some of the relevant problems of intelligent control. To date, most researchers have focused on the study of smart/smart architectures. Smart architecture refers to the integration of actuators, sensors in structural components and the use of some kind of control unit, or enhanced signal processing by materials or structural components. The so-called intelligent architecture in the present reference does not essentially contain intelligent algorithms/intelligent controllers. The emphasis here is on developing intelligent controllers in intelligent architectures.

The application applies the integrated control system based on the smart structure to the active structure sound control of a closed cavity. Limited discrete distributed control of smart architectures is employed. Each smart architecture includes a controller that can operate independently to address local noise control issues. All smart structures are coupled into a complete system through the upper tissues. The integrated control system not only solves the coupling problem between smart structures, but also integrates the advantages of different control modes, and is beneficial to realizing the application and popularization of active structure sound control in practice.

Disclosure of Invention

The technical problem is as follows:

active control of vibration noise is rarely applied in practice, mainly due to the defects of low reliability, difficult installation and maintenance and the like of most control systems. The invention provides an integrated control technology based on a smart structure, integrates the advantages of different control methods through the smart structure and a coordination structure, and effectively overcomes the defects of the existing vibration noise active control system.

The technical scheme is as follows: in order to solve the technical problems, the invention adopts the following technical scheme.

An integrated control technology of vibration noise in a closed cavity is characterized in that:

for a rectangular closed cavity containing multiple elastic plates, when one of the elastic plates (taking plate a as an example) is subjected to an external interference force F, the elastic plate a generates vibration and radiates noise into the cavity, and the vibration and the noise are coupled with sound waves in the cavity to form an in-cavity coupled noise field. Other elastic plates are acoustically excited and vibrate and produce acoustic radiation in a similar mechanism to plate a. A plurality of PZT piezoelectric ceramic patches are pasted on the elastic plate a to be used as actuators, 4 microphones are arranged in the cavity to be used as error sensors and are respectively fixed at (0.8,1.1,0.05), (0.43,0.57,0.5), (0.05,0.05,0.95) and (0.8,0.05,0.05) m positions in the cavity.

Because intra-cavity noise is mainly affected by acoustic-solid coupling, the noise control problem at each coupled natural frequency is considered a local control problem and is solved by a smart structure. The smart architecture includes sensors, actuators, and controllers. Acoustic field in the investigated closed cavity at a coupling natural frequency of 36Hz (f)₁),148Hz(f₂),171Hz(f₃),196Hz(f₄),254Hz (f₅) And 295Hz (f)₆) Is large, so for the 6 resonance frequencies f_k(k 1-6) 6 Smart Structures (SS) were designed and SS was used_kIs shown, in which SS₁～SS₆Are respectively used for controlling f₁～f₆Noise at frequency. PZT in smart structure_kThe position of the actuator is determined according to the optimized sound potential energy profile，PZT₁～PZT₆Are arranged at (0.47,0.35) m, (0.55,0.65) m, (0.65,0.7) m, (0.58,0.74) m, (0.54,0.43) m and (0.35,0.42) m on the board a, respectively. The thickness of the plates a and b is h_a＝h_b6 mm. The parameters of the PZT patches were: thickness h_p0.254mm, modulus of elasticity E_pzt＝7.24×10¹⁰N m^-2Poisson ratio v_p0.3, dielectric constant d₃₁＝2.74×10^-10m V^-1The length and width of the PZT patch are both 20 mm.

The SS is a broad integration of sensors, actuators, and controllers, with the emphasis on controllers being developed herein. The controller includes a series of functions and functional blocks within it to implement various functional behaviors. The start-up function is used to determine the start-up conditions of the SS, which is defined as

In the formula (I), the compound is shown in the specification,

to couple natural frequency f_kThe primary sound potential energy of the upper part,

is the noise threshold at that frequency. Considering the auditory perception of the human ear and the relationship between the A-weighted sound level and the relative sound pressure level, T₃₆,T₁₄₈,T₁₇₁,T₁₉₆,T₂₅₄And T₂₉₅72dB,44dB,42dB,40dB,38dB and 37dB, respectively. The SS transmits a signal 1 to the upper organization if formula (1) is satisfied, and otherwise transmits a signal 0 to the upper organization. The upper layer organization sends control instructions to the SS to determine the operating state of the SS. And if the control instruction 1 sent by the upper layer organization is received, the SS activates operation, otherwise, the SS cannot activate. The transition behavior of the startup state and the active state is described by a finite state machine. The mixing function is defined as

