Embodiments described herein utilize Non-Destructive Inspection (NDI) scan data obtained during a process performed on a surface of a structure to update a location of an NDI scanner on the surface. A subsurface feature within the structure is detected based on the NDI scan data, which are correlated with pre-defined position data for the subsurface feature. A measured location of the NDI scanner on the surface is corrected based on the pre-defined position data for the subsurface feature.

FIELD

This disclosure relates to the field of non-destructive inspection (NDI) and, in particular, to NDI processes that are performed on structures.

BACKGROUND

Building an aircraft may include attaching components to a support structure that provides structural rigidity. For example, the support structure may include hoop-wise frames and longitudinal elongated stringers, to which skin panels are attached. Together, the combination of skin panels and support structure defines a portion of the airframe of the aircraft.

Aircraft structures may be inspected at different times to determine whether the aircraft structures achieve a design criterion and/or are free from damage. For example, an aircraft structure may be inspected during manufacturing to ensure that the aircraft structure has been fabricated to specification. In another example, the aircraft structure may be inspected during service of the aircraft to ensure that the structure has not been damaged during operation of the aircraft.

Such inspections may be performed to determine whether subsurface anomalies are present within the aircraft structure. While subsurface anomalies may not be observable on an outside surface of the aircraft structure, various inspection processes can be performed that may reveal the presence of such subsurface anomalies. One type of inspection that may be performed is a Non-Destructive Inspection (NDI) test. NDI may also be referred to as Non-Destructive Evaluation or Examination (NDE) or Non-Destructive Testing (NDT). The techniques used to perform NDI testing vary widely, although NDI testing in general share a common trait that they do not permanently change the structure under inspection.

The inspection of aircraft structures may be performed by human operators using handheld devices, and/or by robotic assets. However, the NDI data generated during these processes requires measuring an accurate location of the NDI scanner in order to allow for the locations of the anomalies to be determined accurately, but acquiring accurate location data for NDI applications can be challenging.

Therefore, there is a need to improve upon the positioning aspects of NDI anomaly detection processes.

SUMMARY

Embodiments described herein utilize Non-Destructive Inspection (NDI) scan data to update a location of an NDI scanner on a surface of a structure. A subsurface feature within the structure is detected based on the NDI scan data, which is correlated with pre-defined position data for the subsurface feature. A measured location of the NDI scanner on the surface is corrected based on the pre-defined position data for the subsurface feature.

One embodiment comprises an apparatus that includes an NDI scanner and a controller. The NDI scanner generates NDI scan data during a process performed on a surface of a structure. The controller detects a subsurface feature within the structure based on the NDI scan data, accesses pre-defined position data for the subsurface feature, and corrects a measured location of the NDI scanner on the surface of the structure based on the pre-defined position data for the subsurface feature.

Another embodiment comprises a method of correcting a measured location of an NDI scanner during a process performed on a surface of a structure. The method comprises detecting a subsurface feature within a structure based on NDI scan data generated by an NDI scanner, accessing pre-defined position data for the subsurface feature, and corrects a measured location of the NDI scanner on the surface of the structure based on the pre-defined position data for the subsurface feature.

Another embodiment comprises an inspection vehicle. The inspection vehicle includes an NDI scanner that generates NDI scan data during a process performed on a surface of a structure. The inspection vehicle further includes a movement system that moves the inspection vehicle on a surface of the structure, and a position detector that measures a location of the inspection vehicle on the surface relative to a known location on the surface of the structure. The inspection vehicle further includes a controller. The controller directs the movement system to move the inspection vehicle on the surface along a pre-defined path, activates the NDI scanner to generate the NDI scan data, and detects a subsurface feature within the structure based on transitions in the NDI scan data. The controller accesses pre-defined position data for boundaries of the subsurface feature, and corrects the measured location based on the pre-defined position data for the subsurface feature and the known location.

DETAILED DESCRIPTION

FIG.1depicts a side view of an aircraft100in an illustrative embodiment. Aircraft100includes nose110, wings120, fuselage130, and tail140. Although aircraft100has been depicted to have a particular configuration for purposes of discussion, aircraft100may have other configurations in other embodiments. Aircraft100may go through a manufacturing process, a certification process, and a delivery process prior to being placed in service by a customer. Once aircraft100is placed into service, aircraft100may be scheduled for routine maintenance and service.

