1. ECE 445 Spring 2019 - Head Orientation Tracking Module for Headphones
Group 46
Molly Fane, Sally Zhou, Cary Zhu
Cary

2. Introduction
Worked with Professor Eli Fieldsteel, Director of Experimental Music Studios
Deliver a more immersive and realistic audio experience
Make it feel as though the sound is coming from fixed positions in a room despite moving your head
Cary

3. Objective A device capable of
Attaching to any pair of over-the-ear headphones
Communicating accurate data about the orientation of the head back to computer
Orientation: roll, pitch, yaw
Cary

4. Physical Diagram
Cary - sensor sends data to the computer, computer sends sound signal to the box

5. Sally

6. PCB Indicator LED’s Sensor Chip & Peripherals Bluetooth Connections
Bluetooth Module
Battery Connector Jack
3.3v Regulator
5v Regulator
Test Points for Code Upload
Sally
ATMega2560 Chip

7. PCB Design: Extra Features
EAGLE used to design PCB
Schottky Diodes on USB and 9V power supplies.
Test points
Power LED
Status LED
USB and Bluetooth breakout boards.
Molly

8. Power Unit Battery: 9V Battery (5% Tolerance) Regulators
The regulators take 9 volts from battery to produce 5±0.5V and 3.3±0.3V
Capable of delivering 0.501A for 3.3V
Capable of delivering 0.50mA for 5V
Cary

9. Power Unit Schematic
Cary - 5V for atmega2560 and bluetooth

10. Computational Unit: Microcontroller
Drives accelerometer, magnetometer to produce orientation
Used ATmega2560 Chip
Drives Bluetooth controller
Programmed using USB breakout board
Sally

11. Computational Unit: Bluetooth Transceiver
Sustains connection with computer for a minimum 5 meters away
Returns data at 9600 Baud (50Hz framerate for 3 float-64 values)
Accessed through serial connection within SuperCollider or through a PuTTY Terminal
Sally

12. Sensor Unit Accelerometer Records 3-axis acceleration data
Magnetometer
Records 3-axis magnetic north data
Used LSM303
Communicate ≥ 30Hz (fastest kHz)
Sally

13. Sensor Unit - Tilt Compensated Heading
Accelerometer outputs gravity vector: (G1, G2, G3)
Magnetometer outputs Magnetic North vector: (N1, N2, N3)
Trigonometry
Molly

14. Sensor Unit - Magnetometer Calibration
Molly

15. Software: Algorithm Calibration Weights and Offsets Low-pass filter
2 tap weighted average
Tilt Compensated Heading Calculation
Bluetooth communication
On/Off with LED status
Reset front direction
Molly

16. Software: Front Calibration
Yaw is calibrated using the current “front” orientation
Updated_Yaw = mod(Sensed_Yaw - Front_Yaw, 2π)
Subtract yaw from instance front reset trigger is pressed from all later yaw calculations
Modulo 360°
Molly

17. Software: SuperCollider Integration
Platform for audio synthesis and algorithmic composition
Sally

18. Challenges PCB Assembly Sensor chip Small capacitors
Lack of test points
Sally

19. Challenges PCB Assembly Sensor chip Small capacitors
Lack of test points
Sally

20. Challenges Code often would not upload to ATMega2560
Irregular behavior
Did not diagnose problem before damaging original board
Cary - often faulty capacity

21. Future Development
Improved PCB design for better portability and integration
Have a complete sound system to produce a variety of types of sounds
Possible projects with VR applications
Cary

22. Acknowledgements Professor Eli Fieldsteel Zhen Qin
Professor Arne Fliflet
ECE 445 Course Staff
Cary

23. Thank You
Questions?
Sally