Piezoelectric active and passive integrated structure health monitoring method and system

Abstract

The invention relates to the field of health monitoring of composite material structures for aerospace, in particular to a piezoelectric type active and passive integrated structure health monitoring method and system. The invention provides a piezoelectric type active and passive integrated structure health monitoring method, which is based on a piezoelectric type active and passive integrated structure health monitoring system comprising a piezoelectric type active and passive sensor network, a lower computer and a host unit. The method has the advantages that active and passive switching logic for setting a voltage threshold value and piezoelectric signal arrival time is adopted, an active path scanning strategy for optimizing an active scanning path in combination with passive monitoring information is adopted, and meanwhile, passive impact monitoring and active damage monitoring are combined; the technical effect of efficiently and rapidly obtaining detailed damage information of the spacecraft structure is achieved. Besides, in the execution process, set parameters can be dynamically adjusted according to real-time data, an active scanning path set is optimized, and multi-collaborative improvement of monitoring efficiency, accuracy, real-time performance and flexibility is achieved at low hardware cost.

Description

Technical Field

[0001] The present invention relates to the field of structural health monitoring of composite materials for aerospace, and particularly to a piezoelectric integrated active and passive structural health monitoring method and system. Background Art

[0002] A reusable spacecraft refers to a spacecraft that can quickly penetrate the atmosphere and freely travel between the Earth's surface and space to transport crew and payloads. Developing reusable spacecraft technology is one of the main means to reduce the cost of manned space missions. Monitoring the damage condition during the service of a reusable spacecraft is very important. Its area to be monitored is large, which poses high requirements for the real-time performance, accuracy, autonomy and intelligence level of the monitoring system.

[0003] Composite materials are widely used in the structural design of reusable spacecrafts due to their high strength, high specific stiffness, good fatigue resistance and designability. However, during the service of spacecraft composite materials, when facing complex chemical / physical environments, the safety of engineering structures is vulnerable to threats. In particular, the impact of tiny foreign objects may form various almost invisible damages inside the composite materials, which will lead to the degradation of structural performance and seriously threaten the in-service safety of the spacecraft.

[0004] Therefore, effective structural health monitoring is crucial for timely detecting and evaluating these damages. According to different monitoring mechanisms, the structural health monitoring technologies of spacecrafts can be divided into two categories: passive monitoring and active monitoring. Passive monitoring realizes real-time impact monitoring by capturing the response signals of the monitored structure. Common passive monitoring methods include acoustic emission technology, fiber Bragg grating monitoring technology, piezoelectric passive impact monitoring technology, etc. Active monitoring, on the other hand, actively excites a certain form of wave signal to the structure, uses sensors distributed throughout the structure to receive the response signals, analyzes the differences in the response signals before and after damage, and extracts the characteristic information of the damage, so as to realize damage monitoring and diagnosis. Common active monitoring methods include monitoring technologies based on piezoresistance impedance method, eddy current-based monitoring methods, ultrasonic guided wave monitoring technology, etc.

[0005] However, passive monitoring can only perform basic positioning and energy reconstruction, and cannot accurately evaluate the size and shape of the damage; active monitoring mostly relies on exhaustive scanning or manual adjustment, with low efficiency and long detection time, which may cause small damages to expand under load. Combining passive monitoring with active monitoring can effectively make up for the deficiencies of both and improve the overall effect of spacecraft structural health monitoring.

[0006] Chinese Patent CN116559286A was published on August 8, 2023, disclosing a method and system for integrated active and passive composite material structural health monitoring. By means of an active and passive sensor network, impact events are monitored in real time to generate stress wave signals. After analyzing the signals, the host unit generates control information to control the conversion from passive monitoring to active detection, thereby conducting active scanning to obtain active monitoring results, achieving integrated active and passive detection of composite material structures, promptly detecting damages, and ensuring structural safety. However, this solution relies on a matrix switching mechanism, with poor flexibility and slow response speed, and still cannot meet the requirements of high precision and high timeliness.

