A system for real-time monitoring of aircraft airframe structural strength

Abstract

This invention discloses a system for real-time monitoring of aircraft airframe structural strength, relating to the field of aerospace strength testing technology. It includes an aircraft structural test component analysis module and a strength assessment analysis module. The output of the aircraft structural test component analysis module is electrically connected to a sensor monitoring module. This system for real-time monitoring of aircraft airframe structural strength conducts static tests on aircraft structural test components, uses finite element method simulation to determine the location of the most severe stress concentration on the aircraft structural component, and records this location. If multiple stress concentration points exist, multiple locations are recorded. Based on these stress concentration locations, fiber optic strain sensors are attached to the corresponding positions on the aircraft structural component. Unidirectional strain sensors are attached to the root of the stress concentration to measure the strain value in the direction of maximum stress. The sensors, in conjunction with a data acquisition and recording module, simultaneously receive time synchronization from the aircraft flight parameter system, ensuring the time-stamp synchronization of the recorded data packets in the monitoring system.

Description

Technical Field

[0001] This invention relates to the field of aviation strength testing technology, specifically a system for real-time monitoring of the structural strength of an aircraft airframe. Background Art

[0002] Aircraft structural strength monitoring technology is a multidisciplinary technology for ensuring aircraft structural integrity, developed alongside aircraft life extension efforts. To ensure both extended service life and structural integrity, frequent inspections, maintenance, and repairs are necessary, consuming significant human and material resources. Systems that monitor aircraft structural strength in real time can detect damage early, allowing for timely maintenance or repair, thus reducing direct operational and maintenance costs.

[0003] For aircraft with integrated structural designs, new types of defects and damage may occur during manufacturing, assembly, and use. These defects and damages will have a critical impact on the load-bearing and load-bearing characteristics of the structure as well as the failure mode. Therefore, it is necessary to monitor and evaluate the potential defects and damages of such structures in order to avoid causing aircraft failures. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a system for real-time monitoring of the structural strength of an aircraft fuselage, thus solving the problems mentioned in the background section.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a system for real-time monitoring of the structural strength of an aircraft fuselage, comprising an aircraft structural test piece analysis module and a strength assessment analysis module. The output of the aircraft structural test piece analysis module is electrically connected to a sensor monitoring module, which includes a fiber optic strain sensor and a three-flower strain gauge. The fiber optic strain sensor used in the sensor monitoring module is small in size, lightweight, corrosion-resistant, and resistant to electromagnetic interference. It is equipped with a data acquisition terminal, mainly consisting of fiber optic demodulation equipment, to acquire strain signals at a sampling rate of kHz. The output of the sensor monitoring module is electrically connected to a data acquisition and recording module, and the output of the data acquisition and recording module is electrically connected to a data processing module. The strength assessment analysis module is electrically interconnected with the output of the data processing module.

[0006] Furthermore, the aircraft structural test component analysis module mainly uses finite element simulation calculations to determine the areas of most severe stress concentration in the aircraft structural components, which serve as key monitoring points for the sensors.

[0007] Furthermore, the data acquisition and recording module includes a data acquisition unit, a conversion unit, a compression unit, and a recording unit, and the output terminal of the data acquisition unit is electrically connected to the conversion unit, the output terminal of the conversion unit is electrically connected to the compression unit, and the output terminal of the compression unit is electrically connected to the recording unit.

[0008] Furthermore, the data acquisition unit mainly collects sensor detection data, the conversion unit performs A / D conversion of the data, converting the data into a format that can be recognized by the operation, the compression unit compresses the data, and the recording unit mainly records test parameter data, test data, and the operation log of the entire data system. The data recording unit synchronously records the original monitoring data to facilitate subsequent data analysis and reconstruction. The data acquisition and recording modules simultaneously receive time synchronization from the aircraft flight parameter system to ensure the time synchronization of the recorded data packets in the monitoring system.

[0009] Furthermore, a unidirectional fiber optic strain sensor is installed at the root of the stress concentration to measure the strain value in the direction of maximum stress. At least four three-flower strain gauges are attached within 30 mm of this strain sensor to measure the strain in the direction of maximum stress, the strain at 90° to the direction of maximum stress, and the strain at 45° to the direction of maximum stress, respectively.

