Best Practices for Using the GNSS/INS devices in Automotive Applications

The MTi GNSS/INS are designed to use acceleration derived from GNSS data to improve orientation and position estimates of a vehicle in motion. This also helps compensate for transient accelerations. However the estimates of position, velocity, and heading may be challenged in automotive applications when GNSS reception is limited and when maneuvering at slow speeds or stopped.

The primary documentation for configuring and getting the most out of your GNSS/INS device is the product's Datasheet.

Here are some additional general tips for getting the most out of a GNSS/INS device for automotive applications:

  • The "General" filter profile typically gives the best performance for various applications. Other filter profiles should only be used in special circumstances.
  • The "Automotive" filter profile (MTi-G-710 only) makes use of holonomic constraints, by assuming that the Yaw of the device can be directly derived from the GNSS course over ground. This means that it is essential for the x-axis of the MTi to be aligned with the driving direction of the car, preferably at a mounting accuracy of 1 degree. The vehicle should also not experience significant amounts of side slip. When these requirements are met, the Automotive filter profile can achieve a better performance than the General filter profile.
  • We generally do not recommend using the "GeneralMag" filter profile due to the high potential to encounter magnetic disturbances in automotive applications. However if the magnetic field environment is suitable (i.e. you do not anticipate passing near magnetic disturbances or fields) and if proper MFM calibration for fixed magnetic fields is done very well, it can be used and it can be effective.
  • For initial true north heading when the vehicle has not begun moving yet, use the "GeneralMag" filter if the conditions above are met, otherwise it may be necessary to calculate your own determination of true north heading with raw magnetometer data. However using the raw magnetometer data for initial heading will include errors if the magnetic field is disturbed. The GNSS/INS devices will yield effective true north heading once it has achieved GNSS fix and begun traveling at a sufficient velocity.
  • The No Rotation Update command can be used during initialization and periodically to help with gyro bias estimation when GNSS cannot help. This is the most effective extra way to help stabilize yaw if high speeds with GNSS fix cannot be maintained. The "HighPerformanceEDR" filter (MTi-G-710 only) does this automatically.
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