阅读说明：本技术 检查系统和方法 (Inspection system and method ) 是由 V·V·纳拉德加 C·S·莱斯特 M·马霍尼 于 2020-10-09 设计创作，主要内容包括：一种检查系统包括一个或多个处理器以及可操作地耦合到一个或多个处理器的红外(IR)拍摄装置。一个或多个处理器控制微波发射器在第一扫频期间将具有所指定的频率范围内的不同频率的微波依次发射到对象中。IR拍摄装置在通过微波的不同频率中的每个频率来加热对象之后生成对象的热图像数据。一个或多个处理器分析热图像数据,并且确定所指定的频率范围内的所选频率,与所指定的频率范围中的一个或多个其他频率相比,所述所选频率提供对所述对象的更大的加热。一个或多个处理器还响应于通过微波的所选频率对所述对象的加热而分析所述对象的选择热图像数据,以检测所述对象中的元素。(An inspection system includes one or more processors and an Infrared (IR) camera operably coupled to the one or more processors. The one or more processors control the microwave emitter to sequentially emit microwaves having different frequencies within the specified frequency range into the subject during the first sweep. The IR camera generates thermal image data of the object after heating the object by each of the different frequencies of microwaves. One or more processors analyze the thermal image data and determine a selected frequency within the specified frequency range that provides greater heating of the object than one or more other frequencies in the specified frequency range. The one or more processors also analyze selected thermal image data of the object to detect elements in the object in response to heating of the object by selected frequencies of microwaves.)

1. An inspection system, comprising:

one or more processors configured to couple with the microwave emitters and control the microwave emitters to sequentially emit microwaves having different frequencies within a specified frequency range into the subject during a first sweep of the subject; and

an Infrared (IR) camera operably coupled to the one or more processors and configured to generate thermal image data of the object after heating the object by each of the different frequencies of microwaves during the first scan frequency,

wherein the one or more processors are configured to analyze the thermal image data from the IR camera and determine a selected frequency within the specified frequency range that provides greater heating of the object than one or more other frequencies in the specified frequency range, and

wherein the one or more processors are further configured to analyze selected thermal image data of the object to detect elements in the object in response to heating of the object by the selected frequencies of microwaves.

2. The inspection system of claim 1, wherein the selected thermal image data is a subset of the thermal image data generated during the first frequency sweep or generated during a subsequent second frequency sweep of the microwave emitter over the object.

3. The inspection system of claim 1, wherein the one or more processors are configured to detect an element in the object by identifying a thermal signature in the selected thermal image data that represents a type of the element.

4. The inspection system of claim 1, wherein the one or more processors are configured to control the microwave emitter to emit the microwaves having the different frequencies into the common portion of the object at different times.

5. The inspection system of claim 1, wherein the one or more processors are configured to control the microwave emitter to emit the microwaves having the different frequencies into each of a plurality of different portions of the object during the first sweep frequency of the microwave emitter.

6. The inspection system of claim 5, wherein the selected frequency is a first selected frequency corresponding to a first portion of the plurality of different portions of the object, and wherein

The IR camera is configured to generate thermal image data of a second portion of the object after heating the second portion by each of the different frequencies of microwaves during the first scan frequency, an

The one or more processors are configured to analyze the thermal image data of the second portion and determine a second selected frequency within the specified frequency range corresponding to the second portion that provides greater heating of the second portion than one or more other frequencies in the specified frequency range.

7. The inspection system of claim 1, wherein prior to analyzing the selected thermal image data, the one or more processors are configured to control the microwave emitter to perform a second frequency sweep over the object such that the microwave emitter emits microwaves into the object having only the selected frequency, and

the IR camera is configured to generate the selected thermal image data of the object after heating by the microwaves during the second frequency sweep.

8. The inspection system of claim 1, wherein the one or more processors are further configured to control the microwave emitter to emit microwaves having a plurality of different power levels into the subject during the first scan frequency of the subject.

9. The inspection system of claim 8, wherein the IR camera is configured to generate thermal image data of the object after heating the object with each of the different frequencies of microwaves at each of the different power levels during the first scan frequency.

10. The inspection system of claim 1, wherein the one or more processors are configured to control the microwave emitter to emit microwaves that penetrate a surface coating on the object, the surface coating being thicker than one inch.

Technical Field

The subject matter described herein relates to non-destructive object inspection.

Background

Microwave enhanced thermography (thermography) or microthermography involves directing a high energy microwave signal from a microwave source onto the surface of a region of interest to heat the region of interest. An Infrared (IR) camera generates resulting heated thermal image data that can be analyzed for indications of sub-surface elements within the region of interest. Subsurface elements (e.g., defects in a test object) can be detected based on characteristics of the temperature distribution along the surface as depicted in the thermal image data. For example, microwaves impinging (e.g., an inert microwave) on a subsurface element may be absorbed, reflected, or scattered differently than microwaves adjacent to the subsurface element, such that the subsurface element may experience a different heating rate attributable to the microwaves than adjacent regions of the object. This heating variation may be represented in a temperature distribution depicted in the thermal image data, such that the temperature distribution can be analyzed to detect the presence of sub-surface elements, and potentially also identify sub-surface elements.

The ability and efficiency of using microwave thermography for detecting sub-surface elements (e.g., defects) in an object is reduced for thicker object structures relative to thin object structures. For example, some microwaves may not penetrate the full depth of the region of interest due to the material properties of the object and the characteristics of the microwaves. Even for microwaves that do penetrate full depth, depth can cause degraded resolution, which can reduce accuracy by causing false detection and/or false identification of sub-surface elements. Depth may also cause slower processing times due in part to interference and slower heat transfer rates through the object. Emitting microwaves toward the object at a greater energy level is an inaccurate and inefficient means for attempting to improve the accuracy and efficiency of inspecting thick object structures.

Disclosure of Invention

In one or more embodiments, an inspection system is provided that includes one or more processors and an Infrared (IR) camera operably coupled to the one or more processors. The one or more processors are configured to couple with the microwave emitter and control the microwave emitter to sequentially emit microwaves having different frequencies within a specified frequency range into the object during a first frequency sweep (sweep) of the object. The IR camera is configured to generate thermal image data of the object after heating the object by each of the different frequencies of microwaves during the first scan frequency. The one or more processors are configured to analyze thermal image data from the IR camera and determine a selected frequency within the specified frequency range that provides greater heating of the object than one or more other frequencies in the specified frequency range. The one or more processors are further configured to analyze selected thermal image data of the object to detect elements in the object in response to heating of the object by the selected frequency of microwaves.

In one or more embodiments, a method is provided that includes performing a first frequency sweep of a microwave emitter over one or more portions of an object. During a first sweep, the microwave emitter emits microwaves having a plurality of different frequencies within the specified frequency range into the subject in turn at each of the one or more portions. The method includes generating thermal image data for each of one or more portions of the subject via an Infrared (IR) camera after heating by microwaves having different frequencies during a first scan frequency. The method includes determining, for each of one or more portions of the object, a respective selected frequency within the specified frequency range by analyzing the thermal image data. The microwaves having the selected frequency provide greater heating of the corresponding portion than one or more other frequencies in the designated frequency range. The method also includes analyzing selected thermal image data for each of the one or more portions generated by the IR camera when heated by microwaves having a corresponding selected frequency to detect a thermal signature (signature) representative of an element in the object. The selection thermal image data is a subset of the thermal image data generated during the first sweep or generated during a subsequent second sweep of the microwave emitter over one or more portions of the object.

