Non-contact automated measurement for interface gaps

1 . A method of joining two sheets of material together, comprising:

moving a robot over the sheets of material to each of a plurality of fastening locations;

at each of the fastening locations, drilling a pilot hole through the sheets of material;

automatically measuring an interface gap between the sheets of material at each of the pilot holes using a gap measurement end effector on the robot and by inserting a sheathe through the pilot hole;

making one or more shims having a size based on the interface gap between the sheets of material,

installing the shims in the interface gap; and

tacking the sheets together using the robot, wherein tacking the sheets together includes:

automatically drilling full-sized holes in the sheets using a drill end effector on the robot,

verifying, through the full-sized holes, that any remaining gaps are within a desired tolerance; and

automatically inserting fasteners in the full-sized holes using a fastener insertion end effector on the robot.

2 . The method of claim 1 , further comprising:

verifying the full-sized holes are within a preferred tolerance.

3 . The method of claim 2 wherein the verifying the full-sized holes are within a preferred tolerance includes measuring a diameter of the full-sized holes.

4 . The method of claim 1 , further comprising:

measuring a size of each of the pilot holes using a hole measurement end effector on the robot.

5 . The method of claim 1 , wherein the making comprises making one or more shims having a size and thickness based on the interface gap between the sheets of material.

6 . The method of claim 1 , wherein automatically measuring the interface gap using the gap measurement end effector includes:

automatically driving a fiber optic probe into the pilot hole;

determining a profile by scanning walls of the pilot hole via the fiber optic probe; and

determining whether an interface gap exists at the walls of the pilot hole based on the profile.

7 . The method of claim 1 , further comprising:

installing a set of tracks on the sheets; and

mounting the robot on the set of tracks for movement along the tracks to each of the pilot holes.

8 . A portion of an aircraft fabricated according to the method of claim 1 .

9 . A system for fastening two sheets of material together, comprising:

a robot that is operated by a controller;

an end effector on the robot in conjunction with the controller configured to automatically drill pilot holes through the sheets of material;

an end effector on the robot in conjunction with the controller configured to automatically measure an interface gap between the sheets of material within the pilot holes by inserting a sheathe through the pilot holes, whereby one or more shims having a size based on the interface gap between the sheets of material are made and installed in the interface gap; and

an end effector on the robot in conjunction with the controller configured to tack the sheets together, wherein tacking the sheets together includes:

automatically drilling full-sized holes in the sheets,

verifying, through the full-sized holes, that any remaining gaps are within a desired tolerance; and

automatically inserting fasteners in the full-sized holes.

10 . The system of claim 9 , wherein the robot is mounted for movement along a surface of the sheets of material.

11 . The system of claim 9 , further comprising:

an end effector on the robot configured to automatically measure a size of the full-sized holes.

12 . The system of claim 9 , further comprising:

an end effector on the robot configured to verify the full-sized holes are within a preferred tolerance.

13 . The system of claim 9 , wherein:

the robot includes a carriage, and

the end effector on the robot configured to automatically measure the interface gap is mounted on the carriage.

14 . The system of claim 13 , further comprising:

a set of tracks removably mounted on the sheets of material,

wherein the carriage is mounted on and movable along the tracks.

15 . The system of claim 9 , wherein the end effector configured to automatically measure the interface gap includes:

a fiber optic probe configured to scan walls of the pilot holes for interface gaps,

an actuator configured to adjust a position of the fiber optic probe within the pilot holes; and

a control unit that detects an interface gap at the walls of the pilot hole based on a data from the fiber optic probe.