Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: dsesmg on September 28, 2009, 04:42:15 AM

Title: matching an encoder pulse to a certain pitch.
Post by: dsesmg on September 28, 2009, 04:42:15 AM
Hi, I want to desperately find out solution for my conveyor.
I've built a conveyor that can sort out objects according to their weight.
You can think of a simple weight sorting machine.
I am using chain links which has attachment that looking like this.
http://www.flickr.com/photos/34955071@N02/3961551085/#sizes/o/ (http://www.flickr.com/photos/34955071@N02/3961551085/#sizes/o/)
According to the pitch of chain attachments, I am using an encoder to send the specific encoder pulse to a microcontroller. Ofcourse the specific encoder pulse will match the pitch of chain attachments so that the microcontroller could detect object location and send the object to its corresponding dischrage area.
Ok, my question and problem is this.
I adjusted the specific encoder pulse according to the position of the chain attachment. It means I locate one chain attachment in the center position of load cell. When that one(chain attachment) make a full revolution, it doesn't accurately positioned in the center position of loadcell at the timing when the encoder send pulse to the microcontroller. It is located differently like sometimes it is positioned half of the loadcell position, sometimes, 1/3, sometimes, 1/4. This is the problem.
Is this because the chain attachment has tolerance and this tolerance has accumulated to make such unaccurate positionning?