Patent Description:
In a variety of industries, inspection tools are used to detect damaged or deteriorated components. For example, in the aviation industry, certain gas turbine engines include thousands of internal components, including hundreds of compressor and turbine blades, which need to be frequently inspected to ensure they are in working order and not damaged.

Concerning the prior art, <CIT> discloses the scanning of cavities with restricted accessibility. <CIT> discloses a probe insertion system.

Reference now will be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the present disclosure, not limitation of the disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims.

As used herein, the terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

Accordingly, a value modified by a term or terms, such as "about," is not to be limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. For example, the approximating language may refer to being within a <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> percent margin. These approximating margins may apply to a single value, either or both endpoints defining numerical ranges, and/or the margin for ranges between endpoints.

Further, as used herein, the term "substantially" may refer to an amount that is more than halfway, e.g., greater than <NUM>%, greater than <NUM>%, greater than <NUM>%, greater than <NUM>%, greater than <NUM>%, greater than <NUM>%, greater than <NUM>%, greater than <NUM>%, or greater than <NUM>%.

Additionally, the term "rotor blade," without further specificity, is a reference to the rotating blades of either the compressor or the turbine, which include both compressor rotor blades and turbine rotor blades. The term "stator blade," without further specificity, is a reference to the stationary blades of either the compressor or the turbine, which include both compressor stator blades and turbine stator blades. The term "compressor blade," without further specificity, is a reference to both compressor rotor blades and compressor stator blades. Thus, without further specificity, the term "blades" is inclusive to all type of turbine engine blades, including compressor rotor blades, compressor stator blades, turbine rotor blades, and turbine stator blades. Further, the descriptive or standalone term "blade surface" may reference any type of turbine or compressor blade and may include any or all portions of the blade, including the suction side face, pressure side face, blade tip, blade shroud, platform, root, and shank.

Finally, given the configuration of compressor and turbine about a central common axis, as well as the cylindrical configuration common to many combustor types, terms describing position relative to an axis may be used herein. In this regard, it will be appreciated that the term "radial" refers to movement or position perpendicular to an axis. Related to this, it may be required to describe relative distance from the central axis. In this case, for example, if a first component resides closer to the central axis than a second component, the first component will be described as being either "radially inward" or "inboard" of the second component. If, on the other hand, the first component resides further from the central axis than the second component, the first component will be described herein as being either "radially outward" or "outboard" of the second component. Additionally, as will be appreciated, the term "axial" refers to movement or position parallel to an axis. Finally, the term "circumferential" refers to movement or position around an axis. As mentioned, while these terms may be applied in relation to the common central axis that extends through the compressor and turbine sections of the engine, these terms may also be used in relation to other components or sub-systems of the engine.

During operation of a gas turbine engine, the blades of both the compressor and turbine are subject to damage from a variety of sources, including creep from long-term exposure to heat, cracks and stress from fatigue, and nicking in the blade surface from foreign particles of dust and other materials present in the air flowing through the gas turbine engine. Such incidents of damage introduce deformations in the surface of blades, concomitantly reducing the overall efficiency and increasing the fuel consumption needed for the gas turbine engine to operate at a desired output. Moreover, damage to engine components may result in increased maintenance costs and decreased engine life.

To determine blade surface damage, the gas turbine engine is occasionally removed from operation, disassembled, and inspected to ensure that the blades are properly functioning. A major component of this inspection typically includes a visual inspection of the surfaces of each blade, looking for signs of damage, including deformations, tears, rips, holes, cracks, and any other defects. The inspection may be performed manually for each surface of each blade, introducing a high amount of error and variability in the process of maintaining blades. Moreover, for the inspection process to yield meaningful results, an enormous investment in both time and labor resources is required. Further, if multiple inspectors are being used to inspect the engine, inspector-to-inspector variations typically exist with respect to the thoroughness and/or accuracy of the inspection. In some cases, inspectors may use a camera to perform these visual inspections. Accordingly, an improved method of determining defects of a gas turbine engine would be welcomed in the art.

In general, the present subject matter generally relates to a system and method for improved inspection of a gas turbine engine. In particular, the present disclosure relates to a tool assembly including a body; a first camera; a second camera; and a controller configured to receive data indicative of one or more images of a reference feature from the first camera, determine data indicative of a first spatial position of the first camera based at least in part on the received data indicative of the one or more images of the reference feature, and determine data indicative of a second spatial position of the second camera based on the first spatial position. The controller may further be configured to receive data indicative of one or more images of a target feature using the second camera; determine data indicative of one or more dimensions of the target feature based at least in part on the received data indicative of the one or more images of the target feature, receive data indicative of one or more images of a reference feature from the first camera; determine data indicative of a first spatial position of the first camera based at least in part on the received data indicative of the one or more images of the reference feature; and determine data indicative of a second spatial position of the second camera based on the first spatial position, a known spatial relationship between the first location and the second location, or both; and generate a three-dimensional representation of the target feature. The three-dimensional representation of the target feature may be used to locate, inspect, and/or measure defects within the gas turbine engine.

The invention is defined in the appended independent claims.

Referring now to the drawings, <FIG> illustrates a cross-sectional view of one embodiment of a gas turbine engine <NUM> that may be utilized within an aircraft in accordance with aspects of the present subject matter, with the gas turbine engine <NUM> being shown having a longitudinal or axial centerline axis <NUM> extending therethrough for reference purposes. In general, the gas turbine engine <NUM> may include a core gas turbine engine (indicated generally by reference character <NUM>) and a fan section <NUM> positioned upstream thereof. The core engine <NUM> may generally include an outer casing <NUM> that is substantially tubular and defines an annular inlet <NUM>. In addition, the outer casing <NUM> may further enclose and support a booster compressor <NUM> for increasing the pressure of the air that enters the core engine <NUM> to a first pressure level. A high pressure, multi-stage, axial-flow compressor <NUM> may then receive the pressurized air from the booster compressor <NUM> and further increase the pressure of such air. The pressurized air exiting the high-pressure compressor <NUM> may then flow to a combustor <NUM> within which fuel is injected into the flow of pressurized air, with the resulting mixture being combusted within the combustor <NUM>. The high energy combustion products are directed from the combustor <NUM> along the hot gas path of the gas turbine engine <NUM> to a first (high pressure) turbine <NUM> for driving the high pressure compressor <NUM> via a first (high pressure) drive shaft <NUM>, and then to a second (low pressure) turbine <NUM> for driving the booster compressor <NUM> and fan section <NUM> via a second (low pressure) drive shaft <NUM> that is generally coaxial with first drive shaft <NUM>. After driving each of turbines <NUM> and <NUM>, the combustion products may be expelled from the core engine <NUM> via an exhaust nozzle <NUM> to provide propulsive jet thrust.