[0007] Therefore, how to efficiently and rapidly obtain detailed damage information of spacecraft structures through effective technical means remains an urgent problem to be solved in the field of structural health monitoring. Summary of the Invention

[0008] To solve the technical problem of how to efficiently and rapidly obtain detailed damage information of spacecraft structures, the present invention provides a piezoelectric integrated active and passive structural health monitoring method, including the following steps: S100. The piezoelectric integrated active and passive sensor network monitors in real time the piezoelectric signals triggered by impact events and transmits the piezoelectric signals to the lower computer. S200. When the lower computer determines that the piezoelectric signal reaches the set voltage threshold, it generates a request message and transmits it to the host unit. S300. After receiving the request message, the host unit conducts rough positioning of the impact event to obtain rough positioning information of the impact event. S400. The host unit constructs a set of active scanning paths based on the rough positioning information of the impact event. S500. The host unit controls the piezoelectric integrated active and passive sensor network to conduct active scanning according to the set of active scanning paths and returns the scanning results, completing the piezoelectric integrated active and passive structural health monitoring of the composite material.

[0009] In one embodiment, in step S200, if the lower computer determines that the piezoelectric signal does not reach the set voltage threshold, this monitoring behavior ends.

[0010] In one embodiment, step S300 includes: S310. The host unit obtains information of the 3 passive piezoelectric sensors closest to the impact event. S320. Locate the specific monitoring unit where the impact event occurs based on the information of the 3 passive piezoelectric sensors to complete the rough positioning of the impact event.

[0011] In one embodiment, step S400 includes: S410. The host unit acquires the information of the passive piezoelectric sensor closest to the impact event and determines the sub-region of the monitoring unit where the impact event occurs. S420. Set all the active piezoelectric sensors in the sub-region of the detection unit as excitation sensors to obtain a set of excitation sensors. S430. Taking the excitation sensor as the coordinate origin, set a search radius r and a minimum resolution angle θ to form a search area circle, obtain the set of receiving sensors in the search area circle, and based on the set of receiving sensors, obtain the set of scanning paths for a single excitation sensor. S440. Integrate all the sets of scanning paths of the set of excitation sensors to obtain the set of active scanning paths.

[0012] Further, step S430 includes: S431. Taking any excitation sensor in the set of excitation sensors as the coordinate origin, set a search radius r and a minimum resolution angle θ to form a search area circle. S432. In the search area circle, from 0° to 360°, select the active piezoelectric sensor closest to the excitation sensor along the radial direction as the receiving sensor to obtain the set of receiving sensors for the excitation sensor. S433. Integrate the scanning paths independently formed by the excitation sensor and the receiving sensors in the set of receiving sensors one by one to obtain the set of scanning paths for a single excitation sensor.

[0013] Furthermore, the size of the search radius r is inversely proportional to the layout density of the active piezoelectric sensors and directly proportional to the size of the damage influence range; among them, the size of the damage influence range can be evaluated by the number of passive sensors receiving the piezoelectric signal caused by the impact event and the strength of the piezoelectric signal.

[0014] Furthermore, the minimum resolution angle θ is inversely proportional to the expected search accuracy and directly proportional to the expected response speed.

[0015] The present invention also provides a piezoelectric integrated active and passive structural health monitoring system, including: A piezoelectric integrated active and passive sensor network for real-time monitoring of the piezoelectric signal caused by the impact event and transmitting the piezoelectric signal to the lower computer. The lower computer is used to analyze and compare the magnitudes of the piezoelectric signals, generate request information, and transmit it to the host unit. The host unit is used to perform rough positioning of the impact event after receiving the request information, construct a set of active scanning paths, and control the piezoelectric integrated active and passive sensor network to perform active scanning to obtain the return result.

[0016] In one embodiment, the piezoelectric active and passive sensor network is composed of a number of adjacent monitoring units. Passive piezoelectric sensors are arranged at the four corners of each monitoring unit, and active piezoelectric sensors are arranged in an array within each monitoring unit. All the passive piezoelectric sensors in the piezoelectric active and passive sensor network constitute a passive monitoring network, and all the active piezoelectric sensors constitute an active scanning network.