[0010] Furthermore, the data processing module includes a data analysis unit, an early warning unit, a real-time feedback unit, a counting unit, and a transmission unit. The output terminal of the data analysis unit is electrically connected to the early warning unit, the output terminal of the early warning unit is electrically connected to the real-time feedback unit and the counting unit, and the output terminal of the counting unit is electrically connected to the transmission unit.

[0011] Furthermore, the data analysis unit is used to analyze the data collected by the data acquisition and recording module, that is, to check whether there are any abnormalities in the data. The early warning unit compares the maximum value in the analyzed data with historical data. If it is too high, the abnormal location information is fed back to the staff terminal through the real-time feedback unit. The counting unit is used to record the number of times the abnormality occurs.

[0012] Furthermore, the intensity assessment and analysis module includes a receiving unit, a processing unit, a conversion unit, a calculation unit, and a mapping unit. The output terminal of the receiving unit is electrically connected to the processing unit, the output terminal of the processing unit is electrically connected to the conversion unit, the output terminal of the conversion unit is electrically connected to the calculation unit, and the output terminal of the calculation unit is electrically connected to the mapping unit.

[0013] Furthermore, the receiving unit is used to receive data, the processing unit is used to process the transmitted strain monitoring data, the conversion unit converts the monitoring data of the fiber optic strain sensor into principal strain and principal stress data, the calculation unit calculates the equivalent stress based on the converted principal strain and principal stress data, and the mapping unit constructs stress amplitude and average stress bar graphs based on the equivalent stress of the data to analyze the structural strength state of key parts.

[0014] Furthermore, the output terminal of the strength assessment and analysis module is electrically connected to a marking module, and the marking module includes a data tracking unit, a positioning unit, and a marking unit. The output terminal of the data tracking unit is electrically connected to the positioning unit, and the output terminal of the positioning unit is electrically connected to the marking unit.

[0015] This invention provides a system for real-time monitoring of the structural strength of an aircraft fuselage, which has the following beneficial effects:

[0016] This system, designed for real-time monitoring of aircraft structural strength, employs a finite element method to determine the location of the most severe stress concentration in an aircraft structural component through static testing of the component. If multiple stress concentration points exist, these locations are recorded. Based on these stress concentration points, fiber optic strain sensors are then attached to the corresponding positions on the aircraft structural component. Unidirectional strain sensors are attached to the root of the stress concentration to measure the strain value in the direction of maximum stress. The system, in conjunction with a data acquisition and recording module, receives time synchronization from the aircraft flight parameter system, ensuring the time-stamped synchronization of the recorded data packets. An early warning unit is also included to promptly alert the system in case of abnormalities. Furthermore, the system, combined with a strength assessment and analysis module, analyzes the structural strength status of critical components.

[0017] 1. This system for real-time monitoring of aircraft structural strength, through the configuration of an aircraft structural test piece analysis module, enables static testing of aircraft structural test pieces to obtain basic parameters of the structural material. Based on this, the system uses finite element simulation calculations to determine the areas of most severe stress concentration in the aircraft structural parts. These areas are typically stress concentration points, and the system records these areas to determine the sensor installation locations. This module not only enables detailed analysis of local aircraft structures but also reduces the need for sensor deployment, thus minimizing resource waste.

[0018] 2. This system for real-time monitoring of aircraft structural strength utilizes a sensor monitoring module and a data acquisition and recording module in a coordinated manner. The sensor monitoring module employs fiber optic strain sensors, which are small in size, lightweight, corrosion-resistant, and resistant to electromagnetic interference. The data acquisition unit, primarily equipped with fiber optic demodulation equipment, acquires strain signals at a 1kHz sampling rate, improving signal acquisition accuracy. Simultaneously, the data acquisition unit receives time synchronization from the aircraft flight parameter system, ensuring the time-stamped synchronization of the recorded data packets in the monitoring system. The data recording unit synchronously records the original monitoring data, facilitating subsequent data analysis and reconstruction.

[0019] 3. This system for real-time monitoring of aircraft structural strength, through the setting of a data processing module, can further process the data collected by the data acquisition and recording module, and analyze the data through a data analysis unit to determine whether there are any anomalies. When the data is higher than the historical data during the analysis, the early warning unit and the real-time feedback unit will feed back the abnormal location information to the staff terminal, and the recording unit will record the number of times the anomaly occurs, so as to facilitate the staff to determine and check the feedback location later.

