**2.1. Sensing module**

Master control module uses ATmega2560 with the Arduino program written to read motion data of sensor. Ten-axis motion sensor combined with the accelerometer, gyroscope, magnetometer, and the barometer to acquire attitude angle data through the inter-integrated circuit (I2C) is adopted. The communication module uses Bluetooth transmit data wirelessly to the processing software. The block diagram of the 11-DOF sensing module is shown in **Figure 2**.

**Figure 2.** The block diagram of the sensing module.