In one or more embodiments, an inspection system is provided that includes a microwave emitter, one or more processors, and an Infrared (IR) camera. One or more processors are operatively coupled to the microwave emitter and the IR camera. The one or more processors are configured to control the microwave emitter to emit microwaves into a plurality of different portions of the object during a first frequency sweep of the object and during a subsequent second frequency sweep of the object. The IR camera is configured to generate thermal image data of each of the portions of the object after heating the portions by microwaves during a first frequency sweep and during a second frequency sweep. During the first sweep, the one or more processors are configured to control the microwave emitter to emit microwaves having a plurality of different frequencies within the specified frequency range into each of the plurality of portions in turn, such that microwaves having a first frequency within the specified frequency range are emitted into a first one of the portions during a first time period, and microwaves having a second frequency within the specified frequency range are emitted into the first portion during a second time period after the first time period. The one or more processors are configured to analyze thermal image data generated by the IR camera during the first sweep to determine, for each of the portions of the object, a respective selected frequency within the specified frequency range that provides greater heating of the corresponding portion of the object than other frequencies of microwaves transmitted into the corresponding portion. During the second frequency sweep, the one or more processors are configured to control the microwave emitter to emit microwaves having only the respective selected frequency into each corresponding portion of the object.

The present invention provides a set of technical solutions, as follows.

Technical solution 1. an inspection system, comprising:

one or more processors configured to couple with the microwave emitters and control the microwave emitters to sequentially emit microwaves having different frequencies within a specified frequency range into the subject during a first sweep of the subject; and

an Infrared (IR) camera operably coupled to the one or more processors and configured to generate thermal image data of the object after heating the object by each of the different frequencies of microwaves during the first scan frequency,

wherein the one or more processors are configured to analyze the thermal image data from the IR camera and determine a selected frequency within the specified frequency range that provides greater heating of the object than one or more other frequencies in the specified frequency range, and

wherein the one or more processors are further configured to analyze selected thermal image data of the object to detect elements in the object in response to heating of the object by the selected frequencies of microwaves.

Solution 2. the inspection system of any preceding solution, wherein the selected thermal image data is a subset of the thermal image data generated during the first sweep, or generated during a subsequent second sweep of the microwave emitter over the object.

Solution 3. the inspection system of any preceding solution, wherein the one or more processors are configured to detect an element in the object by identifying a thermal signature in the selected thermal image data representative of the type of the element.

Solution 4. the inspection system of any preceding solution, wherein the one or more processors are configured to control the microwave emitters to emit the microwaves having the different frequencies into the common portion of the object at different times.

Solution 5. the inspection system of any preceding solution, wherein the one or more processors are configured to control the microwave emitter to emit the microwaves having the different frequencies into each of a plurality of different portions of the subject during the first sweep of the microwave emitter.

Solution 6. the inspection system of any preceding solution, wherein the selected frequency is a first selected frequency corresponding to a first portion of the plurality of different portions of the object, and wherein

The IR camera is configured to generate thermal image data of a second portion of the object after heating the second portion by each of the different frequencies of microwaves during the first scan frequency, an

The one or more processors are configured to analyze the thermal image data of the second portion and determine a second selected frequency within the specified frequency range corresponding to the second portion that provides greater heating of the second portion than one or more other frequencies in the specified frequency range.

Solution 7. the inspection system of any preceding solution, wherein, prior to analyzing the selected thermal image data, the one or more processors are configured to control the microwave emitter to perform a second frequency sweep over the object such that the microwave emitter emits microwaves into the object having only the selected frequency, and

the IR camera is configured to generate the selected thermal image data of the object after heating by the microwaves during the second frequency sweep.

Technical solution 8 the inspection system of any preceding claim, wherein the one or more processors are further configured to control the microwave emitter to emit microwaves having a plurality of different power levels into the subject during the first scan frequency of the subject.

Solution 9 the inspection system of any preceding solution, wherein the IR camera is configured to generate thermal image data of the object after heating the object with each of the different frequencies of microwaves at each of the different power levels during the first scan.

The inspection system of any of the preceding claims, wherein the one or more processors are configured to control the microwave emitter to emit microwaves that penetrate a surface coating on the object, the surface coating being thicker than one inch.

Solution 11. the inspection system of any preceding solution, wherein the one or more processors are configured to determine the selected frequency for the object based on which frequency of microwaves within the specified frequency range provides the greatest heating of the object.

Solution 12. the inspection system of any preceding solution, further comprising a drone, wherein the microwave emitter and the IR camera are mounted to the drone.

Technical solution 13. a method, comprising:

performing a first sweep of the microwave emitter over one or more portions of the object, wherein during the first sweep, the microwave emitter emits microwaves having a plurality of different frequencies within the specified frequency range into the object in turn at each of the one or more portions;

generating thermal image data for each of the one or more portions of the subject via an Infrared (IR) camera after heating by the microwaves having the different frequencies during the first scan frequency;

determining, for each of the one or more portions of the object, a respective selected frequency within the specified frequency range by analyzing the thermal image data, wherein microwaves having the selected frequency provide greater heating of the corresponding portion than one or more other frequencies in the specified frequency range; and

analyzing selected thermal image data for each of the one or more portions generated by the IR camera when heated by microwaves having corresponding selected frequencies to detect a thermal signature representative of an element in the object, and

wherein the selected thermal image data is a subset of the thermal image data generated during the first sweep or generated during a subsequent second sweep of the microwave emitter over the one or more portions of the object.

Solution 14. the method of any preceding solution, wherein the microwaves having the different frequencies are emitted by the microwave emitter sequentially such that microwaves having a first frequency within the specified frequency range are emitted into a first portion of the one or more portions during a first time period, and microwaves having a second frequency within the specified frequency range are emitted into the first portion during a second time period after the first time period.

Solution 15 the method of any preceding solution, wherein prior to analyzing the selected thermal image data, the method further comprises performing a second frequency sweep of the microwave emitter over the one or more portions of the object, wherein during the second frequency sweep the microwave emitter emits microwaves having only the respective selected frequency into each corresponding portion of the object, and

generating the selected thermal image data for each of the one or more portions of the object via the IR camera after heating by the microwaves during the second frequency sweep.

Solution 16. the method of any preceding claim, wherein determining the respective selected frequency of each of the one or more portions of the object comprises determining which of the frequencies of microwaves within the specified frequency range provides greater heating of the corresponding portion than all of the other frequencies of microwaves in the specified frequency range.

Solution 17. the method of any preceding solution, wherein the respective selected frequency for each of the one or more portions of the object is further determined based on a penetration depth of the microwaves transmitted into the object.

Solution 18. the method of any preceding solution, wherein during the first sweep frequency, the microwave emitter is further controlled to emit microwaves having a plurality of different power levels into each of the one or more portions of the subject in turn.

