One of the pitfalls of modern engineering is that it’s entirely possible to end up in a situation where a product or solution has been designed by someone who has never left a desk. Which wouldn’t be a problem if things didn’t have a tendency to work differently in real life than they do in theory.
One of those things is automatic chicken coop doors, which have to operate reliably in not only a wide range of climates but with a number of possible physical limitations as well. [Vinnie] has taken on the challenge of building one which actually accomplishes all of these tasks, after realizing that the off-the-shelf solutions were victims of design over practicality.
[Vinnie] designed this door to be operated by the one thing that’s always 100% reliable: gravity. A linear actuator lifts the door at the beginning of the day, and then at night it’s allowed to fall back down in its track. A latch secures it against smarter intruders like raccoons. [Vinnie] has found that this lifting mechanism holds up much better in mud, snow, ice, and other difficult conditions than any other method he’s tried so far.The system is built around a ATmega1284P, and calculates the sunrise and sunset times each day to know when to open or close the door. He’s built the system as a state machine which makes it more robust during power outages, which is a necessity since his chicken coop is mobile and is frequently out of range of WiFi and is battery powered.
The approach [Vinnie] takes to automation is something that has application outside of his own farmstead. Using state machines instead of schedules, ensuring the design is as simple as possible and works within its environment, and minimizing reliance on electric and data infrastructure can go a long way to solving problems that might not appear when designing something on paper.
He’s been automating many other things on his farm as well, and it’s worth checking it out if you haven’t seen it already.