My concept...
I did look at the Denver air port project and luckily my scope is not as big as that. We are just doing a tiny part for the airport baggage handling system. Our scope is the check-in counters and the transport of the luggage to be handed over the airport's baggage sorting system. Our scope ends there when we hand over the luggage to the sorting system. And the sorting system is the most complex of all.
Anyway, i have come out with a concept which i think may work. As shown in the dwg above, i have 10 check in counters and i have the main conveyor belt running at a fixed speed. Therefore, i may do away with the encoders. The luggage is of fixed length i.e. 1m maximum and so no worries about the different sizes of the luggage.
I plan to divide the main conveyor belt into logical windows of equal size. Let's 10 logical windows. I will then translate the logical windows into a table in my plc. This table is initialise to be free upon startup.
I have photocells on the check-in counters to detect and stop the luggage while waiting for a free/unoccupied window. Once it is free, i will inject the luggage into the respective windows and set them as occupied. After t1 as i know the speed of conveyor is constant, i will move the index table as shown.
With the help of the table, i will then know which window is occupied and when i can inject new luggage into the free window.
The constraints is that if there is a power failure or plc failure, upon startup the operators must clear the whole conveyor line as the plc index table is initialised to be zeros.....
Please feel free to comment as this is an initial concept. I may have overlook many things.....
regards,
ApplePLC07
ps. yep we may not have past experience in this kind of project but we got to start somewhere... if projects are given to experts only, then most of newbies will be out of job...