WO2009071602A2

WO2009071602A2 - Sensor network and state monitoring device for an aircraft and state monitoring method

Info

Publication number: WO2009071602A2
Application number: PCT/EP2008/066741
Authority: WO
Inventors: Thomas Becker; Jordi Sabater; Peter Sollberger
Original assignee: Eads Deutschland Gmbh; Hochschule für Technik und Architektur Luzern
Priority date: 2007-12-03
Filing date: 2008-12-03
Publication date: 2009-06-11
Also published as: DE102007058102B4; WO2009071602A3; DE102007058102A1

Abstract

The invention relates to a sensor network for measuring environmental parameters on the structure of an aircraft. For this purpose, a plurality of sensor units (12) is fastened on the structure of an aircraft, with which identifiers are associated for localization of the sensor units (12).

Description

SENSOR NETWORK AND STATUS MONITORING DEVICE FOR AN AIRCRAFT AND STATUS MONITORING PROCESS

The invention relates to a sensor network for measuring environmental parameters on the structure of an aircraft. Moreover, the invention relates to a condition monitoring device provided with such a sensor network. Furthermore, the invention relates to an aircraft provided with it. Finally, the invention relates to a condition monitoring method for an aircraft.

The structure of an aircraft is subject to various forces that can cause stretching, cracking or other damage. For regular maintenance, therefore, the structure of aircraft is investigated by various non-destructive methods to safeguard aviation. These methods include in particular the visual inspection, but also ultrasound or, if possible, radiographic measurements.

Mechanical loads due to impact, air resistance and gravity are the most frequent strains on the structure of an aircraft. These structures cause the structure to deform plastically. When the burdens exceed a threshold, permanent damage and weakening of the material occur. Such overloads can not always be avoided.

It is known that the stress-overload characteristics of a material are temperature-dependent. In other words, a stress that does not harm a structure at room temperature, at temperatures below 0 ⁰ C, damage the structure.

So far, forces occurring at the structure are at best measured centrally. An exact assignment or localization of measured values is not possible.

From DE 698 10 975 T2, a sensor system is known which has a multiplicity of sensors which deliver data to a main computer by means of a communication bus. The sensor system includes, among other things, a bus conversion device which converts the signals between two such communication bus systems.

WO 01/61301 A1 discloses a method for the determination of mechanical stresses, for example in ships and aircraft. To determine these mechanical stresses sensors for measuring the mechanical stress, such as strain gauges, attached to the surface to be measured. The measurement results of the sensors are transmitted to a central unit via a digital measurement bus.

The DE 10 2006 020 341 A1, the expert takes a sensor for a measuring point and a method for its verification. The sensor can transmit the measured data wirelessly to a tester. In regular operation, the sensors are connected via wire cables.

WO 98/44400 shows a method for automatic assignment of addresses in a bus system, in particular FireWire. A system control unit maintains a list showing which devices are are orders. This list is updated when the connected device is relocated to another port.

DE 10 2004 025 319 A1 discloses a seat status display system for passenger spaces of aircraft and vehicles. For this purpose, a sensor arrangement is provided in each seat, which serves to detect the state of a seat. For this purpose, the sensor arrangements can have, for example, an occupancy sensor and a belt sensor. An operating and display unit is electrically connected to the sensor arrangements via a bus and can graphically represent the states of the individual seats.

DE 40 12 367 A1, the expert takes an air data system for aircraft in which a pressure measurement is performed at different locations of the aircraft. The data obtained is used for engine control.

Against this background, the object is to provide a device and a method by means of which a distribution of mechanical loads on a structure can be reliably determined in a simple manner.

To solve this object, a sensor network for measuring parameters on the structure of an aircraft is proposed, which has a plurality of sensor devices, which are designed for attachment to a structure of the aircraft, wherein the sensor devices are associated with identifiers for locating the sensor devices.

