Dual-arm robot control system for nondestructive evaluation

Abstract

To provide a system for nondestructive evaluation of an object that uses a spherical coordinate system to control two robotic arms.SOLUTION: In some examples, the system comprises a radiation source coupled to one robotic arm, a radiation detector coupled to the other robotic arm, and a control unit. The control unit is configured to determine, on the basis of input, a first position located on a first surface of a first sphere within a spherical coordinate system, determine, on the basis of the input, a second position located on a second surface of a second sphere within the spherical coordinate system, wherein the second position is located opposite to the first position with respect to a midpoint of the spherical coordinate system, and control a motion of a radiation source robotic arm and a detector robotic arm such that the radiation source and the radiation detector move to different ones of the first position and the second position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] [Related application data] This application claims priority to U.S. patent application Ser. No. 16 / 885,115, filed May 27, 2020, entitled "DUAL ROBOT CONTROL SYSTEMS FOR NON-DESTRUCTIVE EVALUATION," which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to non-destructive evaluation of objects. [Background technology]

[0003] X-ray digital radiography (DR) is a commonly used non-invasive and non-destructive imaging technique that uses digital X-ray detectors, such as flat panel detectors, charge-coupled device (CCD) cameras, or complementary metal-oxide semiconductor (CMOS) cameras, or linear diode arrays (LDAs). X-ray computed tomography (CT) is a procedure that creates 3D images of an object using computer-processed X-ray radiographs acquired at different viewing angles. A tomographic image of an object is an image of a conceptually two-dimensional "slice" of the object. A computing device can use the tomographic image of the object to generate a three-dimensional image of the object. X-ray CT can be used in industrial applications to perform non-destructive evaluation of objects. Summary of the Invention

[0004] Generally, the present disclosure relates to nondestructive evaluation (NDE), such as industrial X-ray radiography, computed tomography (CT), and metrology. The present disclosure describes an apparatus and method that allows for nondestructive evaluation of an object from many different viewpoints while also simplifying the alignment of the radiation source and detector for the user. The techniques of the present disclosure provide the instrumentation design, user control mechanism, and software algorithms for the apparatus. The apparatus can be used for the NDE of naturally occurring objects, such as rock core samples, as well as for the NDE of manufactured parts and systems, such as metal castings, engine parts, and completed engine units. The apparatus can include a radiation source, a radiation detector, and a sample manipulator, each associated with a motion control system. The sample manipulator can position the sample so that radiographs can be obtained at different positions and viewing angles.

[0005] In one example, the present disclosure describes a system for non-destructive evaluation of an object, the system comprising: a first robotic arm; a radiation source coupled to the first robotic arm and configured to emit radiation; a second robotic arm; a radiation detector coupled to the second robotic arm and configured to measure the radiation emitted by the radiation source; a stage configured to support the object for non-destructive evaluation; and a control unit configured to: determine, based on an input, a first position located on a first surface of a first sphere in a spherical coordinate system; determine, based on the input, a second position located on a second surface of a second sphere in the spherical coordinate system, wherein the second position is located opposite the first position with respect to a center of the spherical coordinate system; and control movement of the first robotic arm and the second robotic arm such that the radiation source and the radiation detector move to different positions of the first position and the second position.

[0006] In another example, the present disclosure describes a non-transitory computer-readable data storage medium having stored thereon instructions that, when executed by a system for non-destructive evaluation of an object disposed on a stage, cause the system to: determine, based on an input, a first position located on a first surface of a first sphere in a spherical coordinate system; determine, based on the input, a second position located on a second surface of a second sphere in the spherical coordinate system, wherein the second position is located opposite the first position with respect to a center of the spherical coordinate system; and control movement of a first robotic arm and movement of a second robotic arm such that a radiation source and a radiation detector move to different ones of the first and second positions.

[0007] In another example, the present disclosure describes a method including: determining, based on input to a system for non-destructive evaluation of an object positioned on a stage, a first position located on a first surface of a first sphere in a spherical coordinate system; determining, based on the input, a second position located on a second surface of a second sphere in the spherical coordinate system, wherein the second position is located opposite the first position with respect to a center of the spherical coordinate system; and controlling movement of a first robotic arm and movement of a second robotic arm such that a radiation source and a radiation detector move to different positions of the first position and the second position.

[0008] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description, drawings, and claims. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of an exemplary equipment setup for a non-destructive evaluation (NDE) system, in accordance with one or more techniques of the present disclosure.

[0010] [Figure 2] FIG. 2 is a conceptual block diagram of some example components of the equipment setup of FIG. 1.

[0011] [Figure 3] FIG. 2 is a conceptual side view of an example coordinate system used by the NDE system of FIG. 1 to align the radiation source and the radiation detector, in accordance with one or more techniques of the present disclosure.

[0012] [Figure 4] FIG. 4 is a conceptual perspective view of the example coordinate system of FIG. 3.

[0013] [Figure 5] FIG. 1 is a conceptual perspective view of another example coordinate system, in accordance with one or more techniques of the present disclosure.

[0014] [Figure 6] FIG. 1 is a side view of another example NDE system, in accordance with one or more techniques of the present disclosure.

[0015] [Figure 7A] FIG. 1 is a diagram of an example graphical user interface (GUI) of an NDE system, in accordance with one or more techniques of the present disclosure. [Figure 7B] FIG. 1 is a diagram of an example graphical user interface (GUI) of an NDE system, in accordance with one or more techniques of the present disclosure.

[0016] [Figure 8] 1 is a flowchart illustrating an example operation of an NDE system, in accordance with one or more techniques of this disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] Nondestructive evaluation (NDE) or nondestructive analysis (NDA) of an object may involve noninvasively imaging, measuring, or otherwise evaluating two-dimensional or three-dimensional structures. Commonly used techniques for NDE in medical or industrial imaging include X-ray radiography and computed tomography (CT). One or more example techniques of the present disclosure relate to industrial applications of X-ray CT or metrology. For example, FIG. 1 is a schematic diagram illustrating an overhead view of an example equipment setup in accordance with one or more techniques of the present disclosure. As shown in the example of FIG. 1 , an NDE system 10, such as an industrial CT system, may include a radiation source 12 and a radiation detector 14. The radiation source 12 may emit electromagnetic radiation, such as an X-ray beam 16. Therefore, in some instances, the present disclosure may refer to the radiation source 12 or a similar device as an “X-ray generator.” In some examples, the X-ray beam 16 may be cone-shaped. In other examples, the X-ray beam 16 may be fan-shaped. In some examples, X-ray source 12 generates X-rays having an energy range of 20 keV to 600 keV. In other examples, X-ray source 12 may generate X-rays in other energy ranges. In other examples, beam 16 may include other frequencies in the electromagnetic spectrum, such as a gamma ray beam.