It should be appreciated that each compressor <NUM>, <NUM> may include a plurality of compressor stages, with each stage including both an annular array of stationary compressor vanes and an annular array of rotating compressor blades positioned immediately downstream of the compressor vanes. Similarly, each turbine <NUM>, <NUM> may include a plurality of turbine stages, with each stage including both an annular array of stationary nozzle vanes and an annular array of rotating turbine blades positioned immediately downstream of the nozzle vanes.

Additionally, as shown in <FIG>, the fan section <NUM> of the gas turbine engine <NUM> may generally include a rotatable, axial-flow fan rotor assembly <NUM> that is configured to be surrounded by an annular fan casing <NUM>. It should be appreciated by those of ordinary skill in the art that the fan casing <NUM> may be configured to be supported relative to the core engine <NUM> by a plurality of substantially radially-extending, circumferentially-spaced outlet guide vanes <NUM>. As such, the fan casing <NUM> may enclose the fan rotor assembly <NUM> and its corresponding fan rotor blades <NUM>. Moreover, a downstream section <NUM> of the fan casing <NUM> may extend over an outer portion of the core engine <NUM> so as to define a secondary, or by-pass, airflow conduit <NUM> that provides additional propulsive jet thrust.

It should be appreciated that, in several embodiments, the second (low pressure) drive shaft <NUM> may be directly coupled to the fan rotor assembly <NUM> to provide a direct-drive configuration. Alternatively, the second drive shaft <NUM> may be coupled to the fan rotor assembly <NUM> via a speed reduction device <NUM> (e.g., a reduction gear or gearbox) to provide an indirect-drive or geared drive configuration. Such a speed reduction device(s) may also be provided between any other suitable shafts and/or spools within the gas turbine engine <NUM> as desired or required.

During operation of the gas turbine engine <NUM>, it should be appreciated that an initial air flow (indicated by arrow <NUM>) may enter the gas turbine engine <NUM> through an associated inlet <NUM> of the fan casing <NUM>. The air flow <NUM> then passes through the fan rotor blades <NUM> and splits into a first compressed air flow (indicated by arrow <NUM>) that moves through airflow conduit <NUM> and a second compressed air flow (indicated by arrow <NUM>) which enters the booster compressor <NUM>. The pressure of the second compressed air flow <NUM> is then increased and enters the high pressure compressor <NUM> (as indicated by arrow <NUM>). After mixing with fuel and being combusted within the combustor <NUM>, the combustion products <NUM> exit the combustor <NUM> and flow through the first turbine <NUM>. Thereafter, the combustion products <NUM> flow through the second turbine <NUM> and exit the exhaust nozzle <NUM> to provide thrust for the gas turbine engine <NUM>.

As indicated above, the gas turbine engine <NUM> may also include a plurality of access ports defined through its casings and/or frames for providing access to the interior of the core engine <NUM>. For instance, as shown in <FIG>, the gas turbine engine <NUM> may include a plurality of access ports <NUM> (only three of which are shown) defined through the outer casing <NUM> for providing internal access to one or both of the compressors <NUM>, <NUM>. Similarly, as shown in the illustrated embodiment, the gas turbine engine <NUM> may include a plurality of access ports <NUM> (only three of which are shown) defined through the outer casing <NUM> for providing internal access to one or both of the turbines <NUM>, <NUM>. In several embodiments, the access ports <NUM>, <NUM> may be spaced apart axially along the core engine <NUM>. For instance, the compressor access ports <NUM> may be spaced apart axially along each compressor <NUM>, <NUM> such that at least one access port <NUM> is located at each compressor stage for providing access to the compressor vanes and blades located within such stage. Similarly, the turbine access ports <NUM> may be spaced apart axially along each turbine <NUM>, <NUM> such that at least one access port <NUM> is located at each turbine stage for providing access to the nozzle vanes and turbine blades located within such stage.

It should be appreciated that, although the access ports <NUM>, <NUM> are generally described herein with reference to providing internal access to one or both of the compressors <NUM>, <NUM> and/or for providing internal access to one or both of the turbines <NUM>, <NUM>, the gas turbine engine <NUM> may include access ports providing access to any suitable internal location of the gas turbine engine <NUM>, such as by including access ports that provide access within the combustor <NUM> and/or any other suitable component of the gas turbine engine <NUM>. Furthermore, the present disclosure may be used to inspect any component of the gas turbine engine <NUM>.

It will be appreciated that the exemplary gas turbine engine <NUM> depicted in <FIG> and described above is provided by way of example only. In other embodiments, the gas turbine engine <NUM> may have any other suitable configuration, such as a geared connection with the fan rotor blades <NUM>; a variable pitch fan; any suitable number of shafts/spools, compressors, or turbines; etc. Additionally, although depicted as a ducted turbofan engine, in other embodiments, the gas turbine engine <NUM> may be configured as an unducted turbofan engine, a turboshaft engine, a turboprop engine, a turbojet engine, etc..

