EGR 450
Manufacturing Controls
Automatic Litter Cleaner Project
Introduction
The purpose of the project is to learn how to realized an automatic
control system(design, implement, and maintain). The system must meet functional
requirements, including intregating many devices. Every fifteen minutes
the cleaner will turn on and cycle through, removing any waste made during
that time period. The automated system must also contained some safety
device just in case the cat jumps in during an operating cycle. At the
present time their is a similar system in the market.
Solution
Controller-
- SLC-150
Programmable Controller-
- The processor unit houses solid state circuitry that
integrates processor, I/O interface circuitry, and memory that will process
and manipulate programmed information. This causes output devices to be
energized and de-energized in response to the On/Off status of input devices.
Input Devices
- Allen
Bradley 42GRU-9002 Photoelectric Sensor-
- Photoelectric sensors are used in many applications and
industries to provide accurate detection of objects without physical contact.
in its most basic form a photo sensor can be thought os as a limit switch-like
device, where the mechanical actuator or lever arm function is replaced
by a beam of light. The series 9000 sensors are designed to perform in
many harsh environments. It has 2 in. minimum sensing distance through
30 ft maximum with 3" reflector. Operating volts range from 70-264V
AC/DC, 50/60 Hz. and 15 mA. The photo eye has a selectable Light/Dark output
energized. The device comes with a 2 meter long 300V cable. The indicator
on the photo eye are as following: Green=Power, Yellow=Output, and Red=Margin.
- Light duty Limit Switches-
- Radioshack N.O or N.C. switch.
Outpur Devices
- 12V
DC Motor-
- Motor provide enough torque to move waste out of the
litter box.
- 12V DC LEDs-
- A light emitting diode was used for to show when the
power is on and also when the litter cleaner goes through a cleaning cycle.
The LEDs have a forward supply voltage of 12V DC typ. - 14 V DC maximum.
The LEDS are rated at 24 mcd brightness with a viewing angle of +- 25 degrees.
Materials
- 1.25" x .25" flat aluminum
- spiral cable wrap
- 20 AWG solid hook-up wire- 300V, 80C, 1/64 PVC
- project
enclosure-4" x 2" x1", strong durable ABS plastic
- 12 -p wiring
terminal block - 15A, 250V
- litter box- 1' x 1.5' x 4" strong durable plastic
- plexiglass- 4" x 12" x .25"
- machine screws- 4-40 screws with various lenghts
PLC Program Design Forms
Problems
1. The sifting comb doesnot run smooth on the track due
to 45 degree corners (turn). During some cycles the comb got stuck in the
corners. Redesign of the track is recommended (rounding out the corners).
2. The Leds used for indicting the power and cycle, need
to be change to 12V AC. The SLC-150 has AC triacs output capability.
Other than that the project turn out to be succesful.
The program work and the mechanism used to remove the waste from the litter
box worked.
Conclusion
Things I accomplished are:
1. Learned how to automate a repetative process using
a SLC-150, input devices, and output devices.
2. Learned theoretical procces design.
3. Learned to write PLC programs.
4. Learned how to integrate devices to come up with a
working system.