[0020] 4. This system for real-time monitoring of the structural strength of an aircraft fuselage, through the setting of a strength assessment and analysis module, enables the receiving unit to receive the monitored data and convert the monitoring data from the fiber optic strain sensor into principal strain and principal stress data. In conjunction with the calculation unit, the equivalent stress is calculated based on the converted principal strain and principal stress data. The calculated data is then combined to construct stress amplitude and average stress bar graphs to facilitate the analysis of the structural strength status of key parts.

[0021] 5. This system for real-time monitoring of the structural strength of an aircraft fuselage, through the setting of a marking module, enables the data tracking unit to track areas with large strain after the structural strength status of critical parts is determined, and the positioning unit to locate the critical parts. In conjunction with the marking unit, the data of the critical parts is marked, which facilitates the subsequent staff to quickly find abnormal locations and facilitates the maintenance and repair process. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the layout process of the aircraft airframe structural strength monitoring system of the present invention;

[0023] Figure 2 This is a schematic diagram of the installation of the fiber optic strain sensor of the present invention;

[0024] Figure 3 This is a schematic diagram of the overall workflow of the present invention;

[0025] Figure 4 This is a schematic diagram of the workflow of the data acquisition and recording module of the present invention;

[0026] Figure 5 This is a schematic diagram of the workflow of the data processing module of the present invention;

[0027] Figure 6 This is a schematic diagram of the workflow of the strength assessment and analysis module of the present invention;

[0028] Figure 7 This is a schematic diagram of the workflow of the anomaly marking module of the present invention.

[0029] In the diagram: 1. Aircraft structural test component analysis module; 2. Sensor monitoring module; 201. Fiber optic strain sensor; 202. Tri-flower strain gauge; 3. Data acquisition and recording module; 301. Data acquisition unit; 302. Conversion unit; 303. Compression unit; 304. Recording unit; 4. Data processing module; 401. Data analysis unit; 402. Early warning unit; 403. Real-time feedback unit; 404. Counting unit; 405. Transmission unit; 5. Strength assessment and analysis module; 501. Receiving unit; 502. Processing unit; 503. Conversion unit; 504. Calculation unit; 505. Mapping unit; 6. Marking module; 601. Data tracking unit; 602. Positioning unit; 603. Marking unit. Detailed Implementation

[0030] like Figure 1-7 As shown, the present invention provides a technical solution: a system for real-time monitoring of the structural strength of an aircraft body, including an aircraft structural test piece analysis module 1 and a strength assessment analysis module 5. The output end of the aircraft structural test piece analysis module 1 is electrically connected to a sensor monitoring module 2. The sensor monitoring module 2 includes a fiber optic strain sensor 201 and a three-flower strain gauge 202. The fiber optic strain sensor 201 selected by the sensor monitoring module 2 is small in size, light in weight, corrosion-resistant, and resistant to electromagnetic interference. It is equipped with a data acquisition end mainly based on fiber optic demodulation equipment to acquire strain signals at a sampling rate of 1kHz. The output end of the sensor monitoring module 2 is electrically connected to a data acquisition and recording module 3, and the output end of the data acquisition and recording module 3 is electrically connected to a data processing module 4. The strength assessment analysis module 5 is electrically interconnected with the output end of the data processing module 4.

[0031] like Figure 1-3 As shown, the aircraft structural test component analysis module 1 mainly uses the finite element simulation calculation method to determine the part of the aircraft structural component with the most severe stress concentration, which is then used as the key monitoring point for the sensor.

[0032] The specific operation is as follows: by setting up the aircraft structural test piece analysis module 1, static tests are performed on the aircraft structural test piece to obtain the basic parameters of the structural material. Then, the finite element simulation calculation method is used to determine the part of the aircraft structural piece with the most severe stress concentration. The most severe part is usually the stress concentration point. The most severe part is recorded and then the installation position of the sensor is determined. This module can not only perform detailed analysis on the local structure of the aircraft, but also reduce the deployment of sensors and reduce the waste of resources.

