Dynamic position data correction using nondestructive testing.

Abstract

To improve an aspect of position specification of a NDI abnormality detection process.SOLUTION: Non-destructive inspection (NDI) scan data obtained during a process performed on a surface 210 of a structure 206 is used to update a location of a NDI scanner 208 on the surface 210. A subsurface feature 212 within the structure 206 is detected based on the NDI scan data 222 that is correlated to the predefined location data 220 as to the subsurface features 212. A measured position of the NDI scanner 208 on the surface 210 is corrected based on the predefined position data 222 as to subsurface features 212.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to the field of non-destructive testing (NDI), and more particularly to NDI processes performed on structures. [Background technology]

[0002] Building an aircraft can include mounting components to support structures that provide structural rigidity. For example, the support structures can include hoop-like frames and longitudinal stringers to which the skin panels are attached. The combination of the skin panels and the support structures together define a portion of the aircraft fuselage.

[0003] An aircraft structure may be inspected at various times to determine whether the aircraft structure achieves design criteria and / or to determine whether the aircraft structure is free of damage. For example, an aircraft structure may be inspected during production to ensure that the aircraft structure is manufactured to specifications. In another example, an aircraft structure may be inspected while the aircraft is in service to ensure that the structure is not damaged during the operation of the aircraft.

[0004] Such inspections may be performed to determine whether subsurface anomalies exist in the aircraft structure. Although subsurface anomalies may not be observable on the exterior surface of the aircraft structure, various inspection processes may be performed that may reveal the presence of such subsurface anomalies. One type of inspection that may be performed is non-destructive inspection (NDI) testing. NDI is sometimes referred to as non-destructive evaluation or investigation (NDE) or non-destructive testing (NDT). The techniques used to perform NDI tests vary widely, but NDI tests generally share the common characteristic of not causing any permanent changes to the structure being inspected.

[0005] Inspection of aircraft structures can be performed by human operators using handheld devices and / or by robotic equipment, however, the NDI data generated in these processes requires precise position measurements of the NDI scanner to enable precise localization of anomalies, and obtaining precise position data for NDI applications can be difficult.

[0006] Therefore, improvements are needed in the localization aspect of the NDI anomaly detection process. Summary of the Invention

[0007] The embodiments described herein utilize non-destructive inspection (NDI) scan data to update the position of an NDI scanner on a surface of a structure. Subsurface features within the structure are detected based on the NDI scan data that is correlated to predefined position data for the subsurface features. The measured position of the NDI scanner on the surface is corrected based on the predefined position data for the subsurface features.

[0008] One embodiment includes an apparatus comprising an NDI scanner and a controller, where the NDI scanner generates NDI scan data during a process performed on a surface of a structure, and the controller detects subsurface features within the structure based on the NDI scan data, accesses predefined position data for the subsurface features, and corrects a measured position of the NDI scanner on the surface of the structure based on the predefined position data for the subsurface features.

[0009] Another embodiment includes a method of correcting a measured position of an NDI scanner during a process performed on a surface of a structure, the method including detecting subsurface features in the structure based on NDI scan data generated by the NDI scanner, accessing predefined position data for the subsurface features, and correcting a measured position of the NDI scanner on the surface of the structure based on the predefined position data for the subsurface features.

[0010] Another embodiment includes 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 motion system that moves the inspection vehicle over the surface of the structure and a position detector that measures a position of the inspection vehicle on the surface relative to a known position on the surface of the structure. The inspection vehicle further includes a controller. The controller directs the motion system to move the inspection vehicle over the surface along a predefined path, operates the NDI scanner to generate NDI scan data, and detects subsurface features in the structure based on transitions in the NDI scan data. The controller accesses predefined position data for boundaries of the subsurface features and corrects the measured positions based on the predefined position data and the known positions of the subsurface features.