[0017] Further, the monitoring area of each monitoring unit is divided into 4 sub-areas, which are sequentially marked as sub-area A, sub-area B, sub-area C, and sub-area D.

[0018] In summary, compared with the prior art, the present invention has the following beneficial effects: The piezoelectric active and passive integrated structural health monitoring method provided by the present invention determines the set of active scanning paths according to the piezoelectric signals of passive monitoring and the active damage monitoring scanning strategy, and then switches to the active scanning mode. The active piezoelectric sensors in the monitoring unit are used to perform ultrasonic guided wave scanning monitoring along the determined scanning paths for accurate damage assessment. It combines the advantages of passive impact monitoring and active damage monitoring, and is supplemented by the active and passive switching logic, further reducing the resource waste caused by the indiscriminate switching of the active scanning mode and the risk of missing real-time impact events. It can efficiently and quickly obtain detailed damage information of the spacecraft structure, and at the same time improve the monitoring efficiency and the monitoring accuracy of potential damage areas.

[0019] The piezoelectric active and passive integrated structural health monitoring system provided by the present invention can realize the timely and accurate monitoring of the damage of the spacecraft structure by using piezoelectric sensors to monitor impact events in real time, intelligently switch the monitoring mode, progressively locate the damage, and construct an active scanning path to perform precise scanning with ultrasonic guided waves. During the execution process, it can also dynamically adjust the set parameters according to real-time data, optimize the set of active scanning paths, reduce redundant scanning, and has high flexibility and execution efficiency. It can adapt to different degrees of impact damage monitoring, and realizes the multiple coordinated improvement of monitoring efficiency, accuracy, real-time performance, and flexibility at a relatively low hardware cost.

[0020] Other features and beneficial effects of the present invention will be described in the subsequent specification, and some of them will become obvious from the specification, or be understood by implementing the present invention. The objectives and other beneficial effects of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims, and drawings. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0022] Figure 1 Schematic diagram of the working process of the piezoelectric active-passive integrated structural health monitoring method provided in Embodiment 1 of the present invention; Figure 2 Schematic diagram of the layout of the piezoelectric active-passive sensor network provided in Embodiment 1 of the present invention; Figure 3 Schematic diagram of the structure for determining the sub-region of the monitoring unit provided in Embodiment 1 of the present invention; Figure 4 Schematic diagram of the working process of constructing the set of active scanning paths provided in Embodiment 1 of the present invention; Figure 5 Schematic diagram of constructing the set of scanning paths of a single excitation sensor provided in Embodiment 1 of the present invention; Figure 6 Schematic diagram of the working process of constructing the set of scanning paths of a single excitation sensor provided in Embodiment 1 of the present invention; Figure 7 Schematic diagram of the working process of optimizing the set of active scanning paths provided in Embodiment 1 of the present invention. Detailed implementation manners

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0024] Embodiment 1 Refer to Figure 1 , this embodiment provides a piezoelectric active-passive integrated structural health monitoring method, based on a piezoelectric active-passive integrated structural health monitoring system including a piezoelectric active-passive sensor network, a lower computer, and a host unit, and includes the following steps: S100. The piezoelectric active-passive sensor network monitors in real time the piezoelectric signals triggered by impact events and transmits the piezoelectric signals to the lower computer; S200. When the lower computer determines that the piezoelectric signal reaches the set voltage threshold, it generates a request message and transmits it to the host unit; S300. After receiving the request information, the host unit performs rough positioning of the impact event to obtain rough positioning information of the impact event; S400. The host unit constructs an active scanning path set based on the rough positioning information of the impact event; S500. The host unit controls the piezoelectric active and passive sensor network to perform active scanning according to the active scanning path set and returns the scanning result, completing the piezoelectric active and passive integrated structural health monitoring of the composite material.

