Robotic end effector including multiple abrasion tools

1. A method comprising using a robotic end effector to perform surface preparation on a surface of an aircraft fuselage, the end effector including first, second and third abrasion tools having their backing pads in a triangular arrangement, the surface preparation including selectively extending, retracting and operating the abrasion tools and rotating the abrasion tools as a group as the end effector is moved in a relatively straight path along the fuselage from tail to nose without having to change the abrasion tools.

2. The method of claim 1 , wherein edge sanding is performed by selectively retracting, extending, operating, and rotating the abrasion tools.

3. The method of claim 2 , wherein the edge sanding is performed at doors, windows and joins in the fuselage.

4. The method of claim 1 , further comprising applying a constant pressure to the abrasion tools through serially-connected ball joints.

5. A robot system comprising a robotic end effector including first, second and third abrasion tools having backing pads arranged in a triangular arrangement about an axis of rotation, wherein the abrasion tools are rotatable as a group about the axis, and each abrasion tool is selectively operable, retractable and extendable.

6. The system of claim 5 , wherein nominal centers of the backing pads form an equilateral triangle.

7. The system of claim 5 , wherein the end effector further includes an actuator for each abrasion tool, each actuator independently operable to selectively extend and retract its corresponding abrasion tool.

8. The system of claim 5 , wherein the abrasion tools are random orbital abrasion tools.

9. The system of claim 5 , wherein the backing pads have an overlapping relationship.

10. The system of claim 5 , further comprising a ball joint assembly for each abrasion tool, each ball joint assembly including a first ball joint connected to its corresponding abrasion tool, and a second ball joint connected between the first ball joint and the robotic end effector.

11. The system of claim 7 , wherein each actuator is operable to selectively withdraw its abrasion tool from surface preparation and selectively return its abrasion tool for surface preparation.

12. The system of claim 10 , wherein each ball joint assembly further includes a linear actuator, connected to the second ball joint, for applying constant pressure to its corresponding abrasion tool.

13. The system of claim 12 , wherein the linear actuator includes a pneumatic double compression cylinder and a pressure regulator for regulating pressure in the cylinder so a constant force is applied to its corresponding abrasion tool.

14. The system of claim 5 , further comprising a robot having at least six axes for positioning and orienting the end effector.

15. The system of claim 14 , wherein the robot includes a robot arm and a wrist.

16. A system comprising:

a multi-axis robot; and

an end effector including first, second and third random orbital abrasion tools in a triangular arrangement, the abrasion tools selectively retractable, extendable and operable; ball joint assemblies coupled to the abrasion tools; linear actuators connected to the ball joint assemblies; and pressure transducers for regulating the linear actuators to apply constant pressure to the abrasion tools regardless of orientation of the end effector.

17. The system of claim 16 , wherein the multi-axis robot includes a wrist and an arm between the wrist and the end effector.

18. The system of claim 17 , wherein the multi-axis robot is a six-axis robot.

19. The system of claim 16 , each ball joint assembly including a first ball joint connected to its corresponding abrasion tool, and a second ball joint connected between the first ball joint and its corresponding linear actuator.

20. The system of claim 19 , wherein the abrasion tools are arranged about an axis of rotation, and wherein the abrasions tools are rotatable as a group about the axis.