To track the movement of the copter in flight, a stable IMU with minimal swing effect has to be used. There are several low cost IMU's available on the market, similar to the one in the flight controller. While these are great for tracking instantaneous movement, they are not good at tracking movement over time. Due to noise and swinging of the gyro while accelerating in any direction, the tracking will be skewed while moving up and down the cave. This mostly results in incorrect or unreliable scanning data.
Xsens Technologies are well known in the industry for producing stable and accurate IMU's. Their product series \href{https://www.xsens.com/products/mti-1-series/}{MTi 1} features all the specifications needed for the copter and was chosen as the primary IMU for the project.
Upon initialization of the \texttt{IMU} code, a request to go to configuration mode is sent to the MTi. The MTi is now prepared to be configured. \texttt{IMU} then transmit the configuration data, which enables the output of Euler Angles and Free Acceleration data at 100Hz.
See Figure~\ref{fig:imuflowchart} for a visual representation of the communication flow. \texttt{IMU} first transmits a request of configuration mode, waits for a confirmation response, and then continues to transmit configuration data. When the configuration is complete, a request of measurement mode is sent to the MTi. The MTi will now continuously transmit data at the configured rate.
The data received \texttt{8bits} at a time. Each data point transmitted contains \texttt{32bits}, formatted as a standard \texttt{IEEE 754 float}. The data is shifted into a temporary \texttt{32bit unsigned int} and then a \texttt{memcopy} is executed from the \texttt{int} to a \texttt{float}. The data points are then sent over to \texttt{MSP} and stored.