[0025] Preferably, before performing the above steps, it is necessary to initialize the piezoelectric active and passive integrated structural health monitoring system and enter the passive monitoring mode; In specific implementation, the host unit initializes the piezoelectric active and passive integrated structural health monitoring system. The host unit includes a human-computer interaction and information visualization module. Relevant parameters and relevant settings are initialized through the human-computer interaction and information visualization module. These parameters include the virtual model of the structure to be measured, the layout of the piezoelectric active and passive sensor network, signal acquisition parameters, guided wave parameters, etc. After initialization, it enters the passive monitoring mode and is controlled by the lower computer.

[0026] Further, in step S200, if the lower computer determines that the piezoelectric signal does not reach the set voltage threshold, the monitoring behavior ends this time.

[0027] In specific implementation, the piezoelectric active and passive integrated structural health monitoring system sets a voltage threshold, and the voltage threshold is set based on engineering experience and the electrical characteristics of the system; when an impact event occurs, the lower computer compares the voltage value of the piezoelectric signal caused by the impact event with the set voltage threshold. If the voltage does not reach the threshold, the event is ignored. If the voltage reaches or exceeds the threshold, a request information is generated and the system performs rough positioning of the impact event.

[0028] Further, step S300 includes: S310. The host unit obtains information of the 3 passive piezoelectric sensors closest to the impact event; S320. Locate the specific monitoring unit where the impact event occurs according to the information of the 3 passive piezoelectric sensors, and complete the rough positioning of the impact event.

[0029] Refer to Figure 2 、 Figure 3, The piezoelectric active and passive sensor network is composed of several adjacent monitoring units. Passive piezoelectric sensors are arranged at the four corners of each monitoring unit, and active piezoelectric sensors are arranged in an array within each monitoring unit. All the passive piezoelectric sensors in the piezoelectric active and passive sensor network constitute a passive monitoring network, and all the active piezoelectric sensors constitute an active scanning network. The monitoring area of each said monitoring unit is further divided into 4 sub-areas, sequentially marked as sub-area A, sub-area B, sub-area C, and sub-area D; During specific implementation, since there is a certain propagation delay in the process of the piezoelectric signal generated by the impact propagating inside the structure, there will be a difference in the time when different passive piezoelectric sensors receive the piezoelectric signal. As Figure 2 shown, according to the sequence of arrival of the piezoelectric signals, the 3 passive piezoelectric sensors closest to the impact event can be found, so as to locate the specific monitoring unit where the impact event occurs and achieve rough positioning of the impact event; It should also be noted that the collected piezoelectric signals can also be used for subsequent other processing.

[0030] Furthermore, referring to Figures 2 to 5 , step S400 includes: S410. The host unit obtains the information of the passive piezoelectric sensor closest to the impact event and determines the sub-area of the monitoring unit where the impact event occurs; S420. Set all the active piezoelectric sensors in the sub-area of the detection unit as excitation sensors to obtain an excitation sensor set; S430. Taking the excitation sensor as the coordinate origin, form a search area circle, obtain the set of receiving sensors in the search area circle, and obtain the set of scanning paths of a single excitation sensor based on the set of receiving sensors; S440. Integrate all the sets of scanning paths of the excitation sensor set to obtain an active scanning path set.

[0031] Even further, referring to Figure 5 , Figure 6 , step S430 includes: S431. Taking any excitation sensor in the excitation sensor set as the coordinate origin, set a search radius r and a minimum resolution angle θ to form a search area circle; S432. Inside the search area circle, from 0° to 360°, select the active piezoelectric sensor closest to the excitation sensor along the radial direction as the receiving sensor to obtain the set of receiving sensors of the excitation sensor; S433. Integrate the scanning paths independently formed by the excitation sensor and the receiving sensors in the set of receiving sensors one by one to obtain the set of scanning paths of a single excitation sensor.