An inspection system according to claim 19, comprising:

a microwave emitter;

one or more processors operatively coupled to the microwave emitter and configured to control the microwave emitter to emit microwaves into a plurality of different portions of a subject during a first frequency sweep of the subject and during a subsequent second frequency sweep of the subject; and

an Infrared (IR) camera operably coupled to the one or more processors and configured to generate thermal image data for each of the portions of the object after the portions are heated by the microwaves during a first frequency sweep and during a second frequency sweep,

wherein during the first sweep, the one or more processors are configured to control the microwave emitter to emit microwaves having a plurality of different frequencies within a specified frequency range into each of the plurality of portions in turn, such that microwaves having a first frequency within the specified frequency range are emitted into a first one of the portions during a first time period and microwaves having a second frequency within the specified frequency range are emitted into the first portion during a second time period subsequent to the first time period,

wherein the one or more processors are configured to analyze the thermal image data generated by the IR camera during the first scan to determine, for each of the portions of the object, a respective selected frequency within the specified frequency range that provides greater heating of the corresponding portion of the object than other frequencies of microwaves emitted into the corresponding portion, and

wherein during the second frequency sweep, the one or more processors are configured to control the microwave emitter to emit microwaves having only the respective selected frequency into each corresponding portion of the object.

Solution 20. the inspection system of any preceding solution, wherein the one or more processors are configured to analyze the thermal image data generated by the IR camera during the second frequency sweep to detect a thermal signature representative of an element in the object.

Solution 21. the inspection system of any preceding solution, wherein the one or more processors are configured to mechanically direct the microwave emitter during the first scan frequency to emit the microwaves into each of the plurality of portions of the subject.

Solution 22 the inspection system of any preceding solution, wherein the one or more processors are configured to electrically direct the microwave emitter during the first scan frequency using a phased array antenna system to emit the microwaves into each of the plurality of portions of the subject.

Drawings

The inventive subject matter will be better understood from the following description of non-limiting embodiments, read with reference to the accompanying drawings, in which:

FIG. 1 illustrates an inspection system according to an embodiment;

FIG. 2 illustrates an object to be inspected by an inspection system according to an embodiment;

FIG. 3 is a workflow diagram illustrating a first frequency sweep of a microwave emitter of an inspection system according to an embodiment;

FIG. 4 is a workflow diagram illustrating a second frequency sweep of a microwave emitter of an inspection system according to an embodiment;

FIG. 5 is a flow diagram of a method for inspecting an object according to an embodiment;

FIG. 6 illustrates a first example use application of the inspection system; and

FIG. 7 illustrates a second example use application of the inspection system.

Detailed Description

Embodiments described herein provide inspection systems and methods for non-destructively evaluating a surface structure of an object for the presence of elements (e.g., defects) at or below the surface structure. The disclosed inspection system and method utilizes microwaves to enhance thermography. For example, the surface structure of the object is heated by non-contact microwave excitation, and a thermal profile or signature resulting from the heating is captured in thermal image data using an optical sensor, such as an Infrared (IR) camera. The existing elements may be detected based on the identified characteristics in the thermal signature of the object structure that indicate the elements of known type. The type of element may be various types of defects such as air pockets (air pockets), delaminations, cracks, splits, etc. Microwaves have the ability to penetrate deep into dielectric materials with little attenuation, which allows the systems and methods disclosed herein to be used with thicker non-conductive structures (e.g., structural layers up to or greater than one inch thick). Inspection systems and methods can be used to detect sub-surface elements beneath the surface of an object. Sub-surface elements may not be visible along the surface of the object, and thus image-based inspection techniques using visible light may not be able to detect the sub-surface elements. In accordance with one or more embodiments, inspection systems and methods are capable of detecting surface elements along the surface of an object in addition to sub-surface elements.

In embodiments disclosed herein, the accuracy and efficiency of the inspection process is enhanced by individually adjusting (tune) the characteristics of the microwaves used to heat each portion of the object being inspected, thereby tailoring the excitation microwaves to each portion of the object. For example, a respective selected microwave frequency may be determined for each portion of the object based on how well the microwaves at the different frequencies heat the respective portion of the object. For example, the rate of temperature increase in a respective portion of the object may depend on the material properties of the portion (e.g., permittivity, dipole orientation, thermal conductivity, etc.), the structural properties of the portion (e.g., coating thickness, surface uniformity, etc.), and the characteristics of the microwaves (e.g., energy level, frequency, phase, etc.). The thermal image data analyzed for detection of the sub-surface elements is thermal image data generated in response to heating of the corresponding portion by only those microwaves having respective selected microwave frequencies. Performing thermographic examination of an object based on excitation by specifically chosen microwaves for each respective portion of the object may provide desirable results, such as increased detection accuracy (due in part to enhanced thermal resolution) and reduced energy consumption. For example, energy efficiency may be improved because the process determines the frequencies within the specified range that provide the maximum heating efficiency for each portion of the object, and uses only those microwaves of selected frequencies for heating the object to provide thermal image data for defect analysis. By adjusting to determine the selected frequency, the energy efficiency of the inspection process may be improved, and/or the total amount of energy consumed may be reduced relative to pre-existing microwave thermographic imaging techniques.

Fig. 1 illustrates an inspection system 100 according to an embodiment. The inspection system 100 performs a non-destructive evaluation of the object 102 using microwave enhanced thermography for detecting sub-surface elements 104 within the object 102. The object 102 is shown in cross-section in fig. 1. Inspection system 100 includes a microwave emitter 106, an optical sensor 108, and a controller 110 having one or more processors 112. In one embodiment, the optical sensor 108 is an Infrared (IR) camera that senses the intensity of one or more IR wavelengths of light. Alternatively, the optical sensor 108 may sense the intensity of one or more other wavelengths of light.

A controller 110 is operatively coupled to the microwave emitter 106 and the optical sensor 108 and is configured to control the operation of both devices. For example, the controller 110 is communicatively connected to the microwave emitter 106 and the optical sensor 108 via one or more wired or wireless communication channels. The controller 110 generates control signals that are communicated to the microwave emitter 106 and the optical sensor 108 via the communication channel. Controller 110 includes or represents any processor-based or microprocessor-based system including systems using microcontrollers, Reduced Instruction Set Computers (RISC), Application Specific Integrated Circuits (ASIC), logic circuits, GPUs, FPGAs, and any other circuit or processor capable of executing the functions described herein.

The microwave emitter 106 (also referred to herein as an emitter) is connected to a microwave generator 114 or source. For example, the emitter 106 and generator 114 may be components of a common microwave device. A microwave generator 114 generates microwaves that are emitted by the emitter 106 toward a target region 116 of the object 102. For example, the transmitter 106 may include one or more antennas, lenses, or the like for directing the transmission of microwaves toward the target area. The emitter 106 may be mechanically and/or electrically adjustable to selectively direct the microwave radiation field 122 emitted therefrom to different target areas. In a non-limiting example, the transmitter 106 may represent a probe that is spaced apart from the microwave generator 114 and mechanically connected to the generator 114 via an electrical cable or cable 118.

The microwave radiation field 122 emitted by the emitter 106 impinges on a surface 120 of the object 102 and penetrates the surface 120 within the target region 116. The target region 116 extends a depth below the surface 120 into the interior of the object 102. The microwaves heat the target area 116. In one or more embodiments, the object 102 has a non-metallic outer structure or coating 124 that is inspected by the inspection system 100. For example, the outer structure 124 may have a composition that includes one or more of a ceramic, a polymer, carbon fibers, glass fibers, and/or various other dielectric materials. The microwaves heat the outer structure 124 via volumetric or dielectric loss heating. For example, the microwave radiation may vibrate molecules (e.g., dipoles) in the material of the object 102, which generates heat. Heat is transferred through the material of the object 102 based on the properties of the material (e.g., heat capacity, density, etc.). The optical sensor 108 is used to obtain a temperature change or distribution in the irradiated portion of the object. For example, the optical sensor 108 is positioned to have a field of view 125 of the surface 120 of the object 102, the field of view 125 being aligned with the target region 116. The optical sensor 108 generates thermal image data representing thermal energy radiated from the surface 120. For example, the data represents the intensity of thermal energy received from the surface 120 (e.g., thermal energy radiated and/or reflected therefrom). At least some of the thermal energy may be attributable to microwave inductive heating of the outer structure 124 of the object 102.