The illustrative embodiments described herein enable NDI crawlers, NDI robots, and NDI automated scanners self-correcting positioning capabilities by correlating pre-defined location data about subsurface features in the structure with NDI data collected during an inspection. The use of self-correcting NDI scanning systems improves the accuracy of the NDI process while expediting the NDI processes. The accuracy of the NDI process is improved by reducing location errors during the NDI scan, while the use of automated scanning systems expedites the NDI process.

Typical automated NDI scanning systems utilize location systems to position and orient an NDI scanner relative to a structure under inspection. However, location systems are subject to measurement errors which can be reflected in the accuracy of locating anomalies detected by the NDI process. Further, NDI crawlers may utilize localized location systems that provide an estimated position of their location on the surface of the structure, which is also subject to measurement errors. Deviations in a location of an NDI crawler on the surface of a structure under inspection can shift the measured locations of any anomalies detecting during the NDI process, which makes a precise localization of the anomalies difficult. While external location systems may be used to measure a position of NDI scanning devices, the setup and execution of external location guides (e.g., optical fiducials) requires an operator to set up and position the external location guides correctly. Further, such set up and positioning of the external location guides adds additional time to the NDI process.

In the illustrative embodiments described herein, NDI scan data generated by an NDI scanner during a process performed on a surface of a structure is analyzed to detect a subsurface feature within a structure, and pre-defined position data for the subsurface feature is accessed. A measured location of the NDI scanner on a surface of the structure is corrected based on the pre-defined position data for the subsurface feature.

The illustrative embodiments described herein may be employed during the manufacturing process, and/or the certification process, and/or the delivery process, and/or after being placed in service by the customer. In particular, the illustrative embodiments described herein may be utilized to improve the manufacturing process for aircraft100by expediting the assembly and/or the inspection of aircraft100, while reducing the costs associated with manufacturing aircraft100. Further, the illustrative embodiments described herein may be utilized to expedite the routine maintenance or service process for aircraft100, thereby reducing the costs associated with inspecting aircraft100.

FIG.2illustrates an inspection environment200in an illustrative embodiment. Inspection environment200may be used to inspect aircraft100ofFIG.1. In this embodiment, inspection environment200includes an inspection apparatus202which may be used to perform an inspection204of a structure206. Structure206may include any type of fabricated structure, including aircraft structures (e.g., nose110of aircraft100, wing120of aircraft100, fuselage130of aircraft100, and tail140of aircraft100). In this embodiment, inspection204is performed using an NDI scanner208of inspection apparatus202. For example, NDI scanner208may be placed proximate to a surface210of structure206during an anomaly detection process. In the illustrative embodiments described herein, NDI scanner208is capable of detecting a subsurface feature212. Subsurface feature212may include any type of fabricated part, such as ribs underneath skin panels that form wing120, stringers underneath skin panels that form fuselage130, or the feature may be a change in the surface structure, such as a change in thickness, density, porosity, holes, cutouts, etc.

In this embodiment, inspection apparatus202further includes a controller214, which coordinates the activities of inspection apparatus202. While the specific hardware implementation of controller214is subject to design choices, one particular embodiment may include one or more processors216coupled with a memory218. Processor216includes any hardware device that is able to perform functions. Processor216may include one or more Central Processing Units (CPU), microprocessors, Digital Signal Processors (DSPs), Application-specific Integrated Circuits (ASICs), etc. Some examples of processors include INTEL® CORE™ processors, Advanced Reduced Instruction Set Computing (RISC) Machines (ARM®) processors, etc. Memory218includes any hardware device that is able to store data. For instance, memory218may store NDI scan data220, which is generated by NDI scanner208during inspection204of structure206. Memory218may also store pre-defined position data222regarding subsurface feature212of structure206. Memory218may include one or more volatile or non-volatile Dynamic Random-Access Memory (DRAM) devices, FLASH devices, volatile or non-volatile Static RAM devices, hard drives, Solid State Disks (SSDs), etc. Some examples of non-volatile DRAM and SRAM include battery-backed DRAM and battery-backed SRAM. Although processor216is illustrated as being part of inspection apparatus202, in other embodiments processor216may be separate or outside of inspection apparatus202and connected to inspection apparatus with a cable or connected through a wireless communication link.

