The "Big Dawg" Feeder

This is not an ordinary dog feeder

It is a weapon built for endurance, an instrument of control over hunger itself. The weak offer fragile devices that falter under pressure - feeders so frail they split open at the first scratch of a claw, crumble beneath the weight of a hungry beast, and surrender to chaos before the battle even begins. This is not one of them.

Rising 1 meter into the air, The "Big Dawg" Feeder stands like a fortress of steel (but it's actually plastic). Its 40-liter reservoir holds a stockpile of sustenance, delivered by the relentless force of an olds elevator — precise, efficient, unyielding.

Designed for the battlefield, it withstands the assaults of claws, teeth, and rage without faltering. Eight dogs are fed with certainty, without hesitation, without failure.

It is not a feeder.
It is a standard of strength.
It is the enduring power that hunger cannot overcome.

But it didn't work. After countless hours of design work and 3D Printing, the elevator required too much torque to turn it because of a jamming issue in the scoop system. We hope to release a version two which will work, but right now, we have no time left.

Features

• Feeds up to 8 dogs
• Meal time scheduling
• Beautiful Web UI
• Snack function
• Food Level Low Alert
• Holds up to 40L of dog food

Olds Elevator

This project uses the concept of an olds elevator. An explanation video can be found here

Assembly Instructions

Assembly Instructions can be found at the following links

• Bevel Gears Assembly
• Motor Assembly
• Elevator Tube Assembly
• Discharge Chute Assembly
• Base Plate Assembly

Code

The code can be found at the GitHub Repository along with the setup instructions for the Raspberry Pi and Arduino.

The Raspberry Pi runs Node RED.

In the UI flow a UI control node outputs to a function that will call up the dog's feeding times and display them in the form node. When a form is saved, it's values are stored in the global context. Underneath those nodes there is another form node that is connected to a node that saves the forms values in the flow context. These nodes allow the user to choose a snack amount for their dogs. A form node lets the user log food added or taken out of the feeder so that the feeder can keep a rough estimate of the amount of food left. An error message will be triggered if the food level drops below 100g.

In the Feed Control flow an inject node injects: the current time as a JavaScript Date object and the dog's form data. This is fed into a node that converts the times from the dog's form data to JS Date objects. These values are fed into a function node that checks if it is time to be fed and of they have been fed already in that minute to prevent overfeeding. If it is time to be fed then it returns the JS object (found below) that contains the dog's id, the meal name, the amount of food and the time. If it is not time to be fed then the function returns null

msg.payload = {
  dogName: msg.dogID,
  meal: mealName,
  amount: dog[mealName + "Amount"],
  time: mealTime
};

The above object is passed into an MQTT out node which sends the object to the Arduino.

Arduino

When the Arduino powers up, it connects to Wi-Fi and subscribes to the MQTT topic: dogfeeder/receive. Then it zeroes the stepper2 using a magnetic hall sensor.

When a message is sent to the Arduino, the messageHandler function takes in the data and parses it to JSON. It then checks if the dogName is a list of dogs or just one dog. Then it gets the stepper positions for each dog from this function below:

int getDogAngle(const char* dogName) {
  if (strcmp(dogName, "dog1data") == 0) return 0 * 3;
  if (strcmp(dogName, "dog2data") == 0) return 90 * 3;
  if (strcmp(dogName, "dog3data") == 0) return 180 * 3;
  if (strcmp(dogName, "dog4data") == 0) return 270 * 3;
  if (strcmp(dogName, "dog5data") == 0) return 0 * 3;
  if (strcmp(dogName, "dog6data") == 0) return 90 * 3;
  if (strcmp(dogName, "dog7data") == 0) return 180 * 3;
  if (strcmp(dogName, "dog8data") == 0) return 270 * 3;
  return -1;
}

Once it has the correct positions, it queues the feed job. When it's turn comes, the job is dequeued and processed. The Arduino turns the stepper drivers on, stepper2 turns to the correct bowl and stepper1 dispenses the food.

Software Used

• Autodesk Fusion 360
• Dassault Systèmes SOLIDWORKS
• Fritzing
• Arduino IDE
• Bambu Studio
• Node-RED

Parts List

• 2x Nema 23 Stepper Motor
• 2x Stepper Motor Driver @ 4.2A (DQ542MA)
• 1x AC-DC Power Supply @ 24VDC 6.5A
• 2x 25mm x 47mm x 12mm Deep Grove Ball Bearing
• 2x 25mm x 52mm x 15mm Deep Groove Ball Bearing
• 1x 10mm x 19mm x 5mm Deep Groove Ball Bearing
• 2kg eSUN Black PETG
• 1x 70L Plastic Storage Tub
• 1x 8mm x 1000mm Fiberglass Rod
• 1x 20mm x 17.3mm x 2000mm Steel Tube
• 1x Arduino Uno R4 Wi-Fi
• 1x Raspberry Pi 5 8GB (or equivalent)
• Protoboard/Breadboard
• M-M Jumper Wires
• Wire
• 1x 10A 250V AC Kettle Plug and Switch (C14)
• 1x 5V (10A 250V) Relay
• 1x Hall Effect Sensor
• Neodymium N38 6mmx2mm magnets
• M3 Button Head Hex Socket Machine Screws (10mm, 16mm, 20mm)
• M5 Button Head Hex Socket Machine Screws (10mm, 16mm, 20mm)
• M5 Countersunk Head Hex Socket Machine Screws (10mm, 16mm, 20mm)
• M5 Socket Screws (20mm, 25mm, 30mm, 35mm, 40mm)
• Nuts and washers for screws above

3D Printed Parts

Print Settings

eSUN PETG

eSUN ePLA-ST

Strength

Standard

Same as Strength but with these changes

Supports

Screw Base

Discharge Chute_Bottom