[0011] The described features, functions, and advantages may be achieved independently in various embodiments or may be combined in yet further embodiments, further details of which can be seen with reference to the following description and drawings. [Brief description of the drawings]

[0012] Some embodiments are now described, by way of example only, with reference to the accompanying drawings, in which the same reference numbers represent the same elements or the same types of elements in all the drawings, in which:

[0013] [Figure 1] 1 illustrates a side view of an aircraft in an illustrative embodiment. [Diagram 2] FIG. 1 is a block diagram of an inspection environment in an example embodiment. [Diagram 3] FIG. 3 is a block diagram illustrating further details of the NDI scanner of FIG. 2 in an example embodiment. [Figure 4-5] 3 is a block diagram of the inspection apparatus of FIG. 2 in another exemplary embodiment. [Figure 6-7] 1 is a flowchart of a method for correcting a measured position for an apparatus including an NDI scanner during inspection of a structure. [Figure 8] FIG. 1 is a block diagram of an inspection vehicle in an example embodiment. [Figure 9] 2 illustrates a wing diagram of the aircraft of FIG. 1 in an exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The drawings and the following description show certain exemplary embodiments. Those skilled in the art will understand that various configurations, not explicitly described or shown herein, can be conceived that embody the ideas described herein and are within the intended scope of the claims that follow this description. Furthermore, any examples described herein should be construed as aiding in the understanding of the ideas of the present disclosure and not as limiting. As a result, the present disclosure is not limited to the specific embodiments or examples described below, but only by the claims and their equivalents.

[0015] 1 illustrates a side view of an aircraft 100 in an exemplary embodiment. Aircraft 100 includes a nose 110, wings 120, a fuselage 130, and a tail 140. Although aircraft 100 is depicted as having a particular configuration for purposes of illustration, aircraft 100 may have other configurations in other embodiments. Aircraft 100 may undergo a manufacturing process, a certification process, and a delivery process before being placed into service by a customer. Once aircraft 100 is in service, routine maintenance and service may be scheduled for aircraft 100.

[0016] The example embodiments described herein can enable auto-correction localization capabilities of NDI crawlers, NDI robots, and NDI scanners by correlating pre-defined position data for subsurface features within a structure with NDI data collected during inspection. The use of an auto-correction NDI scanning system improves the accuracy of the NDI process while facilitating the NDI process. The use of an auto-correction NDI scanning system expedites the NDI process while the accuracy of the NDI process is improved by reducing position errors during the NDI scan.

[0017] A typical automated NDI scanning system utilizes a localization system to determine the position and orientation of the NDI scanner relative to the inspected structure. However, localization systems are subject to measurement errors, which may affect the accuracy of locating anomalies detected by the NDI process. Additionally, the NDI crawler may utilize a local localization system that provides an estimate of its position on the surface of the structure, which is also subject to measurement errors. Deviations in the position of the NDI crawler on the surface of the inspected structure may shift the measured position of anomalies detected during the NDI process, which makes accurate locating of the anomalies difficult. An external localization system may be used to measure the position of the NDI scanning device, but setting and creating an external position guide (e.g., an optical fiducial) requires an operator to accurately set and position the external position guide. Additionally, setting and positioning such an external position guide further increases the time of the NDI process.

[0018] In an example embodiment described herein, NDI scan data generated by an NDI scanner during a process performed on a surface of a structure is analyzed to detect subsurface features within the structure, and predefined position data for the subsurface features is accessed. A measured position of the NDI scanner on the surface of the structure is corrected based on the predefined position data for the subsurface features.

[0019] The example embodiments described herein may be used during the production and / or certification and / or delivery process, and / or after entry into service by a customer. In particular, the example embodiments described herein may be utilized to improve the manufacturing process of aircraft 100 by facilitating assembly and / or inspection of aircraft 100 while reducing costs associated with manufacturing aircraft 100. Furthermore, the example embodiments described herein may be utilized to reduce costs associated with inspection of aircraft 100 by facilitating the process of routine maintenance and servicing of aircraft 100.

[0020] FIG. 2 illustrates an inspection environment 200 in an example embodiment. The inspection environment 200 may be used to inspect the aircraft 100 of FIG. 1. In this embodiment, the inspection environment 200 includes an inspection device 202 that may be used to perform an inspection 204 of a structure 206. The structure 206 may include any type of manufactured structure, such as an aircraft structure (e.g., the nose 110 of the aircraft 100, the wing 120 of the aircraft 100, the fuselage 130 of the aircraft 100, and the tail 140 of the aircraft 100). In this embodiment, the inspection 204 is performed using an NDI scanner 208 of the inspection device 202. For example, the NDI scanner 208 may be positioned near a surface 210 of the structure 206 during the anomaly detection process. In the example embodiment described herein, the NDI scanner 208 may detect subsurface features 212. The subsurface features 212 may include any type of manufactured part, such as a rib under the skin panel forming the wing 120 or a stringer under the skin panel forming the fuselage 130, or the feature may be a variation in the surface structure, such as a variation in thickness, density, porosity, holes, notches, etc.