[0033] As shown in the figure Figure 3 and Figure 4 As shown, the data acquisition and recording module 3 includes a data acquisition unit 301, a conversion unit 302, a compression unit 303, and a recording unit 304. The output of the data acquisition unit 301 is electrically connected to the conversion unit 302, the output of the conversion unit 302 is electrically connected to the compression unit 303, and the output of the compression unit 303 is electrically connected to the recording unit 304. The data acquisition unit 301 mainly collects sensor detection data. The conversion unit 302 is used for A / D conversion of the data, converting the data into a format that can be recognized. The compression unit 303 is used for data compression. The recording unit 304 mainly records test parameter data, test data, and the operation log of the entire data system. The data recording unit 304 records the original monitoring data synchronously, which is convenient for later data analysis and reconstruction. The data acquisition and recording module 3 also receives time synchronization from the aircraft flight parameter system to ensure the time synchronization of the recorded data packets in the monitoring system.

[0034] The specific operation is as follows: through the cooperation between the sensor monitoring module 2 and the data acquisition and recording module 3, the sensor monitoring module 2 adopts a fiber optic strain sensor 201, which has the advantages of small size, light weight, corrosion resistance and electromagnetic interference resistance. The data acquisition end, mainly equipped with fiber optic demodulation equipment, acquires strain signals at a sampling rate of 1kHz. The unidirectional fiber optic strain sensor 201 is installed at the root of stress concentration to measure the strain value in the direction of maximum force. At least four three-flower strain gauges 202 are attached within 30mm of this strain sensor to measure the strain in the direction of maximum force, the strain at 90° to the direction of maximum force, and the strain at 45° to the direction of maximum force, respectively, to improve the accuracy of signal acquisition. At the same time, the data acquisition end receives time synchronization from the aircraft flight parameter system to ensure the time stamp synchronization of the recorded data packets in the monitoring system. The data recording end records the original monitoring data synchronously for easy data analysis and reconstruction later.

[0035] like Figure 3 and Figure 5As shown, the data processing module 4 includes a data analysis unit 401, an early warning unit 402, a real-time feedback unit 403, a counting unit 404, and a transmission unit 405. The output of the data analysis unit 401 is electrically connected to the early warning unit 402. The output of the early warning unit 402 is electrically connected to the real-time feedback unit 403 and the counting unit 404, respectively. The output of the counting unit 404 is electrically connected to the transmission unit 405. The data analysis unit 401 is used to analyze the data collected by the data acquisition and recording module 3, i.e., to check whether there are any abnormalities in the data. The early warning unit 402 compares the maximum value in the analyzed data with historical data. If it is too high, the real-time feedback unit 403 will feed back the abnormal location information to the staff terminal. The counting unit 404 is used to record the number of times the abnormality occurs.

[0036] The specific operation is as follows: Through the setting of the data processing module 4, the data processing module 4 can further process the data collected by the data acquisition and recording module 3. The data analysis unit 401 analyzes the data and determines whether there are any abnormalities. When the data is higher than the historical data during the analysis, the early warning unit 402 and the real-time feedback unit 403 will feed back the abnormal location information to the staff terminal. The counting unit 404 is used to record the number of times the abnormality occurs, which is convenient for the staff to determine and check the feedback location later.

[0037] like Figure 3 and Figure 6 As shown, the strength assessment and analysis module 5 includes a receiving unit 501, a processing unit 502, a conversion unit 503, a calculation unit 504, and a mapping unit 505. The output of the receiving unit 501 is electrically connected to the processing unit 502, the output of the processing unit 502 is electrically connected to the conversion unit 503, the output of the conversion unit 503 is electrically connected to the calculation unit 504, and the output of the calculation unit 504 is electrically connected to the mapping unit 505. The receiving unit 501 is used to receive data, the processing unit 502 is used to process the transmitted strain monitoring data, the conversion unit 503 converts the monitoring data of the fiber optic strain sensor 201 into principal strain and principal stress data, the calculation unit 504 calculates the equivalent stress based on the converted principal strain and principal stress data, and the mapping unit 505 constructs stress amplitude and average stress bar graphs based on the equivalent stress of the data to analyze the structural strength state of key parts.

[0038] The specific operation is as follows: by setting the strength assessment and analysis module 5, the receiving unit 501 receives the monitored data and converts the monitoring data of the fiber optic strain sensor 201 into principal strain and principal stress data. The calculation unit 504 calculates the equivalent stress based on the converted principal strain and principal stress data. The calculated data is then combined to construct stress amplitude and average stress bar graphs to facilitate the analysis of the structural strength status of key parts.

