Patent Application
20070018083
The present invention relates generally to structural health monitoring. More specifically, the present invention relates to structural analysis layers having distributed electronics.
The diagnostics and monitoring of structures, such as that carried out in the structural health monitoring field, are often accomplished by employing arrays of sensing elements. While many advances have been made, the field continues to be challenged by a need to for increased accuracy and performance from its structural health monitoring systems, leading many to employ ever greater numbers of sensors/actuators. However, the larger the number of these elements, the greater the number of wires required for their operation.
Because individual sensing elements must often be placed separately, affixing a large array of such sensing elements can be tedious and time consuming. In addition, as each individual sensing element can require one or, commonly, multiple wires, large arrays of sensing elements can require a large number of individual wires, which may be difficult to handle and place. The securing of such large numbers of wires can often be painstaking and time consuming, as well. It is therefore desirable to combine these large numbers of elements, and their wires, together in such a manner that the abovementioned difficulties are avoided, or at least reduced.
Additionally, the demand for improved performance from structural health monitoring sensor arrays has led to the use of larger arrays. This in turn has led to greater signal noise and interference problems, especially in the monitoring of large structures where the controller and array may be separated by large distances. It is therefore further desirable to combine structural health monitoring sensor elements and their associated electronics in such a way as to improve performance and reduce detrimental effects such as noise and interference, while also reducing the difficulty in affixing such complicated systems to the structures they monitor.
The invention can be implemented in numerous ways, including as a system, device, or apparatus. Several embodiments of the invention are discussed below.
In one embodiment, a structural health monitoring system comprises a flexible substrate configured for attachment to a structure, a plurality of sensors affixed to and spatially distributed upon the flexible substrate, and at least one controller affixed to the flexible substrate and in electronic communication with at least one sensor of the plurality of sensors. The at least one controller is configured to control a function of the at least one sensor.
In another embodiment, a structural health monitoring system comprises a flexible substrate configured for attachment to a body, a plurality of sensors affixed to and spatially distributed upon the flexible substrate, the plurality of sensors configured for monitoring the structural health of the body, and a distributed control network having elements distributed across the flexible substrate. The control network is configured to govern functions of the plurality of sensors so as to control the monitoring of the structural health of the body.
Other aspects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which:
Like reference numerals refer to corresponding parts throughout the drawings. Also, it is understood that the depictions in the figures are diagrammatic and not necessarily to scale.
In one embodiment of the invention, a sensor array is embedded within a flexible layer, which can then be attached to a structure and employed to monitor its structural health. The sensor array employs transducers, capable of acting as both passive sensors and active actuators. These transducers are controlled by local electronics also embedded within the flexible layer. The invention includes numerous different arrangements of these electronic controllers and their associated transducers. For example, each transducer can have its own controller embedded nearby. Alternatively, one controller can control a number of transducers, and can therefore be embedded in various configurations proximate to one or more of the transducers it controls. The embedding of controllers local to the transducers they control generates a number of advantages. As one example, the close proximity of the controllers to their sensors tends to reduce interference and signal noise, yielding cleaner and more reliable data. In addition, the controllers can include various components that impart other advantages, such as wireless transceivers for reducing the number of wires needed within the flexible layer, and local processors for reducing or eliminating the need for a remote data processor.
For ease of installation, the sensor network can be placed on a flexible dielectric substrate to form a diagnostic layer.
The diagnostic layer 100 and its operation are further described in U.S. Pat. No. 6,370,964 to Chang et al., which is hereby incorporated by reference in its entirety and for all purposes. Construction of the diagnostic layer 100 is also explained in U.S. patent application Ser. No. 10/873,548, filed on Jun. 21, 2004, which is also incorporated by reference in its entirety and for all purposes. It should be noted that the present invention is not limited to the embodiments disclosed in the aforementioned U.S. patent application Ser. No. 10/873,548, but instead encompasses the use of flexible sensor layers having any configuration.
For illustration,
In one embodiment, the sensors 102 can be piezoelectric transducers capable of reacting to a propagating stress wave by generating a voltage signal. Analysis of these signals highlights properties of the stress wave, such as its magnitude, propagation speed, frequency components, and the like. Such properties are known to be useful in structural health monitoring.
The data acquisition unit 118 and other electronics are often located remotely from the diagnostic layer 100 and sensors 102. As one or more (and typically many) wires must usually be run between the electronics and the sensors 102, such systems often are vulnerable to electrical interference and other disadvantages, as described above. Accordingly,
It should be noted that the invention is not limited to the embodiments described above. Specifically, the controllers described above can be any electronic component, or collection thereof, suitable for governing or controlling one or more functions of a sensing or actuating element. In this aspect, the invention includes any control network whose elements can be distributed across a flexible layer while maintaining the ability to control any function of a number of sensors or actuators. For example, the controllers can be simple processors that control the application of power to an actuator in response to an initiating signal, so as to direct the actuator to generate a stress wave at certain times. An equally simple processor can be set up to gather and process the data from a sensing element. The controllers can also contain additional components for executing more complex functions, such as switching between different actuators and sensors within the groups of transducers they control. For example, the controllers can include memory that stores a signal profile, and instructions for inducing a transducer to produce a stress wave signal having that profile. Other components can also allow the controllers to process data from multiple sensors simultaneously or control several actuators at once, as well as execute more complex data analysis such as filtering, signal conditioning, and mathematical operations and algorithms for structural analysis methods. Likewise, the controllers can employ known components such as wireless transceivers, that allow each controller to wirelessly communicate with remote devices, eliminating the need for wires to connect the controllers to those remote devices and further simplifying the layout and maintenance of layers 200. The components described above are known, and include processors, local memory for storing data and instructions for carrying out the tasks described above, switching circuits, frequency filters, and wireless transceivers.
It should also be noted that the invention encompasses other configurations of the apparatuses shown. For instance, while
The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the invention. Thus, the foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. For example, each processor can control one or more sensing/actuating elements, and can be placed at various locations proximate to the elements they control. In addition, each controller can be equipped with a processor, local memory, and any other components it needs to carry out various functions, including but not limited to data collection, conditioning, and analysis, signal generation, and wireless communication. These components can include filters, switches, and wireless transceivers. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.
This application claims priority to U.S. Provisional Patent Application No. 60/690,337, filed on Jun. 13, 2005, the disclosure of which is hereby incorporated by reference in its entirety and for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 60690337 | Jun 2005 | US |