[0021] In this embodiment, the inspection device 202 further includes a controller 214 that coordinates the operation of the inspection device 202. While the specific hardware implementation of the controller 214 is left to design choice, one particular embodiment may include one or more processors 216 coupled to a memory 218. The processor 216 includes any hardware device capable of performing a function. The processor 216 may include one or more central processing units (CPUs), microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), and the like. Some examples of processors include INTEL® CORE™ processors, advanced reduced instruction set computing (RISC) machine (ARM®) processors, and the like. The memory 218 includes any hardware device capable of storing data. For example, the memory 218 may store NDI scan data 220 generated by the NDI scanner 208 during the inspection 204 of the structure 206. Additionally, the memory 218 may store predefined position data 222 for the subsurface features 212 of the structure 206. The memory 218 may 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 the processor 216 is shown as being part of the test equipment 202, in other embodiments, the processor 216 may be separate or external to the test equipment 202 and may be connected to the test equipment by a cable or wireless communication link.

[0022] In operation, the inspection device 202 utilizes position information 224 during the inspection 204. The position information 224 includes a measured position of the NDI scanner 208 on the surface 210 of the structure 206 relative to a reference position. The position information 224 can be generated, for example, using a position detector (not shown) within the inspection device 202 or can be generated by an external positioning system that measures the position of the NDI scanner 208 on the surface 210 of the structure 206. The position information 224 can be continuously transmitted to the processor 216 so that the processor 216 has access to the most recent position of the inspection device 202 on the surface 210 of the structure 206. In some embodiments, the position information 224 can be transmitted to the processor 216 periodically and / or in response to an event. The processor 216 can utilize the position information 224 to correlate the NDI scan data 220 generated by the NDI scanner 208 to the subsurface features 212 (e.g., using predefined position data 222 of the subsurface features 212). Additionally, the processor 216 can use the location information 224 to correlate the NDI scan data 220 generated by the NDI scanner 208 with anomalies or inconsistencies detected in the structure 206.

[0023] 3 shows further details of the NDI scanner 208 in an example embodiment. In some embodiments, the NDI scanner 208 may comprise an ultrasonic scanner 302, an infrared thermography scanner 304, an eddy current scanner 306, a microwave scanner 308, a terahertz scanner 310, a millimeter wave scanner 312, a bond test scanner 314, a radiography scanner 316, a laser scanner 318 (e.g., a laser thermography scanner), an X-ray scanner 320, a backscattered X-ray scanner 322, or combinations thereof. An inspection 204 may be performed on the surface 210 of the structure 206 that may reveal information about subsurface features 212 in the structure 206 along with anomalies or inconsistencies in the structure 206.

[0024] The ultrasonic scanner 302 may include an array of transducers that transmit signals to the structure 206 during inspection 204 to reveal subsurface features of the structure 206 and detect responses to these signals. The infrared thermography scanner 304 uses infrared images during inspection 204 of the structure 206 to reveal subsurface features of the structure 206. The eddy current scanner 306 may utilize an array of probes that generate magnetic fields that induce eddy currents in the structure 206 during inspection 204 and detect changes in the eddy currents due to subsurface features of the structure 206. The microwave scanner 308 may transmit microwaves to the structure 206 during inspection 204 to reveal subsurface features of the structure 206 and detect responses to the microwaves. The terahertz scanner 310 may utilize inspection signals in the range of 0.3 to 3 terahertz, while the millimeter wave scanner 312 may utilize inspection signals in the range of 30 gigahertz to 300 gigahertz. The bond test scanner 314 utilizes various modes of operation to inspect a wide range of materials and material combinations used in multi-layer bonded structures and modern composites. The radiographic scanner 316 utilizes x-rays or gamma rays as the inspection signal, while the laser scanner 318 (e.g., a laser thermography scanner) can utilize coherent light as the inspection signal.