Referring now to <FIG>, a partial, cross-sectional view of the first (or high pressure) turbine <NUM> described above with reference to <FIG> is illustrated in accordance with embodiments of the present subject matter. As shown, the first turbine <NUM> may include a first stage turbine nozzle <NUM> and an annular array of rotating turbine blades <NUM> (one of which is shown) located immediately downstream of the first stage turbine nozzle <NUM>. The first stage turbine nozzle <NUM> may generally be defined by an annular flow channel that includes a plurality of radially-extending, circularly-spaced nozzle vanes <NUM> (one of which is shown). The vanes <NUM> may be supported between a number of arcuate outer bands <NUM> and arcuate inner bands <NUM>. Additionally, the circumferentially spaced turbine blades <NUM> may generally be configured to extend radially outwardly from a rotor disk (not shown) that rotates about the axial centerline axis <NUM> (<FIG>) of the gas turbine engine <NUM>. Moreover, a turbine shroud <NUM> may be positioned immediately adjacent to the radially outer tips of the turbine blades <NUM> so as to define the outer radial flowpath boundary for the combustion products <NUM> flowing through the turbine <NUM> along the hot gas path of the engine <NUM>.

As indicated above, the turbine <NUM> may generally include any number of turbine stages, with each stage including an annular array of nozzle vanes and follow-up turbine blades <NUM>. For example, as shown in <FIG>, an annular array of nozzle vanes <NUM> of a second stage of the turbine <NUM> may be located immediately downstream of the turbine blades <NUM> of the first stage of the turbine <NUM>.

Moreover, as shown in <FIG>, a plurality of access ports <NUM> may be defined through the turbine casing and/or frame, with each access port <NUM> being configured to provide access to the interior of the turbine <NUM> at a different axial location. Specifically, as indicated above, the access ports <NUM> may, in several embodiments, be spaced apart axially such that each access port <NUM> is aligned with or otherwise provides interior access to a different stage of the turbine <NUM>. For instance, as shown in <FIG>, a first access port 64A may be defined through the turbine casing/frame to provide access to the first stage of the turbine <NUM> while a second access port 64B may be defined through the turbine casing/frame to provide access to the second stage of the turbine <NUM>.

It should be appreciated that similar access ports <NUM> may also be provided for any other stages of the turbine <NUM> and/or for any turbine stages of the second (or low pressure) turbine <NUM>. It should also be appreciated that, in addition to the axially spaced access ports <NUM> shown in <FIG>, access ports may be provided at differing circumferentially spaced locations. For instance, in one embodiment, a plurality of circumferentially spaced access ports may be defined through the turbine casing/frame at each turbine stage to provide interior access to the turbine <NUM> at multiple circumferential locations around the turbine stage.

Referring now to <FIG>, a partial, cross-sectional view of the high pressure compressor <NUM> described above with reference to <FIG> is illustrated in accordance with embodiments of the present subject matter. As shown, the compressor <NUM> may include a plurality of compressor stages, with each stage including both an annular array of fixed compressor vanes <NUM> (only one of which is shown for each stage) and an annular array of rotatable compressor blades <NUM> (only one of which is shown for each stage). Each row of fixed compressor vanes <NUM> is generally configured to direct air flowing through the compressor <NUM> to the row of compressor blades <NUM> immediately downstream thereof.

Moreover, as indicated above, the compressor <NUM> may include a plurality of access ports <NUM> defined through the compressor casing/frame, with each access port <NUM> being configured to provide access to the interior of the compressor <NUM> at a different axial location. Specifically, in several embodiments, the access ports <NUM> may be spaced apart axially such that each access port <NUM> is aligned with or otherwise provides interior access to a different stage of the compressor <NUM>. For instance, as shown in <FIG>, first, second, third and fourth access ports 62A, 62B, 62C, 62D are illustrated that provide access to four successive stages, respectively, of the compressor <NUM>.

It should be appreciated that similar access ports may also be provided for any of the other stages of the compressor <NUM> and/or for any of the stages of the booster compressor <NUM>. It should also be appreciated that, in addition to the axially spaced access ports <NUM> shown in <FIG>, access ports may be also provided at differing circumferentially spaced locations. For instance, in one embodiment, a plurality of circumferentially spaced access ports may be defined through the compressor casing/frame at each compressor stage to provide interior access to the compressor <NUM> at multiple circumferential locations around the compressor stage.

Referring now to <FIG>, a perspective, schematic view of a tool assembly <NUM> is shown within a gas turbine engine <NUM> in accordance with an exemplary embodiment of the present subject matter. In certain embodiments, the gas turbine engine <NUM> depicted schematically in <FIG> may be configured in a similar manner as the exemplary gas turbine engine <NUM> of <FIG>.

In general, the tool assembly <NUM> includes a body <NUM>, a first camera <NUM> fixed to the body <NUM> at a first location XL and in a first spatial position, a second camera <NUM> fixed to the body <NUM> at a second location YL and in a second spatial position, and a controller <NUM> in operative communication with the first camera <NUM> and the second camera <NUM>. Additionally, in the exemplary embodiment, the spatial relationship between the first location XL and the second location YL is known. The body <NUM>, according to the claimed invention, is elongated and defines a local longitudinal direction Li, a latitudinal direction L<NUM>, and a transverse direction T. The first location XL is spaced from the second location YL along the longitudinal direction Li. As will be explained more in depth below, the spatial position of an object may refer to both the relative position and the relative orientation of the object. For example, the first spatial position comprises a first position XP and a first orientation Xo of the first camera <NUM> relative to the body <NUM>, and the second spatial position comprises a second position YP and a second orientation Yo of the second camera <NUM> relative to the body <NUM>. As used herein, the term "orientation" refers to the angular orientation of a camera's field of view or focal line in a three-dimensional space.