In the formula, h_amRepresenting resonant terms of the slab and cavity, M_amRepresenting the modal quality of the panel a, D_m,kRepresenting the secondary generalized modal forces. D_kReflects the amount of contribution of all PZT actuators to noise reduction and weights the control factor of SS to the global output. The optimization function adopts a quadratic optimization algorithm, and the calculation result is established on the basis of the output of the mixing function. Thus, the optimization function employs global optimization. It outputs the optimized control voltage of all the actuators and outputs the control voltage V via the output distribution function block_kTo the corresponding PZT_kAn actuator. Therefore, the control system has high control performance of centralized control. In addition, the controller contains an update function that is executed in either the activated or deactivated state of the SS.

The behavioral relationships between SSs are coordinated through an upper level organization called a coordination structure. It includes a three-step coordination procedure and two coordination mechanisms. When the SS sends an enabling signal 1 to the coordination structure, the coordination structure starts to execute the first step procedure: admission (whether start-up is agreed to). Whether the start-up is agreed upon depends on the admission function given below

E_pmax≥T (3)

In the formula, E_pmaxRepresenting the maximum acoustic potential within the cavity and T represents the threshold for the overall noise field and is taken to be 50 dB. The SS can be granted start-up and proceed to the next step only if equation (3) is satisfied, otherwise the SS is denied entry. If equation (3) holds and only one SS is agreed to start, the coordination structure agrees directly to its activation. If several SSs send start signals at the same time and are agreed to start, the coordination structure performs a step 2 procedure, the decision, which SS is activated, is decided by a contention mechanism. The contention mechanism is performed by the decision function given below

In the formula (f)_maxThe maximum sonopotential energy frequency in the cavity. The decision function is in the SS which is agreed to start but not activatedIs performed. When y is_kY is the minimum value (∈ Y)_kmin，SS_kIs activated to run. If only one SS is activated, it receives the positive command 1 from the coordination structure and the corresponding control factors and performs the initialization function. The remaining SSs receive a negative command 0 and cannot be activated. If several SSs are activated at the same time, the coordination structure starts to execute the step 3 procedure: and (4) cooperation. The cooperation mechanism is designed by assigning corresponding control factors. Because the contribution of the PZT actuator to noise attenuation depends on the secondary generalized modal force D_m,kIt is therefore defined as the control factor. By the formula (2), D_kCan be expressed as

In the formula, "· indicates dot multiplication. The column vectors of the first matrix to the right of the equation are all the same, each column being denoted as D_hmThe number of column vectors is the same as the number of PZT actuators. Each column of the second matrix to the right of the equation corresponds to a PZT actuator. When the coordinates of the PZT patch center on the plate a are determined, the mode shape function of the plate a

Is a constant. By expression of secondary generalized modal forces

It can be seen that D_m,kIs a constant. Therefore, the constant vector W_k＝[D_1,k,D_2,k,…,D_m,k]^TFrom mixing function D_kExtracted out of the collaboration function block stored in the coordination structure. Joint control between SSs is achieved through a mixing function, and coupling between SSs is smoothly solved through a coordination structure.

And establishing an integrated control system. The internal design of each SS is substantially the same for ease of installation and maintenance of the control system. The internal functions and functional blocks of each SS are the same except for the start-up function. Simply changeLower threshold value

The interchange between SSs can be realized. Each SS is an independent control system that can operate independently. In addition, when a new SS is added, the adjustment of the control system can be completed only by adding the corresponding control factor of the new SS in the coordination structure. The flexible butt joint of the control factors and the mixing function realizes the centralized control of the system and solves the behavior conflict and cooperation among the SSs. And the system can realize intelligent logic judgment by adopting a bottom-up starting application and a top-down activation response mode. The decision of which SS to activate and which SSs need joint control is made through a coordination structure, and an integrated SS-based control system is established through the coordination structure.

Has the advantages that: compared with the prior art, the invention has the following advantages:

the system can receive all sensor signals and generate global optimal control voltage by the sensor signals, so that the system has the characteristic of high control performance of centralized control. The system adopts a modular design, so that the system has the characteristics of high reliability and fault tolerance of decentralized control, easiness in installation and maintenance and the like. Therefore, the integrated control technology based on SS integrates the advantages of centralized control and decentralized control, and effectively overcomes the defects of poor reliability, difficult execution and maintenance and the like in the prior art.

