For Rend Lake College Professor Chris Nielsen’s Automated Control Systems students, it was Judgement Day. A whole semester’s worth of hard work would be on display for everyone to see.
The culmination of over four months of work was built into class projects - two fully operational aluminum can crushers.
This year, to make it easier on himself, Nielsen decided to select the project. In the past, projects have included an automated car wash, a grain dispenser and a paper-folding device. That left a lot of variables in terms of operational requirements and difficulty for the instructor, who may have to trouble-shoot if groups encountered glitches along the way.
Automated Controls is a course designed to acquaint students with the control of automated industrial machinery, with emphasis on electrical, electronic and pneumatice control systems, ladder diagramming and troubleshooting experiences.
In March, each group submitted a written plan, which included a detailed description of the plan and how it would work; a list of switching and power devices, including the function of each; raw materials and their role in the finished product; at least one drawing of the proposed machine, and potential problems and anticipated solutions to be implemented in the event problems occur.
The following were general requirements of the operational finished product. Additional features to enhance the machine’s operation and/or set it apart from the other were optional.
* The crusher must have a hopper or magazine that holds at least 12 aluminum soda cans.
* To receive full-credit, the machine must crush 12 cans in 60 seconds, without interruption or adjustment.
* The machine must reject any non-aluminum can into a reject bin.
* The machine must have a crushed-can bin, which when full, will halt the machines operation and light a sensor indicating that status.
Another important aspect, weighing in at fifty percent of the total grade, was a detailed operator’s manual. The manual was required to contain, at the very least, all power wiring and hosing diagrams, logic diagrams, PLC ladder logic, PLC I/O connections, mechanical diagrams and a description of the purpose and operation of the system. The detailed description of the control system operation was to include each device and its role in the overall system.
Then, a simulation was held, giving the groups exactly one week to work out all the glitches before Judgement Day.
When all was said and done, and judgement was upon them, both groups hit the switches and held collectively their breaths. Their fears were all for naught when both machines fired up and began sending the soda cans down the chute.
The moods turned light and students began joking about the long, difficult project and the pitfalls encountered along the way.
Unfortunately for Nielsen, his extension cord took the brunt of the abuse, when one of the students accidently severed it. But those are the chances you take when you offer students the use of anything in the classroom for their projects.