Notably, for the embodiment depicted, the first orientation Xo defines an angle with the second orientation Yo in a plane defined by the longitudinal direction Li and transverse direction T greater than <NUM>, such as greater than <NUM> degrees, such as greater than <NUM> degrees, such as greater than <NUM> degrees, such as less than <NUM> degrees. More specifically, for the embodiment shown, the angle defined between the first orientation Xo and the second orientation Yo in the plane defined by the longitudinal direction Li and transverse direction T is equal to about <NUM> degrees. Also, for the embodiment shown, the first and second orientations Xo, Yo are each parallel to the plane defined by the latitudinal direction L<NUM> and transverse direction T. However, in one or more embodiments, one or both of the first and second orientations Xo, Yo may instead define an angle greater than <NUM> with the plane defined by the latitudinal direction L<NUM> and transverse direction T. The exemplary tool assembly <NUM> depicted further includes an attachment member <NUM> to attach the body <NUM> to another structure. In one embodiment, as shown in <FIG> and <FIG>, the attachment member <NUM> can be attached to a structure <NUM> external to the tool assembly <NUM>, e.g., outside of the body of the gas turbine engine <NUM>. The attachment member <NUM> may be attached to or part of a robotic arm, a telescoping arm, a reel, a cable, or any other structure <NUM> that may maneuver the tool assembly <NUM> into a desired position relative to the gas turbine engine <NUM>. As used herein, the term "structure <NUM>" may refer to any of the above listed examples.

In an exemplary embodiment, the body <NUM> is a rigid body to which the first camera <NUM> and the second camera <NUM> are attached. In alternative embodiments, the body <NUM> may be semi-rigid (e.g., semi-flexible) to allow for easier positioning. For example, the body <NUM> may have one or more sections or segments where the body <NUM> is flexible, while the other sections or segments remain rigid. In certain embodiments, the sections where the first camera <NUM> and the second camera <NUM> are located, as well as the sections in between the cameras, may remain rigid. However, it will be appreciated that each rigid section may be pivoted or otherwise moved relative to the adjacent section as long as the relative positioning is known. In other embodiments, the body <NUM> may include a hinge that can be locked into a particular position. The first camera <NUM> may be on an opposite side of the locked hinge of the body <NUM> from the second camera <NUM>. Alternatively, the first location XL and the second location YL may be on the same side of the hinge. As mentioned previously, the body <NUM> may be elongated and may further have any of the above described properties.

In the exemplary embodiment, and as shown in <FIG>, the first camera <NUM> is positioned in view of a reference feature <NUM>. The reference feature <NUM> may be located on a first component <NUM> of the gas turbine engine <NUM>. In the exemplary embodiment, the second camera <NUM> is positioned in view of a target feature <NUM>, with the target feature <NUM> located on a second component <NUM>. As used herein, the terms "reference feature" and "target feature" may be used to refer to locations, portions, or other identifiable regions on one or more components of the gas turbine engine <NUM> between which the relative positioning and relative orientation is known or may otherwise be calculated or deduced. For example, if controller <NUM> knows the dimensions of the reference feature <NUM>, the controller <NUM> may be able to determine the dimensions of the target feature <NUM> based on their known spatial relationship. In one specific non-limiting embodiment, the reference feature <NUM> is a tip of a turbine blade, and the target feature <NUM> is the tip of a compressor blade. In another non-limiting embodiment, the reference feature <NUM> is a compressor blade, and the target feature <NUM> is a part of a stator vane. Additionally, the reference feature <NUM> may refer to part of the turbine shroud <NUM>, while the target feature <NUM> is a part of a compressor blade or stator vane. In other additional embodiments, the reference feature <NUM> and/or the target feature <NUM> may refer to part of an airfoil or a guide vane.

Further, it will be appreciated that the reference feature <NUM> and the target feature <NUM> may be located on any component of the gas turbine engine <NUM>. The component may be internal or external to the gas turbine engine <NUM>. For example, the body <NUM> may be partially inserted within the gas turbine engine <NUM> such that the second camera <NUM> is in view of an internal component while the first camera <NUM> remains external to the gas turbine engine <NUM> and in view of an external component. Alternatively, the first camera <NUM> may be in view of an internal component while the second camera <NUM> is in view of an external component. Additionally, according to some embodiments, the target feature <NUM> may be located on a second component <NUM> of the gas turbine engine <NUM>, as shown in <FIG>. Alternatively, the reference feature <NUM> and the target feature <NUM> may be located on the same component of the gas turbine engine <NUM>. For example, the reference feature <NUM> and the target feature <NUM> may both be located on the first component <NUM> or may both be located on the second component <NUM>. It will be understood that such feature examples are specific to a gas turbine engine <NUM> and that in utilization in another inspection scenario or example alternative reference and target features would be applicable.

Still referring to <FIG>, the first camera <NUM> and the second camera <NUM> are shown fixed to the body <NUM> in the exemplary embodiment, where the body <NUM> is elongated. In another embodiment, the first camera <NUM> and the second camera <NUM> are embedded within the body <NUM>. In other embodiments, the first camera <NUM> and/or the second camera <NUM> are mounted on top of the body <NUM>. In yet other embodiments, the first camera <NUM> may be fixed to the body <NUM> while the second camera <NUM> is embedded within the body <NUM>, or vice versa.

Furthermore, the location of the first camera <NUM> relative to the second camera <NUM> (or rather, a difference between the first location XL and the second location YL), along with the first spatial position of the first camera <NUM> within the gas turbine engine provides a reference to determine the second spatial position of the second camera <NUM> within the gas turbine engine <NUM>. As mentioned previously, the spatial position of an object refers to both the relative position and the relative orientation of the object. For example, the first camera <NUM> may have a first position XP and a first orientation Xo within the gas turbine engine <NUM>, collectively, the first spatial position. The first position XP and a first orientation Xo are relative to the reference feature <NUM> that is within view of the first camera <NUM>. Likewise, the second camera <NUM> may have a second position YP and a second orientation Yo within the gas turbine engine <NUM>, collectively, the second spatial position. In the exemplary embodiment, the second position YP and the second orientation Yo are relative to the target feature <NUM> that is within view of the second camera <NUM>. The first relative position XP may refer to a distance between the first camera <NUM> and the reference feature <NUM> on the first component <NUM> and the first relative orientation Xo may refer to, e.g., a vector from the reference feature <NUM> to the first camera <NUM>. Similarly, the second position YP may refer to a distance between the second camera <NUM> and the target feature <NUM> on the second component <NUM> and the second orientation Yo may refer to, e.g., a vector from the target feature <NUM> to the second camera <NUM>.