Drawings

Figure 1 is a model of an acoustic chamber containing two elastic panels.

Figure 2 controls the acoustic potential energy in the front chamber.

FIG. 3 is a graph of the optimized sound potential energy profile at each coupled natural frequency. (a) f. of₁＝36Hz；(b)f₂＝148Hz；(c)f₃＝171Hz； (d)f₄＝196Hz；(e)f₅＝254Hz；(f)f₆＝295Hz。

Fig. 4 internal architecture of the SS controller.

Fig. 5a startup state transition behavior of SS.

Fig. 5b the operation state transition behavior of the SS.

FIG. 6 an integrated control system architecture.

Fig. 7 is a control flow of the integrated control system.

Fig. 8 contains the control performance of the integrated control system of the SS.

FIG. 9 SS₁And SS₄The control effect of the integrated control system in case of failure.

FIG. 10 addition of SS₆Substituted SS₃And comparing the front control effect and the rear control effect.

Detailed Description

The present invention will be further described with reference to the accompanying drawings.

The invention provides an integrated control technology for vibration noise in a closed cavity, which has the following implementation mode:

a local control problem is defined. For a rectangular closed cavity containing multiple elastic plates, as shown in fig. 1, when one of the elastic plates (taking plate a as an example) is subjected to an external interference force F, the elastic plate a generates vibration to radiate noise into the cavity, and generates coupling with the sound wave in the cavity to form an in-cavity coupling noise field. Other elastic plates are acoustically excited and vibrate and produce acoustic radiation in a similar mechanism to plate a. Several PZT piezoelectric ceramic patches are pasted on the elastic plate a as actuators, 4 microphones are arranged in the cavity as error sensors, and are respectively fixed at (0.8,1.1,0.05), (0.43,0.57,0.5), (0.05,0.05,0.95) m positions in the cavity. Because intra-cavity noise is mainly affected by acoustic-solid coupling, the noise control problem at each coupled natural frequency is considered a local control problem and is solved with a smart structure. The smart architecture includes sensors, actuators, and controllers. Acoustic field in the investigated closed cavity at a coupling natural frequency of 36Hz (f)₁),148Hz(f₂),171Hz(f₃), 196Hz(f₄),254Hz(f₅) And 295Hz (f)₆) The noise above is large, as shown in fig. 2, and therefore for the 6 resonance frequencies f_kNoise on (k 1-6) 6 Smart structures were designed and denoted SS_kWherein SS₁～SS₆Are respectively used for controlling f₁～f₆Noise at frequency. PZT in smart structure_kPosition of the actuatorIs determined according to the optimized sound potential energy profile, wherein PZT₁～PZT₆Are arranged at (0.47,0.35) m, (0.55,0.65) m, (0.65,0.7) m, (0.58,0.74) m, (0.54,0.43) m and (0.35,0.42) m on the board a, respectively, as shown in fig. 3. The thickness of the plates a and b is h_a＝h_b6 mm. The parameters of the PZT patches were: thickness h_p0.254mm, modulus of elasticity E_pzt＝7.24×10¹⁰N m^-2Poisson ratio v_p0.3, dielectric constant d₃₁＝2.74×10^-10m V^-1The length and width of the PZT patch are both 20 mm.

And (5) smart structure design. The SS integrates sensors, actuators, and controllers in a broad sense, and the controller is developed with emphasis on this application. The controller internally includes a series of functions and function blocks to implement various functional behaviors, as shown in fig. 4. The start-up function is used to determine the start-up conditions of the SS, which is defined as

In the formula (I), the compound is shown in the specification,

is the noise threshold at that frequency. Considering the auditory perception of the human ear and the relationship between the A-weighted sound level and the relative sound pressure level, T₃₆,T₁₄₈,T₁₇₁,T₁₉₆,T₂₅₄And T₂₉₅72dB,44dB,42dB,40dB,38dB and 37dB, respectively. The SS transmits a signal 1 to the upper organization if formula (1) is satisfied, and otherwise transmits a signal 0 to the upper organization. The upper layer organization sends control instructions to the SS to determine the operating state of the SS. And if the control instruction 1 sent by the upper layer organization is received, the SS activates operation, otherwise, the SS cannot activate. The transition behavior of the startup state and the active state is described by a finite state machine, as shown in fig. 5a and 5b, respectively. The mixing function is defined as