[0018] The sample can be mounted on a manipulator. In system 10, the manipulator can include a rotary stage 18 (i.e., a rotation stage) having a rotation axis 20. The rotary stage 18 can be configured to hold and rotate a sample or object 22 and can be positioned between the X-ray source 12 (i.e., an X-ray generator) and the radiation detector 14. As a result, radiographs can be acquired at different projection angles or viewpoints by rotating the sample within the X-ray beam 16. Thus, in some examples where the manipulator includes a rotation stage 18, the computing system of system 10 can acquire radiographs at different rotation angles at different detector positions and process the radiographs to assemble them into a three-dimensional radiograph of the sample. In some examples, the rotary stage 18 can include an 18-inch nickel-plated aluminum turntable platter.

[0019] The radiation detector 14 may include a flat panel X-ray detector (FPD), as shown in the example of FIG. 1. In other examples, the radiation detector 14 may include a lens-coupled scintillation detector, a linear diode array (LDA), or another type of radiation detector. The FPD may include a layer of scintillation material, such as cesium iodide, fabricated on amorphous silicon on a glass detector array. The scintillator layer absorbs X-rays and emits visible light photons, which are then detected by a solid-state detector. The detector pixel size may range from tens of micrometers to hundreds of micrometers. In some examples where the radiation detector 14 includes a flat panel X-ray detector, the pixel size of the radiation detector 14 may range from 25 micrometers to 250 micrometers. In some examples, the pixel size of the radiation detector 14 may range from approximately 25 micrometers to approximately 250 micrometers. Furthermore, the field of view of a typical commercial FPD may range from approximately 100 mm to 500 mm. Commercial FPDs can be used in applications requiring a wide field of view.

[0020] High-resolution applications may require a lens-coupled detector, such as a charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) detector, which uses an optical lens to relay the emitted visible light to the detector. In some examples, the lens may provide a magnification ranging from 1x to 100x, resulting in an effective pixel size of 0.1 micrometers to 20 micrometers. In some examples where the radiation detector 14 includes a lens-coupled detector, the pixel size of the radiation detector 14 is in the range of 0.1 micrometers to 10 micrometers. Furthermore, in some examples where the radiation detector 14 includes a lens-coupled detector, the field of view may be in the range of 0.2 mm to 25 mm.

[0021] A user of the system 10 may be interested in capturing images (e.g., X-ray images) of a part, sample, or object 22 from multiple different angles to thoroughly evaluate its internal structure. Some conventional imaging systems may include components configured to manipulate either or both of the radiation source 12 and / or detector 14 along a generally linear axis. For example, conventional imaging systems may include rails, gears, and / or other mechanical components configured to linearly translate the radiation source 12 and / or detector 14 along orthogonal Cartesian axes, such as a horizontal axis (e.g., toward and away from the object 22) and / or a vertical axis. In these examples, the user may need to manually reorient the object 22 relative to the radiation source 12 and detector 14 to image the object 22 from different rotational angles. This can be difficult or inconvenient when the object 22 is relatively large, bulky, and / or heavy. Accordingly, some other conventional imaging systems comprise a “C-arm” system in which the radiation source 12 and the detector 14 are mounted on opposite ends of a machine shaped like the letter “C.” In some instances, the C-shaped machine then rotates around the object 22 to image the object from multiple angles. A typical example of this type of C-arm system is a dentist's X-ray machine, which rotates around a patient's head to image the patient's teeth from multiple perspectives. In other instances, the object being evaluated may be placed on a rotary stage, which can rotate the object relative to the radiation source and detector. However, because both the radiation source 12 and the detector 14 are rigidly coupled to the same structure, typical C-arm systems are similarly limited in mobility in that the stage and / or C-arm can only rotate about a single vertical or horizontal axis; for example, the C-arm system can only image the object 22 along an axis directly orthogonal (e.g., perpendicular) to the axis of rotation of the C-arm structure.

[0022] A more advanced imaging system, such as the NDE system 10 shown in FIG. 1, may include two robotic arms 24, 26. The radiation source 12 and the detector 14 are mounted at the distal ends of different ones of the robotic arms 24, 26. The robotic arms 24, 26 can then be manipulated independently to image the object 22 from multiple angles along multiple different axes of rotation. Each of the robotic arms 24, 26 may include one or more joints 30A-30F (collectively, "joints 30") that define multiple degrees of freedom in three-dimensional space for imaging the object 22. For example, each robotic arm may include six joints. However, these additional degrees of freedom provide both advantages and disadvantages. While the robotic arms 24, 26 can improve imaging of the object 22, the dual-arm robotic arms 24, 26 of a system such as system 10 may impose additional (e.g., excessive) complexity on the imaging process. For example, to successfully image or measure the object 22, the radiation source 12 and detector 14 must be aligned diametrically opposite one another with respect to the object 22. Because each robotic arm 24, 26 may be manually manipulated (e.g., via a graphical user interface, a variable speed multi-directional joystick, or other user input device) independently of the other robotic arm, some dual-arm robotic arm type systems may require significant trial and error and / or manual positioning to properly align the radiation source 12, object 22, and radiation detector 14.

[0023] In some examples consistent with the present disclosure, the NDE system 10 includes a control unit, such as an image acquisition system 28. The control unit is configured to receive input indicating at least a desired imaging angle (e.g., imaging viewpoint) and a desired imaging magnification, and to automatically align the radiation source 12, the object 22, and the detector 14 based on the user input. For example, the image acquisition system 28 can determine the radiation source position and the detector position based on the desired imaging angle and / or the desired imaging magnification, and then control the joints of a robotic arm to position the radiation source and the detector at their respective positions.

[0024] The image acquisition system 28 can include a computing system. Exemplary types of computing systems include a personal computer, a server computer, a mainframe computer, a laptop computer, a dedicated computer, etc. The image acquisition system 28 can perform a computer-controlled image acquisition procedure that includes (e.g., consists of) determining a radiation source position and a detector position based on input and then controlling any of a plurality of controllable mechanical components of the system 10 to move (e.g., rotate and / or translate) the radiation source 12 toward the radiation source position and the radiation detector 14 toward the detector position. In some examples according to the present disclosure, the image acquisition system 28 can determine (e.g., generate or calculate) the radiation source position and the detector position according to positions defined by a spherical coordinate system, where the radiation source position is located at a point on the surface of a first imaginary sphere 32 and the detector position is located at a point on the surface of a second imaginary sphere 34, and the two imaginary spheres are concentric, e.g., share a common center 33 with the spherical coordinate system.

[0025] Figure 2 is a conceptual block diagram illustrating some example components of system 10 of Figure 1 in accordance with the techniques of this disclosure. In the example of Figure 2, system 10 includes housing 11, radiation source 12, radiation detector 14, rotary stage 18, first robotic arm 24, second robotic arm 26, image acquisition system 28, orientation units 46 and 48, and pressure sensor 50. In other examples, system 10 may include more, fewer, or different components.

[0026] In some examples, one or more components of system 10 are housed within housing 11. Housing 11 can include radiation shielding, e.g., protective shielding, that can withstand radiation energy at a constant potential of up to 240 kilovolts (kV). In some examples, the enclosure can have dimensions of approximately 158 inches wide by approximately 98 inches deep by approximately 123 inches high (e.g., approximately 401 cm wide by approximately 249 cm deep by approximately 312 cm high). Housing 11 can be constructed from lead and / or steel components and defines a motorized sliding access door for accessing rotary stage 18 and placing object 22 for nondestructive evaluation (e.g., imaging or metrology). Housing 11 can further include an interior light, a covered cable access port, and an "X-ray on" warning light.

