Okay. I'm sorry if the following is obvious, but as you do not mention this, I will state it here:
Systems of this sort are normally divided into two parts:
A. The inspection system that produces the product good/bad signal.
B. The plant system for dealing with the identified products. Normally this will be implemented in a PLC, and will consist of:
- A detector (e.g. photocell) to detect the presence of the product at a known position. Fixed and probably very close to the inspection position (presumably also fixed).
- A quadrature encoder to track the exact movement along the conveyor
- A delay to wait before the product reaches the kick-off position. If there may be more than one product between the inspection position and the kick-off position, then things get more complicated as you have to track each individual product. Basically you wind up with a FIFO clocked by the encoder. Obviously you no longer need ultrafast hardware, as the delay can be adjusted to accommodate things like signal propagation delays and actuator timing. However they will need to be consistent.
- Safety system so that the kick-off cannot operate without all the guards around it, despite whatever you are doing adjusting the vision system.
You might think that a fixed delay, or a delay adjusted by the nominal conveyor speed will meet your needs, but my experience is that it is far better to measure the actual conveyor movement, as this will automatically deal with speed changes, drive roll slippage etc.