The distance between the first location XL and the second location YL along the body <NUM> is known. Similarly, the relative positions between the first spatial position and the second spatial position are known. Specifically, the second orientation Yo relative to the first orientation Xo is known (e.g., about <NUM> degrees in the embodiment shown), and the second position Yp relative to the first position XP is known. In the exemplary embodiment, the controller <NUM> will receive data indicative of one or more images of a reference feature <NUM> from the first camera <NUM> and determine data indicative of the first spatial position of the first camera <NUM> within the gas turbine engine <NUM> based at least in part on the received data indicative of the one or more images of the reference feature <NUM>. Once the controller <NUM> has determined the first spatial position of the first camera <NUM> within the gas turbine engine <NUM>, it can then determine the second spatial position of the second camera <NUM> within the gas turbine engine <NUM> using the known relative locations XL, YL and the first and second spatial positions of the first and second cameras <NUM>, <NUM> (e.g., the known first and second spatial positions of the first and second cameras <NUM>, <NUM> relative to the body <NUM>).

Further, the controller <NUM> can be configured to receive data indicative of one or more images of a target feature <NUM> using the second camera <NUM> and to determine data indicative of dimensions of the target feature <NUM> based at least in part on the received data indicative of the one or more images of the target feature <NUM>. The controller <NUM> may use the determined data indicative of the dimensions of the target feature <NUM> to generate a three-dimensional representation of the target feature <NUM>. This three-dimensional representation of the target feature <NUM> may include measurements relating to the depth, size, and/or location of the target feature <NUM>. In the exemplary embodiment, the target feature <NUM> is a defect on a component, e.g., the second component <NUM>, and the three-dimensional representation can be used to inspect the defect and determine maintenance and/or remediation methods that are needed, if any.

In other embodiments, the tool assembly <NUM> further includes additional cameras, such as a third camera <NUM> fixed to the body <NUM> at a third location ZL spaced from the first location XL and the second location YL, where the distance between ZL, YL, and/or XL is known. In such an embodiment, the third camera <NUM> is positioned in view of an auxiliary feature <NUM>. The auxiliary feature <NUM> may be located on the same component as the reference feature <NUM>, the target feature <NUM>, or both. Alternatively, as shown in <FIG>, the auxiliary feature <NUM> may be located on a third component <NUM> of the gas turbine engine <NUM> that is different from both the first component <NUM> and the second component <NUM>. The third camera <NUM> has a third spatial position, where the third spatial position is known relative to the first spatial position, the second spatial position, or both. The third camera <NUM> may have a third position ZP and a third orientation Zo, within the gas turbine engine <NUM>, collectively, the third spatial position. The third position ZP and a third orientation Zo are relative to the auxiliary feature <NUM> that is within view of the third camera <NUM>. In embodiments where the tool assembly <NUM> further includes additional cameras, the controller <NUM> may be further configured to determine the third spatial position based at least in part on the first spatial position of the first camera <NUM> and/or the second spatial position of the second camera <NUM>, obtain one or more images of the auxiliary feature <NUM> using the third camera <NUM>, derive one or more dimensions of the auxiliary feature <NUM>, and generate a three-dimensional representation of the auxiliary feature <NUM> based at least in part on the determined data indicative of the one or more dimensions of the auxiliary feature <NUM>.

The cameras can represent any suitable imaging device including any optical sensor capable of capturing still or moving images. Suitable types of cameras may be a CMOS camera, a CCD camera, an analog, a digital camera, a video camera or any other type of device capable of capturing an image. It is further contemplated that a borescope camera or an endoscope camera can be utilized. Further still, the camera may be a monocular camera or a binocular camera. For example, in some embodiments, the first camera <NUM> and the second camera <NUM> may record images at a rate of at least about <NUM> frames-per-second (FPS) and may have a resolution of greater than <NUM> megapixels (MP), such as greater than <NUM> MP, <NUM> MP, or <NUM> MP, and up to about <NUM> MP. The first camera <NUM> and the second camera <NUM> may each include a time mechanism to enable the camera to record images periodically after a specified time interval. Additionally, or alternatively, where either the first camera <NUM> or the second camera <NUM> are positioned in view of blades, the tool assembly <NUM> may include a trigger mechanism that is activated by rotation of the blades. In some embodiments, the first camera <NUM>, the second camera <NUM>, or both may include a video recording device, such that the first camera <NUM> is capable of recording video of the first component <NUM> and/or the second camera <NUM> is capable of recording video of the second component <NUM>.

Additionally, the first camera <NUM> and second camera <NUM> may be calibrated before images are taken. In particular, calibration of the first and second cameras <NUM> and <NUM> may include estimating intrinsic and/or extrinsic parameters to ensure accuracy. For example, the first and second cameras <NUM> and <NUM> may be calibrated to account for angular separation and/or circumferential distance between pixels. Camera calibration may also account for lens distortions and lens mounting errors (e.g., after the first camera <NUM> and the second camera <NUM> are fixed to the body <NUM>). Further, calibrating the cameras may also help measure dimensions or determine the location of the camera within the gas turbine engine <NUM>. It will be appreciated that the first and second cameras <NUM> and <NUM> may additionally or alternatively be calibrated in any other way.

Further, in other embodiments, the first camera <NUM>, the second camera <NUM>, or both may include any other image sensing devices, such as infrared, ultrasound, inductive, position encoder, and/or eddy-current sensing devices. Specifically, in the illustrated embodiment, the first camera <NUM> and the second camera <NUM> may each include one or more sensors 90A, 90B, such as positioning sensors. As used herein, the term "positioning sensors" may refer to any sensors that are capable of providing feedback to the controller <NUM> to help position the body <NUM>. For example, the sensors 90A, 90B may be proximity sensors, optical sensors, and/or tactile sensors. Further, in the exemplary embodiment, the one or more sensors 90A, 90B provides data to the controller <NUM>. For example, the sensors may help position the body <NUM> within the gas turbine engine <NUM>. In other embodiments, the one or more sensors 90A, 90B may locate entryways or passages for the tool assembly <NUM>.

