Snowy’s eating — tweeting my cats weight & dining habits with a Raspberry Pi

Snowy enjoying her food while being measured
Snowy enjoying her food while being measured

Project Overview

There are two scales — one for weighing the cat; and an independent weight measure for her food. As Snowy enters the cat scale, an initial measurement is taken for her current weight along with an starting weight for her food. An overhead and lateral camera takes a photo every 5 seconds.

Diagram indicting two scales and camera placement
Diagram indicting two scales and camera placement
Snowy The Cat on Twitter

Hardware — how much food?

I needed to build two scales — one for the food and one for the cat. So another excuse for online shopping for a collection of load cells and load cell amplifiers.

A “straight bar” load cell
A “straight bar” load cell
Load cell mounted between boards
Load cell mounted between boards

Hardware — cat weight

To accurately weigh Snowy I needed a larger scale. I wanted a surface large enough for her body and tail so she could be weighted whist she was eating. The first step required measuring the length of a cat

Snowy was not helpful when I tried to measure her length
Snowy was not helpful when I tried to measure her length
Wooden offset bracket for load cell
Offset bracket for load cell
Closeup of wooden mounting bracket
Closeup of wooden mounting bracket
The four load cells are mounted to each corner and wired together
The four load cells are mounted to each corner and wired together
Two HX711 amplifier modules connected to the Raspberry Pi
Two HX711 amplifier modules connected to the Raspberry Pi

Real world testing

My first experiment was a dismal failure. After waiting an eternity for Snowy to approach the weigh station, she quickly discovered a flaw in my design.

Snowy avoiding the scale in version 1
Snowy avoiding the scale in version 1
Small walls around her food encouraged Snowy to stand on the scale
Small walls around her food encouraged Snowy to stand on the scale
Final cat weigh station — now painted
Final cat weigh station — now painted

What’s next

This blog covers the initial hardware steps for the ongoing catfit data project. Further blogs will describe data processing, trend analytics and data visualisation.

Links

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Simon Aubury

Simon Aubury

Day job: data steaming & system architecture. Night gig: IoT and random project hacking