A state monitoring device provided with such a sensor network and an aircraft provided therewith and / or with such a sensor network and a method for monitoring the state of a structure of an aircraft are the subject matter of the subsidiary claims.

Advantageous embodiments of the invention are the subject of the dependent claims. The sensor network according to the invention has the advantage that it enables an immediate measurement of parameters, such as acceleration, at different points of the structure of the aircraft with pinpoint accuracy. Furthermore, the measured parameters can be assigned to exact positions on the structure by the unique identifier of the sensor devices.

In an advantageous embodiment, the sensor devices have communication devices with which the measured parameters can be read out. Furthermore, these communication devices are advantageously designed for wireless information transmission. This has the advantage that the sensor devices can also be arranged at locations where a cable routing would be difficult to realize.

The communication devices can be designed to transmit the identifier together with the measured environmental parameters. Thus, with a transmission of the measured parameters, an assignment of the received parameters to a sensor device and thus to a location on the structure is possible directly.

In an advantageous embodiment, the sensor devices have temperature sensor units. Thus, it is possible to determine a temperature distribution in the structure. Furthermore, this information is useful to evaluate the maximum stress of the structure depending on the temperature.

The sensor devices advantageously have acceleration sensor units. With the aid of the acceleration values, deflections of the structure can be calculated.

In a particularly preferred embodiment, the sensor network and / or the monitoring device are designed such that by means of the acceleration sensors, the current deflection and / or the current location of the sensors can be detected. In particular, the detected location or the detected deflection can be combined with the those of other sensors. Thus, loads of structural areas that are between sensors and which are thus not directly detectable by the sensors can be detected in an advantageous manner.

A detection of the current location or the current deflection can in particular be obtained from the acceleration measurements by integration, in particular with the aid of the identifiers associated with the respective sensors and the information contained therein about the original location in the state without load

The acceleration sensor units may be designed to measure an acceleration in all three spatial directions. Thus, not only the amount of acceleration but also its direction can be detected.

The sensor devices advantageously have signal processing units for preprocessing signals from the sensor units. This can significantly reduce the amount of data to be transmitted. The signal processing units can be designed to correlate the signals of the sensor units.

In an advantageous embodiment, the signal processing units have tables for storing material data, by means of which the signals of the sensor units can be correlated.

The sensor devices can be designed to measure the distance from each other. This allows the detection of strains or compressions of the structure. To measure the distance, the current acceleration measurements in the individual sensors are used in a preferred embodiment.

In particular, a method according to the invention comprises the following steps: using the sensor network or the condition monitoring device; Reading the values measured by the sensor devices as well as the identifiers;

Locating the respective sensor device based on the identifier, so as to obtain a location determination for the parameter value read.

The method according to the invention has the advantage that parameters of the structure can be measured locally with little wiring effort. Low wiring costs result in a lower weight of the sensor system.

By using acceleration sensors in the sensor devices one of the most important parameters of the structural load can be measured.

If the deflection of the sensor devices is calculated from the measured acceleration values, then the strain of the structure can be derived therefrom.

The correlation of measured temperature and deflection measured values allows adaptation of the maximum values for the load to temperature-dependent material properties.

Deciding whether damage to the structure is likely due to the correlated temperature and acceleration measurements allows for a targeted impact on the length of the maintenance interval and can help pinpoint damage.

By measuring a distance between the sensor means located by means of identification, and a comparison of the measured distance with a stored reference value for these sensor devices, material deformations in the structure can be detected. The current distance can be detected by integration in a preferred embodiment using current acceleration measurements. Advantageously, a load distribution can be determined via the sensor network.

A comparison of two load distributions recorded at the same time offset under the same conditions and an estimation of the probability of damage to the structure due to the differences in the load distributions advantageously brings about early warning of damage. Thus it is already possible in flight to estimate whether damage to the structure is to be expected. According to the data collected in this estimation, maintenance intervals can be shortened or extended.