[0032] In specific implementation, as Figure 3 shown, there are a total of n piezoelectric sensors in a single monitoring unit, which are evenly distributed in sub-regions A, B, C, and D. According to the arrival time of the passive piezoelectric signals, the passive sensor closest to the location of the impact event can be determined, thereby locating the sub-region where the impact event occurs; Assume that the impact event occurs in sub-region A. The active piezoelectric sensor group in sub-region A can be expressed as , where n represents the number of active piezoelectric sensors located in region A. For each active piezoelectric sensor in sub-region A, it will be used as an excitation sensor during the active damage monitoring of this impact event; As Figure 5 shown, taking each excitation sensor in the impacted sub-region A as the coordinate origin to establish a coordinate system, setting the search radius r and the minimum resolution angle θ to form a search region circle. From 0° to 360°, the active piezoelectric sensor closest to the excitation sensor is selected as the receiving sensor along the radial direction. The m receiving sensors obtained by the search form the receiving sensor set, denoted as ; Each excitation sensor and each receiving sensor in its corresponding receiving sensor set form an independent scanning path, which is denoted as . Therefore, the set of scanning paths for each excitation sensor can be expressed as ; Perform a union operation on the sets of scanning paths of all the excitation sensors in sub-region A, , and then the active scanning path set can be obtained.

[0033] Furthermore, the size of the search radius r is inversely proportional to the layout density of the active piezoelectric sensors and directly proportional to the size of the damage influence range. Among them, the size of the damage influence range can be evaluated by the number of passive sensors that receive the piezoelectric signals triggered by the impact event and the strength of the piezoelectric signals; Specifically, the search radius r determines the monitoring range starting from the excitation sensor. Therefore, its set value should be selected according to the scale of the structure, the range affected by damage, and the signal reception ability of the active piezoelectric sensors, etc. If the structure is large or damage may occur at a position far from the excitation point, the search radius r should be appropriately increased to ensure that the entire monitoring area can be covered. When the damage range is small or the receiving sensors are arranged densely, the search radius r can be appropriately reduced to improve the calculation efficiency and avoid redundancy.

[0034] Furthermore, the minimum resolution angle θ is inversely proportional to the expected search accuracy and directly proportional to the expected response speed. Specifically, the minimum resolution angle θ controls the angular resolution between the active piezoelectric sensors. The smaller the angle, the more receiving signals of the receiving sensors can be detected, improving the positioning accuracy. However, it will also increase the computational burden and processing time. Therefore, when setting θ, a balance needs to be found between detection accuracy and real-time performance. If high-precision damage positioning is expected, a smaller θ can be selected so that the number of receiving sensors in each area is larger, thereby improving the resolution. But if the real-time performance requirement is high or the number of active piezoelectric sensors is limited, θ should be appropriately increased to reduce the computational complexity and improve the response speed.

[0035] Preferably, in step S431, the search area circle is also divided into 8 sector areas. By presetting 8 areas, the computational complexity can be reduced while ensuring the coverage of the scanning path and the direction resolution of the returned scanning information, significantly improving the damage detection efficiency and positioning accuracy.

[0036] Preferably, for a small impact, the damage-affected range is small, and it may only involve local cracks or dents. At this time, a smaller search radius r and a larger minimum resolution angle θ can be selected to focus on scanning the impact area, reducing the acquisition of redundant data and avoiding unnecessary waste of computing resources. For a large impact, the damage-affected range is relatively wide, and it may involve multiple sub-areas or even multiple monitoring units. In this case, the search radius r and the minimum resolution angle θ need to be increased to ensure that a larger area can be covered, and the scanning path can also be detected in detail using an intelligent full-coverage mode based on parameter optimization. If multiple impacts occur in the same area, the scanning range can be adjusted manually according to the preliminary scanning results, and the scanning area can be gradually expanded to ensure that all potential damages are found. It should be noted that the intelligent full-coverage mode based on parameter optimization is different from the traditional exhaustive scanning. This mode reduces redundant paths by dynamically adjusting the search radius r and the minimum resolution angle θ.

