# Alignment Routines ## Fiber Optic Gyro IMU + Single GNSS Antenna In order to obtain a reliable static alignment for a FOG IMU with a single GNSS antenna, the FOG IMU must be completely static (e.g. the aircraft should be shut off so as to avoid vibrations) BEFORE and AFTER a scan for a period of about 5 minutes. Because static alignment uses the average of the sensor output, it is imperative that the vehicle remains completely stationary during the duration of the alignment. Additionally, we recommend travelling in a straight line for a period of at least 10 seconds, at a minimum velocity of 5 m/s (18 km/h) at the BEGINNING and END of your data collection. Leaving the IMU static before and after a scan will allow the IMU to collect a few minutes of static data. Typically the first 2 minutes of data are used for static alignment followed by the remainder of fine alignment, in which GNSS updates enable the IMU to provide attitude information consistent with the accuracy level achievable by the accelerometer/gyro triad. ## MEMS IMU + Single GNSS Antenna A MEMS IMU with a single GNSS antenna requires kinematic alignment. Kinematic alignment requires kinematic movement. Alignment is performed by estimating the attitude from the GNSS velocity vector. To obtain a successful kinematic alignment during operation, we recommend travelling in a straight line for a period of at least 10 seconds, at a minimum velocity of 5 m/s (18 km/h) at the BEGINNING and END of your data collection. During this time, it is imperative that you ensure the vehicle is moving as straight and as level as possible with an unobstructed clear line of sight. ## MEMS IMU + Dual GNSS Antenna A dual GNSS antenna system will automatically align itself while the system is stationary. We recommend leaving the system stationary for a period of 3-5 minutes under open skies. Despite a MEMS IMU not being capable of static alignment, a dual MEMS GNSS antenna system will compute a high quality vector between the primary and secondary GNSS antenna during this period of stationary data collection resulting in alignment. However, we still recommend performing a kinematic alignment procedure at the BEGINNING and END of your data collection should there be any problem with a stationary alignment. To obtain a successful kinematic alignment during operation, we recommend travelling in a straight line for a period of at least 10 seconds, at a minimum velocity of 5 m/s (18 km/h) at the BEGINNING and END of your data collection. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs-6.phoenixlidar.com/rover/theory-and-workflow/navigation-and-alignment-techniques/alignment-routines.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.