The invention will be explained in more detail with reference to an embodiment which is shown schematically in the accompanying drawings. Show it:

1 shows an aircraft, here an aircraft, with a sensor network,

FIG. 2 is a block diagram of a wireless sensor device; FIG.

3 is a block diagram of a condition monitoring device provided with the sensor device;

4 shows a schematic illustration of a fuselage of the aircraft with a wing monitored by means of the condition monitoring device;

Fig. 5 is a detail view of the detail C of Fig. 4 in a normal load condition and

Fig. 6 shows detail C of Fig. 4 in an overload condition.

In FIG. 1, the example of an aircraft 10 as an aircraft shows how sensor devices 12 are distributed on such an aircraft, here aircraft 10 can. The sensor devices 12 in this way form a sensor network 31 for monitoring the structure of the aircraft 10.

2 shows a block diagram of a wireless sensor device 12. The sensor device 12 has a communication device 14 which comprises an antenna 24 with high-frequency electronics 26, a signal processing unit 16, an acceleration sensor unit 18 and a temperature sensor unit 20. The antenna 24 and the high-frequency electronics 26 are designed for example for radio frequencies (RF part of the sensor device 12).

The acceleration sensor units 18 are preferably triaxial devices that cover the typical load range during operation of the aircraft 10. The temperature sensor units 20 cover typical temperature ranges for aircraft. Here the measuring range extends from -70 ⁰ C to 50 ⁰ C.

Load and stress profiles can be used during the flight or at maintenance intervals. This leads to an on-board, real-time capable condition monitoring system that reduces maintenance costs and increases the usual maintenance intervals.

FIG. 3 shows a state monitoring device 30 forming such a condition monitoring system with a sensor network 31 formed from a plurality of the sensor devices 12 and a central computer 32.

In the following, the function of the state monitoring device 30 is explained in more detail with reference to the illustration in FIGS. 2 and 3. The sensor units 18, 20 transmit measured signals 18a, 20a to the signal processing unit 16. In the signal processing unit 16, the signals 18a, 20a are analyzed and processed. The value 22, which is transmitted from the signal processing unit 16 to the communication unit 14, contains information about the magnitude of the acceleration in each spatial direction, which are correlated with the temperature.

For example, a measured acceleration value is weighted or scored based on stored allowable acceleration-temperature curves or matrices (or tables). For example, the value could indicate the corresponding fraction of the maximum acceleration assumed as a limit at the measured temperature.

By means of the antenna 14 and the high-frequency electronics, the value 22 is sent to a central computer 32. For localization, the high-frequency electronics add an identifier, for example a node number, to the value 22.

In the system proposed here sensors are added to a network node so as to form a sensor device 12 in the form of a wireless network node. Information about parameters influencing the state of the structure can be obtained with the sensor devices 12. Typical parameters that indicate congestion situations are acceleration and temperature, and the combination of these parameters.

The wireless sensor network 31, which is equipped with sensor devices 12, is used to collect basic information about the state of the (aircraft) structure. The sensor devices 12 are distributed throughout the structure so that critical areas can be more intensively monitored by a denser network, whereas less critical areas have less sensor device 12 distribution. An exemplary distribution is shown in FIG.

By analyzing the data determined by the sensor devices 12, it is possible to detect overload situations which can (or have already led to) damage to the structure. It is even possible to Comparison of two series of data collected under the same conditions to immediately detect damage.

This can be achieved, for example, by comparing data recorded in a sensor device 12 in a wing tip 28 with those from a sensor device 12 on the wing root 29.

By double integration of the acceleration difference between the two points - wing tip 28 and wing root 29 - the wing displacement and thus due to the elongation or compression of the wing 42, the mechanical load of the wing 42 can be calculated. If the displacement exceeds certain reference values, an indication of weakening of the structure or even a defect is obtained.

The sensor devices 12 have a wireless communication interface, electronics, at least one supply device and at least one sensor. The electronics have, for example, a sensor control, a memory device, a signal processing device and / or a data processing device.