In yet another embodiment, feedback from the one or more sensors 90A and 90B may be used to provide a dimensional data point relating to the reference feature, the target feature, or both. By way of example, the one or more sensors 90A and 90B may comprise Inertial Measurement Units ("IMUs"). These IMUs may further comprise accelerometers, gyroscopes, magnetometers, and/or any other tools that are capable of obtaining the 3D position and/or orientation of an object. In this particular embodiment, the sensors 90A and 90B may provide a dimensional (e.g., angular) data point for the images taken by either the first camera <NUM>, the second camera <NUM>, or both. For example, the dimensional data point(s) for the images taken by the first camera <NUM> (as well as any calibration information for the first camera <NUM>) may provide a scale for the reference feature <NUM>. Such a configuration may more specifically provide for a scale of the reference features <NUM> to be determined independently of any prior data of the reference feature <NUM> (such as independently of any CAD information or the like).

In other embodiments, the first camera <NUM>, the second camera <NUM>, a light source, and a storage device may form an integrated assembly. The light source may be light emitting diodes (LEDs), fluorescent lights, incandescent lights, or any other suitable light device, and may be oriented to illuminate the compressor blades <NUM> or any other region capable of image record by the first and second cameras <NUM>, <NUM>. Multiple color light sources may be used, such as blue, green, red, white, or other colors. The storage device may be a non-volatile memory device (e.g., a flash memory device) configured to provide a desired storage capacity. In one embodiment, the storage device may provide at least <NUM> GB, <NUM> GB, <NUM> GB, or <NUM> GB of memory, and up to about 2TB of memory.

As noted, the exemplary controller <NUM> depicted in <FIG> is configured to receive the data sensed from the one or more sensors 90A, 90B and, e.g., may make control decisions for the tool assembly <NUM> based on the received data. In one or more exemplary embodiments, the controller <NUM> depicted in <FIG> may be a stand-alone controller <NUM> for the tool assembly <NUM>, or alternatively, may be integrated into one or more other controllers.

Referring particularly to the operation of the controller <NUM>, in at least certain embodiments, the controller <NUM> can include one or more computing device(s) <NUM>. The computing device(s) <NUM> can include one or more processor(s) <NUM> and one or more memory device(s) <NUM>. The one or more processor(s) <NUM> can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, and/or other suitable processing device. The one or more memory device(s) <NUM> can include one or more computer-readable media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, and/or other memory devices.

The one or more memory device(s) <NUM> can store information accessible by the one or more processor(s) <NUM>, including computer-readable instructions <NUM> that can be executed by the one or more processor(s) <NUM>. The computer-readable instructions <NUM> can be any set of instructions that when executed by the one or more processor(s) <NUM>, cause the one or more processor(s) <NUM> to perform operations. In some embodiments, the computer-readable instructions <NUM> can be executed by the one or more processor(s) <NUM> to cause the one or more processor(s) <NUM> to perform operations, such as any of the operations and functions for which the controller <NUM> and/or the computing device(s) are configured, the operations for operating a tool assembly <NUM> (e.g., method <NUM>), as described herein, and/or any other operations or functions of the one or more computing device(s) <NUM>. The computer-readable instructions <NUM> can be software written in any suitable programming language or can be implemented in hardware. Additionally, and/or alternatively, the computer-readable instructions <NUM> can be executed in logically and/or virtually separate threads on processor(s) <NUM>. The memory device(s) <NUM> can further store data <NUM> that can be accessed by the processor(s) <NUM>. For example, the data <NUM> can include data indicative of power flows, data indicative of engine/ aircraft operating conditions, and/or any other data and/or information described herein.

The computing device(s) <NUM> can also include a network interface <NUM> used to communicate, for example, with the other components of the tool assembly <NUM>, the gas turbine engine <NUM> incorporating tool assembly <NUM>, the aircraft incorporating the gas turbine engine, etc. For example, in the embodiment depicted, as noted above, the gas turbine engine <NUM> and/or tool assembly <NUM> further includes one or more sensors 90A, 90B for sensing data indicative of one or more parameters of the gas turbine engine <NUM>, the tool assembly <NUM>, or both. The controller <NUM> of the tool assembly <NUM> is operably coupled to the one or more sensors 90A, 90B through, e.g., the network interface <NUM>, such that the controller <NUM> may receive data indicative of various operating parameters sensed by the one or more sensors 90A, 90B during operation. Further, for the embodiment shown in <FIG>, the controller <NUM> is operably coupled to, e.g., the sensors 90A and 90B on or adjacent to the first camera <NUM> and the second camera <NUM>, respectively. In such a manner, the controller <NUM> may be configured to position the body <NUM> in response to, for example, the data <NUM> sensed by the one or more sensors 90A, 90B. In other embodiments, the first camera <NUM> and the second camera <NUM> may each include one or more sensors 90A, 90B as part of the first and second cameras <NUM>, <NUM>.

The network interface <NUM> can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, and/or other suitable components.

Referring now to <FIG>, a cross sectional view of the compressor blades <NUM> and the tool assembly <NUM> in position for imaging the gas turbine engine <NUM> as described above with reference to <FIG> is illustrated in accordance with aspects of the present subject matter. In the exemplary embodiment, the tool assembly <NUM>, and, more specifically, the body <NUM> is inserted through borescope holes or other access ports <NUM>, <NUM>. The tool assembly <NUM> is thereby able to access the first and second components <NUM>, <NUM> of the gas turbine engine <NUM> without substantially disassembling the gas turbine engine <NUM>.

In the exemplary embodiment, the first component <NUM> is the turbine shroud <NUM>, as shown in <FIG>. As mentioned previously, the first component <NUM> may be internal or external to the gas turbine engine <NUM>. Similarly, the second component <NUM> may be internal or external to the gas turbine engine <NUM>.

