Complementary Filter

IMPORTANT: Features requiring a magnetometer are only available on device models with magnetometers. See Product Description to verify that your device has a magnetometer.

In addition to attitude estimates provided by the primary Estimation Filter, the 3DM-CV7 can provide attitude estimates produced by a separate Complementary Filter which uses scaled accelerometer and gyroscope data to estimate pitch and roll and allows the option of using the magnetometer data (-AHRS only) to correct the heading estimate.

The Complementary Filter is completely independent and runs in parallel with the Estimation Filter. Attitude estimates are computed by blending the integrated gyro output with pitch and roll estimates from the accelerometer data, using the assumption that linear acceleration is on average equal to zero.

The user can independently enable or disable the pitch/roll correction and the magnetometer heading correction (-AHRS only), as well as independently set the time constant for each correction using the Complementary Filter Settings (0x0C,0x51) command. If the magnetometer is enabled (-AHRS only), the magnetic field measurement is used to correct heading as well.

The primary strength of the Complementary Filter is its robustness: the estimates will never diverge, even after severe sensor over-ranging. However, it is more sensitive to transient errors caused by linear acceleration and magnetic disturbances. Furthermore, the Complementary Filter does not correct for accelerometer and gyro biases which both impart an angular offset in the attitude estimate. The Complementary Filter is best used as a secondary, partially independent source of attitude estimates that can be used when the Estimation Filter is in Unstable mode.