The Story

My dorm kitchen was improperly maintained by the dorm’s 150 residents, leading the resident assistants to lock the kitchen. I developed a door access device to hold residents accountable by tracking kitchen use. It’s been used for two years now and has over 1,500 logged entries.

Design and Analysis

Mechanical

• 3D printed gear and enclosure.
• Gear ratio chosen to minimize motor wear while keeping unlocking time under 5 seconds.
• Single contact switch with two adjustable limits allows physical range tuning.
• Repairable without removal from door.

Electrical

• Raspberry Pi Zero running a headless Linux distribution.
• Hobbyist motors, motor controller, and power supply, all under $60.

Software

• Secure tunnel exposes a local server to the internet, allowing it to receive HTTP requests.
• Python script controls the motor.
• Google Form script sends HTTP request when the form is completed.
• Google Sheets dashboard tracks recent uses to hold residents accountable.