When the outer structure 124 of the object 102 has at least one sub-surface element 104 (e.g., a defect), the at least one sub-surface element 104 having a different density, heat capacity, and/or other properties relative to the surrounding material of the outer structure 124, the sub-surface element 104 transfers heat differently than the surrounding material. These thermal variations due to the sub-surface elements 104 are reflected in the temperature distribution of the thermal image data generated by the optical sensor 108. For example, some particular types of sub-surface elements 104 (e.g., air pockets) may cause a corresponding pattern or signature in the temperature distribution along the surface 120.

The thermal image data generated by the optical sensor 108 is analyzed by one or more processors 112 of the controller 110 to detect the presence of the sub-surface element 104. The one or more processors 112 may compare the temperature distribution in the received thermal image data to one or more template distributions stored in the memory device 126. The template distribution may be stored in a database, a lookup table, or the like. For example, each template distribution may be associated with a particular type of sub-surface element (e.g., air pockets, delaminations, cracks, tears, metallic foreign bodies, water, etc.), and the template distribution represents a thermal signature for that sub-surface element. The one or more processors 112 detect the presence of a sub-surface element in the object if the temperature distribution in the received thermal image data from the optical sensor 108 has a thermal gradient pattern that matches or corresponds to the thermal signature in one of the template distributions. If the temperature distribution in the received thermal image data does not match or correspond to the thermal signature in any of the template distributions, the one or more processors 112 determine that the object has no subsurface elements. In the illustrated embodiment, the one or more processors 112 are configured to detect the presence of one of the sub-surface elements 104 within the outer structure 124 of the object 102 based on a thermal signature in the thermal image data corresponding to the one of the known types of sub-surface elements.

The controller 110 is configured to control the operation of the microwave emitter 106, the microwave generator 114, and the optical sensor 108. For example, the controller 110 generates control signals to the microwave generator 114 to control characteristics or properties of the microwaves generated by the generator 114, such as frequency, phase, power level (e.g., amplitude, energy), etc., including the timing of the generation of the microwaves. The generator 114 may generate microwaves through various mechanisms (e.g., pseudo-noise, FM chirp, discrete frequency, etc.). The controller 110 generates control signals to the emitter 106 to direct (aim) the microwave radiation field 122. For example, the control signal may automatically mechanically reorient the transmitter 106 relative to the object 102 by rotating (e.g., pivoting, rotating, etc.) the transmitter 106 about a stationary housing. In another example, the control signals may automatically mechanically move the emitter 106 along the length of the object 102 to irradiate different portions thereof. In yet another example, the microwave radiation field 122 may be electronically steered by adjusting the phase of the radio frequency energy emitted by different antenna elements in an array (e.g., a phased array antenna system). Alternatively, the control signal may control movement of a lens or the like of the emitter 106 to enlarge or reduce the coverage area of the microwave radiation field 122. Alternatively, a combination of mechanical and electrical techniques may be used to direct the microwave radiation field 122 along its length to different parts of the object 102. The controller 110 generates control signals to the optical sensor 108 to control the generation of thermal image data (e.g., the timing at which the optical sensor 108 captures thermal radiation from the object 102 to produce thermal image data). The control signal to the optical sensor 108 may also redirect and/or reposition the optical sensor 108 relative to the object 102 to control which portion of the object 102 is in the field of view 125 of the optical sensor 108 at a given time.

One or more processors 112 of controller 110 may operate based on programming instructions stored in memory device 126 or in logic hardwired to processor 112. The memory device 126 may store programming instructions (i.e., software) that specify the functionality of the controller 110, such as its one or more processors 112. For example, the memory device 126 may store one or more protocols for setting up and operating the inspection system 100 to perform microwave-enhanced thermography imaging along one or more portions of the object 102. The memory device 126 may also store information (such as the template distribution described above) used by the one or more processors 112 to analyze the thermal image data for indications of sub-surface elements. Controller 110 may implement programming instructions to autonomously operate inspection system 100.

Optionally, the controller 110 is operatively connected to an input/output (I/O) device 130 and a communication device 132. The I/O device 130 may include a keyboard, touch screen, etc., for enabling an operator (e.g., a person) to manually input commands. The I/O device 130 may also include a display for displaying output information, such as thermal image data generated by the optical sensor 108, alerts, notifications, inspection results, and the like. The wireless communication device 132 may include circuitry for remote communication. For example, the communication device 132 may provide a network connection that enables remote communication to a remote processing or storage device (e.g., a server) via the Internet, a Local Area Network (LAN), or the like. Alternatively, the communication device 132 may be a wireless communication device that includes a transceiver (or separate transmitter and receiver), an antenna, and associated circuitry for wireless communication.

The object 102 on which the microwave enhanced thermography imaging is performed may be an industrial work piece in a device, machine, or vehicle. Some non-limiting examples of objects 102 include rotor blades from a rotor assembly (e.g., airfoils of a wind turbine, turbine blades from an engine, turbocharger, etc.) or compressor blades from an engine, turbocharger, etc. In another non-limiting example, the object 102 may be a surface component of a vehicle, such as a portion of a wing or fuselage of an aircraft. The outer structure 124 of the object 102 may represent a coating, such as a thermal barrier coating. The outer structure 124 may include a non-metallic composite material (which includes multiple layers), such as a carbon fiber composite, a glass fiber composite, a ceramic matrix composite, or the like. Embodiments disclosed herein can be used to inspect thicker outer structures 124, where the thickness is up to or more than one inch. For example, microwaves can penetrate deeper into non-metallic materials, and the control steps described herein for tuning the microwaves into specific portions of the object can enhance inspection resolution at such depths.

Fig. 2 illustrates an object 102 to be inspected by the inspection system 100 according to an embodiment. The object 102 in fig. 2 is a rotor blade 202. The object 102 illustrated in fig. 2 is used to describe an initial stage of a microwave enhanced thermographic imaging inspection method in accordance with an embodiment. The inspection method is performed by the inspection system 100 shown in fig. 1. The initial phase involves virtually dividing the object 102 into one or more portions 204. In fig. 2, blade 202 is divided into three sections 204 along the length of the blade, including a proximal section 204A, an intermediate section 204B, and a distal section 204C. Intermediate portion 204B is between proximal portion 204A and distal portion 204C along the length. Proximal portion 204A is the portion 204 closest to the base 206 of rotor blade 202, which base 206 couples blade 202 to the hub. The portions 204A-C may be divided to have equal or similar area sizes and/or lengths to each other. The division is virtual such that the portion 204 is determined without any physical contact with the blade 202.

Although three portions 204A-C are shown in FIG. 2, the blade 202 (or other object) can be divided into fewer or more than three portions based on application specific considerations. In the simplest example, the inspection system 100 may consider the object 102 to have only a single portion 204, which may be useful when the material composition and structural composition (e.g., thickness, shape, surface treatment, etc.) of the inspection region of the object 102 along the region are known to be uniform. Increasing the number of portions 204 may improve inspection accuracy, particularly for objects 102 that may have varying material and/or structural compositions along the inspection region. The number of partitions 204 may be limited to no more than a specified limit (e.g., 10, 20, or 50 partitions) to avoid slowdown caused by excessive processing demands during inspection. Alternatively, rather than dividing side-by-side in rows along the length, the object 102 may be divided in columns along the width of the object 102, or may be divided in an array of rows and columns. For example, the portion 204 of the array may be virtually tiled on the surface 120 within the area to be inspected.