[0037] Preferably, refer to Figure 7As shown, during the processing, the search radius r and the minimum resolution angle θ can also be dynamically adjusted according to the preliminary scanning results to optimize the set of active scanning paths and improve the monitoring efficiency and accuracy. If the scanning results do not meet the expectations, the search radius r and the minimum resolution angle θ can be reset to form a new set of active scanning paths and perform active scanning again.

[0038] Preferably, to further improve the scanning speed, multiple different receiving sensors can be grouped for synchronous acquisition according to the number of ADC channels in the active scanning network of the piezoelectric integrated active and passive structural health monitoring system, that is, data is acquired in parallel through multiple channels to reduce the single scanning time. For example, if the system supports 8 ADC channels, the receiving sensors can be divided into 8 groups, and each group independently acquires guided wave signals in different directions to achieve a linear increase in scanning efficiency.

[0039] It should also be noted that after the active damage monitoring is completed, the piezoelectric integrated active and passive structural health monitoring system will automatically switch back to the passive mode for continuous impact monitoring.

[0040] Embodiment 2 This embodiment provides a piezoelectric integrated active and passive structural health monitoring system, including a piezoelectric integrated active and passive sensor network, a lower computer, and a host unit; the lower computer is respectively connected to the piezoelectric integrated active and passive sensor network and the host unit, and the host unit is respectively connected to the lower computer and the piezoelectric integrated active and passive sensor network.

[0041] Among them, the piezoelectric integrated active and passive sensor network is used to monitor the piezoelectric signals caused by impact events in real time and transmit the piezoelectric signals to the lower computer; the lower computer is used to analyze and compare the magnitudes of the piezoelectric signals, generate request information, and transmit it to the host unit; the host unit is used to perform rough positioning of impact events, construct a set of active scanning paths, and control the piezoelectric integrated active and passive sensor network to perform active scanning after receiving the request information to obtain the return results.

[0042] The piezoelectric integrated active and passive sensor network is composed of several adjacent monitoring units. Passive piezoelectric sensors are arranged at the four corners of each monitoring unit, and active piezoelectric sensors are arranged in an array within each monitoring unit; all the passive piezoelectric sensors in the piezoelectric integrated active and passive sensor network constitute a passive monitoring network, which can monitor the occurrence of impact events and generate piezoelectric signals in the passive monitoring mode. At the same time, all the active piezoelectric sensors constitute an active scanning network, which can generate guided wave signals for active scanning.

[0043] Furthermore, the monitoring area of each monitoring unit is divided into 4 sub-areas, which are sequentially marked as sub-area A, sub-area B, sub-area C, and sub-area D; In specific implementation, the monitoring unit sub-region is used to further narrow down the location where the impact event occurs, reduce the active scanning noise, so as to improve the scanning rate and accuracy.

[0044] Although a number of terms such as piezoelectric, integrated active and passive, piezoelectric integrated active and passive sensor network, passive monitoring network, active scanning network, monitoring unit, monitoring unit sub-region, passive piezoelectric sensor, active piezoelectric sensor, excitation sensor, receiving sensor, slave computer, host unit, impact event, piezoelectric signal, guided wave signal, voltage threshold, request information, rough positioning of impact event, set of active scanning paths, passive monitoring, active scanning, search radius, minimum resolution angle, search area circle, layout density, damage influence range, expected search accuracy, expected response speed, human-computer interaction and information visualization module, virtual model of the structure under test, layout of piezoelectric integrated active and passive sensor network, signal acquisition parameters, guided wave parameters, small impact, large impact, multiple impacts, dynamic adjustment, grouped synchronous acquisition, etc. are used in this article, the possibility of using other terms is not excluded. The use of these terms is only for the convenience of describing and explaining the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A piezoelectric integrated active and passive structural health monitoring method, characterized in that, It includes the following steps: S100. The piezoelectric active and passive sensor network monitors in real time the piezoelectric signals triggered by impact events and transmits the piezoelectric signals to the lower computer; S200. The lower computer determines that the piezoelectric signal reaches the set voltage threshold, generates a request message, and transmits it to the host unit; S300. After receiving the request message, the host unit performs rough positioning of the impact event to obtain rough positioning information of the impact event; S400. The host unit constructs an active scanning path set according to the rough positioning information of the impact event; S500. The host unit controls the piezoelectric active and passive sensor network to perform active scanning according to the active scanning path set and returns the scanning result, completing the piezoelectric active and passive integrated structural health monitoring of the composite material.

