• What are the sources of error of the MEMS sensors?

    MEMS inertial sensors are subject to several common sources of error: bias, scale factor, misalignments, temperature dependencies, and gyro g-sensitivity.  All VectorNav sensors undergo a rigorous calibration process to minimize these error sources.  Compensation parameters calculated during these calibrations are stored on each individual sensor and digitally applied to the real-time measurements.

  • What are the calibration options for your sensors?

    Our sensors are available with two calibration options:

    • Standard calibration:  single temperature calibration at 25°C (valid ±10°C).
    • Thermal calibration:  extends the calibration process over the full operating temperature range from -40°C to +85°C.
  • What is the difference between standard and thermal calibration options?

    The standard calibration is performed at a single temperature point (25°C), and typically holds performance specifications over the range of 15°C to 35°C. 

    The thermal calibration option extends the calibration process over a wide range of temperatures such that sensors will perform to overall specifications across the full operating temperature range from -40°C to +85°C.

    Detailed information about the calibration process can be found here:
    www.vectornav.com/support/library?id=86

  • How will a standard calibrated sensor perform outside of 15°C to 35°C?

    Standard calibrated sensors will continue to operate over the full temperature range, but will see increasing errors as the temperature increases/decreases away from 25°C.

    Each axis of the accelerometer, gyro, and magnetometer has a unique temperature dependency, which when neglected, will degrade the overall attitude estimates (position and velocity as well for the VN-200) depending on dynamic inputs, attitude with respect to gravity, and numerous other factors.  Some example tests on a VN-100S reported attitude errors between 2-5 degrees when subjected to the full temperature range.

  • Are the specifications on the data sheet “after thermal calibrations”?

    For standard calibrated VN-200 units, the specifications only hold true near 25C (approximately +/- 10C).  Thermally calibrated VN-200 units will hold the specification over the full operating temperature range from -40C to +85C.   One additional note: the attitude accuracy in the data sheet is valid after filter alignment due to sufficient dynamic motion.

  • Why the calibration is important?

    Consumer & Automotive grade MEMS sensors are mass produced with little to no calibration applied

    High accuracy attitude, position, & velocity measurements require individual sensor calibration

    Calibration removes structural errors (difference between expected & measured output) to improve performance of underlying sensors

    Structural errors in accelerometer measurements lead to large errors in pitch, roll, position, and velocity estimates

    sensor calibration

    sensor calibration

    sensor calibration
    Structural errors in gyro measurements have a large impact on the attitude performance of an AHRS & INS Gyro Bias Drift

    Structural errors in magnetometer measurements have a large impact on the heading performance
    structural errors
    structural errors
    structural errors

    structural errors

    structural errors
    structural errors

    structural errors

    All our sensors are individually calibrated on all measurement axes for:

    • Accelerometer bias, scale factor, axis misalignment
    • Gyro bias, scale factor, axis misalignment, gyro-g sensitivity
    • Magnetometer bias, scale factor, misalignment
    • Option for thermal calibration over -40C to +85C