[0027] Image acquisition system 28 is configured to receive input indicating at least a desired imaging angle and a desired imaging magnification, and then automatically align radiation source 12, object 22, and detector 14 based on the input. For example, the received input may include direct (e.g., real-time) user input, or in some instances, may include a set of predetermined instructions stored in a file that image acquisition system 28 imports or otherwise receives.

[0028] Image acquisition system 28 may include a computing system. For example, image acquisition system 28 may perform a computer-controlled image acquisition procedure that includes determining radiation source and detector positions based on received inputs and then controlling any of a plurality of controllable mechanical components of system 10 to move (e.g., rotate and / or translate) radiation source 12 toward the determined radiation source position and radiation detector 14 toward the determined detector position. Image acquisition system 28 may determine (e.g., receive, generate, or calculate) radiation source and detector positions in a spherical coordinate system, where the radiation source positions are located at points on the surface of a first imaginary sphere and the detector positions are located at points on the surface of a second imaginary sphere, the two imaginary spheres being concentric.

[0029] As shown in FIG. 2 , the image acquisition system 28 may include at least a processing circuitry 36, a memory 38, and a user interface 40. The processing circuitry 36 is configured to execute an alignment unit 42 and an imaging unit 44. The alignment unit 42 is configured to receive user input indicating a desired imaging viewpoint (e.g., imaging angle) and / or a desired imaging magnification via a user interface (UI) 40. The user interface 40 may include any suitable user input / output device, such as a graphical user interface, an interactive voice interface, a command line interface, etc. Based on the user input, the alignment unit 42 may determine a radiation source position and a detector position to align the radiation source 12 and the radiation detector 14 on opposite sides of the center of a spherical coordinate system centered on a center 33. In the example shown in FIGS. 1 and 3 , the center 33 is located a predetermined distance above the rotary stage 18, for example, along the rotation axis 20 ( FIG. 1 ). However, as will be described in more detail below, image acquisition system 28 can move center 33 to any position (eg, redefine the position of center 33) based on input received.

[0030] Additionally or alternatively, the alignment unit 42 can determine the radiation source orientation and / or the detector orientation based on the received input. For example, the alignment unit 42 can control the radiation source orientation unit 46 and / or the detector orientation unit 48 to orient the radiation source 12 and / or the radiation detector 14, respectively, so that the radiation source 12 and / or the radiation detector 14 are "pointed" at each other from their respective positions, e.g., so that the radiation beam 16 is directed from the radiation source position 12 to the detector 14. For example, the radiation source orientation unit 46 can be an example of one of the joints 30 of the robot arm 24 (e.g., joint 30C in FIG. 1 ) configured to rotate to change the orientation of the radiation source 12, e.g., a ball-and-socket type joint. Similarly, the detector orientation unit 48 can be an example of one of the joints 30 of the robot arm 26 (e.g., joint 30F in FIG. 1 ) configured to rotate to change the orientation of the radiation detector 14, e.g., a ball-and-socket type joint. In other examples, each of the radiation source directing unit 46 and the detector directing unit 48 may include two or more joints 30 configured to cooperate or work together (e.g., under the control of the alignment unit 42) to mimic the functionality of a single ball-type joint.

[0031] Once the alignment unit 42 has aligned and / or orientated both the radiation source 12 and the radiation detector 14, the imaging unit 44 can non-destructively evaluate (e.g., irradiate and image or measure) the object 22 placed on the rotary stage 18, for example, by causing the radiation source 12 to emit a radiation beam 16 that passes through the object 22 and contacts the surface of the radiation detector 14.

[0032] In some examples, the radiation detector 14 includes a guard plate having at least one pressure sensor 50. The guard plate is configured to disable movement of the robot arm 26 in response to the pressure sensor 50 detecting contact with another item, such as the object 22, the interior surface of the housing 11, the radiation source 12, or the robot arm 24. For example, for some relatively large or irregularly shaped objects 22, movement of the robot arm 26 may cause the radiation detector 14 to contact a portion of the object 22. In these examples, the pressure sensor 50 detects physical contact with the object 22 and causes the image acquisition system 28 to immediately terminate further movement of the robot arm 26, thereby reducing or preventing damage to the object 22. The pressure sensor 50 may include a sensing plate that is highly transparent to the radiation beam 16 and capable of triggering a stop of the robot arm 26 with a response time on the order of milliseconds.

[0033] 3-6 are conceptual diagrams of various exemplary coordinate systems that an NDE system (e.g., alignment unit 42 of image acquisition system 28 of NDE system 10 of FIG. 2) may use to calculate or determine at least a radiation source position 52 of radiation source 12 and a detector position 54 of radiation detector 14. For example, FIG. 3 shows a conceptual side view of an exemplary spherical coordinate system 60 centered about center 33.

[0034] The radiation source 12 is located at a radiation source position 52 that is located at a point in space defined by a spherical coordinate system 60. For example, the alignment unit 42 may define a first virtual sphere 32 located within the spherical coordinate system 60, e.g., centered at the center 33 of the coordinate system 60. The alignment unit 42 may then determine (e.g., calculate and / or assign) the radiation source position 52 to be located at a point on the surface of the first virtual sphere 32. For example, the radiation source position 52 may be defined by three spherical coordinates, e.g., a radius R, an elevation angle θ, and an azimuth angle φ (shown in FIG. 4 ). As shown in FIG. 3 , the radiation source position 52 is located at an elevation angle θ above a horizontal plane 56 that passes through the center 33 of the coordinate system 60. SThe radiation source position 52 is located at a distance of the radiation source radius R from the center 33. S and the source radius R S defines the radius of the first phantom sphere 32.

[0035] Similarly, the radiation detector 14 is located at a detector location 54 that is located at a point in space defined by a spherical coordinate system 60. For example, the alignment unit 42 can define a second virtual sphere 34 that is located within the spherical coordinate system 60, e.g., centered at the center 33 of the coordinate system 60. The alignment unit 42 can then determine (e.g., calculate and / or assign) the detector location 54 to be located at a point on the surface of the second virtual sphere 34. For example, the detector location 54 can be defined by three spherical coordinates: a radius R, an elevation angle θ, and an azimuth angle φ (shown in FIG. 4 ). As shown in FIG. 3 , the detector location 54 is located at an elevation angle θ below a horizontal plane 56. D Here, the detector elevation angle θ D is the radiation source elevation angle θ S The detector position 54 is located at a distance from the center 33 by a detector radius R D and the detector radius R D defines the radius of the second phantom sphere 34.

