Automated scanning systems for non-destructive inspection of curved cylinder-like workpieces

1. A method for scanning a workpiece having a curved section that extends longitudinally and circumferentially, the method comprising:

(a) moving a curved track along first and second linear tracks to a first longitudinal position, the curved track in the first longitudinal position being disposed radially outward from the curved section of the workpiece;

(b) adjusting a position of an NDI sensor unit relative to a carriage to which the NDI sensor unit is adjustably coupled by an extendible arm, the carriage in turn being movable along the curved track;

(c) moving the carriage along the curved track while the curved track is stationary at the first longitudinal position;

(d) during step (c), activating the NDI sensor unit to inspect a first strip-shaped area of the curved section of the workpiece;

(e) processing signals output from the NDI sensor unit to derive a first strip of scan data characterizing a structural state of the first strip-shaped area of the curved section of the workpiece;

(f) during step (c), acquiring location data representing locations of the NDI sensor unit relative to the workpiece; and

(g) mapping the first strip of scan data to a three-dimensional model of the workpiece based on the location data acquired in step (f).

2. The method as recited in claim 1 , further comprising displaying features overlaid on a representation of a portion of the three-dimensional model of the workpiece based on the results of steps (e) and (g).

3. The method as recited in claim 1 , wherein the workpiece has a shape of a full barrel, further comprising rotating the workpiece about a longitudinal axis and then repeating steps (a) through (g).

4. The method as recited in claim 1 , further comprising the following steps:

(h) subsequent to step (c), moving the curved track along the first and second linear tracks from the first longitudinal position to a second longitudinal position, the curved track in the second longitudinal position being disposed radially outward from the curved section of the workpiece;

(i) moving the carriage along the curved track while the curved track is stationary at the second longitudinal position;

(j) during step (i), activating the NDI sensor unit to inspect a second strip-shaped area of the curved section of the workpiece;

(k) processing signals output from the NDI sensor unit to derive a second strip of scan data characterizing a structural state of the second strip-shaped area of the curved section of the workpiece;

(l) during step (i), acquiring location data representing locations of the NDI sensor unit relative to the workpiece using the location tracking system; and

(m) mapping the second strip of scan data to the three-dimensional model of the workpiece based on the location data acquired in step (l).

5. The method as recited in claim 4 , wherein step (h) comprises generating pulses representing incremental longitudinal movements of the curved track along a stationary linear rail and step (i) comprises generating pulses representing incremental circumferential movements of the NDI sensor unit along the curved track.

6. The method as recited in claim 5 , further comprising:

converting the location data representing the locations of the NDI sensor unit during step (c) into simulated encoder pulses suitable for processing by non-destructive inspection scan software; and

correlating the simulated encoder pulses with the first strip of scan data.

7. The method as recited in claim 4 , wherein step (h) comprises the following steps performed during steps (c) and (e): emitting light directed toward retro-reflective targets affixed to the NDI sensor unit; and capturing returned light reflected by said retro-reflective targets, and step (i) comprises computing location data representing the locations of the NDI sensor unit relative to the workpiece based on the captured returned light.

8. The method as recited in claim 1 , wherein the workpiece is a fuselage section.

9. The method as recited in claim 8 , wherein the fuselage section is made of composite material.

10. A system for external scanning of a workpiece having a curved outer mold line, the system comprising:

first and second linear tracks which are mutually parallel;

a curved track disposed in a plane generally transverse to said first and second linear tracks, said curved track being coupled to and translatable relative to said first and second linear tracks;

a carriage coupled to and movable along said curved track;

an extendible arm having a proximal end coupled to said carriage;

an NDI sensor unit coupled to a distal end of said extendible arm;

a location tracking system capable of tracking the location of said NDI sensor unit relative to said workpiece; and

a data processing system capable of receiving scan data from said NDI sensor unit and location tracking data from said location tracking system and then correlating the scan data with the location tracking data.

11. The system as recited in claim 10 , wherein said location tracking system comprises a plurality of cameras, a first plurality of retro-reflective markers attached to the workpiece and arranged in a known pattern; a second plurality of retro-reflective markers attached to the NDI sensor unit and arranged in a known pattern, and a motion capture processor.

12. The system as recited in claim 10 , wherein said extendible arm comprises a first member coupled to said carriage and a second member which is translatable relative to said first member, and said location tracking system comprises:

a first encoder device that outputs signals representing incremental movements of said curved track along said linear tracks;

a second encoder device that outputs signals representing incremental movements of said carriage along said curved track;

a third encoder device that outputs signals representing a distance that said second member of said extendible arm has traveled relative to said first member; and

a computer system programmed to be capable of converting the output signals from said first through third encoder devices into location data representing locations of said NDI sensor unit.

13. The system as recited in claim 10 , further comprising a display system capable of displaying the scan data on a three-dimensional representation of the workpiece based on results of the correlating process performed by said data processing system.

14. A system for scanning a workpiece having a curved section that extends longitudinally and circumferentially, the system comprising:

a pair of linear tracks parallel to a longitudinal direction;

an arch frame that extends circumferentially and is arranged to travel along said linear tracks;

a first actuator which, when activated, causes said arch frame to travel along said linear tracks;

a curved track supported by said arch frame;

a carriage arranged to travel along said curved track;

a second actuator which, when activated, causes said carriage to travel along said curved track;

an extendible arm comprising a first member mounted to said carriage and a second member which is arranged to translate relative to said first member;

a third actuator which, when activated, causes said second member to translate relative to said first member; and

an NDI sensor unit mounted to said second member and operable to acquire scan data during its motion.