Fig. 3 is a workflow diagram 300 illustrating a first frequency sweep of the microwave emitter 106 of the inspection system 100, in accordance with an embodiment. During the first sweep frequency, the microwave emitter 106 is controlled by the controller 110 to emit microwaves having a plurality of different frequencies within the specified frequency range 302 sequentially and continuously into each of the portions 204 of the object 102. The workflow diagram 300 includes a graph 304 depicting the frequency of microwaves transmitted into the object 102 by the transmitter 106 over time. Vertical axis 306 represents frequency and horizontal axis 308 represents time. The transmitter 106 transmits microwaves to the three parts 2 of the object 102 in sequence04A, 204B, 204C. For example, transmitter 106 is at time t₀And t₅Emits microwaves into proximal portion 204A during a first time period in between, at from t₅To t₁₀Into the middle portion 204B, and from t₁₀To t₁₅Into distal portion 204C. As described above, the emitter 106 may be controlled to sweep across the different portions 204 over time by rotating to reorient the emitter 106 relative to the object 102, translating to reposition the emitter 106 relative to the object 102, and/or modifying the electrical characteristics of the microwave radiation field 122 to electrically direct the field 122 over time to each of the different portions 204.

At each portion 204, the transmitter 106 is controlled to transmit microwaves having different frequencies within the specified frequency range 302 in turn. The frequency and other characteristics of the microwaves may be controlled by the microwave generation 114 shown in fig. 1. Transmitter 106 at time t₀And t₁Emits microwaves having a first frequency 310 toward the proximal end portion 204A. The second frequency 312 of microwaves is then directed toward the proximal end portion 204A between times t1 and t 2. Third frequency 314 is then directed toward proximal portion 204A, followed by fourth frequency 316 and then fifth frequency 318 of microwaves. All five frequencies 310, 312, 314, 316, 318 are within the specified frequency range 302. In a non-limiting example, the specified frequency range 302 is between 1.0 Ghz and 2.0 Ghz. The first through fifth frequencies 310, 312, 314, 316, 318 may be 1.1 GHz, 1.2 GHz, 1.3 GHz, 1.4 GHz, and 1.5 GHz, respectively. Microwaves having five different frequencies 310, 312, 314, 316, 318 are emitted into a common portion of the object 102 successively and sequentially at different times. For example, the emitted microwaves have only one of the frequencies 310, 312, 314, 316, 318 at each given time. The emitter 106 may be controlled to scan sequentially through the frequencies 310, 312, 314, 316, 318 in the designated frequency range 302, as indicated by the step-shaped plot line 319 shown in the graph 304.

Although five frequencies 310, 312, 314, 316, 318 are shown in fig. 3, in other embodiments, the transmitter 106 may be controlled to transmit microwaves having more or less than five different frequencies. For example, the limits of the specified frequency range 302 and the number of discrete frequencies measured may be selected based on application specific factors and considerations. Additional application specific factors and considerations may include properties such as the length of time each frequency of microwaves is transmitted into the object, the delay or lag timing between the transmission of two different frequencies into the same portion of the object, the power level or energy level at which microwaves are transmitted from the transmitter 106, and the like. For example, the frequency range 302 and/or other characteristics of the microwaves may be selected to enable the microwaves to penetrate a desired depth into the object 102. The expected depth may represent the thickness of the outer structure 124 to be inspected.

After scanning through all frequencies 310, 312, 314, 316, 318 in proximal portion 204A, microwave emitter 106 is controlled to repeat the process for intermediate portion 204B and then for distal portion 204C. For example, at time t5, emitter 106 is controlled to stop emitting microwaves into proximal portion 204A and to begin emitting microwaves into middle portion 204B. The microwave generator 114 provides the same step-wise progression of five frequencies 310, 312, 314, 316, 318 for the middle and distal portions 204B as for the proximal portion 204A. Thus, each of the five frequencies 310, 312, 314, 316, 318 of microwaves is transmitted into each of the different portions 204A-C of the object 102 in turn.

The optical sensor 108 is controlled to generate thermal image data for each of the portions 204A-C of the object 102 after the portions 204A-C are heated by microwaves during a first scan frequency. For example, the optical sensor 108 is controlled to generate thermal image data indicative of heating of the object 102 caused by each of the different frequencies 310, 312, 314, 316, 318 of the microwaves within each of the different portions 204A-C. The thermal image data may represent a temperature distribution along the surface 120 of the object 102 within the corresponding portion 204. The thermal image data is used by the one or more processors 112 to determine a selected frequency 350 for each of the portions 204A-C of the object 102.

At a time from t₀To t₅The optical sensor 108 is positioned and oriented to have a field of view that includes the proximal end portion 204A. At time t₁Or in the vicinity thereof (e.g., within a specified buffer time period and before the transmitter 106 emits microwaves having the second frequency 312), the optical sensor 108 generates thermal image data 320 associated with the first frequency 310. Thermal image data 320 is indicative of thermal energy radiated through proximal portion 204A attributable to microwaves having first frequency 310. At time t₂Or in the vicinity thereof, the optical sensor 108 generates additional thermal image data 322 associated with the second frequency 312. The optical sensor 108 then at time t₃、t₄And t₅Or generate thermal image data 324, 326, 328 associated with the third, fourth and fifth frequencies 314, 316, 318, respectively, thereabout. All of the thermal image data 320, 322, 324, 326, 328 depicts the same proximal portion 204A of the subject 102, but at different times. The image data 320, 322, 324, 326, 328 represents a collection 352 associated with the proximal end portion 204A.

The differences between the thermal image data 320, 322, 324, 326, 328 in the set 352 may be attributable to changes in the interaction between the microwaves and the object 102. For example, all microwaves may heat the object 102, but some frequencies of microwaves may heat the object 102 at a different rate and/or achieve a different heating amplitude than other frequencies.

At time t₅Thereafter, the optical sensor 108 is repositioned to view the middle portion 204B. Optical sensor 108 at time t₆Or in the vicinity thereof, thermal image data 330 is generated, the thermal image data 330 being indicative of thermal energy radiated by the intermediate portion 204B attributable to heating caused by microwaves having the first frequency 310. Optical sensor 108 at time t₇Or in the vicinity thereof, thermal image data 332 is generated, the thermal image data 332 being indicative of thermal energy radiated by the intermediate portion 204B attributable to heating caused by microwaves having the second frequency 312. Similarly, the optical sensor 108 performs successive generation of thermal image data 334, 336, and 338 indicative of the temperature of the object passing through the third, fourth, and fifth frequencies 314, 316, respectively, at different times,318, to the intermediate portion 204B. The thermal image data 330, 332, 334, 336, 338 represents the set 354 associated with the intermediate portion 204B.

At time t₁₀Thereafter, the optical sensor 108 is repositioned to view the distal portion 204C, and the optical sensor 108 is controlled to continuously generate thermal image data indicative of radiant heat energy along the distal portion 204C. At t₁₁Or in the vicinity thereof, thermal image data 340 is generated, the thermal image data 340 being indicative of heating of distal portion 204C by microwaves having first frequency 310. The optical sensor 108 is controlled to continuously generate thermal image data 342, 346, and 348 at different times indicative of heating of the distal portion 204C by microwaves having the second, third, fourth, and fifth frequencies 312, 314, 316, 318, respectively. The thermal image data 340, 342, 344, 346, 348 represents a collection 356 associated with the distal end portion 204C.

