Presented at DroidCon NYC 2017 (http://droidcon.nyc/) Hackster Project: https://www.hackster.io/oscarsalguero/sentinel-8234b3 Servo Hat Driver on GitHub: https://github.com/RacZo/adafruit-16-channel-servo-hat-driver

1. Sentinel
The First Home Security Robot Powered by Android Things™
https://www.hackster.io/oscarsalguero/sentinel-8234b3
Oscar Salguero
@OscarSalguero

2. Agenda
● Demo
● Motivation
● Hardware
● Software
● Roadmap
● Tips

3. Demo

4. Video

5. Video

6. Motivation

7. ● Home security cameras are expensive
● Most surveillance services have crazy high monthly fees
● Gotta have a camera on each room
● IP cameras are hackable
● Setup is complicated
● Can’t see anything from a WAN without DDNS
● OEM and 3rd party remote viewing apps are unreliable
Motivation

8. ● Don’t talk to other smart home/IoT hardware
● Still use email to send you alerts
● Alert! A leaf moved! (notifications are irrelevant)
● No face detection nor facial recognition
● No image classification
● Can’t find your pet if it walked out of frame
Motivation

9. ● Pets move from room to room or go outside
● Entertainment…? Throw a tennis ball to Fido from
anywhere!
● Check if your pets have food or water
● Keep an eye on the kids
● See if a delivery arrived
Motivation

10. Hardware

11. Rover 5 Platform
https://www.pololu.com/product/1535

12. Raspberry Pi 3, 32GB
SD Card with
Android Things ™
https://www.adafruit.com/product/3292

13. Adafruit DC and
Stepper Motor
HAT for RPi
https://www.adafruit.com/product/2348

14. Adafruit
16-Channel PWM
Servo HAT for RPi
https://www.adafruit.com/product/2327

15. Raspberry Pi
Camera Module
v2
https://www.adafruit.com/product/3099

16. https://www.sparkfun.com/products/
10335
Pan/Tilt Bracket

17. 3D Printed Camera Mount
https://goo.gl/hMTwSb

18. 8Bitdo NES30 Pro
Bluetooth Controller
http://www.8bitdo.com/n30pro-f30pro/

19. Android Phone
https://store.google.com/category/phones

20. ● Stereo speakers
● USB Mic
● 30,000 mah Power bank
● Couple of plastic
expansion plates
● USB and barrel jack
cables, wires
● Standoffs, nuts, screws,
etc.
Other Stuff...

21. Software

22. Android... Android Everywhere!
● Android Studio 3.0 Beta
● Android Things ™
Developer Preview
● Antonio Zugaldia’s
Android Robocar Project
(Adafruit PWM and Motor
Hat Java Library)
http://androidrobocar.com

23. Firebase & Google Cloud

24. DC and Stepper Motor Hat Driver
// I2C Bus Name
public static final String I2C_DEVICE_NAME = "I2C1";
// Motor Hat Address
private static final int MOTOR_HAT_I2C_ADDRESS = 0x60;
// Motor Hat
private AdafruitMotorHat mMotorHat;
// Motors
private AdafruitDcMotor motorFrontLeft, motorFrontRight, motorBackLeft, motorBackRight;
https://github.com/zugaldia/android-robocar

25. DC and Stepper Motor Hat Driver
mMotorHat = new AdafruitMotorHat(I2C_DEVICE_NAME, MOTOR_HAT_I2C_ADDRESS);
motorFrontLeft = mMotorHat.getMotor(1);
motorBackLeft = mMotorHat.getMotor(2);
motorFrontRight = mMotorHat.getMotor(3);
motorBackRight = mMotorHat.getMotor(4);

26. private void moveForward() {
Log.d(LOG_TAG, "Moving forward.");
motorFrontLeft.run(AdafruitMotorHat.FORWARD);
motorFrontRight.run(AdafruitMotorHat.BACKWARD);
motorBackLeft.run(AdafruitMotorHat.BACKWARD);
motorBackRight.run(AdafruitMotorHat.FORWARD);
}
private void turnRight() {
Log.d(LOG_TAG, "Turning right.");
motorFrontLeft.run(AdafruitMotorHat.FORWARD);
motorFrontRight.run(AdafruitMotorHat.FORWARD);
motorBackLeft.run(AdafruitMotorHat.BACKWARD);
motorBackRight.run(AdafruitMotorHat.BACKWARD);
}
DC and Stepper Motor Hat Driver

27. 16 Channel Servo HAT Driver
// Servo Hat Address
private static final int SERVO_HAT_I2C_ADDRESS = 0x41;
// Servo Hat
private AdafruitServoHat mServoHat;
// Servos
private AdafruitServo mTiltServo;
private AdafruitServo mPanServo;
https://github.com/RacZo/adafruit-16-channel-servo-hat-driver

28. 16 Channel Servo HAT Driver
// Servo Hat initialization
mServoHat = new AdafruitServoHat(I2C_DEVICE_NAME, SERVO_HAT_I2C_ADDRESS);
// Variables to configure the servos according to their manufacturer specs
double minAngle = 20.0;
double maxAngle = 150.0;
double minPulseDurationRange = 0.7; // ms
double maxPulseDurationRange = 1.50; // ms
int frequency = 40;

29. // Add the servos to the hat in the order they are connected from index 0 to 15
mPanServo = new AdafruitServo(0, frequency);
mPanServo.setPulseDurationRange(minPulseDurationRange, maxPulseDurationRange);
mPanServo.setAngleRange(minAngle, maxAngle);
mPanServo.setAngle(SERVO_INITIAL_PAN_ANGLE);
mServoHat.addServo(mPanServo);
mTiltServo = new AdafruitServo(1, frequency);
...
mServoHat.addServo(mTiltServo);
…
// Add the servos to the hat in the order they are connected from index 0 to 15
mServoHat.rotateToAngle(mPanServo, 90);
mServoHat.rotateToAngle(mTiltServo, 90);
16 Channel Servo HAT Driver

30. Companion Android App
● See your pet from
anywhere!
● Remote Control
● Live feed (kind off)
● Motion and loud
sound alerts
● Image history &
management

31. Tips

32. Tips
● Draw, sketch or diagram your idea first
● Write down a list of materials and a list of
desirable features
● Research about the technologies such as
APIs, protocols, etc. you’ll need to achieve
the desired features, research about the
parts and materials before purchasing
them; pros/cons matter!
● Use Etcher to push Android Things image
to an SD Card
● Learn to love adb and make a command
cheat sheet

33. Tips
● Add speech-to-text help you debug stuff
● Run and analyze sample code (GitHub), ask
questions (forums, Stack Overflow), watch
how it is done (YouTube)
● Redundancy (if you can, buy more than 1
board)
● Learn about circuits, voltages and currents
beforehand and be mindful about power
requirements
● Use rechargeable batteries
● Always have a wired USB keyboard,
mouse and an HDMI cable at hand
● Try not to burn your fingers when soldering
headers (It hurts!)

34. The Road Ahead
Software Improvements
● Real time video & 2-way audio (Web RTC)
● Face detection and feature tracking
(OpenCV)
● Facial recognition (TF)
● Real time image classification (TF)
● Voice control (Google Voice Actions)
tinyLiDAR (HW + SW)
● Indoor mapping and navigation using
● Follow moving targets
● Autonomous patrolling

35. tinyLIDAR

36. tinyLIDAR

37. Questions?
This presentation is available at:
https://goo.gl/EgvWFd

38. Thank You!
Oscar Salguero
@OscarSalguero