[0036] In some examples, alignment unit 42 is configured to receive further user input, for example via user interface 40, indicating a desired image magnification for imaging object 22 disposed on stage 18. Alignment unit 42 calculates a radiation source radius R based on the desired image magnification. S and detector radius R D where the magnification factor M is equal to the sum of the detector radius and the source radius divided by the source radius, e.g., M=(R D +R s ) / R s

[0037] Once the alignment unit 42 determines the radiation source position 52 and the detector position 54, the alignment unit 42 controls the robotic arms 24, 26 to move the radiation source 12 to the radiation source position 52 and the radiation detector 14 to the detector position 54. In some examples, the robotic arm 24 can be configured to move the radiation source 12 from the current radiation source position to the intended radiation source position 52 according to the prescribed imaginary sphere 32. For example, the robotic arm 24 may first move the radiation source 12 radially inward or outward from the current radiation source radius to the intended radiation source radius R S to the intended radiation source location 52, and then the robotic arm 24 can be rotated (e.g., via joints 30) such that the radiation source 12 moves along the surface of the virtual sphere 32 toward the intended radiation source location 52. Similarly, the robotic arm 26 can be configured to move the radiation detector 14 from the current detector location to the intended detector location 54 according to the defined virtual sphere 34. For example, the robotic arm 26 can first move the radiation detector 14 radially inward or outward from the current detector radius to the intended detector radius R D and then the robot arm 26 can be rotated (e.g., via joint 30) so that the radiation detector 14 moves along the surface of the virtual sphere 34 towards the intended detector position 54.

[0038] In another example, rather than separately controlling the radiation source radius and radiation source angle, the alignment unit 42 can define a series of intermediate way-points between the current radiation source position and the desired radiation source position. The set of way-points can approximate a curve or arc between the current radiation source position and the desired radiation source position, such that each subsequent way-point defines a gradual change in both radius and angle from the center 33. The alignment unit 42 can then control the joints 30 of the robot arm 24 such that the radiation source 12 follows the arc defined by the way-points to reach the intended radiation source position.

[0039] Similarly, the alignment unit 42 can define a series of intermediate way-points between the current detector position and the desired detector position. The set of way-points can approximate a curve or arc between the current detector position and the desired detector position, such that each subsequent way-point defines a gradual change in both radius and angle from the center 33. The alignment unit 42 can then control the joints 30 of the robot arm 26 so that the radiation detector 24 follows the arc defined by the way-points to reach the intended detector position.

[0040] 4 is a perspective view of the exemplary spherical coordinate system 60 of FIG. 3. The radiation source 12 is aligned at a radiation source elevation angle θ S In addition, the radiation source azimuth angle φ "above" the horizontal axis 58 along the horizontal plane 56 S Therefore, the radiation source position 52 can be described by three spherical coordinates (R S ,θ S ,φ S ) Image acquisition system 28 is configured to determine these values for radiation source position 52 based on user input and to control first robotic arm 24 to move radiation source 12 to be located at radiation source position 52.

[0041] Similarly, the radiation detector 14 is rotated at a detector elevation angle θ D in addition to the detector azimuth angle φ “below” the horizontal axis 58 along the horizontal plane 56 D where the detector azimuth angle φ at the detector position 54 D is the radiation source azimuth angle φ of the radiation source position 52 S Therefore, the detector position 54 is given by three spherical coordinates (R D ,θ D ,φ D ) The image acquisition system 28 is configured to determine these three values of the detector position 54 based on user input and to control the second robotic arm 26 to move the radiation detector 14 to be located at the detector position 54.

[0042] In some examples, the image acquisition system 28 may acquire the radiation source direction vector O of the radiation source 12. S and / or the detector orientation vector O of the radiation detector 14 D For example, image acquisition system 28 may control radiation source directing unit 46 (e.g., hinge 30C, or a combination of two or more hinges 30) of robotic arm 24 to rotate radiation source 12 while radiation source 12 is located at radiation source position 52. As shown in FIG. 4 , when image acquisition system 28 controls the movement of radiation source directing unit 46, radiation source orientation vector O S sweeps out a radiation cone 62 that describes the possible paths along which the radiation beam 16 ( FIG. 1 ) can emanate from the radiation source 12. The radiation cone 62 can itself be described by two spherical coordinates within another imaginary sphere centered within the directing unit 46, e.g., a radiation source orientation azimuth angle and a radiation source orientation elevation angle. In some examples, as described further below with respect to FIG. 6 , the radiation source 12 and the radiation detector 14 can be configured to rotate about an axis or vector connecting them. In these examples, the radiation cone 62 can be described by a third coordinate or variable that defines the rotation of the cone about its own axis. Control over this third rotation variable can be useful to enable a “flat-field correction” of the radiation beam 16 relative to the radiation detector 14, such as when the radiation beam 16 does not inherently produce a rotationally symmetric distribution of radiation on the detector 14.

[0043] Similarly, the image acquisition system 28 can control the detector orientation unit 48 (e.g., hinge 30F) of the robot arm 26 to rotate the radiation detector 14 while the radiation detector 14 is located at the detector position 54. As shown in FIG. 4 , when the image acquisition system 28 controls the movement of the orientation unit 48, the detector orientation vector O D is a possible orientation of the plane defined by the surface of the radiation detector 14, or an orientation vector O tangential to the detector plane. DThe directing unit 48 sweeps out a detector facing cone 64 that describes the possible orientations of the radiation source 12 and the radiation detector 14. The detector facing cone 64 may itself be described by two spherical coordinates, e.g., a detector facing azimuth angle and a detector facing elevation angle, within another imaginary sphere centered within the directing unit 48. In some examples, as described further below with respect to FIG. 6, the radiation source 12 and the radiation detector 14 may be configured to rotate about an axis or vector connecting them. In these examples, the radiation cone 64 may be described by a third coordinate or variable that defines the rotation of the cone about its own axis. Control over this third rotation variable may be useful to enable a "flat-field correction" of the radiation beam 16 relative to the radiation detector 14, such as when the radiation beam 16 does not inherently produce a rotationally symmetric distribution of radiation on the detector 14.

[0044] Overall, as shown in FIG. 4 , system 60 defines at least ten degrees of freedom, i.e., three position axes and two orientation axes for each of radiation source 12 and radiation detector 14. As noted above, imaging 60 can define two additional variables for rotation of radiation source 12 and detector 14 about the axis connecting them. These 12 degrees of freedom can enable precise control over imaging of object 22 from virtually any desired viewpoint and magnification. However, these 12 degrees of freedom are not intended to be limiting. Other configurations of imaging 60 may define fewer, additional, and / or different degrees of freedom, e.g., translational and / or rotational axes defined by mechanical components of system 60. For example, FIG. 5 is a conceptual perspective view of another coordinate system 70 that an NDE system (e.g., alignment unit 42 of image acquisition system 28 of NDE system 10 of FIG. 2) can use to calculate or determine at least a radiation source position 52 of radiation source 12 and a detector position 54 of radiation detector 14. Coordinate system 70 may be an example of spherical coordinate system 60 of FIGS. 3 and 4, or may include spherical coordinate system 60 within coordinate system 70. For example, similar to spherical coordinate system 60 of FIGS. 3 and 4, coordinate system 70, as shown in FIG. 5, includes a spherical coordinate system that defines imaginary spheres 32, 34 on which radiation source position 52 and detector position 54 are located, respectively. However, coordinate system 70 may have at least eight additional degrees of freedom that are not shown in FIGS. 3 and 4.

