Half the story

Using machine vision to mount wheels on cars sounds like a pretty interesting application. Logically, there must be at least three parts to the task: determine the rotation of the studs or threaded holes on the wheel hub, and do the same on the wheel itself. Then pick up a wheel, rotate until it’s in angular alignment with hub, place and insert bolts or screw on nuts.

But that’s not what “Smart Camera Helps the Wheels Go ’Round and ’Round” in Vision & Sensors (August 22^nd, 2011,) describes. This article tells us how Matrox Iris smart cameras are used to check hole location on a wheel and to verify the correct wheel has been picked. We are also told that the robot mounts the wheel while the car moves past but, unless my reading skills are slipping (and they may be,) I could find no reference to how the wheel is aligned to allow insertion of studs. Yet this has to happen for the wheel to be secured.

A visit to the integrator’s web site, IBG Automation GmbH, (part of Goeke Group,) was only marginally more helpful. The details are in German but as I read it, this is a 3D application where the cameras are used to check angular orientation of both wheel and hub, guiding the robot appropriately.

I would like to know much more about this. For example, how is the lighting configured, and does the robot need depth perception (Z-axis) to know how far to move when mounting the wheel?

It’s a very interesting application but unfortunately Vision & Sensors is only telling us part of the story.