Coordination between smart structures. The behavioral relationships between the SSs are coordinated by an upper level organization called a coordination structure, which includes a three-step coordination procedure and two coordination mechanisms, as shown in fig. 6. When the SS sends an enabling signal 1 to the coordination structure, the coordination structure starts to execute the first step procedure: admission (whether start-up is agreed to). Whether the start-up is agreed upon depends on the admission function given below

E_pmax≥T (3)

In the formula, E_pmaxRepresents the maximum acoustic potential in the cavity and T represents the threshold value of the whole noise field and is taken as 50dB (which can be set according to actual requirements). The SS can be granted start-up and proceed to the next step only if equation (3) is satisfied, otherwise the SS is denied entry. If equation (3) holds and only one SS is agreed to start, the coordination structure agrees directly to its activation. If several SSs send start signals at the same time and are agreed to start, the coordination structure executes the step 2 program: the decision, i.e., which SS is activated, is determined by a contention mechanism. The contention mechanism is performed by the decision function given below

In the formula (f)_maxThe maximum sonopotential energy frequency in the cavity. The decision function is performed between SSs that are agreed to start but not activated. When y is_k(∈ Y) is the minimum value Y_kminWhile, SS_kIs activated to run. If only one SS is activated, it receives the positive command 1 from the coordination structure and the corresponding control factors and performs the initialization function. The remaining SSs receive a negative command 0 and cannot be activated. If several SSs are activated at the same time, the coordination structure starts to execute the step 3 procedure: and (4) cooperation. The cooperation mechanism is designed by assigning corresponding control factors. Because the contribution of the PZT actuator to noise attenuation depends on the secondary generalized modal force D_m,kIt is therefore defined as the control factor. By the formula (2), D_kCan be expressed as

Is a constant. By expression of secondary generalized modal forces

It can be seen that D_m,kIs a constant. Therefore, the constant vector W_k＝[D_1,k,D_2,k,…,D_m,k]^TFrom mixing function D_kExtracted out of the collaboration function block stored in the coordination structure. Joint control between SSs is achieved by a mixing function. The coupling between SSs is smoothly solved by the coordination structure.

And establishing an integrated control system. The internal design of each SS is substantially the same for ease of installation and maintenance of the control system. The internal functions and functional blocks of each SS are the same except for the start-up function. Simply by changing a lower threshold

The interchange between SSs can be realized. Each SS is an independent control system that can operate independently. In addition, when a new SS is added, the adjustment of the control system can be completed only by adding the corresponding control factor of the new SS in the coordination structure. The flexible butt joint of the control factors and the mixing function realizes the centralized control of the system and solves the behavior conflict and cooperation among the SSs. And the system can realize intelligent logic judgment by adopting a bottom-up starting application and a top-down activation response mode. The decision of which SS to activate for operation and which SSs need joint control is made by a coordination structure and through it an integrated SS based control system is established, as shown in fig. 6. The control flow of the integrated control system is shown in fig. 7.

The advantages of the integrated control system are verified by simulations as follows. To illustrate the ease of installation and maintenance of the system, an SS is assumed₆The acoustic cavity model of figure 1 has dimensions of 0.868m × 1.15.15 m × 1m, plates a and b being resilient aluminium plates and the remainder being rigid plates the disturbance point force F acts on plate a at (0.3,0.4) m and has an amplitude of 1n, the thickness of the aluminium plate is 6mm, the young's modulus E is 71GPa, and the mass density ρ is₁＝2770kg/m³And poisson's ratio υ 0.33. The modal numbers of panel a, panel b and the acoustic cavity are taken as 14, 13 and 12 respectively, and the modal damping ratios thereof are assumed to be 0.01. Sound speed c 340m/s, air mass density rho 1.21kg/m³。