[0045] For example, coordinate system 70 defines a Cartesian coordinate system having x-axis 67, y-axis 68, and z-axis 69 that define the location of a reference point, such as center 33 of spherical coordinate system 70. That is, robot arms 24 and 26 are translatable together (e.g., as a cooperative unit) horizontally and vertically along the x-axis, y-axis, and z-axis to move radiation source 12 and detector 14 relative to rotary stage 18. In the example shown in FIG. 5 , center 33 of the spherical coordinate system (e.g., spherical point (0,0,0)) is initially co-located with origin 66 of the Cartesian coordinate system (e.g., Cartesian point (0,0,0)). However, joints 30 of robot arms 24, 26 are configured to cooperate to mimic Cartesian (e.g., Cartesian) motion that moves robot arms 24 and 26 horizontally and / or vertically relative to rotary stage 18. In other examples, the system 10 may include dedicated mechanical components, such as guide rails, configured to move the robotic arms 24 and 26 solely horizontally and / or vertically relative to the rotary stage 18 .

[0046] In some examples, coordinate system 70 defines a secondary Cartesian coordinate system centered at detector location 54. For example, either or both of robotic arm 26 and radiation detector 14 may comprise mechanical components configured to enable horizontal and / or vertical translation of radiation detector 14 along a plane defined by the surface of radiation detector 14. For example, as shown in FIG. 5, the distal end of robotic arm 26 may comprise a ball screw nut servo motor to rotate radiation detector 14 along a horizontal detector axis D. x Horizontally and / or vertically along the detector axis D y Allowing detector 14 to translate horizontally and / or vertically along a plane tangential to the surface of sphere 34 provides at least two advantages.

[0047] First, by translating detector 14, image acquisition system 28 can acquire a series of radiographs at different detector locations 54 along a plane defined by the surface of detector 14 (e.g., a plane tangential to the surface of sphere 34), the different detector locations being spaced apart by distances finer than the pixel size of radiation detector 14. Image acquisition system 28 can then assemble the radiographs to form a composite radiograph that has higher resolution than the acquired radiographs, as described in detail in commonly assigned U.S. Patent No. 9,459,217.

[0048] Second, by translating the detector 14, the image acquisition system 28 can acquire a series of radiographs at different detector positions 54 along a plane defined by the surface of the detector 14 (e.g., a plane tangential to the surface of the sphere 34). By acquiring radiographs at two or more different detector positions that are larger (e.g., much larger) than the pixel size of the radiation detector 14 but spaced apart by a distance smaller than the detector size, the radiation detector 14 can cover an area larger than the physical size of the radiation detector 14. The image acquisition system 28 can then numerically "stitch" these digital radiographs together to form a composite radiograph having a field of view larger than that defined by the physical size of the detector 14. Furthermore, by acquiring radiographs when the radiation detector 14 is at two or more positions spaced apart by a distance smaller than the pixel size, a sub-pixel sampling effect can be achieved. This technique can be used to generate higher resolution composite radiographs in certain optical configurations and with certain types of samples. When these two techniques are used together in practice, one or both of the imaging field of view and resolution can be significantly increased. Furthermore, these two techniques can be further combined with both conventional volumetric CT and spiral CT techniques to increase the reconstructed three-dimensional (3D) volume and resolution of the object 22 .

[0049] 5 and 6, in some examples, system 70 can further include a set of orthogonal x, y, and z rotation axes 75, 77, and 76. For example, image acquisition system 28 can be configured to cause robotic arms 24 and 26 to rotate both radiation source 12 and detector 14 together about these axes, in addition to being able to translate horizontally and vertically along reference Cartesian x, 67, y, 68, and z, 69 axes. For example, as shown in FIG. 6, a "rotate x-axis" input command can cause alignment system 28 to rotate both robotic arms 24 and 26 about x-axis 75. Similarly, a "rotate y-axis" input command can cause alignment system 28 to rotate both robotic arms 24 and 26 about y-axis 77. Similarly, as shown in FIG. 6, a "rotate Z axis" input command can cause alignment system 28 to rotate either or both radiation source 12 and / or detector 14 about z rotation axis 76, or about vector 72 (FIG. 6) connecting radiation source 12 to detector 14.

[0050] FIG. 5 illustrates two additional degrees of freedom introduced by system 10, specifically by the mechanical characteristics of rotary stage 18. As described above, rotary stage 18 can be configured to rotate about rotary axis 20. As shown in FIG. 5, rotary stage 18 can also be vertically translatable along rotary axis 20. As detailed in commonly assigned U.S. Patent No. 9,459,217, filed April 2, 2014, by simultaneously rotating rotary stage 18 about axis 20 and vertically translating rotary stage 18 along axis 20, image acquisition system 28 can generate helical-type evaluation images of object 22 positioned on stage 18.

[0051] 5, the rotary stage 18 may include a first worm screw and rail set configured to translate the rotary stage 18 horizontally in response to a "rotary table left / right" command. Similarly, the rotary stage 18 may include a second worm screw and rail set configured to translate the rotary stage 18 horizontally (e.g., forward or backward) in response to a "rotary table zoom" command, thereby adjusting the relative distances between the radiation source 12, the object, and the radiation detector 14, thereby adjusting the image magnification of an object placed on the stage. Similarly, the image acquisition system 28 may be configured to move (e.g., rotate and / or translate) any mechanical component of the system 10 around or along any of the aforementioned axes while the imaging unit 44 captures an image of the object 22 (e.g., causes the radiation source 12 to emit radiation toward the radiation detector 14 to irradiate the object 22).

[0052] FIG. 6 is a side view of another exemplary system 80, which may be an example of the system 10 of FIGS. 1 and 2, the system 60 of FIGS. 3 and 4, and / or the system 70 of FIG. 5. When a user of the system 80 begins a new object imaging session, the robotic arms 24, 26 (FIG. 1) may initially be in any position and / or orientation. Accordingly, the system 80 (e.g., the image acquisition system 28 of FIG. 2) may be configured to perform an initial alignment operation upon startup of the system 80. For example, during the alignment operation, the system 80 may control the orientation units 46, 48 (FIG. 2) to rotate (e.g., reorient) the radiation source 12 and / or the detector 14 toward each other while maintaining their spatial (e.g., x, y, z) positions. Although a description of one exemplary alignment operation follows, other operations may be used to align the radiation source 12 and the detector 14.