2. The piezoelectric integrated active and passive structural health monitoring method according to claim 1, characterized in that: In step S200, if the lower computer determines that the piezoelectric signal does not reach the set voltage threshold, this monitoring behavior ends.

3. The piezoelectric active and passive integrated structural health monitoring method according to claim 1, wherein, Step S300 includes: S310. The host unit obtains information of the 3 passive piezoelectric sensors closest to the impact event; S320. According to the information of the 3 passive piezoelectric sensors, the specific monitoring unit where the impact event occurs is located to complete the rough positioning of the impact event.

4. The piezoelectric active and passive integrated structural health monitoring method according to claim 3, characterized in that, Step S400 includes: S410. The host unit obtains information of the passive piezoelectric sensor closest to the impact event and determines the sub-region of the monitoring unit where the impact event occurs; S420. All the active piezoelectric sensors in the sub-region of the detection unit are set as excitation sensors to obtain an excitation sensor set; S430. Taking the excitation sensor as the coordinate origin, a search radius r and a minimum resolution angle θ are set to form a search area circle, an receiving sensor set in the search area circle is obtained, and according to the receiving sensor set, a scanning path set of a single excitation sensor is obtained; S440. Integrate all the scanning path sets of the excitation sensor set to obtain an active scanning path set.

5. The piezoelectric integrated active and passive structural health monitoring method according to claim 4, characterized in that Step S430 includes: S431. Taking any excitation sensor in the excitation sensor set as the coordinate origin, a search radius r and a minimum resolution angle θ are set to form a search area circle; S432. In the search area circle, from 0° to 360°, the active piezoelectric sensor closest to the excitation sensor is selected as the receiving sensor along the radial direction to obtain the receiving sensor set of the excitation sensor; S433. Integrate the scanning paths independently formed by the excitation sensor and the receiving sensors in the receiving sensor set one by one to obtain the scanning path set of a single excitation sensor.

6. The piezoelectric integrated active and passive structural health monitoring method according to claim 5, characterized in that: The magnitude of the search radius r is inversely proportional to the layout density of the active piezoelectric sensors and directly proportional to the size of the damage influence range.

7. The piezoelectric integrated active and passive structural health monitoring method according to claim 5, characterized in that: The minimum resolution angle θ is inversely proportional to the expected search accuracy and directly proportional to the expected response speed.

8. A piezoelectric integrated active and passive structural health monitoring system, characterized in that, It includes: A piezoelectric active and passive sensor network, which is used to monitor in real time the piezoelectric signals triggered by impact events and transmit the piezoelectric signals to the lower computer; A lower computer, which is used to analyze and compare the magnitudes of the piezoelectric signals, generate a request message, and transmit it to the host unit; A host unit, which is configured to perform rough positioning of impact events, construct an active scanning path set, and control the piezoelectric active and passive sensor network to perform active scanning after receiving request information, and obtain a return result.

9. The piezoelectric integrated active and passive structural health monitoring system according to claim 8, characterized in that: The piezoelectric active and passive sensor network is composed of a number of adjacent monitoring units. Passive piezoelectric sensors are arranged at the four corners of each monitoring unit, and active piezoelectric sensors are arranged in an array within each monitoring unit. All the passive piezoelectric sensors in the piezoelectric active and passive sensor network form a passive monitoring network, and all the active piezoelectric sensors form an active scanning network.

10. The piezoelectric integrated active and passive structural health monitoring system according to claim 9, characterized in that: The monitoring area of each monitoring unit is divided into 4 sub-areas, which are sequentially marked as sub-area A, sub-area B, sub-area C, and sub-area D.

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