Low-cost Home Automation with Voice Control

STORY

Background

Today's home automation systems are expensive and often require the ability to install or modify existing hardware in the home. These two barriers to entry prohibit low-income individuals from joining the world of home automation.

My solution was to create an open source node.js server on a Raspberry Pi 2 running Windows 10 IoT Core for controlling preexisting hardware in the home without needing to make any permanent modifications. As a proof of concept, I have set up a basic home automation system in my dorm room using this node.js server.

The node.js server runs on the Raspberry Pi 2 with Windows 10 IoT Core. A Photon is used to  control the actual hardware in the room. There are two ways to interact with the system:

Voice Control

The voice control interface on a mobile device displaying some example queries.

When the microphone is clicked in the web browser, the Raspberry Pi 2 starts recording audio. 
When the microphone is clicked again the audio is sent it to Wit.ai, a natural language API, to process speech and extract intents. The intent is then returned to the Raspberry Pi and the action to accomplish the intent is performed.

The voice control is not limited to just controlling hardware. You can ask for information as well. A few examples include:

• "What is the temperature?"

• "How many feet are in a mile?"

• "What is the address of the closest Chipotle?"

• "How many people are at the Ratty?" (a dinning hall at Brown University)
• "Display all comedy movies" (if you have a Kodi media server)

and many more. It is also exceedingly easy to add new functionality to the node.js server. More information about expanding functionality can be found on this project's Github page.

Control Panel

The control panel interface on a mobile device. You can lock/ unlock the door, turn the overhead lights on/ off, and set the color of the LED strip.

The control panel provides an interface for controlling the various hardware components in the room. It also provides a visualization of the current state of each device (in the image above the door is locked, the overhead lights are on, and the LED strip is off).

The control panel sends requests to the Raspberry Pi running Windows 10 IoT Core which then sends the Photon a message to alter a given hardware component. The control panel utilizes an API provided by the node.js server which can be used to create your own interfaces or mobile apps.

The overhead lights in the room are controlled with a simple servo motor attached to the light switch.

The door lock is controlled by a cable attached between the door handle and a continuous rotation servo. The green PCB in the bottom right of the screen is a Reed switch which detects when the door is unlocked.


The photon board and the mess of cables from the various lights and servos. The individual circuits are available in the schematics section in a much more readable format.

The front door with all of the hardware components.


Install the latest version of Windows IoT Core onto your Raspberry Pi 2.
Install the Node.js tools for Windows IoT bundle onto your Raspberry Pi 2.
Download the zipped version of the node.js server code for this project.
Connect to your Raspberry Pi 2 using power shell.
Copy the unzipped folder to your Raspberry Pi and follow the software setup section in the repository's README.
Start the server using & 'C:\Node.js (Chakra)\Node.exe' C:\path-to-backend-code\bin\www (Be sure to replace path-to-backend-code with the path to the node.js folder on the Raspberry pi you copied over in step 5)

Open your browser to http://:3000 and enjoy!

SCHEMATICS

RGB LED Strip Control

This circuit is used to control the RGB LED strip. The circuit uses N-channel MOSFETs to change the color pins of a 5050 Common anode LED strip (depicted by a single LED in the diagram). A 12v power supply is attached to the barrel connector. The resistors attached to the gate pins of the MOSFETs are 330Ω each.

Door Lock

Download

A continuous rotation servo winds and unwinds a cable to move the door handle. To unlock the door, the servo winds the cable until a magnet on the door handle trips the reed switch (magnet sensor). To lock the door, the servo unwinds the cable for 2 seconds.

Light Switch

Download

A generic servo motor that rotates to one angle for turning the light switch on and another angle for turning the light switch off.

CODE

Photon code used to control the door lock, overhead lights, and the LED strip

C/C++

This code should be uploaded to your Photon board. It matches the pins from the circuits in the schematics section.

#include "rgb-controls/rgb-controls.h"
#include "SparkJson/SparkJson.h"
using namespace RGBControls;

Servo servo;
String method = "";
Color c1(0, 0, 0);
Color c2(0, 0, 0);
Led led(D0, D1, D2);
bool is_locked = true;
bool switch_on = true;

void setup() {
  RGB.brightness(16);
  Spark.function("method", color_method);
  Spark.function("lock", lock);
  Spark.function("switch", mainLight);
  Spark.variable("is_locked", &is_locked, BOOLEAN);
  Spark.variable("switch_on", &switch_on, BOOLEAN);
  
  pinMode(D5, INPUT);
  pinMode(D7, OUTPUT);
  pinMode(WKP, OUTPUT);
  pinMode(RX, OUTPUT);
}

void loop() {
    if (method.equals("fade")) {
        led.fade(c1, c2, 5000);
    }
    
    if (digitalRead(D5) == HIGH) {
        is_locked = false;
        delay(100);
        servo.detach();
    } else {
        is_locked = true;
    }
    digitalWrite(D7, digitalRead(D5));
}

int lock(String state) {
    if (state.equals("lock")) {
        if (!is_locked) {
            is_locked = true;
            servo.attach(RX);
            servo.write(150);
            delay(2000);
            servo.detach();
        }
        return 1;
    } else if (state.equals("unlock")) {
        servo.attach(RX);
        servo.write(30);
        return 0;
    } else {
        return -1;
    }
}

int mainLight(String state) {
    if(state.equals("on")) {
        servo.attach(WKP);
        servo.write(10);
        delay(1200);
        servo.detach();
        switch_on = true;
        return 1;
    } else if(state.equals("off")) {
        servo.attach(WKP);
        servo.write(70);
        delay(1200);
        servo.detach();
        switch_on = false;
        return 0;
    } else {
        return -1;
    }
}


int color_method(String command) {
    char json[100];
    command.toCharArray(json, 100);
    StaticJsonBuffer<512> jsonBuffer;
    JsonObject& root = jsonBuffer.parseObject(json);
    
    if (!root.success())
        return -1;
    
    method = root["method"];
    if (method.equals("fade")) {
        c1 = Color(root["c1"][0], root["c1"][1], root["c1"][2]);
        c2 = Color(root["c2"][0], root["c2"][1], root["c2"][2]);
    } else if (method.equals("set")) {
        c1 = Color(root["c1"][0], root["c1"][1], root["c1"][2]);
        led.setColor(c1);
    }
    
    return 0;
}

Home Automation Backend code

This is the repository for the node.js backend code that runs on the Raspberry Pi 2

michael-gillett / home_automation

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Latest commit to the master branch on 9-21-2015