From fig. 2, the primary acoustic potential energy in the front cavity and the starting function are controlled to find that the following inequality holds: e_p1(36)＝76.24dB≥T₃₆＝72dB,E_p2(148)＝64.8dB≥T₁₄₈＝44dB,E_p3(171)＝63.45dB≥T₁₇₁＝42dB,E_p4(196)＝66.26dB ≥T₁₉₆＝40dB,E_p5(254)＝69.69dB≥T₂₅₄＝38dB. Thus, all SSs satisfy the start-up condition and send the start-up signal to the coordination structure. Obtainable from fig. 2 and the admission function, E_pmaxT is 50dB at 76 dB. The decision function in the coordination structure can know that Y in the Y set₁(0 ═ 36-36 |) is minimal. Thus, SS₁Can receive a control instruction 1 and a control factor W sent by a coordination structure₁＝[0.1348,0.1730,-0.0350,0.0872,-0.0449,-0.0227, -0.1257,-0.0611,-0.1613,0.0159,-0.0813,-0.1656,0.0677,0.0570]^TI.e. SS₁Is activated. The other SSs receive control command 0 and thus remain inactive. Mixing function D_kIs output of D_hmAnd W₁The result of the dot product. On the basis of the output result of the mixing function, the optimal control voltage V can be obtained by optimizing the function₁-7.6673+4.9050i and sends it to PZT₁On the actuator. SS₁The maximum acoustic potential in the cavity after control is 58dB above the frequency 197Hz, as shown in figure 8. In the next signal updating period, the SS is realized because the primary sound field is not changed (obtained by superposing the secondary sound field and the controlled sound field)₁The start signal continues to be sent and the coordination structure directly agrees that it remains active. The remaining SSs that send the start signal use a decision function to decide which is activated. Because of y₄(| 197-196| -1) is the minimum value in the set Y, so SS₄Is activated. Thus, the control factor [ W ] from the coordination structure₁,W₄]＝[0.1348,0.1730,-0.0350,0.0872, -0.0449,-0.0227,-0.1257,-0.0611,-0.1613,0.0159,-0.0813,-0.1656,0.0677,0.0570；0.1378, -0.1200,-0.1389,-0.0332,0.1210,0.0335,0.0023,0.1490,-0.0020,-0.1502,-0.0006,-0.0966, 0.1366,0.0025]^TAnd control instruction 1 are sent to SS at the same time₁And SS₄. The outputs of both SS mixing functions are [ D ]_hm·*W₁,D_hm·*W₄]. The output of the corresponding optimization function is [ V ]₁；V₄]＝[-5.1593+1.7906i；-2.9424+2.4432i]。 V₁And V₄Are respectively sent to PZT by output distribution function blocks₁And PZT₄. Wherein the output allocation function blocks are allocated according to a rule of consistent numberingVoltages, i.e. optimum control voltage V_kCorresponding PZT_k. In SS₁And SS₄After the combined control, the maximum potential energy in the cavity is about 45dB, as shown in FIG. 8. Due to E_pmax＝45dB<T is 50dB, so the coordinator structure no longer accepts the start signal from the inactive SS. The control system begins to run smoothly.

When one or more SSs fail, the control system can maintain stability and have certain control performance. Do not assume SS₁And SS₄Failing to send the start signal. Thus, y₂(112) is the minimum of Y, SS₂And is thereby activated. SS₂The maximum acoustic potential in the cavity after control is about 63dB at 258Hz, as shown in fig. 9. In the second round of signal update, since y₅(| 254-258| -4) is the minimum in Y, and thus SS₅Is also activated. The maximum sound potential energy after the two SS combined control is about 54dB at 298Hz (FIG. 9). In the third round of signal update, due to E_pmax54 ≧ T ≧ 50, and SS alone₃Is not activated, thus SS₃Is directly activated by the coordinating structure. Thus, SS₂、SS₅And SS₃Both can receive the control instruction 1 and the control factor W sent by the coordination structure at the same time₂,W₅,W₃]＝[0.8941,-0.3638, -0.7289,-0.7460,0.2966,0.6082,-0.2999,0.6674,0.1220,-0.5441,0.2502,0.4745,0.9733, -0.2238；0.8555,0.6602,-0.6404,-0.3461,-0.4942,0.2591,-0.3761,-0.9272,-0.2902,0.6941,0.1521,-0.3694,0.9220,0.4076；0.6687,-0.4479,-0.9422,-0.3687,0.6311,0.5196,0.6590, 0.6948,-0.4414,-0.9791,-0.3634,-0.0966,0.0136,0.6848]^T. The output of the mixing function of all three SSs is [ D ]_hm·* W₂,D_hm·*W₅,D_hm·*W₃]. Obtaining an optimized control voltage [ V ] through an optimization function₂；V₅；V₃]＝[0.3982- 0.0744i；1.8647+4.2864i；-3.5442-2.8872i]. Control voltage V₂、V₅And V₃Are respectively sent to PZT by output distribution function block₂、PZT₅And PZT₃. After combined control of three SSsThe sound potential energy in the cavity is greatly reduced, and the maximum sound potential energy is only about 33dB at 139Hz (see figure 9), so that the stability and the control performance of the control system are ensured. At the same time, although SS can be found₂And SS₅Has a combined control effect inferior to that of SS₁And SS₄Good control performance can be achieved by activating more SSs as well, i.e., an integrated control system with redundant SSs can tolerate failure of one or more SSs. Thus, integrated control has higher reliability and fault tolerance than centralized control.