During operation, inspection apparatus202utilizes location information224during inspection204. Location information224comprises a measured location of NDI scanner208on surface210of structure206relative to a reference location. Location information224may be generated, for example, using a location detector within inspection apparatus202(not shown) or by an external location system that measures a location of NDI scanner208on surface210of structure206. Location information224may be sent to processor216continuously such that processor216has access to the most current and up to date location of inspection apparatus202on surface210of structure206. In some embodiments, location information224may be sent to processor216periodically and/or in response to an event. Processor216may utilize location information224to correlate NDI scan data220generated by NDI scanner208with subsurface feature212(e.g., using pre-defined position data222of subsurface feature212). Processor216may also utilize location information224to correlate NDI scan data220generated by NDI scanner208with anomalies or inconsistencies detected in structure206.

FIG.3illustrates additional details of NDI scanner208in an illustrative embodiment. In some embodiments, NDI scanner208may comprise an ultrasonic scanner302, an infrared thermography scanner304, an eddy current scanner306, a microwave scanner308, a terahertz scanner310, a millimeter wave scanner312, a bond tester scanner314, a radiographic scanner316, a laser scanner318(e.g., a laser thermography scanner), an x-ray scanner320, a backscatter x-ray scanner322, or combinations thereof. Inspection204may be performed on a surface210of structure206, which may reveal information regarding subsurface feature212within structure206along with any anomalies or inconsistencies within structure206.

Ultrasonic scanner302may include an array of transducers that send signals into structure206and detect responses to those signals during inspection204that reveal subsurface features of structure206. Infrared thermography scanner304uses infrared images during inspection204of structure206to reveal subsurface features of structure206. Eddy current scanner306may utilize an array of probes that generates a magnetic field during inspection204that induces eddy currents in structure206and detects changes in the eddy currents based on the subsurface features of structure206. Microwave scanner308may transmit microwaves into structure206and detect responses to the microwaves during inspection204that reveal subsurface features of structure206. Terahertz scanner310may utilize inspection signals in the range of 0.3 to 3 terahertz, while millimeter wave scanner312may utilize inspection signals in the range of 30 Gigahertz to 300 Gigahertz. Bond tester scanner314utilizes different modes of operation to inspect a wide range of materials and combinations of materials used in multi-layered bonded structures and modern composites. Radiographic scanner316utilizes x-rays or gamma rays as inspection signals, while laser scanner318(e.g., a laser thermography scanner) may utilize coherent light as inspection signals.

FIG.5is a block diagram of inspection apparatus202in another illustrative embodiment. In this embodiment, inspection apparatus202includes a location detector502, which generates location information224. Location detector502may comprise rotary encoders or other types of location detection systems that measure a displacement of inspection apparatus202relative to structure206. For instance, location detector502may measure a displacement of NDI scanner208on surface210of structure206that is relative to a known location228(seeFIG.2) on surface210of structure206.

Consider that inspection apparatus202is on surface210of structure206and ready to perform inspection204.FIGS.6-7are flow charts of a method600of correcting a measured location of an apparatus that includes an NDI scanner during an inspection of a structure. Method600will be described with respect to inspection environment200, although method600may be performed by other inspection environments or systems, not shown. The steps illustrated for method600are not all inclusive, and method600may include other steps, not shown. Further, the steps of method600may be performed in an alternate order.

During inspection204, NDI scanner208moves relative to structure206and generates NDI scan data220. During the movement of NDI scanner208relative to structure206, updates to location information224allow processor216to correlate the location of NDI scanner208with NDI scan data220generated by NDI scanner208. For instance, NDI scanner208may be placed at known location228on surface210of structure206, and inspection apparatus202programmed to follow a pre-defined path across surface210. Processor216uses the pre-defined path and location information224to direct movement system402to follow the pre-defined path.