[0039] like Figure 3 and Figure 7 As shown, the output terminal of the strength assessment and analysis module 5 is electrically connected to the marking module 6, and the marking module 6 includes a data tracking unit 601, a positioning unit 602 and a marking unit 603. The output terminal of the data tracking unit 601 is electrically connected to the positioning unit 602, and the output terminal of the positioning unit 602 is electrically connected to the marking unit 603.

[0040] The specific operation is as follows: through the setting of the marking module 6, the data tracking unit 601 tracks the parts with large strain, and the positioning unit 602 locates the key parts. In conjunction with the marking unit 603, the data of the key parts are marked, which makes it easier for staff to quickly find abnormal locations and facilitates the maintenance and repair process.

[0041] In summary, this system for real-time monitoring of aircraft structural strength first utilizes the aircraft structural test specimen analysis module 1 to conduct static tests on the test specimen, obtaining the basic parameters of the structural material. Then, using finite element method simulation, the system identifies the location of the most severe stress concentration in the aircraft structural component, which is typically the stress concentration point. This location is recorded. Next, the sensor installation positions are determined. A unidirectional fiber optic strain gauge 201 is installed at the root of the stress concentration to measure the strain value in the direction of maximum stress. At least four three-strain gauges 202 are attached within 30mm of this strain gauge to measure the strain in the direction of maximum stress. The fiber optic strain sensor 201, which measures strain at 90° to the direction of maximum force and strain at 45° to the direction of maximum force, improves the accuracy of signal acquisition. It features small size, light weight, corrosion resistance, and electromagnetic interference resistance. Equipped with a data acquisition unit primarily using fiber optic demodulation equipment, it acquires strain signals at a sampling rate of 1kHz. The data acquisition unit 301 then collects the sensor's detection data, and the conversion unit 302 performs A / D conversion to convert the data into a recognizable format. The compression unit 303 then compresses and transmits the data, and the recording unit 304 records the test parameters, test data, and the entire data. According to the system's operation log, the data recording unit 304 synchronously records the original monitoring data to facilitate subsequent data analysis and reconstruction. The data acquisition and recording module 3 simultaneously receives time synchronization from the aircraft flight parameter system to ensure the time-stamp synchronization of the recorded data packets in the monitoring system. The data then enters the data processing module 4. Through its settings, the data processing module 4 can further process the data collected by the data acquisition and recording module 3. The data analysis unit 401 analyzes the data to determine if there are any anomalies. If the data exceeds historical data levels during analysis, the early warning unit 402 and the real-time feedback unit 403 relay the anomaly location information to the staff terminal. The counting unit 404 records the number of times an anomaly occurs. Then, the receiving unit 501 receives the monitored data and converts the monitoring data from the fiber optic strain sensor 201 into principal strain and principal stress data. The calculation unit 504 calculates the equivalent stress based on the converted principal strain and principal stress data. The calculated data is then combined to construct stress amplitude and average stress bar graphs to facilitate the analysis of the structural strength status of key parts. Finally, the data tracking unit 601 tracks the parts with large strain forces, and the positioning unit 602 locates the key parts. The marking unit 603 marks the data of the key parts to facilitate the quick location of anomalies by staff in the later stages, thus facilitating the maintenance and repair process.