The supply device supplies the sensor device 12 with energy. For this purpose, batteries, energy collection devices and / or energy converters are provided.

For example, acceleration or temperature sensor devices 18, 20 come into consideration as sensors. Furthermore, moisture, gas or other advantageous sensors can be provided.

The communication can be realized by means of different network topologies. For the ground operation of the system, the network does not play an important role. Even point-to-point connections could be possible. To that However, using the system in flight uses a low-consumption, secure and fault-tolerant architecture.

The communication device 14 is accordingly designed so that the desired topologies can be used. If point-to-point connections are desired, these must be provided in the electronics.

In order for the sensor devices 12 to be located, it is provided that they have an identifier which is unique for each sensor device 12. This identifier can be, for example, a code number, a location or - as mentioned above - node number.

The central computer 32, which reads out the information from the sensor devices 12, has an allocation unit 34 for localization, by means of which the identifiers can be assigned to locations on the aircraft 10 or to its structure. This makes it possible to have the central computer 32 calculate a load distribution, in particular a local load distribution.

In order to facilitate the linking of the identifier with the sensor data, it is provided according to an advantageous embodiment that the communication device 14 transmits its identifier with each data record that is transmitted.

Another interesting factor of the system proposed here is that the network allows the measurement of a load and stress profile over the aircraft structure by means of direct signal and data processing in flight.

The amount of computations performed in the signal processing unit 16 is highly dependent on the available power. If the sensor device 12 is wired (which is possible, but less preferred due to the need for cabling), then enough power could be available to perform a large number of calculations using an internal database of material information. In contrast, an ultra-sparse same wireless sensor device 12 mainly reduce and store signals. The data is only transmitted to the central computer 32 upon request, where it is additionally processed to create a general load profile.

In addition, the data can be linked to other information, such as an exact distance measurement between the nodes. This makes it possible to measure the change in position or the deviation of the structure. This could increase the value of records relating to congestion situations in parts of the structure.

In the following, it is explained in more detail how the condition monitoring device 30 determines the structure of an aircraft, e.g. of the aircraft 10 can monitor. In Fig. 4, the hull 40 and a wing 42 of the aircraft 10 is shown schematically.

As can be seen in Fig. 5, which shows a detail of the wing 42, and also in Fig. 1, several of the sensor means 12 are provided on the wing 42 at some distance from each other which measure the acceleration and temperature at the individual locations , By means of the measurement of the accelerations, as explained above, in the central computer 32, the individual deflections and thus the current locations or location differences of the sensor devices 12 are determined relative to one another. Fig. 5 shows a case of normal deflection in a healthy structure under load.

In FIG. 6, damage has occurred in an intermediate region 44 between the sensor devices 12. By evaluating the acceleration values of the sensor devices 12 with respect to their location assigned by the identifier, such damage can also be detected when it occurs in the intermediate region 44. By detecting the load distribution, impermissible loads can also be detected at an early stage at the intermediate areas between the sensor devices and appropriate countermeasures initiated.

By measuring a distance between the sensor devices 12 located by means of identification and a comparison of the measured distance with a stored reference value for these sensor devices 12, material deformations in the structure can be detected. For details of the measurement of the distance and for further details of the device described herein, reference is expressly made to the German patent application DE 10 2007 044 301.5-51 (filing date 17.09.2007) and the international patent application PCT / EP2008 / 007492 (filing date 11.09.2008). These applications are incorporated by reference into the present application.

LIST OF REFERENCE NUMBERS

10 plane

12 sensor device

14 communication device

16 signal processing unit

18 acceleration sensor unit

18a signal

20 temperature sensor unit

20a signal

22 value

24 antenna

26 high-frequency electronics

28 wing tip

29 wing root

30 Condition monitoring device

31 sensor network

32 central computer

34 allocation unit

40 hull

42 wings

44 intermediate area

Claims

A sensor network (31) for measuring parameters on the structure of an aircraft, comprising a plurality of sensor means (12) adapted to be mounted on a structure of the aircraft, the sensor means (12) having identifiers for locating the sensor means (12). assigned.