[0025] 4 is a block diagram of the inspection apparatus 202 in another example embodiment. In this embodiment, the inspection apparatus 202 further includes a motion system 402. The motion system 402 operates to move the NDI scanner 208 over the surface 210 of the structure 206. For example, during the inspection 204, the motion system 402 can move the NDI scanner 208 along a predefined path across the surface 210 of the structure 206. For example, the processor 216 can utilize the position information 224 during the inspection 204 to guide the NDI scanner 208 along a predefined path across the surface 210 of the structure 206. The motion system 402 can include a robotic arm 404 (e.g., to which the NDI scanner 208 is attached), wheels 406, tracks 408, legs 410, or a combination thereof.

[0026] 5 is a block diagram of the inspection device 202 in another example embodiment. In this embodiment, the inspection device 202 includes a position detector 502 that generates the position information 224. The position detector 502 may comprise a rotary encoder or other type of position detection system that measures the displacement of the inspection device 202 relative to the structure 206. For example, the position detector 502 may measure the displacement of the NDI scanner 208 on the surface 210 of the structure 206 relative to a known position 228 (see FIG. 2) on the surface 210 of the structure 206.

[0027] Consider that the inspection device 202 is on the surface 210 of the structure 206 and is ready for the inspection 204 to begin. Figures 6 and 7 are a flow chart of a method 600 for correcting a measured position of a device including an NDI scanner during inspection of a structure. Although the method 600 is described with respect to the inspection environment 200, the method 600 may be performed by other inspection environments or systems not shown. The steps shown for the method 600 are not all inclusive, and the method 600 may include other steps not shown. Additionally, the steps of the method 600 may be performed in a different order.

[0028] During the inspection 204, the NDI scanner 208 moves relative to the structure 206 and generates NDI scan data 220. During the movement of the NDI scanner 208 relative to the structure 206, updating of the position information 224 allows the processor 216 to correlate the position of the NDI scanner 208 to the NDI scan data 220 generated by the NDI scanner 208. For example, the NDI scanner 208 can be positioned at a known location 228 on the surface 210 of the structure 206, and the inspection device 202 can be programmed to follow a predefined path across the surface 210. The processor 216 uses the predefined path and position information 224 to direct the motion system 402 to follow the predefined path.

[0029] The processor 216 detects (see step 602) subsurface features 212 in the structure 206 based on the NDI scan data 220. For example, the processor 216 may perform an edge detection process on the NDI scan data 220 to detect boundaries 226, 227 of the subsurface features 212 in the structure 206 (see step 704 of FIG. 7).

[0030] The processor 216 accesses predefined position data 222 for the subsurface feature 212 (see step 604). For example, the predefined position data 222 can indicate the boundaries 226, 227 of the subsurface feature 212 (see step 702 of FIG. 7). The processor 216 corrects the measured position of the NDI scanner 208 on the surface 210 of the structure 206 based on the predefined position data 222 for the subsurface feature 212 (see step 606). For example, as the NDI scanner 208 moves along the surface 210, measurement errors in the position of the NDI scanner 208 can occur. Using the predefined position data 222 for the subsurface feature 212, the processor 216 can correct the position information 224. In some embodiments, the processor 216 can direct the motion system 402 to change the position of the NDI scanner 208 on the surface 210 based on the correction of the measured position of the NDI scanner 208 (see optional step 608). For example, if the NDI scanner 208 is following a predefined path relative to the structure 206, the processor 216 may determine that the NDI scanner 208 is not actually on the predefined path and reposition the NDI scanner 208 accordingly.

[0031] 8 is a block diagram of an example embodiment of an inspection vehicle 802. In this embodiment, the inspection vehicle includes the controller 214, the NDI scanner 208, the movement system 402, and the position detector 502, all of which have been previously described.

[0032] Figure 9 illustrates a top view of a portion of wing 120 of aircraft 100 in an example embodiment. Additionally, Figure 9 illustrates a predefined path 902 across a surface 904 that inspection vehicle 802 is programmed to follow, starting at a known location 906.

[0033] To begin inspection 804 of the wing 120, the inspection vehicle 802 is positioned at a known position 906 on the surface 904 of the wing 120. In this embodiment, the position detector 502 measures the position of the inspection vehicle 802 on the surface 904 of the wing 120 relative to the known position 906. For example, the position detector 502 may be a displacement detector that updates the position information 224 as the movement system 402 moves the inspection vehicle 802 relative to the wing 120. As a displacement detector, the position detector 502 may be implemented as a rotary encoder attached to one or more wheels 406 or tracks 408 of the movement system 402.