Thus, the optical sensor 108 generates a respective set of thermal image data for each of the portions 204 of the object 102 to be examined. In fig. 3, each of the three sets 352, 354, 356 is analyzed by the one or more processors 112 for determining, for each of the portions 204A-C, a respective selected frequency 350 within the specified frequency range 302. The one or more processors 112 are configured to determine the selected frequency 350 based on how well each of the measured frequencies 310, 312, 314, 316, 318 of microwaves heats the corresponding portion 204A, 204B, 204C of the object 102. The selected frequency 350 of each portion 204A-C provides greater heating of the corresponding portion as compared to one or more other frequencies in the specified frequency range 302. The selected frequency 350 may be determined to be a frequency that provides greater heating of the corresponding portion than all other frequencies in the range 302. For example, the one or more processors 112 may select, for each portion 204, one of the frequencies 310, 312, 314, 316, 318 of the microwave that provides the maximum amount and/or rate of temperature increase (e.g., the steepest temperature gradient) in the allotted time. The temperature increase is determined based on thermal image data generated by the optical sensor 108.

For the set 352 associated with the proximal end portion 204A, the one or more processors 112 may analyze the thermal image data 320, 322, 324, 326, 328. The one or more processors 112 may subtract the neighboring image data to generate a difference image indicative of heating attributable to the corresponding frequency of microwaves. For example, the thermal image data 320 may be subtracted or otherwise compared to the template thermal image of the proximal end portion 204A prior to the excitation to determine the rate or degree of heating of the proximal end portion 204A caused by the first frequency 310. In a non-limiting example, the processor 112 determines that the thermal image data 328 indicates a maximum degree or rate of heating in the set 352, and thus the fifth frequency 318 associated with that thermal image data 328 is determined to be the selected frequency 350 of the proximal end portion 204A.

Regardless of the analysis of the set 352, the one or more processors 112 analyze and compare the thermal image data 330, 332, 334, 336, 338 in the set 354 to determine the selected frequency 350 corresponding to the intermediate portion 204B. The processor 112 also separately analyzes and compares the thermal image data 340, 342, 344, 346, 348 in the collection 356 to determine the selected frequency 350 corresponding to the distal end portion 204C. In a non-limiting example, processor 112 determines that thermal image data 332 indicates a maximum degree or rate of heating in set 354 and that thermal image data 346 indicates a maximum degree or rate of heating in set 356. Thus, the second frequency 312 associated with the thermal image data 332 is determined as the selected frequency 350 of the intermediate portion 204B, and the fourth frequency 316 associated with the thermal image data 346 is determined as the selected frequency 350 of the distal portion 204C. The three selected frequencies 350 corresponding to the portions 204A-C are shown in the table 360 of FIG. 3. Table 360 indicates that different selected frequencies can be determined for different portions of the same object. For example, the selected frequencies of different portions of the same object may differ due to material variations and/or structural variations between portions. For example, one portion of the outer structure of the object may have a greater number of composite layers and/or a different composition of one or more layers than another portion, such that the layers react differently to microwaves.

Alternatively, one or more of the excitation microwaves may be based on frequencies other than frequencyThe plurality of properties determines a selected frequency 350 of different portions 204 of the object 102. For example, in addition to varying the frequency of microwaves transmitted to each of the portions 204, the transmitter 106 may be controlled to sequentially transmit microwaves having a plurality of different power levels or energy levels during the first sweep. In a non-limiting example, transmitter 106 is at slave time t₀To t₁Emits microwaves having a first frequency 310 and a low power level from time t₁To t₂Transmitting microwaves having a first frequency 310 and a medium power level, and from time t₂To t₃Microwaves are emitted having a first frequency 310 and a high power level. The terms low, medium and high for power level are relative terms. The transmitter 106 then begins at time t₃To t₄Microwaves are emitted having a second frequency 312 and a low power level. Thus, in addition to testing the effects of different frequencies, the inspection system 100 may also test different power levels. In this example, the optical sensor 108 is controlled to generate thermal image data at each of the different frequencies 310, 312, 314, 316, 318 and each of the three different power levels, resulting in a set 352 having 15 individual thermal images rather than only five as shown in fig. 3. Processor 112 determines the selected frequency 350 by analyzing the 15 thermal images and selecting from them.

Fig. 4 is a workflow diagram 400 illustrating a second frequency sweep of the microwave emitter 106 of the inspection system 100, in accordance with an embodiment. The workflow diagram 400 includes a graph 404 that depicts the frequency of microwaves transmitted by the transmitter 106 into the object 102 over time during a second sweep. The microwave emitter 106 is controlled by the controller 110 during the second frequency sweep to emit microwaves having only the selected frequency 350 into each corresponding portion 204 of the object 102. For example, when emitter 106 is positioned to emit microwaves into proximal portion 204A, emitter 106 only emits microwaves having a fifth frequency 318, which fifth frequency 318 represents a selected frequency 350 of proximal portion 204A. When the transmitter 106 subsequently transmits microwaves into the intermediate portion 204B along a frequency sweep, the microwaves directed to the intermediate portion 204B have only a second frequency 312, the second frequency 312 representing a selected frequency 350 of the intermediate portion 204B. Transmitter 106 thereafter transmits microwaves having only fourth frequency 316 to distal section 204C, as fourth frequency 316 represents selected frequency 350 of distal section 204C.

The optical sensor 108 generates selected thermal image data of each portion 204 of the object 102 after heating by microwaves during the second frequency sweep. The thermal image data generated during the second frequency sweep is referred to as selected thermal image data because it is based on the heating caused by the corresponding selected frequency 350. For example, the optical sensor 108 is controlled to be at time t₁Or in the vicinity thereof, to generate selected thermal image data 410 of proximal portion 204A. The second sweep occurs after the first sweep described in FIG. 3, so time t in graph 404₁And time t in the graph 304 shown in fig. 3₁Is different. The selected thermal image data 410 depicts a temperature distribution along the surface 120 of the object 102 within the proximal end portion 204A in response to heating caused by microwaves having a respective selected frequency 350 (e.g., fifth frequency 318).

The optical sensor 108 is controlled to be at time t₂Or near it, to generate the selected thermal image data 412 for the intermediate portion 204B. The selected thermal image data 412 depicts a temperature distribution along the surface 120 of the object 102 within the intermediate portion 204B in response to heating caused by microwaves having a corresponding selected frequency 350 (e.g., the second frequency 312). The optical sensor 108 is controlled to be at time t₃Or in the vicinity thereof, to generate selected thermal image data 414 of distal portion 204C. The selected thermal image data 414 depicts a temperature distribution along the surface 120 of the object 102 within the distal portion 204C in response to heating caused by microwaves having a corresponding selected frequency 350 (e.g., the fourth frequency 316). Thus, the second frequency sweep is performed using only the selected frequency 350 of the microwaves, the selected frequency 350 being selected based on the desired heating quality provided by the selected frequency 350. For example, because the selected frequency 350 is adjusted to the corresponding portion 204 of the object 102, exciting the material of the object 102 using the selected frequency 350 may provide enhanced resolution of the interior volume of the object 102, which enables more accurate detection of subsurface elements.