Claims

1. A system for real-time monitoring of the structural strength of an aircraft fuselage, characterized in that, The system includes an aircraft structural test piece analysis module (1) and a strength assessment analysis module (5). The output of the aircraft structural test piece analysis module (1) is electrically connected to a sensor monitoring module (2). The sensor monitoring module (2) includes a fiber optic strain sensor (201) and a three-flower strain gauge (202). The fiber optic strain sensor (201) selected by the sensor monitoring module (2) is small in size, light in weight, corrosion-resistant, and resistant to electromagnetic interference. It is equipped with a data acquisition terminal mainly based on fiber optic demodulation equipment to acquire strain signals at a sampling rate of 1kHz. The output of the sensor monitoring module (2) is electrically connected to a data acquisition and recording module (3). The data acquisition and recording module (3) is electrically connected to the data processing module (4) at its output end. The intensity assessment and analysis module (5) is electrically interconnected with the output end of the data processing module (4). The intensity assessment and analysis module (5) includes a receiving unit (501), a processing unit (502), a conversion unit (503), a calculation unit (504), and a mapping unit (505). The receiving unit (501) is electrically connected to the processing unit (502) at its output end. The processing unit (502) is electrically connected to the conversion unit (503) at its output end. The conversion unit (503) is electrically connected to the calculation unit (505) at its output end. 04), the output of the calculation unit (504) is electrically connected to the mapping unit (505), the receiving unit (501) is used to receive data, the processing unit (502) is used to process the transmitted strain monitoring data, the conversion unit (503) converts the monitoring data of the fiber optic strain sensor (201) into principal strain and principal stress data, the calculation unit (504) calculates the equivalent stress for the converted principal strain and principal stress data, the mapping unit (505) constructs stress amplitude and average stress bar graphs for the equivalent stress of the data, and analyzes the structural strength state of key parts. The output of the strength assessment and analysis module (5) is electrically connected to a marker. The marking module (6) includes a data tracking unit (601), a positioning unit (602), and a marking unit (603). The output of the data tracking unit (601) is electrically connected to the positioning unit (602), and the output of the positioning unit (602) is electrically connected to the marking unit (603). Through the setting of the marking module (6), the data tracking unit (601) tracks the parts with large strain, and the positioning unit (602) positions the key parts. The marking unit (603) marks the data of the key parts, which makes it easier for staff to quickly find abnormal locations and facilitates the maintenance and repair process.

2. The system for real-time monitoring of aircraft airframe structural strength according to claim 1, characterized in that: The aircraft structural test component analysis module (1) mainly uses the finite element simulation calculation method to determine the part of the aircraft structural component with the most severe stress concentration, which is then used as the key monitoring point for the sensor.

3. The system for real-time monitoring of aircraft airframe structural strength according to claim 1, characterized in that: The data acquisition and recording module (3) includes a data acquisition unit (301), a conversion unit (302), a compression unit (303), and a recording unit (304). The output terminal of the data acquisition unit (301) is electrically connected to the conversion unit (302), the output terminal of the conversion unit (302) is electrically connected to the compression unit (303), and the output terminal of the compression unit (303) is electrically connected to the recording unit (304).

4. The system for real-time monitoring of aircraft airframe structural strength according to claim 3, characterized in that: The data acquisition unit (301) mainly collects sensor detection data, the conversion unit (302) is used for A / D conversion of data, converting data into a format that can be recognized, the compression unit (303) is used for data compression, the recording unit (304) mainly completes the recording of test parameter data, test data, and the operation log of the entire data system, the data recording unit (304) records the original monitoring data synchronously, which is convenient for later data analysis and restoration, and the data acquisition and recording module (3) simultaneously receives time synchronization from the aircraft flight parameter system to ensure the time synchronization of the recorded data packets in the monitoring system.

5. The system for real-time monitoring of aircraft airframe structural strength according to claim 1, characterized in that: A unidirectional fiber optic strain sensor (201) is installed at the root of stress concentration to measure the strain value in the direction of maximum force. At least four three-flower strain gauges (202) are attached within 30 mm of this strain sensor to measure the strain in the direction of maximum force, the strain at 90° to the direction of maximum force, and the strain at 45° to the direction of maximum force.

6. The system for real-time monitoring of aircraft airframe structural strength according to claim 1, characterized in that: The data processing module (4) includes a data analysis unit (401), an early warning unit (402), a real-time feedback unit (403), a counting unit (404), and a transmission unit (405). The output terminal of the data analysis unit (401) is electrically connected to the early warning unit (402). The output terminal of the early warning unit (402) is electrically connected to the real-time feedback unit (403) and the counting unit (404), respectively. The output terminal of the counting unit (404) is electrically connected to the transmission unit (405).

7. A system for real-time monitoring of aircraft airframe structural strength according to claim 6, characterized in that: The data analysis unit (401) is used to analyze the data collected by the data acquisition and recording module (3), that is, to check whether there are any abnormalities in the data. The early warning unit (402) compares the maximum value in the analyzed data with historical data. If it is too high, the real-time feedback unit (403) will feed back the abnormal location information to the staff terminal. The counting unit (404) is used to record the number of times the abnormality occurs.

Images