In addition, in SS₂And SS₅After the combined control, it was found that the maximum acoustic energy potential in the cavity at the frequency of 298Hz was mainly caused by the resonant frequency of 295Hz (see fig. 10 and 2). Thus, the frequency 298Hz noise can be reduced by adding a new SS (SS)₆) To solve the problem. As shown in FIG. 3(f), SS₆/PZT₆Is located at (0.35,0.42) m of the plate a. Thus, a secondary generalized modal force/control factor is determined, i.e., W₆＝[0.8699,0.7148,0.5208,-0.2824,0.4280, -0.1691,-0.5580,-0.9469,-0.4586,-0.5670,0.1812,-0.4958,-0.8549,0.6075]^T. Only the addition of SS in the cooperative functional blocks of the coordination structure is required₆Corresponding control factor W₆And in SS₆In setting a start function E_p6(295)≥T₂₉₅If 37dB, SS₆It can be installed into a system for controlling the sound field. In addition, the control system does not require any adjustment. Due to the fact that in the primary sound field E_p6(295)＝70.09dB≥T₂₉₅37dB, the start-up condition is satisfied, and y₆(298 | -3) is the minimum value in the set Y and is therefore SS₆Is activated instead of SS₃. Optimal control voltage V is distributed through output distribution function block₂(＝-1.6443+1.1888i)、V₅(2.6337-3.8144i) and V₆To PZT (-5.5779+2.8537i) separately₂、PZT₅And PZT₆The above. SS₂、SS₅And SS₆After the combined control, the maximum acoustic potential in the cavity is only around 30dB at a frequency of 269Hz, as shown in fig. 10. Therefore, in SS₆Substituted SS₃The system then has better controlAnd (4) performance. Of course, the SS may also be removed from the system₃Then easily transforming it into SS₆. Thus, the SS can be easily added or removed from the integrated control system to achieve better control performance, i.e., the system has the easy installation and maintenance features of decentralized control.

In conclusion, the integrated control system based on the smart structure provided by the invention integrates the advantages of centralized control and decentralized control, effectively overcomes some defects of the existing vibration noise active control system, and is beneficial to realizing the application and popularization of vibration noise active control in practice.

Claims

1. An integrated control technology of vibration noise in a closed cavity is characterized in that:

for a rectangular closed cavity containing multiple elastic plates, when one of the elastic plates (taking the plate a as an example) is acted by an external interference force F, the elastic plate a generates vibration to radiate noise into the cavity, and generates coupling with sound waves in the cavity so as to form an in-cavity coupling noise field. Other elastic plates are acoustically excited and vibrate and produce acoustic radiation in a similar mechanism to plate a. Several PZT piezoelectric ceramic patches are pasted on the elastic plate a as actuators, 4 microphones are arranged in the cavity as error sensors, and are respectively fixed at (0.8,1.1,0.05), (0.43,0.57,0.5), (0.05,0.05,0.95) m positions in the cavity.