Selected thermal image data 410, 412, 414 generated during the second sweep of the microwave transmitter 106 is communicated to and/or accessed by the one or more processors 112. The processor 112 separately analyzes the selected thermal image data 410, 412, 414 to detect a thermal signature representative of a sub-surface element in the object 102 (e.g., the sub-surface element 104 shown in fig. 1). As described above with reference to fig. 1, the processor 112 may analyze each of the selected thermal image data 410, 412, 414 by comparing the temperature distribution in each selected thermal image data 410, 412, 414 to a stored template distribution associated with different types of sub-surface elements (e.g., air pockets, delaminations, cracks, metallic foreign bodies, water, etc.). If the temperature distribution in the thermal image data 410 is selected, for example, to have a thermal gradient pattern that matches or corresponds to a thermal signature in one of the template distributions, the one or more processors 112 detect the presence of the sub-surface elements in the proximal portion 204A of the object 102. The processor 112 may also identify the detected sub-surface elements in the proximal portion 204A as cracks if the matching template distribution is associated with cracks. The processor 112 may separately determine whether sub-surface elements are present in each of the portions 204A-C of the object 102.

In an alternative embodiment, rather than performing the second sweep of the microwave emitter 106 to emit microwaves into the portions 204A-C of the object 102, the selected thermal image data analyzed by the processor 112 to detect the presence of sub-surface elements can be a subset of the thermal image data generated during the first sweep. Referring back to FIG. 3, after processor 112 determines the respective selected frequency 350 for each portion 204A-C, thermal image data generated during the first sweep based on the heating provided by the selected frequency 350 can be used as the selected thermal image data. For example, when it is determined that the fifth frequency 318 represents the selected frequency 350 of the proximal portion 204A based on analysis of the thermal gradient in the thermal image data 328, that thermal image data 328 may be used as the selected thermal image data. The one or more processors 112 may perform sub-surface element detection analysis on the thermal image data 328. Similarly, a sub-surface element detection analysis may be performed on the thermal image data 332 of the intermediate portion 204B and the thermal image data 346 of the distal portion 204C. Thus, the sub-surface element detection and selection of desired microwave properties for each portion of the object may be performed for the same image data generated during a single sweep of the object (rather than performing two sweeps).

Fig. 5 is a flow diagram 500 of a method for inspecting an object according to an embodiment. The method may be performed using the inspection system 100 shown in fig. 1. One or more of the steps of the method may be performed by the controller 110 of the inspection system 100 or one or more processors 112 thereof. Alternatively, the method may include additional steps not shown in fig. 5, fewer steps than shown in fig. 5, different steps than shown in fig. 5, and/or the steps may be performed in a different order than shown in fig. 5.

At 502, a first frequency sweep of the microwave emitter 106 is performed over one or more portions of the object 102. During the first sweep, the microwave emitter 106 emits microwaves having a plurality of different frequencies (e.g., frequencies 310, 312, 314, 316, 318) within the specified frequency range 302 into the subject in turn at each of the one or more portions 204 (e.g., 204A-C). The different frequency microwaves are transmitted by the microwave transmitter 106 in sequence such that microwaves having a first frequency 310 within the designated frequency range 302 are transmitted into a first portion 204A of the one or more portions 204 during a first time period, and microwaves having a second frequency 312 within the designated frequency range 302 are transmitted into the first portion 204A during a second time period after the first time period. Optionally, the microwave emitter 106 may also be controlled to emit microwaves having a plurality of different power levels into each of the one or more portions 204 of the object 102 in turn.

At 504, thermal image data for each of the one or more portions 204 of the object 102 is generated via the optical sensor 108 after the one or more portions 204 are heated by microwaves having different frequencies during the first scan frequency. For example, optical sensor 108 may capture multiple thermal images of first portion 204A, where each thermal image of first portion 204A represents a temperature distribution caused by heating according to a different frequency of microwaves within frequency range 302.

At 506, for each of the one or more portions 204 of the object 102, a respective selected frequency 350 within the specified frequency range 302 is determined by analyzing the thermal image data. The microwaves having the selected frequency 350 provide greater heating of the corresponding portion than one or more other frequencies in the designated frequency range 302. For example, the selected frequency 350 of the microwaves may provide greater heating of the corresponding portion 204 than all other frequencies of microwaves in the designated frequency range 302. The respective selected frequency 350 may optionally also be determined based on the penetration depth of the microwaves emitted into the object 102. For example, only frequencies of microwaves having the ability to penetrate the intended depth into the object are considered candidates for representing the selected frequency 350.

Optionally, the method continues to 508 where a second frequency sweep of the microwave emitter 106 is performed over one or more portions 204 of the object 102 at 508. During the second frequency sweep, the microwave emitter 106 emits microwaves having only the respective selected frequency 350 into each corresponding portion 204 of the object 102. At 510, selected thermal image data (e.g., selected thermal image data 410, 412, 414 shown in fig. 4) for each of the one or more portions 204 of the object 102 is generated via the optical sensor 108 after heating by microwaves during a second frequency sweep. At 512, the selected thermal image data for each of the one or more portions 204 is analyzed to detect a thermal signature representative of the sub-surface element 104 in the object 102.

Alternatively, the method proceeds from 506 directly to 512 without performing a second frequency sweep. For example, the selected thermal image data analyzed for sub-surface element detection can be a subset of the thermal image data generated during the first sweep, such as the thermal image data 328, 332, 346 shown in fig. 3.

FIG. 6 illustrates a first example use application of inspection system 100. All or at least part of the inspection system 100 is mounted on an Unmanned Aerial Vehicle (UAV) or drone (drone) 600. For example, the microwave generator 114 (shown in fig. 1), the transmitter 106, and the optical sensor 108 are all mounted on the UAV 600. The UAV 600 is controlled to move the transmitter 106 and optical sensor 108 within the proximity of the object to perform a non-contact inspection of the object in accordance with the processes described herein. In the illustrated embodiment, the object is an airfoil 602 of a wind turbine (e.g., a windmill) 604. The inspection method described in fig. 5 may include controlling the UAV 600 to fly proximate to the respective airfoil 602 being inspected. The UAV 600 may enable inspection methods to be performed on tall or hard-to-reach objects, and also on objects in motion (e.g., rotating wind turbine airfoils 602).

FIG. 7 illustrates a second example use application of inspection system 100. In fig. 7, all or at least part of inspection system 100 is mounted on a land-based mobile robotic device 700 (referred to herein as a robot). For example, the microwave generator 114 (shown in fig. 1), the emitter 106, and the optical sensor 108 are mounted on the robot 700. The robot 700 is controlled to move along the ground in order to position the emitter 106 and the optical sensor 108 within the proximity of the object. In the illustrated embodiment, the object is an aircraft 702 (e.g., a wing 704 of the aircraft 702). The inspection method described in fig. 5 may include controlling the robot 700 to travel along the wing 704 being inspected.

At least one technical effect of the embodiments described herein is the ability to perform more accurate and energy efficient detection of elements (e.g., defects) beneath the surface of an object under inspection. Another technical effect is the ability to perform non-contact element detection for objects having varying material and/or structural compositions and also for thicker outer structures up to or exceeding one inch.

