Using Machine Vision to Assemble the F-22 Fuselage
“Using a beam of light as an “alignment pin” for making critical aircraft fuselage section mates.”
Precision Alignment Using Machine Vision
Progressive Assembly Platform Automation System (PAPAS)
Mid-Aft Mate Alignment System (MAMAS)
A machine vision camera called a “vision pin” is mounted inside a precision housing and a calibration method was devised to determine the precise center of image sensor. On an opposite facing clevis, a precision bored face of a “light pin” is exposed to the camera. These two items essentially create a virtual alignment pin that is made of a light beam. It is extremely accurate and as it is made exclusively of photons, it never gets stuck while trying to make a complex alignment and mate.
It is essential to note the system is not a simple closed loop tracking system with each vision pin independently attempting to achieve an independent goal. Three-dimensional measurements are being made in 4 places on each fuselage module. Three-dimensional motion is being induced in 4 other places on each fuselage module. The motion induced from any position affects the measurements in all axes at all positions. Conversely, to achieve a three-dimensional alignment at any one measurement position, requires movement at all the hard-point positions. The system works because the calculations to induce precisely the right motion to solve for 22 measurements using 7 axes of control on each module at each position determines how much and in what direction to move each motor before any movement take place.
When the left and right balls are within the outer circle, the MAMAS system is close enough to make accurate measurements. Selecting “RUN” causes the alignment. When the balls are within the inner circle, the water and butt alignment is within tolerance. The station alignment is shown on the bar below the circles.