Additionally, as shown in <FIG>, the position of the tool assembly <NUM> allows the first camera <NUM> and the second camera <NUM> to view the reference feature <NUM> and the target feature <NUM>, respectively. As mentioned previously, the attachment member <NUM> and structure <NUM> (shown schematically in <FIG>) are used to maneuver the body <NUM> until it is in position within the gas turbine engine <NUM>. The body <NUM> is in position when each of the first camera <NUM> and the second camera <NUM> have at least the reference feature <NUM> and the target feature <NUM>, respectively, within its field of view. In <FIG>, the reference feature <NUM> is located on the first component <NUM>, and the target feature <NUM> is located on the second component <NUM>. The second component <NUM> is the component that is within the field of view of the second camera <NUM> as shown. As used herein, the term "field of view" of a camera is defined as the maximum area of a sample that a camera can image and is typically dependent, at least in part, on the focal length of the lens of the camera. The field of view may also be defined in any other manner as known to those of ordinary skill in the art.

Now that the structure of the tool assembly <NUM> has been described, an exemplary method <NUM> of using the tool assembly <NUM> will be described. <FIG> illustrates a flow diagram of one embodiment of a method for inspecting components of the gas turbine engine <NUM> described above with reference to <FIG>. In general, the method <NUM> images, measures, and models the target feature <NUM>.

As shown in <FIG>, method <NUM> generally includes, at <NUM>, positioning the body <NUM> such that the first camera <NUM> is in view of the reference feature <NUM>; at <NUM>, receiving data indicative of one or more images of the reference feature <NUM> from the first camera <NUM>; at <NUM>, determining a first spatial position of the first camera <NUM> based at least in part on the received data indicative of the one or more images of the reference feature <NUM>; and, at <NUM>, determining a second spatial position of the second camera <NUM> based on the first spatial position. Additionally, in other embodiments, the method may further include receiving data indicative of one or more images of a target feature <NUM> using the second camera <NUM>. Furthermore, in the exemplary embodiment, the controller <NUM> is also configured to generate a three-dimensional representation of the target feature <NUM> and/or to derive dimensions of the target feature <NUM>. Each of these blocks will be described below in more detail.

At <NUM>, the body <NUM> is positioned such that the first camera <NUM> is in view of a reference feature <NUM>. In the exemplary embodiment, the body <NUM> is positioned such that the first camera <NUM> is within view of the reference feature <NUM> of the first component <NUM> and such that the second camera <NUM> is in view of the target feature <NUM> of the second component <NUM> of the gas turbine engine <NUM>. However, as mentioned previously, the reference feature <NUM> and the target feature <NUM> may be located on the same component. Further, in one embodiment, the reference feature <NUM> may refer to the entirety of the first component <NUM>. In the exemplary embodiment, the reference feature <NUM> refers to a compressor blade. However, it will be appreciated that the reference feature <NUM> may refer to any other component of a gas turbine engine <NUM>. In an alternative embodiment, the reference feature <NUM> is a portion of the first component <NUM>, such as a specific feature of the first component <NUM>. For example, the reference feature <NUM> may be only a tip of a compressor blade. Positioning the body <NUM> may additionally include inserting the body <NUM> into the gas turbine engine <NUM>. The body <NUM> may be inserted into the gas turbine engine <NUM> through borescope holes or other access ports <NUM>, <NUM>. Further, the attachment member <NUM> and structure <NUM> may help position the body <NUM> such that the first camera <NUM> is within view of the reference feature <NUM> and such that the second camera <NUM> is in view of the target feature <NUM>.

At <NUM>, the controller <NUM> receives data indicative of one or more images of the reference feature <NUM> from the first camera <NUM>. In the exemplary embodiment, the first camera <NUM> will take one or more images of the reference feature <NUM> that is within its field of view. The data indicative of the one or more images can be saved in the storage device temporarily, e.g., in RAM, or permanently, e.g., transferred to a more permanent storage device.

In the exemplary embodiment, the information regarding the reference feature <NUM> is already known. This information may be three-dimensional information of the reference feature <NUM>. As used herein, the term "three-dimensional information" refers to size, location, and/or depth of the reference feature <NUM>. In particular, the location of the reference feature <NUM> may refer to a spatial position within a three-dimensional space, e.g., the L<NUM>L<NUM>T plane. The controller <NUM> may obtain the information by estimating, determining, or measuring actual measurements of the reference feature <NUM> or in any other manner that would reasonably be able to obtain this information. In the exemplary embodiment, obtaining the three-dimensional information regarding the reference feature <NUM> includes obtaining information from a computer aided design (CAD) model. The CAD model may be inputted by a user or gathered from a database. The CAD model may also be derived through parallax using monocular cameras. In one specific non-limiting embodiment, the reference feature <NUM> may be located on the first component <NUM>, which may, for example, be a rotor blade. In this case, the model number for the first component <NUM> (rotor blade, in this example) may provide sufficient information. Additionally, in this embodiment, a user can then input the model number into the controller <NUM> to search a database of CAD models, blueprints, schematics, or any other type of reference information that is capable of providing three-dimensional information.

Furthermore, where the tool assembly <NUM> further comprises one or more sensors 90A and 90B, the three-dimensional information may be obtained from the one or more sensors 90A and 90B. In one particular embodiment, for example, the one or more sensors 90A and 90B may further comprise IMUs, as mentioned above. The IMUs may provide this three-dimensional information to the controller <NUM>.

At <NUM>, the controller <NUM> determines the first spatial position of the first camera <NUM> based at least in part on the one or more images of the reference feature <NUM>. The first spatial position may be derived using an algorithm executed by the controller <NUM> and can be stored in the storage memory device. The spatial position of an object may be stored in coordinates form, in vector form, or in any other form that may describe the object's spatial position.

In the exemplary embodiment, the controller <NUM> will be able to determine the first spatial position of the first camera <NUM> relative to the reference feature <NUM> based at least in part on the images of the reference feature <NUM> and the known information of the reference feature <NUM>. For example, by comparing the images of the reference feature <NUM> taken using the first camera <NUM> with the known three-dimensional information about the reference feature <NUM>, the controller <NUM> will be able to determine the first spatial position of the first camera <NUM> relative to the reference feature <NUM>.

