Inertial measurement units (IMU) are commonly used where position, motion information must be processed. It is commonly 9 degrees of freedom (DOF) modules used that include LSM303 3 axis accelerometer and 3 axis magnetometer, ITG-3200 3 axis gyro. These are considered enough for precisely calculating position of board carrying all sensors. Amandaghassaei was working on project where orientation information was needed. So instead of purchasing available board, he built one which saved a bit of money, but mos importantly had all he needed.
He included Atmega328p microcontroller which reads all sensor data and then can send it through I serial interface. He made 6 pin header to accept standard FTDI interface module. PCB was fabricated by using milling machine. Milling and soldering was a bit challenging since footprints of both sensor chips are really tiny.