[0053] The system 80 can receive user input, for example, via a GUI 90A shown in FIG. 7A , including a user-defined “sphere midpoint” value 94A. The sphere midpoint value can include a number between 0 and 1 that indicates the desired location of the reference point 66 (e.g., center of rotation) along the source-detector vector 72 at which the system 80 will perform the alignment. The user can specify the value of the sphere midpoint value 94A and then activate the “Robot Alignment” input button 92 to cause the system 80 to perform the alignment. In some examples, the system 80 can then use the sphere midpoint value 94A to calculate a percentage of the current distance between the radiation source 12 and the detector 14. The system 80 can store this percentage as a variable “Radiation Source Z”: Radiation source Z = length (radiation source - detector) x midpoint

[0054] System 80 then projects this distance onto the XZ plane 78, which effectively removes the y component: Focus XZ = length (radiation source xz - detector xz) x midpoint

[0055] The system 80 can then use the sphere midpoint 94A to determine the location of the reference point 66 between the radiation source 12 and the detector 14: ref = source + midpoint × (detector - source)

[0056] System 80 can then use these two distances and reference point 66 to calculate the initial x-axis rotation and initial y-axis rotation of the spherical mode: yRot=sin -1 ref.x-radiation source x / focal point XC xRot=sin -1 ref.y - radiation source y / radiation source Z

[0057] The system 80 can then determine the detector Z as the remaining distance between the radiation source 12 and the detector 14: Detector Z = length (radiation source - detector) - radiation source Z

[0058] The system 80 can then set the Z-axis rotation (zRot) value, the detector x-axis offset (detector X) value, and the detector y-axis offset (detector Y) value to zero. The system 80 can then route these values to their respective axes in the spherical coordinate system.

[0059] Once the system 80 has completed the alignment of the radiation source 12 and the detector 14, the system 80 can then determine the radiation source position and the detector position according to a spherical coordinate system, as shown in Figures 3-5. For example, when any spherical movement (e.g., rotation) of the arms 24, 26 is performed, the system 80 can convert the current spherical axis values, as shown in GUI 90A of Figure 7A, into linear coordinates (e.g., radiation source position and orientation and detector position and orientation), as shown in GUI 90B of Figure 7B, and the system 80 can then use the linear coordinates to move the robot arms 24, 26.

[0060] In some instances, the orientation of the "y" axis of rotation 77 can be considered "global" because it is not affected by rotations within the system. Meanwhile, in some instances, the "x" axis of rotation 75 and the "z" axis of rotation 76 can be considered "local" in that their orientation changes depending on the amount of "y" axis rotation. For example, rotating the y axis 77 by 45 degrees adjusts the orientation of the x axis of rotation 75 by 45 degrees, but rotating the x axis 75 by 45 degrees may not change the orientation of the y axis 77.

[0061] In some examples, the system 80 can calculate the detector normal ("detNorm") vector 74 from the sphere x-axis rotation and y-axis rotation. Similarly, unit Z is a unit vector 76 (0,0,1) in the z direction. xRot, yRot, and zRot are user-specified values from the respective sphere axes: detNorm = Rotation(Rotation(unit Z, xRot), yRot)

[0062] The detector horizontal position vector ("detHoriz") and detector vertical position vector ("detVert") are calculated similarly using all rotation axes: detHoriz = Rotation (units X, xRot, yRot, zRot) detVert = Rotation (units Y, xRot, yRot, zRot)

[0063] Using these vectors, the system 80 can calculate the 3D linear position of the detector 14 as an offset from the sphere reference point 66. detZ, detX, and detY are user-specified values from the respective sphere axes: detPos=ref+detZ×detNorm+detX×detHoriz+detY×detVert

[0064] Since the detector 14 and radiation source 12 are aligned with the detector normal vector 74, the system 80 can perform a simplified calculation using the detector normal vector 74 to determine the position of the radiation source 12: Radiation source Pos=ref-Radiation source Z×detNorm

[0065] The system 80 calculates the linear x-axis rotation of the detector 14 and radiation source 12 from the projection of the detector normal vector 74: Linear XRot=tan -1 detNorm.y / length(detNorm.xz)

[0066] The system 80 can then translate the invariant spherical y-axis rotation and the invariant spherical z-axis rotation into linear rotations of both the detector 14 and the radiation source 12 .

[0067] Other examples of system 80 may have different graphical user interfaces (e.g., having more, fewer, or different components) than those shown in FIGS. 7A and 7B . For example, a “simplified” example user interface may allow a user to input three-dimensional position and orientation vectors for each of radiation source 12 and radiation detector 14. The three-dimensional position and orientation vectors may be received in Cartesian (x, y, z) notation or spherical (R, θ, φ) notation. A more complex example user interface may allow a user to control each joint 30 ( FIG. 1 ) of robotic arms 24, 26 and may enable similar kinematics that allow for more precise control over joints 30.

[0068] In some examples, the user interface of the system 80 may include a graphical representation of the system 80 based on received input. For example, the user interface may display a three-dimensional representation of the positions and orientations of the radiation source 12, the radiation detector 14, the radiation beam 16, the object 22, the stage 18, and the center 33 relative to one another. The user interface may provide a user input mechanism that allows a user to rotate the viewpoint of the graphical representation. In some examples, the system 80 may be configured to display a physical representation of the virtual center 33 of a spherical coordinate system. For example, the system 80 may include a laser or LED configured to illuminate a location within the housing 11 ( FIG. 2 ) directly above or below the corresponding center 33 of the spherical coordinate system. In other examples, the system 80 may include a mechanical indicator of the center 33 configured to move within the housing 11 as the system 80 moves the virtual center 33 (e.g., as the radiation source 12 and detector 14 move together relative to the rest of the system 80).

[0069] 8 is a flowchart illustrating an example operation of a non-destructive evaluation system, such as an industrial CT system or metrology system, in accordance with one or more techniques of this disclosure. The example operation of FIG. 8 is described with reference to the example system 10 of FIG. 1 and FIG. 2, although the example operation of FIG. 8 is not so limited.

[0070] 8, image acquisition system 28 (e.g., a computing device of system 10) receives (800) input indicating a desired imaging viewpoint and / or a desired imaging magnification for X-ray imaging of object 22, which may be positioned on rotary stage 18 of system 10. The input may include direct (e.g., real-time) user input, or in some examples, may include a set of predetermined instructions stored in a file that image acquisition system 28 imports or otherwise receives.

[0071] The image acquisition system 28 determines (e.g., generates, selects, calculates, and / or assigns) a radiation source position 52 of the radiation source 12 and a detector position 54 of the radiation detector 14 based on the received input. In some examples, the image acquisition system 28 may first determine the radiation source position 52 and then determine the detector position 54 (e.g., opposite the radiation source position 52) based on the radiation source position 52. In other examples, the image acquisition system 28 may first determine the detector position 54 and then determine the radiation source position 52 (e.g., opposite the detector position 54) based on the detector position 54. In other examples, the image acquisition system 28 may independently determine the radiation source position 52 and the detector position 54 based on the received input.

[0072] In some examples, based on the input, the image acquisition system 28 can determine (802) a first position (e.g., radiation source position 52) located on the surface of a first virtual sphere located in a spherical coordinate system. Similarly, the image acquisition system 28 can determine (804) a second position (e.g., detector position 54) located on the surface of a second virtual sphere located in the same spherical coordinate system. The second position is located opposite the first position with respect to the center of the spherical coordinate system. Each of the radiation source position 52 and the detector position 54 can be described by three spherical coordinates (R, θ, φ) with respect to the center 33 of the spherical coordinate system. In some examples, the image acquisition system 28 can further determine and control a radiation source orientation 62 and a detector orientation 64 to direct the radiation beam 16 from the radiation source 12 toward the surface of the radiation detector 14.

