Alexander Lopez
Internet Connected Door Opener

Project Overview

Problem Statement

When I moved into my college dorm room, I quickly realized that my roommate and I had a nack for losing our keys. As a result we decided to build a machine to open our door for us; therefore, we could reduce the chance of being locked out.

Solution

The solution to the problem was a machine that would be able to open my door for me. I thought about the possible ways to achive this and eventually settled on the idea of having a web interface and a machine that would operate remotely from that interface. The machine would eventually consist of a stepper motor, an ESP8266 NodeMCU, and a few other parts. This machine is attached to the door, and then acts as a server that responds to clients. When a client presses a button on the website, the server responds by turning on the stepper motor.

Moreover, the full parts list and skills required are as follows.

Code can be found at my github.

Development Process

Prototype One

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The first prototpe consisted of one NodeMCU and a relay module with 4 relays. The relays would be used to modulate the poles of a two pole stepper motor by using the Stepper.h library included with the Arduino IDE.

A better solution

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After testing the relay module method, I realized the correct solution to the problem was to use a stepper driver to control the stepper motor. The driver chosen was the A4988 Stepper Driver. This was due to its low cost and versatility.

Starting Version 2

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The new design was soldered onto a breadboard pcb in order to make it more robust for testing the machine on the door. The problem with the breadboard before was that it was prone to falling apart when mounted vertically.

Version 2 completed

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The first working version of the door opener is pictured above. The first version of the door opener was inefficient with space because it used a very large assembly to pull on the door handle. Unfortunately, at the time, this was all we had to solve the problem.

Starting Version 3

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After identifyig the shortcommings of Version 2, I decided to move on to a custom solution. This allowed me to move away from the soldered breadboard and create a custom housing for the new pcb design. It also gave my roommate and I the opprotunituy to address the problem regarding the size of the machine that physically opened the door.

Version 3 Complete

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Depicted in the images is the current version of the door opener, Version 3. At this point most of the issues with previous versions have been addressed. The size of the apparatus that pulls on the door handle has been decreased to the size of a single stepper motor, the web interface has been refined, and the computer itself appears sleek and clean.

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