At <NUM>, the controller <NUM> determines the second spatial position of the second camera <NUM>. In the exemplary embodiment, the controller <NUM> executes an algorithm to use the now known first spatial position of the first camera <NUM> to calculate the second spatial position of the second camera <NUM>. As the relative spatial position between the first camera <NUM> and the second camera <NUM> along the body <NUM> is known, the controller <NUM> will be able to determine the second spatial position based on this known relative spatial position and the first spatial position determined at <NUM>.

Method <NUM> may further include obtaining one or more images of the target feature <NUM> using the second camera <NUM>. In the exemplary embodiment, the target feature <NUM> is a feature on the second component <NUM>. The target feature <NUM> may be a defect or any particular part of the second component <NUM>. The one or more images of the target feature <NUM> and/or the second spatial position of the second camera <NUM> may be used to derive data indicative of one or more dimensions of the target feature <NUM>. The dimensions of the target feature <NUM> may be stored on the storage memory device. Further, in the exemplary embodiment, the received data indicative of one or more dimensions of the target feature <NUM> is used to create a three-dimensional representation of the target feature <NUM>. In one embodiment, the three-dimensional representation may be a point cloud. A point cloud is set of data points defined in a coordinate system and may include color and depth data. In some embodiments, the point cloud may be used to create a CAD model. The CAD model may use any CAD software, and may be generated from any of a large variety of well-known computer aided design (CAD) software systems such as AutoCAD®, TurboCAD®, DesignCAD 3D Max, etc. In other embodiments, the CAD model may be a topographical model, a surface model, a wireframe model, a shell model, or any other type of CAD model. It will be appreciated that the present disclosure includes any other representation that may accurately portray the target feature <NUM>.

Additionally, in some embodiments, each of the first camera <NUM> and the second camera <NUM> may obtain two or more sets of images, where each set of images includes one or more images. The first set of images may be taken when the first camera <NUM> and the second camera <NUM> are in a first position. The second set of images may be taken when the first and second cameras <NUM> and <NUM> are at a second position spaced apart from the first position by a circumferential distance, e.g., an engine rotation angle. Specifically, if the rotor is moving, each set of images may be taken synchronously (e.g., at or substantially around the same time) by the first and second cameras <NUM> and <NUM>. In this particular embodiment, the circumferential distance is calculated using at least one reference feature <NUM> in the first and second sets of images from the first camera <NUM>. Alternatively, where the tool assembly <NUM> also includes sensors 90A and 90B, and where the sensors 90A and 90B further include IMUs, the circumferential distance may be obtained from the IMUs. The first and second sets of images taken by the second camera <NUM> may then be used to determine the dimensions of the target feature <NUM> based on the circumferential distance.

It will also be appreciated that the tool assembly <NUM> may be used in any compatible machine across different industries. One of ordinary skill in the art will recognize that the inherent flexibility of the tool assembly <NUM> allows for inspection and maintenance in different industrial machines of varying sizes. For example, in some embodiments, the tool assembly <NUM> may further include a third camera <NUM> fixed at a third location and at a third spatial position along the body <NUM>, where the third camera <NUM> is positioned in view of an auxiliary feature <NUM> and/or third component <NUM>. In these embodiments, the method <NUM> will further include the steps of determining the third spatial position based at least in part on the first spatial position and/or the second spatial position; receiving data indicative one or more images of the auxiliary feature <NUM> using the third camera <NUM>, determining data indicative of one or more dimensions of the auxiliary feature <NUM>, and generating a three-dimensional representation of the auxiliary feature <NUM> based at least on the determined data indicative of one or more dimensions of the auxiliary feature <NUM>. For example, the tool assembly <NUM> may also include four, five, six, seven, or more cameras operating in the same manner as described. Moreover, the additional cameras may be operated simultaneously with the first camera <NUM> and the second camera <NUM> to allow for simultaneous imaging of multiple features and/or components. These embodiments would allow for greater efficiency in routine inspection and maintenance and may help identify and measure defects in a multitude of internal machines and components including, but not limited to, those of gas turbine engines.

For example, during operation of a machine, damage can occur from normal wear and tear, as well as other causes. Such incidents of damage may reduce the overall efficiency and productivity of the machine. Moreover, damage to machine components may result in increased maintenance costs and decreased engine life. Accordingly, maintenance of the machine typically requires an inspection of the components. In many cases, these inspections may be executed by a user-inspector and is both time and labor intensive. Moreover, inspections may yield varying results, depending on the user-inspector. The tool assembly <NUM> could be used to perform these inspections and to increase the efficiency of the inspections. Although the tool assembly <NUM> is described herein with reference to machines and gas turbine engines specifically, the tool assembly <NUM> is also applicable to other fields, e.g., the medical field to inspect difficult to reach places and/or to estimate sizes of tumors and other foreign objects within a human body.

Claim 1:
A tool assembly (<NUM>) for inspecting a gas turbine engine (<NUM>), the tool assembly (<NUM>) comprising:
an elongated body (<NUM>), wherein the elongated body (<NUM>) defines a local longitudinal direction (L1), a latitudinal direction (L2), and a transverse direction (T);
a first camera (<NUM>), having a first orientation (Xo) relative to the elongated body (<NUM>), fixed to the elongated body (<NUM>) at a first location;
a second camera (<NUM>), having a second orientation (Yo) relative to the elongated body (<NUM>), fixed to the elongated body (<NUM>) at a second location (YL) spaced from the first location (XL), wherein the first orientation (Xo) defines an angle with the second orientation (Yo) in a plane defined by the longitudinal direction (L1) and transverse direction (T) greater than <NUM>; and
a controller (<NUM>) in operative communication with the first camera (<NUM>) and the second camera (<NUM>), the controller (<NUM>) being configured to:
receive data indicative of one or more images of a reference feature (<NUM>) from the first camera (<NUM>);
determine data indicative of a first spatial position of the first camera (<NUM>) based at least in part on the received data indicative of the one or more images of the reference feature (<NUM>); and
determine data indicative of a second spatial position of the second camera (<NUM>) based on the first spatial position.