[0073] Once the image acquisition system 28 determines a first position on the surface of the first virtual sphere and a second position on the surface of the second virtual sphere, the image acquisition system 28 (e.g., the alignment unit 42 of the image acquisition system 28) controls the robot arms 24 and 26 to move the radiation source 12 and the radiation detector 14 to different positions among the first position and the second position (806).

[0074] Once the radiation source 12 and radiation detector 14 are in place, the image acquisition system 28 (e.g., the imaging unit 44 of the image acquisition system 28) can image the object 22, for example, by causing the radiation source 12 to emit (e.g., irradiate) a radiation beam 16 that passes through the object 22 and strikes the radiation detector 14.

[0075] The following paragraphs provide additional example techniques of the present disclosure.

[0076] Example 1: In some examples, a system for non-destructive evaluation of an object includes a first robotic arm, a radiation source coupled to the first robotic arm and configured to emit radiation, a second robotic arm, a radiation detector coupled to the second robotic arm and configured to measure the radiation emitted by the radiation source, a stage configured to support the object for non-destructive evaluation, and a control unit configured to: determine, based on an input, a first position located on a first surface of a first sphere in a spherical coordinate system; determine, based on the input, a second position located on a second surface of a second sphere in the spherical coordinate system, the second position being opposite the first position with respect to a center of the spherical coordinate system; and control movement of the first robotic arm and the second robotic arm such that the radiation source and the radiation detector move to different ones of the first position and the second position.

[0077] EXAMPLE 2: In some examples of the system of Example 1, the control unit is further configured to receive an input indicating an imaging angle for evaluation of the object, and determine a first position and a second position based on the imaging angle.

[0078] EXAMPLE 3: In some examples of the system of Example 1 or Example 2, the control unit is further configured to control a radiation source orientation of the radiation source such that radiation is directed toward the detector from the first position or the second position, and to control a detector orientation of the detector such that the detector is directed toward the radiation source from the first position or the second position.

[0079] Example 4: In some examples of the system of any one of Examples 1 to 3, the control unit is further configured to: receive an input indicating a magnification for evaluating the object; determine a radiation source position that defines a radiation source radius based on the magnification; and determine a detector position that defines a detector radius based on the magnification, wherein the magnification is equal to the sum of the detector radius and the radiation source radius divided by the radiation source radius, and the radiation source position and the detector position are different positions from the first position and the second position.

[0080] Example 5: In some examples of the system of any one of Examples 1 to 4, the control unit is further configured to cause the radiation source to irradiate the object in response to controlling the movement of the first robotic arm and the second robotic arm.

[0081] Example 6: In some examples of the system of any one of Examples 1 to 5, the radiation detector includes a guard plate having at least one pressure sensor, and the guard plate is configured to disable movement of the second robotic arm in response to the pressure sensor detecting contact with the item.

[0082] Example 7: In some examples of the system of any one of Examples 1 to 6, the control unit is further configured to acquire a series of radiographs at different detector positions along a plane tangential to a second surface of a second sphere in a spherical coordinate system, the different detector positions being spaced apart by a distance finer than a pixel size of the radiation detector, and assemble the radiographs to form a composite radiograph having a higher resolution than the acquired radiographs.

[0083] Example 8: In some examples of the system of any one of Examples 1 to 7, the control unit is further configured to: acquire a series of radiographs at different detector positions along a plane tangential to a second surface of a second sphere in a spherical coordinate system, the different detector positions being spaced apart by a distance greater than a pixel size of the radiation detector but less than a physical size of the detector; and assemble the radiographs to form a composite radiograph having an area greater than the physical size of the detector.

[0084] Example 9: In some examples, a computer-readable storage medium includes program instructions that, when executed by a system for non-destructive evaluation of an object disposed on a stage, cause the system to: determine, based on an input, a first position located on a first surface of a first sphere in a spherical coordinate system; determine, based on the input, a second position located on a second surface of a second sphere in the spherical coordinate system, the second position located opposite the first position with respect to a center of the spherical coordinate system; and control movement of a first robotic arm and movement of a second robotic arm such that a radiation source and a radiation detector move to different ones of the first position and the second position.

[0085] EXAMPLE 10: In certain examples of the computer-readable medium of Example 9, the input indicates an imaging angle for evaluation of the object, and the program instructions, when executed, further cause the system to determine a first position and a second position based on the imaging angle.

[0086] EXAMPLE 11: In some examples of the computer-readable medium of Example 9 or Example 10, the program instructions, when executed, cause the system to: control a radiation source orientation of the radiation source such that radiation is directed from a radiation source position to the detector; and control a detector orientation of the detector such that the detector is directed from a detector position to the radiation source, wherein the radiation source position and the detector position comprise different positions of a first position and a second position.

[0087] Example 12: In some examples of the computer-readable medium of any one of Examples 9 to 11, the program instructions, when executed, cause the system to: receive an input indicating a magnification factor for evaluating the object; determine a radiation source position that defines a radiation source radius based on the magnification factor; and determine a detector position that defines a detector radius based on the magnification factor, wherein the magnification factor is equal to the sum of the detector radius and the radiation source radius divided by the radiation source radius, and wherein the radiation source position and the detector position comprise different ones of the first position and the second position.

[0088] EXAMPLE 13: In some examples of the computer-readable medium of any one of Examples 9-12, the program instructions, when executed, further cause the radiation source to irradiate the object in response to controlling movement of the radiation source robot arm and the detector robot arm.

[0089] Example 14: In some examples of the computer-readable medium of any one of Examples 9 to 13, the program instructions, when executed, further cause the system to acquire a series of radiographs at different detector locations along a plane tangential to a second surface of a second sphere in a spherical coordinate system, the different detector locations being spaced apart by a distance finer than a pixel size of the detector, and assembling the radiographs to form a composite radiograph having a higher resolution than the acquired radiographs.

[0090] Example 15: In some examples, a method includes determining, based on input to a system for non-destructive evaluation of an object positioned on a stage, a first position located on a first surface of a first sphere in a spherical coordinate system; determining, based on the input, a second position located on a second surface of a second sphere in the spherical coordinate system, the second position being located opposite the first position with respect to a center of the spherical coordinate system; and controlling movement of a first robotic arm and movement of a second robotic arm such that a radiation source and a radiation detector move to different positions of the first position and the second position.

[0091] Example 16: In some examples of the method of Example 15, the input indicates an imaging angle for evaluation of the object, and the method further includes determining a radiation source position and a detector position based on the imaging angle, wherein the radiation source position and the detector position include different positions of the first position and the second position.

[0092] EXAMPLE 17: In some examples of the method of Example 15 or Example 16, the method further includes controlling a radiation source orientation of the radiation source such that radiation is directed from a radiation source position to a detector, and controlling a detector orientation of the detector such that the detector is directed from a detector position to the radiation source, wherein the radiation source position and the detector position comprise different positions of a first position and a second position.

[0093] Example 18: In some examples of the method of any one of Examples 15 to 17, the method further includes receiving an input indicating a magnification for evaluating the object; determining a radiation source position that defines a radiation source radius based on the magnification; and determining a detector position that defines a detector radius based on the magnification, wherein the magnification is equal to the sum of the detector radius and the radiation source radius divided by the radiation source radius, and the radiation source position and the detector position include different positions from the first position and the second position.

