I have to detect the position of a plastic bottle tap in a tray. The tray is 60 x 60 cm (2ftx2ft). The bottle tap is 1 cm (0.4 inch) diameter and is always in the correct position that is with the internal threaded mouth to the tray.
I can manufacture the tap with any component inside or any drawing on the external surface.
The question is: Which is the most economical technology to locate te position of the tap?
magnetic? code bars and laser beam reader like in supermarkets? black and white vision? others?

 

I think that you could test with two throughbeam lasers. If the tray can move itself along an axle and it is possible to check this displacement, then, if it is possible to put one throughbeam oriented at 90° on the movement direction and the second throughbeam will be oriented at 45°. Now, if the beam are crossing on the edge of the tray and this point moves precisely on the edge, the x position is given when the 90° beam meets the tap (the sensor n°1 switches and we get the measure from the zero).
Y position is given by the sensor 2 switching. In fact: we can get the distance between the switch 1 and switch 2; the sensor 2 beam is 45° oriented and is tang(45°)=1.
Laser throughbeam may be XU2P18PP340DL by Telemecanique.
Hoping to be useful.
Best regards.
G. Rossi.
Schneider Electric Branch office - Bologna.