In one or more embodiments, an inspection system includes one or more processors and an Infrared (IR) camera. The one or more processors are configured to couple with the microwave emitters and control the microwave emitters to sequentially emit microwaves having different frequencies within a specified frequency range into the subject during a first sweep of the subject. The IR camera is operably coupled to the one or more processors and configured to generate thermal image data of the object after heating the object by each of the different frequencies of microwaves during the first scan frequency. The one or more processors are configured to analyze thermal image data from the IR camera and determine a selected frequency within the specified frequency range that provides greater heating of the subject than one or more other frequencies in the specified frequency range. The one or more processors are further configured to analyze selected thermal image data of the object to detect elements in the object in response to heating of the object by selected frequencies of microwaves.

Optionally, the selected thermal image data is a subset of the thermal image data generated during a first sweep, or generated during a subsequent second sweep of the microwave emitter over the object.

Optionally, the one or more processors are configured to detect the element in the object by identifying a thermal signature in the selected thermal image data representative of the type of the element.

Optionally, the one or more processors are configured to control the microwave emitter to emit microwaves having different frequencies into the common portion of the object at different times.

Optionally, the one or more processors are configured to control the microwave emitter to emit microwaves having different frequencies into each of a plurality of different portions of the subject during a first sweep of the microwave emitter.

Optionally, the selected frequency is a first selected frequency corresponding to a first portion of the plurality of different portions of the object. The IR camera is configured to generate thermal image data of a second portion of the object after heating the second portion by each of the different frequencies of microwaves during the first scan. The one or more processors are configured to analyze the thermal image data of the second portion and determine a second selected frequency within the specified frequency range corresponding to the second portion. The second selected frequency provides greater heating of the second portion than one or more other frequencies in the specified frequency range.

Optionally, prior to analyzing the selected thermal image data, the one or more processors are configured to control the microwave emitter to perform a second frequency sweep over the object such that the microwave emitter emits microwaves into the object having only the selected frequency. The IR camera is configured to generate selected thermal image data of the object after heating by microwaves during a second frequency sweep.

Optionally, the one or more processors are further configured to control the microwave emitter to emit microwaves having a plurality of different power levels into the subject during a first scan frequency of the subject. Optionally, the IR camera is configured to generate thermal image data of the object after heating the object by each of the different frequencies of the microwaves at each of the different power levels during the first scan frequency.

Optionally, the one or more processors are configured to control the microwave emitter to emit microwaves that penetrate the surface coating on the object. The surface coating is thicker than one inch.

Optionally, the one or more processors are configured to determine the selected frequency of the object based on which frequency of microwaves within the specified frequency range provides the greatest heating of the object.

Optionally, the inspection system further comprises a drone. The microwave emitter and the IR camera are mounted to the drone.

In one or more embodiments, a method includes performing a first frequency sweep of a microwave emitter over one or more portions of an object. During a first sweep, the microwave emitter emits microwaves having a plurality of different frequencies within the specified frequency range into the subject in turn at each of the one or more portions. The method includes generating thermal image data for each of one or more portions of the subject via an Infrared (IR) camera after heating by microwaves having different frequencies during a first scan frequency. The method also includes determining, for each of one or more portions of the object, a respective selected frequency within the specified frequency range by analyzing the thermal image data. The microwaves having the selected frequency provide greater heating of the corresponding portion than one or more other frequencies in the designated frequency range. The method includes analyzing selected thermal image data for each of one or more portions generated by the IR camera when heated by microwaves having a corresponding selected frequency to detect a thermal signature representative of an element in the object. The selection thermal image data is a subset of the thermal image data generated during the first sweep or generated during a subsequent second sweep of the microwave emitter over one or more portions of the object.

Optionally, microwaves having different frequencies are emitted by the microwave emitter sequentially such that microwaves having a first frequency within the specified frequency range are emitted into a first portion of the one or more portions during a first time period, and microwaves having a second frequency within the specified frequency range are emitted into the first portion during a second time period after the first time period.

Optionally, prior to analyzing the selected thermal image data, the method further comprises performing a second frequency sweep of the microwave emitter over the one or more portions of the object. During a second frequency sweep, the microwave transmitter transmits microwaves having only the respective selected frequency into each corresponding portion of the object. The method also includes generating, via the IR camera, selected thermal image data for each of the one or more portions of the object after heating by the microwaves during the second frequency sweep.

Optionally, determining the respective selected frequency of each of the one or more portions of the object comprises determining which frequency of microwaves within the specified frequency range provides greater heating of the corresponding portion than all other frequencies of microwaves in the specified frequency range.

Optionally, the respective selected frequency of each of the one or more portions of the object is further determined based on a penetration depth of microwaves emitted into the object.

Optionally, during the first sweep frequency, the microwave emitter is further controlled to emit microwaves having a plurality of different power levels into each of the one or more portions of the subject in turn.

Optionally, the method further comprises mounting the microwave emitter and the IR camera on a drone, and controlling the drone to fly proximate to the object.

Optionally, the method further comprises mounting the microwave emitter and the IR camera on a land-based mobile robotic device, and controlling the land-based mobile robotic device to move proximate to the object.

In one or more embodiments, an inspection system includes a microwave emitter, one or more processors, and an Infrared (IR) camera. The one or more processors are operatively coupled to the microwave emitter and configured to control the microwave emitter to emit microwaves into a plurality of different portions of the object during a first frequency sweep of the object and during a subsequent second frequency sweep of the object. The IR camera is operably coupled to the one or more processors and configured to generate thermal image data for each of the portions of the object after heating the portions by microwaves during a first frequency sweep and during a second frequency sweep. During the first sweep, the one or more processors are configured to control the microwave emitter to emit microwaves having a plurality of different frequencies within the specified frequency range into each of the plurality of portions in turn, such that microwaves having a first frequency within the specified frequency range are emitted into a first one of the portions during a first time period, and microwaves having a second frequency within the specified frequency range are emitted into the first portion during a second time period after the first time period. The one or more processors are configured to analyze thermal image data generated by the IR camera during the first scan frequency to determine, for each of the portions of the object, a respective selected frequency within the specified frequency range that provides greater heating of the corresponding portion of the object than other frequencies of microwaves transmitted into the corresponding portion. During the second frequency sweep, the one or more processors are configured to control the microwave emitter to emit microwaves having only the respective selected frequency into each corresponding portion of the object.

Optionally, the one or more processors are configured to analyze thermal image data generated by the IR camera during the second frequency sweep to detect a thermal signature representative of an element in the object.

Optionally, the one or more processors are configured to mechanically direct the microwave emitter during the first scan frequency so as to emit microwaves into each of the plurality of portions of the subject.

Optionally, the one or more processors are configured to electrically direct the microwave emitter during the first scan frequency using a phased array antenna system to emit microwaves into each of the plurality of portions of the subject.

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the presently described subject matter are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments "comprising" or "having" an element or a plurality of elements having a particular property may include additional such elements not having that property.

The above description is illustrative and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the subject matter described herein without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the disclosed subject matter, they are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the subject matter described herein should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "in which" are used as the plain-english equivalents of the respective terms "comprising" and "wherein". Furthermore, in the following claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Furthermore, the limitations of the following claims are not written in a methodological-plus-functional form and are not intended to be based on 35 u.s.c. § 112 (f), unless and until such claims limit the use of the phrase "means for …" followed by a functional statement that lacks further structure.

This written description uses examples to disclose several embodiments of the subject matter described herein, including the best mode, and also to enable any person skilled in the art to practice embodiments of the disclosed subject matter, including making and using devices or systems and performing methods. The patentable scope of the subject matter described herein is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.