[0094] Example 19: In some examples of the method of any one of Examples 15 to 18, the method further includes causing the radiation source to irradiate the object in response to controlling the movement of the first robotic arm and the second robotic arm.

[0095] Example 20: In some examples of the method of any one of Examples 15 to 19, the method further includes acquiring a series of radiographs at different detector locations along a plane tangential to a second surface of a second sphere in a spherical coordinate system, the different detector locations being spaced apart by a distance finer than a pixel size of the detector, and assembling the radiographs to form a composite radiograph having a higher resolution than the acquired radiographs.

[0096] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. 1. A system for non-destructive evaluation of an object, comprising: a first robotic arm; a radiation source coupled to the first robotic arm and configured to emit radiation; a second robotic arm; and a radiation detector coupled to the second robotic arm and configured to measure radiation emitted by the radiation source; a stage configured to support the object for non-destructive evaluation; a control unit; The control unit comprises: determining a first location located on a first surface of a first sphere within a spherical coordinate system based on the input; determining a second location located on a second surface of a second sphere within the spherical coordinate system based on the input, the second location being opposite the first location with respect to a center of the spherical coordinate system; controlling the movement of the first robot arm and the second robot arm such that the radiation source and the radiation detector move to the first position and the second position, respectively; configured to: The control unit acquiring a series of radiographs at different detector locations along a plane tangential to the second surface of the second sphere in the spherical coordinate system, the different detector locations being spaced apart by a distance finer than a pixel size of the radiation detector; assembling the radiographs to form a composite radiograph having a higher resolution than the acquired radiographs; The system is further configured to:

2. The control unit receiving the input indicating an imaging angle for evaluation of the object; determining the first position and the second position based on the imaging angle; The system of claim 1 , further configured to:

3. The control unit controlling a radiation source orientation of the radiation source such that radiation is directed from the first position or the second position toward the radiation detector; controlling a detector orientation of the radiation detector so that the radiation detector is directed toward the radiation source from the first position or the second position; The system of claim 1 , further configured to:

4. The control unit receiving the input indicating a magnification for evaluation of the object; determining a radiation source position that defines a radiation source radius based on the magnification; determining a detector position that defines a detector radius based on the magnification, wherein the sum of the radius of the radiation detector and the radius of the radiation source divided by the radius of the radiation source equals the magnification, and the radiation source position and the radiation detector position are each one of the first position and the second position; The system of claim 1 , further configured to:

5. The system of claim 1 , wherein the control unit is further configured to cause the radiation source to irradiate the object in response to controlling movement of the first robotic arm and the second robotic arm.

6. 10. The system of claim 1, wherein the radiation detector comprises a guard plate having at least one pressure sensor configured to disable movement of the second robotic arm in response to the pressure sensor detecting contact with an item.

7. The control unit acquiring a series of radiographs at different detector locations along a plane tangential to the second surface of the second sphere in the spherical coordinate system, the different detector locations being spaced apart by a distance greater than a pixel size of the radiation detector but less than a physical size of the radiation detector; assembling the radiographs to form a composite radiograph having an area larger than the physical size of the radiation detector; The system of claim 1 , further configured to:

8. A computer-readable storage medium containing program instructions, The program instructions, when executed by a system for non-destructive evaluation of an object disposed on a stage, cause the system to: determining a first location located on a first surface of a first sphere within a spherical coordinate system based on the input; determining a second location located on a second surface of a second sphere within the spherical coordinate system based on the input, the second location being opposite the first location with respect to a center of the spherical coordinate system; controlling the movement of the first robot arm and the movement of the second robot arm such that a radiation source and a radiation detector move to the first position and the second position, respectively; Let them do this, When the program instructions are executed, the system: acquiring a series of radiographs at different detector locations along a plane tangential to the second surface of the second sphere in the spherical coordinate system, the different detector locations being spaced apart by a distance finer than a pixel size of the radiation detector; assembling the radiographs to form a composite radiograph having a higher resolution than the acquired radiographs; A computer-readable storage medium further comprising:

9. 9. The computer-readable storage medium of claim 8, wherein the input indicates an imaging angle for evaluation of the object, and the program instructions, when executed, further cause the system to determine the first position and the second position based on the imaging angle.

10. When the program instructions are executed, the system: controlling a radiation source orientation of the radiation source such that radiation is directed from a radiation source position towards the radiation detector; controlling a detector orientation of the radiation detector such that the radiation detector is directed from a detector position toward the radiation source, wherein the radiation source position and the radiation detector position include each of the first position and the second position; The computer-readable storage medium of claim 8 , further comprising:

11. When the program instructions are executed, the system: receiving the input indicating a magnification for evaluation of the object; determining a radiation source position that defines a radiation source radius based on the magnification; determining a detector position that defines a detector radius based on the magnification factor, wherein the magnification factor is equal to a sum of a radius of the radiation detector and a radius of the radiation source divided by the radius of the radiation source, and the radiation source position and the radiation detector position comprise each of the first position and the second position; The computer-readable storage medium of claim 8 , further comprising:

12. 10. The computer-readable storage medium of claim 8, wherein the program instructions, when executed, further cause the radiation source to irradiate the object in response to controlling movement of the first robotic arm and the second robotic arm.

13. determining a first location located on a first surface of a first sphere within a spherical coordinate system based on input to a system for non-destructive evaluation of an object disposed on a stage; determining a second location located on a second surface of a second sphere within the spherical coordinate system based on the input, the second location being opposite the first location with respect to a center of the spherical coordinate system; controlling the movement of the first robot arm and the movement of the second robot arm such that a radiation source and a radiation detector move to the first position and the second position, respectively; Including, acquiring a series of radiographs at different detector locations along a plane tangential to the second surface of the second sphere in the spherical coordinate system, the different detector locations being spaced apart by a distance finer than a pixel size of the radiation detector; assembling the radiographs to form a composite radiograph having a higher resolution than the acquired radiographs; The method further comprises:

14. 14. The method of claim 13, wherein the input indicates an imaging angle for evaluation of the object, the method further comprising determining a radiation source position and a detector position based on the imaging angle, the radiation source position and the radiation detector position comprising respective ones of the first position and the second position.

15. controlling a radiation source orientation of the radiation source such that radiation is directed from a radiation source position towards the radiation detector; controlling a detector orientation of the radiation detector such that the radiation detector is directed from a detector position toward the radiation source, wherein the radiation source position and the radiation detector position include each of the first position and the second position; The method of claim 13 further comprising:

16. receiving the input indicating a magnification for evaluation of the object; determining a radiation source position that defines a radiation source radius based on the magnification; determining a detector position that defines a detector radius based on the magnification factor, wherein the magnification factor is equal to a sum of a radius of the radiation detector and a radius of the radiation source divided by the radius of the radiation source, and the radiation source position and the radiation detector position comprise each of the first position and the second position; The method of claim 13 further comprising:

17. The method of claim 13 , further comprising causing the radiation source to irradiate the object in response to controlling movement of the first robotic arm and the second robotic arm.

Images