User:BDolge/BDolge/AutomaticPetFeeder/CDIO/Minimal Design

Problem Statement

The challenge was to design a pet feeder that would allow the owner to limit a pet's access to food and control the quantity of food dispensed at a given time.

The Design Process

Requirements for each element or component derived from system level goals and requirements

The pet food bowl housing needed to be relatively small, allow access to food relatively quickly when approached, and hide food relatively quickly if the wrong pet approached. It also needed to be easy to clean and buildable using materials found in the HCC Engineering Lab. The food "hopper" which holds the bulk food and dispenses it at the appropriate time also needed to take up as little space as possible, in conjunction with the bowl housing. It was decided that it should dispense food in 1/4 cup increments. It also had to be built out of materials in the Engineering lab. Both of these would be required to act in response to a pet wearing or implanted with an RFID chip approaching the apparatus.

Alternatives in design

The group initially considered using a bowl rotator that would hide 3 bowls and make one accessible at all times. This idea was set aside when it became clear that the servos we had to work with were not powerful enough to turn a platform holding four bowls, and using a DC motor would have required adding sensors and became unnecessarily complicated. It also used a "screw" feeder to dispense food, rather than the final rotating food dispenser. The screw feeder would have been more complicated to measure the quantity of food, though it may have used less torque to control.

The initial design

The initial design consisted of a cylindrical or rectangular housing to hold pet food, with a rotating dispenser below it. Food from that dispenser was fed through a tube to the bowl housing. The bowl sat in the forward compartment and the components that operate it in the rear compartment. When a pet approached, an arduino received the signal from an RFID reader and instructed the bowl housing to retract its lid. Then, the arduino instructed the food dipenser to release the appropriate number of 1/4 cup food increments into the bowl.

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  Pet Food Storage and Dispenser
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  Bowl housing without components - to illustrate lid/ groove design
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  Feeder box with gear components

The sketchup file containing these designs can be found here.