2. Sensor network according to claim 1, characterized in that the sensor devices (12) have communication devices (14) with which the measured parameters can be read out.

3. Sensor network according to claim 2, characterized in that the communication means (14) are designed for wireless information transmission.

4. Sensor network according to one of claims 2 or 3, characterized in that the communication means (14) are designed for transmitting the identifier together with the measured parameters.

5. Sensor network according to one of the preceding claims, characterized in that the sensor devices (12) have temperature sensor units (18).

6. Sensor network according to one of the preceding claims, characterized in that the sensor devices (12) have acceleration sensor units (20).

7. Sensor network according to claim 6, characterized in that with the acceleration sensor units (20) acceleration in all three spatial directions can be measured.

8. Sensor network according to one of claims 6 or 7, characterized in that it is designed to determine a deflection of a sensor device (12) from the acceleration detected by the acceleration sensor unit (20).

9. Sensor network according to claim 8, characterized in that it is designed to Verlgeich the deflections of a plurality of sensor devices (12).

10. Sensor network according to one of the preceding claims, characterized in that the sensor devices (18, 20) signal processing units (16) for preprocessing signals (18a, 20a) of the sensor units (18, 20).

11. Sensor network according to claim 10, characterized in that the signal processing units (16) for the correlation of the signals (18a, 20a) of the sensor units (18, 20) are formed.

12. Sensor network according to one of claims 10 or 11, characterized in that the signal processing units (16) have tables for storing material data, by means of which the signals (18a, 20a) of the sensor units (18, 20) are correlatable.

13. Sensor network according to one of the preceding claims, characterized in that the sensor devices (12) are designed to measure the distance from each other.

14. Sensor network according to claim 13 and claim 6, characterized in that the distance can be measured by evaluating the acceleration values.

A condition monitoring apparatus for monitoring the structure of an aircraft for loading characterized by a sensor network (31) according to any one of the preceding claims and a central computer (32).

16. Aircraft with a sensor network (31) according to one of claims 1 to 14 and / or a condition monitoring device according to claim 15.

17. A method for measuring parameters on a structure of an aircraft and / or for monitoring the structure of the aircraft, characterized by the following steps: a) using a sensor network (31) according to one of claims 1 to 14 and / or a condition monitoring device according to claim 15; b) reading the values measured by the sensor devices (12) and the identifiers; c) Locating the respective sensor device (12) on the basis of the identifier so as to obtain a location determination for the parameter value read out.

18. The method according to claim 17, characterized by the use of sensor devices (12) with acceleration sensors (18) and

Calculate the deflection of the sensor devices (12) from the measured acceleration values.

19. The method according to claim 18, characterized by the step: correlation of measured temperature, displacement and acceleration measured values.

The method of claim 19, characterized by the step of: deciding whether damage to the structure is likely due to the correlated temperature and acceleration measurements.

21. The method according to any one of claims 17 to 20, characterized by the step:

Measuring the distance between the sensor means (12) located by means of identification, and

Comparing the measured distance with a stored reference value for these sensor devices (12).

22. The method according to claim 21.dadurch in that the distance is determined from the detected by means of the sensor device acceleration measurements.

23. The method according to any one of the preceding claims, characterized by the step:

Determining a load distribution over the sensor network.

24. Method according to one of the preceding claims, characterized by:

Compare two records recorded under the same conditions to avoid damage to the structure due to differences in the data. records.

25. The method according to claim 24, characterized in that measured data sets are stored and compared with later recorded by the same sensor means (12) records.

26. The method according to claim 24 or 25, characterized in that the data sets to be compared are measured at different locations and the comparison result is compared with predetermined values for these locations.