[0034] To begin the inspection 804, the processor 216 activates the NDI scanner 208 and directs the motion system 402 to move the inspection vehicle 802 along a predefined path 902. As the inspection vehicle 802 moves along the predefined path 902, NDI scan data 220 is generated. The NDI scan data 220 may reveal various subsurface features (e.g., subsurface components) of the wing 120, such as ribs 908-912. The processor 216 analyzes the NDI scan data 220 to detect transitions that represent, for example, boundaries 914-923 of the ribs 908-912 captured by the NDI scan data 220. Of course, other subsurface features, such as stringers, spars, brackets, fasteners, and the like, may also be detected by analyzing the NDI scan data 220.

[0035] The processor 216 accesses predefined position data 222 for the boundaries 914-923 of the ribs 908-912. For example, the predefined position data 222 may spatially define the boundaries 914-923 of the ribs 908-912 on the wing 120 and their positions relative to the known position 906. As the inspection vehicle 802 moves along the predefined path 902, the position detector 502 measures the displacement of the inspection vehicle 802 relative to the known position 906. This measurement is not perfect and is subject to error. In particular, the error in the measurement increases as the inspection vehicle 802 moves along the predefined path 902. This increase in measurement error may lead to the inspection vehicle 802 deviating from the predefined path 902, which is undesirable. For example, if the inspection vehicle 802 does not move along the predefined path 902, the inspection 204 may need to be re-performed.

[0036] The processor 216 correlates the predefined position data 222 for the boundaries 914-923 of the ribs 908-912 to the transitions in the NDI scan data 220 that represent the boundaries 914-923 and uses information about the known location 906 to correct the position measured by the position detector 502. For example, the predefined position data 222 may spatially define the boundary 923 of the rib 912 relative to the known location 906. When the processor 216 detects the transitions in the NDI scan data 220 that represent the boundary 923, the processor 216 may use information from the predefined position data 222 to calculate the displacement of the NDI scanner 208 along the predefined path 902 relative to the known location 906. The processor 216 may then calculate the deviation between the displacement of the NDI scanner 208 on the wing 120 relative to the known location 906 and the measured displacement of the NDI scanner 208 on the wing 120 relative to the known location 906. This deviation is a measurement error and can be corrected by updating the displacement measured by the position detector 502 with a corrected value.

[0037] In some embodiments, an action is performed when the deviation is greater than a threshold. For example, when the deviation is greater than a threshold, the processor 216 can direct the movement system 402 to change the position of the inspection vehicle 802 on the wing 120. For example, the movement system 402 can be used to move the position of the inspection vehicle 802 back to a previous known point (e.g., known position 906) on the wing 120 when the deviation is greater than a threshold.

[0038] In some embodiments, the inspection vehicle 802 is programmed to collect NDI scan data 220 during the inspection 204 by following a predefined path 902 across the wing 120 while simultaneously recalibrating the position information 224 using detected boundaries 914-923 in the NDI scan data 220 and the predefined position data 222. This type of operation allows the inspection vehicle 802 to quickly and accurately perform the inspection 204 of the wing 120 with little or no operator supervision, thus expediting the inspection 204.

[0039] Any of the various elements shown in the figures or described herein may be implemented as hardware, software, firmware, or any combination thereof. For example, an element may be implemented as dedicated hardware. A dedicated hardware element may be referred to as a "processor," "controller," or some similar terminology. When provided by a processor, the functionality may be provided by a single dedicated processor, a single shared processor, or multiple individual processors, some of which may be shared. Furthermore, explicit use of the terms "processor" or "controller" should not be construed as referring only to hardware capable of executing software, but may include, without being limited to, digital signal processor (DSP) hardware, network processors, application specific integrated circuits (ASICs) or other circuitry, field programmable gate arrays (FPGAs), read only memory (ROM) for storing software, random access memory (RAM), non-volatile storage, logic circuitry, or any other physical hardware component or module, even if not explicitly stated.

[0040] Furthermore, an element may be implemented as instructions that can be executed by a processor or computer to perform the function of the element. Some examples of instructions are software, program code, and firmware. The instructions, when executed by a processor, are operable to direct the processor to perform the function of the element. The instructions may be stored in a storage device that can be read by the processor. Some examples of storage devices are digital or solid-state memory, magnetic storage media such as magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media.

[0041] Although specific embodiments have been described herein, the scope of the invention is not limited to those specific embodiments. Rather, the scope of the invention is defined by the following claims and any equivalents thereof.