15. The system as recited in claim 14 , further comprising:

a first encoder device that outputs signals representing incremental movements of said arch frame along said linear tracks;

a second encoder device that outputs signals representing incremental movements of said carriage along said curved track;

a third encoder device that outputs signals representing a distance that said second member of said extendible arm has traveled relative to said first member; and

a computer system programmed to be capable of performing the following operations:

(a) tracking the location of said NDI sensor unit to acquire location data representing locations of said NDI sensor unit based on signals outputted by said first, second and third encoder devices;

(b) controlling said first, second and third actuators to cause said NDI sensor unit to travel along said curved track from a first circumferential position to a second circumferential position while said NDI sensor unit is adjacent to an outer mold line of the workpiece and said curved track is stationary;

(c) while said NDI sensor unit is traveling along said curved track from the first circumferential position to the second circumferential position and said curved track is stationary, controlling said NDI sensor unit to interrogate the workpiece and acquire a strip of scan data; and

(d) mapping the strip of scan data to a three-dimensional model of the workpiece based on location data acquired as said NDI sensor unit travels along said curved track from the first circumferential position to the second circumferential position.

16. The system as recited in claim 15 , further comprising a display monitor, wherein said computer system is further programmed to control said display monitor to display the strip of scan data overlaid on an image of a three-dimensional representation of the workpiece.

17. The system as recited in claim 16 , wherein said computer system comprises:

a data acquisition device connected to receive signals outputted by said second and third encoder devices and programmed to convert those signals into simulated encoder pulses; and

an inspection scanning subsystem connected to receive simulated encoder pulses from said data acquisition device and scan data from said NDI sensor unit, and programmed to decode received simulated encoder pulses into position data and then associate that position data with the scan data for display, wherein the position data represents coordinates of said NDI sensor unit with respect to the coordinate system of the workpiece.

18. The system as recited in claim 14 , further comprising:

a first plurality of retro-reflective markers attached to the workpiece;

a second plurality of retro-reflective markers attached to said arch frame;

a third plurality of retro-reflective markers attached to said extendible arm;

a plurality of cameras having said retro-reflective markers within respective fields of view;

a motion capture subsystem programmed to convert images from said cameras into calibration data representing a position and an orientation of the workpiece with respect to a motion capture coordinate system and first location data representing positions and orientations of said NDI sensor unit with respect to the motion capture coordinate system during movement of said NDI sensor unit; and

a motion tracking subsystem connected to receive said first location data from said motion capture subsystem and programmed to output second location data which is a function of the first location data received from said motion capture subsystem, said second location data representing positions and orientations of said NDI sensor unit with respect to a coordinate system of the workpiece.

19. The system as recited in claim 18 , further comprising:

a data acquisition device connected to receive said second location data from said motion tracking subsystem and programmed to convert portions of said second location data received from said motion tracking subsystem into simulated encoder pulses; and

an inspection scanning subsystem connected to receive simulated encoder pulses from said data acquisition device and scan data from said NDI sensor unit, and programmed to decode received simulated encoder pulses into position data and then associate that position data with the scan data for display, wherein the position data represents coordinates of said NDI sensor unit with respect to the coordinate system of the workpiece.

20. The system as recited in claim 19 , further comprising a display monitor and a display computer programmed to control said display monitor to display the scan data overlaid on an image of a three-dimensional representation of the workpiece.

21. A system for scanning a workpiece having a curved section that extends longitudinally and circumferentially, the system comprising:

a pair of linear tracks parallel to a longitudinal direction;

a curved track that extends circumferentially and is arranged to travel along said linear tracks;

a first actuator which, when activated, causes said curved track to travel along said linear tracks;

a carriage arranged to travel along said curved track;

a second actuator which, when activated, causes said carriage to travel along said curved track;

an extendible arm comprising a first member mounted to said carriage and a second member which is arranged to translate relative to said first member;

a third actuator which, when activated, causes said second member to translate relative to said first member; and

an NDI sensor unit mounted to said second member and operable to acquire scan data during its motion.

22. The system as recited in claim 21 , further comprising:

a first encoder device that outputs signals representing incremental movements of said curved track along said linear tracks;

a second encoder device that outputs signals representing incremental movements of said carriage along said curved track;

a third encoder device that outputs signals representing a distance that said second member of said extendible arm has traveled relative to said first member; and

a computer system programmed to be capable of performing the following operations:

(a) tracking the location of said NDI sensor unit to acquire location data representing locations of said NDI sensor unit based on signals outputted by said first, second and third encoder devices;

(b) controlling said first, second and third actuators to cause said NDI sensor unit to travel along said curved track from a first circumferential position to a second circumferential position while said NDI sensor unit is adjacent to an outer mold line of the workpiece and said curved track is stationary;

(c) while said NDI sensor unit is traveling along said curved track from the first circumferential position to the second circumferential position and said curved track is stationary, controlling said NDI sensor unit to interrogate the workpiece and acquire a strip of scan data; and

(d) mapping the strip of scan data to a three-dimensional model of the workpiece based on location data acquired as said NDI sensor unit travels along said curved track from the first circumferential position to the second circumferential position.

23. The system as recited in claim 22 , further comprising a display monitor, wherein said computer system is further programmed to control said display monitor to display the strip of scan data overlaid on an image of a three-dimensional representation of the workpiece.