Because intra-cavity noise is mainly affected by acoustic-solid coupling, the noise control problem at each coupled natural frequency is considered a local control problem and is solved by a smart structure. The smart architecture includes sensors, actuators, and controllers. Acoustic field in the investigated closed cavity at a coupling natural frequency of 36Hz (f)₁),148Hz(f₂),171Hz(f₃),196Hz(f₄),254Hz(f₅) And 295Hz (f)₆) Is large, so for the 6 resonance frequencies f_k(k 1-6) 6 Smart Structures (SS) were designed and SS was used_kIs shown, in which SS₁～SS₆Are respectively used for controlling f₁～f₆Noise at frequency. PZT in smart structure_kThe position of the actuator is determined according to an optimized sound potential energy profile, PZT₁～PZT₆Are arranged at (0.47,0.35) m, (0.55,0.65) m, (0.65,0.7) m, (0.58,0.74) m, (0.54,0.43) m and (0.35,0.42) m on the board a, respectively. The thickness of the plates a and b is h_a＝h_b6 mm. The parameters of the PZT patches were: thickness h_p0.254mm, modulus of elasticity E_pzt＝7.24×10¹⁰N m^-2Poisson ratio v_p0.3, dielectric constant d₃₁＝2.74×10^-10m V^-1The length and width of the PZT patch are both 20 mm.

The SS integrates sensors, actuators, and controllers in a broad sense, and the controller is developed with emphasis on this application. The controller includes a series of functions and functional blocks within it to implement various functional behaviors. The start-up function is used to determine the start-up conditions of the SS, which is defined as

In the formula (I), the compound is shown in the specification,

is the noise threshold at that frequency. Considering the auditory perception of the human ear and the relationship between the A-weighted sound level and the relative sound pressure level, T₃₆,T₁₄₈,T₁₇₁,T₁₉₆,T₂₅₄And T₂₉₅72dB,44dB,42dB,40dB,38dB and 37dB, respectively. The SS transmits a positive signal 1 to the upper organization if formula (1) is satisfied, and otherwise transmits a negative signal 0 to the upper organization. The upper layer organization sends control instructions to the SS to determine the operating state of the SS. And if the control instruction 1 sent by the upper layer organization is received, the SS activates operation, otherwise, the SS cannot activate. The transition behavior of the startup state and the active state is described by a finite state machine. The mixing function is defined as

In the formula, h_amRepresenting resonant terms of the slab and cavity, M_amRepresenting the modal quality of the panel a, D_m,kRepresenting the secondary generalized modal forces. D_kReflects the amount of contribution of all PZT actuators to noise reduction and weights the control factor of SS to the global output. The optimization function adopts a quadratic optimization algorithm, and the calculation result is established on the basis of the output of the mixing function. Thus, the optimization function employs global optimization. It outputs the optimized control voltage of all the actuators and outputs the control voltage V via the output distribution function block_kTo the corresponding PZT_kAn actuator. Therefore, the control system has high control performance of centralized control. In addition, the controller also contains an update function that will be executed in either the activated or deactivated state of the SS to achieve adaptivity.

E_pmax≥T (3)

In the formula (f)_maxThe maximum sonopotential energy frequency in the cavity. The decision function is performed between SSs that are agreed to start but not activated. When y is_kY is the minimum value (∈ Y)_kmin，SS_kIs activated to run. If only one SS is activated, it receives the positive command 1 from the coordination structure and the corresponding control factors and performs the initialization function. The remaining SSs receive a negative command 0 and cannot be activated. If several SSs are activated at the same time, the coordination structure starts to execute the step 3 procedure: and (4) cooperation. The cooperation mechanism is designed by assigning corresponding control factors. Because the contribution of the PZT actuator to noise attenuation depends on the secondary generalized modal force D_m,kIt is therefore defined as the control factor. By the formula (2), D_kCan be expressed as

Is a constant. By expression of secondary generalized modal forces

And establishing an integrated control system. For easy installation and maintenance of the control system, each SThe internal design of S is all substantially the same. The internal functions and functional blocks of each SS are the same except for the start-up function. Simply by changing a lower threshold

The interchange between SSs can be realized. Each smart structure is an independent control system and can be operated independently. In addition, when a new SS is added, the adjustment of the control system can be realized only by adding the corresponding control factor of the new SS in the coordination structure. The flexible butt joint of the control factors and the mixing function realizes the centralized control of the system and solves the behavior conflict and cooperation between smart structures. And the system can realize intelligent logic judgment by adopting a bottom-up starting application and a top-down activation response mode. The system can receive all sensor signals and generate global optimization control voltage through the sensor signals, so that the system has the characteristic of high control performance of centralized control. The system adopts a modular design, so that the system has the characteristics of high reliability and fault tolerance of decentralized control, easiness in installation and maintenance and the like. Thus, an integrated control system based on smart structure is established for active control of vibration noise.