Claims

1. An NDI scanner configured to generate non-destructive inspection (NDI) scan data during a process performed on a surface of an aircraft structure; a position detector configured to measure a position of the NDI scanner while the NDI scanner moves over the surface of the aircraft structure; a controller that stores predefined position data for one or more subsurface features in the aircraft structure and receives the measured positions of the NDI scanner from the position detector; the controller is configured to detect the subsurface features in the aircraft structure based on the NDI scan data, access and compare the predefined position data for the subsurface features to the measured positions of the NDI scanner from the position detector, and correct the measured positions of the NDI scanner on the surface of the aircraft structure based on the predefined position data for the subsurface features; The subsurface features are selected from the group consisting of ribs, stringers, girders, brackets, fasteners, holes, and notches.

2. 2. The inspection device of claim 1, wherein the controller is configured to detect the subsurface features in the aircraft structure by identifying edge information in the NDI scan data that corresponds to boundaries of the subsurface features.

3. The inspection apparatus of claim 1 or 2, wherein the process includes an anomaly detection process.

4. The inspection apparatus of any one of claims 1 to 3, wherein the NDI scanner comprises an ultrasound scanner.

5. The inspection apparatus of any one of claims 1 to 4, further comprising a translation system configured to change the position of the NDI scanner on the surface of the structure based on the correction of the measured position.

6. The inspection apparatus of claim 5 , wherein the motion system comprises a robotic arm, and the NDI scanner is mounted to the robotic arm.

7. The inspection device of claim 5 , wherein the locomotion system comprises wheels, tracks, or legs, or a combination of wheels, tracks, and legs.

8. the predefined position data for the subsurface feature indicates a boundary of the subsurface feature; The inspection apparatus of any one of claims 1 to 7, wherein the controller is configured to detect the sub-surface features in the aircraft structure by performing an edge detection process on the NDI scan data.

9. Detecting subsurface features within an aircraft structure based on non-destructive testing (NDI) scan data generated by an NDI scanner during a process performed on a surface of the aircraft structure and measuring the position of the NDI scanner; accessing predefined position data for the subsurface features and comparing it to the measured positions of the NDI scanner; and correcting the measured position of the NDI scanner on the surface based on the predefined position data for the subsurface features; The method, wherein the subsurface features are selected from the group consisting of ribs, stringers, spars, brackets, fasteners, holes, and notches.

10. The step of detecting subsurface features comprises: performing an edge detection process on the NDI scan data.

10. The method of claim 9, comprising:

11. repositioning the NDI scanner on the surface of the aircraft structure based on the correction of the measured position. The method of claim 9 or 10, further comprising:

12. the predefined position data for the subsurface feature indicates a boundary of the subsurface feature; The step of detecting subsurface features comprises: performing an edge detection process on the NDI scan data. The method according to any one of claims 9 to 11, comprising:

13. The method of any one of claims 9 to 12, wherein the process comprises an anomaly detection process.

14. An inspection vehicle, a non-destructive inspection (NDI) scanner configured to generate NDI scan data during a process performed on a surface of the aircraft structure; a movement system configured to move the NDI scanner over the surface of the aircraft structure; and a position detector configured to measure a position of the inspection vehicle on the surface relative to a known position on the surface of the aircraft structure; a controller configured to direct the motion system to move the inspection vehicle over the surface along a predefined path, operate the NDI scanner to generate the NDI scan data, and detect subsurface features within the aircraft structure based on transitions in the NDI scan data; the controller is configured to access predefined position data for a boundary of the subsurface feature and compare it to a measured position of the inspection vehicle from the position detector, and to correct the measured position based on the predefined position data and the known position of the subsurface feature; The subsurface features are selected from the group consisting of ribs, stringers, spars, brackets, fasteners, holes, and notches.

15. The inspection vehicle of claim 14 , wherein the motion system comprises a robotic arm, and the NDI scanner is mounted to the robotic arm.

16. The inspection vehicle of claim 14 , wherein the locomotion system comprises wheels, tracks, or legs, or a combination of wheels, tracks, and legs.

17. An inspection vehicle according to any one of claims 14 to 16, wherein the NDI scanner comprises an ultrasonic scanner.

18. An inspection vehicle according to any one of claims 14 to 17, wherein the process includes an anomaly detection process.

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