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 (HS).
The first step in any project needs to begin with defining a solid and concise statement. As our groups were first assigned Heidi Schultz had already had an idea of what she wanted to design. Even with a preliminary design I knew that there were still a plethora of questions and concerns that needed to be addressed. The first and foremost, which I knew from previous experience, was establishing a client base. Knowing exactly what our customer market was would allow us to gear our design specifically for who we wanted to sell to. For example, I brought up the point that whatever our final product was going to be it needed to be of an appropriate size because having pets I knew that I wouldn't want another bulk item sitting in my living room. The conceive process in any project, especially a group project, is ultimately the most important task of them all. It not only drives a common agreement in moving forward but it is the decision that I refer back to every time there's a question regarding what, specifically, I need to accomplish (MT).
- relatively small
- allow access to food relatively quickly when approached
- hide food relatively quickly if the wrong pet approached
- easy to clean
- buildable using materials found in the HCC Engineering Lab
- dispense food in 1/4 cup increments
- act in response to a pet wearing or implanted with an RFID chip approaching the apparatus (HS).
- bowl rotator that would hide 3 bowls and make one accessible at all times- 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.
- "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.
Other alternatives considered included:
- Automatically dispensed vs. owner-measured food
- Magnet vs. RFID control
- Food inside a transparent box with RFID triggered door-lock vs. food bowl inside containment.
- 3D-printed housing vs. handmade
- Battery vs. corded power supply
- cylindrical or rectangular housing to hold pet food
- "screw/twisting" style dispenser below it.
- Food from dispenser fed through a tube to a bowl on a rotating platform
- When a pet approached, an arduino received the signal from an RFID reader and instructed the appropriate bowl to rotate out of a covered compartment and into the open for access, then food would be dispensed into the bowl.
- Then, the arduino instructed the food dipenser to release the appropriate number of 1/4 cup food increments into the bowl.
- The RFID reader would read microchips that were either implanted under the pet's skin or worn on a collar.
Prototype out of available materials scaled for a small dog or cat Includes:
- Arduino for control
- 9 volt battery for power
- servos for movement
- Hosing from wood or plastic
The next step would be to create an improved prototype out of superior materials , taking into consideration any feedback or discoveries from Prototype 1 and making appropriate changes. Once this prototype has been perfected we create scaled up versions in sizes appropriate for larger pets. The larger versions may need increased torque from a servo and possibly increased power to support the torque-providing device (HS).
Modeling and simulation
Each piece of the physical unit was designed in Sketchup2014 prior to prototyping. This allowed for detailed evaluation of specifications and potential issues prior to creation. I believe this led to a smoother constructions process (HS). The file can be reached here
Aesthetics and human factors
We attempted to keep the entire apparatus as small in overall size as possible. It takes up a floor space of 12"x6" and a wall space of approximately 6" x 18-24".
The prototype is not nearly as attractive as the final product ought to be. Ideally we would use a smooth, attractive plastic for most of the pieces to improve aesthetic value and make cleaning the unit easy. The final product will also not allow easy access to the moving, electrical, and mechanical components - lids and covers will be secured with screws.
- 3x6x12 inch box with a groove 1/8 inch from the top edge for the lid to slide in
- right side is slightly larger to allow for a piece of rack gear to protrude into the compartment and link with the gear assembly and still be able to retract completely to open
- mounts for the servo (see the below image)
- converted the measurements to inches and used those illustrated in the image below.
- box lid slides 5.75 inches but the box was only 3 inches high and the servo that turns the gears can only turn 180 degrees. So, any gear that fits inside the box would not have a large enough diameter to have a circumference (that moves the lid) large enough.
- Gears 0.9 and 2.25 inches in diameter create the proper turning distance of 5.75 inches when the servo turns them 105.4 degrees.
- Gear Creation:
- Sketchup plugin that allows for relatively easy gear creation can be downloaded at ||http://www.ohyeahcad.com/download/%7C%7C.
- this plugin only works in Sketchup 8 or earlier versions, downloadable at ||http://google-sketchup-pro.en.softonic.com%7C%7C.
- After downloading both of these files the plugin .rbz file must be manually placed into the Google > Sketchup8 > plugins folder. The gear function is found under menu item Draw > Involute Gear.
- I left the pressure angle at 20 degrees (If the gear teeth are not perfectly square, that is, they are slightly rounded or cut off at an angle, the pressure angle is the angle between the vertical side of the tooth and the line that angles away from it to the horizontal side of the tooth).
- The teeth and pitch radius determine whether the teeth of two gears fit together. Pitch radius 0.45 and 1.125 inches. 12 and 30 gear teeth respectively.
- teeth:gear ratio must be the same for each gear (See images below).
The tail end of this semester saw this project passed on to another group which consisted of Carlos Fernandez, Kevin Szostak, Arien Motaher, Asad Gillani,and Eldrick Kinmakon. Our group was able to push the project forward by completing initial design concepts created by the previous group,as well as address concerns that were to be revisited later by the prior group.
Components that were brought to fruition at this point of the project include:
- 3D printed wheel which holds and dispenses food
- Mountable container to release food to wheel
Currently working on the Implement phase of the project, we still have to map out all of the potential dilemmas we face with the project. All files and code prepared for this project can be found here.
During the implement phase of the project, the second group was able to take the completed components of the project and attempt to assemble them so as to bring the physical aspect to fruition. A New physical unit was completed utilizing wood, with openings created to affix the following:
- Servo motors
- Arduino Unit
- Food Container
Bolts were inserted into the 3d printed Wheel to help stabilize the unit during motion. The unit was sanded down so that it would pose no risk to any of the team members that worked on it, or any animal that my approach it should it be used. In order to attract any animal that may not know what it was, the unit was spray painted red so as to draw attention.