Processor216accesses pre-defined position data222for subsurface feature212(see step604). For instance, pre-defined position data222may indicate boundaries226-227of subsurface feature212(see step702ofFIG.7). Processor216corrects a measured location of NDI scanner208on surface210of structure206based on pre-defined position data222for subsurface feature212(see step606). For instance, as NDI scanner208moves along surface210, a measurement error of the location of NDI scanner208may occur. Using pre-defined position data222regarding subsurface feature212, processor216is able to correct location information224. In some embodiments, processor216may direct movement system402to relocate NDI scanner208on surface210based on the correction to the measured location of NDI scanner208(see optional step608). For example, if NDI scanner208is following a pre-defined path relative to structure206, processor216may determine that NDI scanner208is not actually on the pre-defined path and reposition NDI scanner208accordingly.

FIG.8is a block diagram of an inspection vehicle802in an illustrative embodiment. In this embodiment, inspection vehicle includes controller214, NDI scanner208, movement system402, and location detector502, all previously described.

FIG.9illustrates a top view of a portion of wing120of aircraft100in an illustrative embodiment. Also illustrated inFIG.9is a pre-defined path902across a surface904that inspection vehicle802is programmed to follow, with the starting location at a known location906.

To begin inspection804of wing120, inspection vehicle802is placed at known location906on surface904of wing120. In this embodiment, location detector502measures a location of inspection vehicle802on surface904of wing120that is relative to known location906. For instance, location detector502may be a displacement detector that updates location information224as movement system402moves inspection vehicle802relative to wing120. As a displacement detector, location detector502may be implemented as a rotary encoder attached to one or more wheels406or continuous tracks408of movement system402.

To begin inspection804, processor216activates NDI scanner208and directs movement system402to move inspection vehicle802along pre-defined path902. As inspection vehicle802moves along pre-defined path902, NDI scan data220is generated. NDI scan data220is capable of revealing the various subsurface features of wing120, including ribs908-912(e.g., subsurface parts). Processor216analyzes NDI scan data220to detect transitions which represent, for example, boundaries914-923of ribs908-912captured by NDI scan data220. Of course, other subsurface features may be detected by analyzing NDI scan data220, such as stringers, spars, brackets, fasteners, etc.

Processor216accesses pre-defined position data222for the boundaries914-923of ribs908-912. For example, pre-defined position data222may spatially define boundaries914-923of ribs908-912in wing120and their locations relative to known location906. As inspection vehicle802moves along pre-defined path902, location detector502measures a displacement of inspection vehicle802relative to known location906. This measurement is not perfect, and is subject to error. In particular, the error in measurement may compound as inspection vehicle802moves along pre-defined path902. The compounding of this measurement error may result in inspection vehicle802moving off of pre-defined path902, which is undesirable. For instance, if inspection vehicle802does not move along pre-defined path902, then inspection204may need to be performed again.

Processor216correlates pre-defined position data222for boundaries914-923of ribs908-912with transitions in the NDI scan data220that represent boundaries914-923, and uses information about known location906to correct the location measured by location detector502. For example, pre-defined position data222may spatially define boundary923of rib912relative to known location906. As processor216detects a transition in NDI scan data220that represents boundary923, processor216can calculate the displacement of NDI scanner208along pre-defined path902relative to known location906using information from pre-defined position data222. Processor216may then calculate a deviation between the displacement of NDI scanner208on wing120relative to known location906, and the measured displacement of NDI scanner208on wing120relative to known location906. This deviation is a measurement error that can be corrected by updating the displacement measured by location detector502with the corrected values.

In some embodiments, an action is performed when the deviation is greater than a threshold value. For instance, when the deviation is greater than a threshold value, then processor216may direct movement system402to re-position inspection vehicle802on wing120. For instance, if the deviation is greater than a threshold value, the movement system402may be used to reposition inspection vehicle802back to a previous known point on wing120(e.g., known location906).

In some embodiments, inspection vehicle802is programmed to follow pre-defined path902across wing120, thereby collecting NDI scan data220during inspection204, while concurrently re-calibrating location information224using boundaries914-923detected within NDI scan data220and pre-defined position data222. This type of activity allows inspection vehicle802to rapidly and accurately perform inspection204of wing120with little or no oversight by an operator, thus expediting inspection204.

Although specific embodiments were described herein, the scope is not limited to those specific embodiments. Rather, the scope is defined by the following claims and any equivalents thereof.