Complementary IIR filters

1. What is the complementary filter?
2. Is Kalman filter a complementary filter?
3. Is Butterworth a FIR or IIR?

What is the complementary filter?

The complementary filter is a computationally inexpensive sensor fusion technique that consists of a low-pass and a high-pass filter. In this application of inertial-sensor-based attitude estimation, the gyroscope's dynamic motion characteristics are complementary to that of the accelerometer and magnetometer.

Is Kalman filter a complementary filter?

So basically the Kalman filter contains the complementary filter, and will behave as such with the most basic system possible that basically provides no additional information.

Is Butterworth a FIR or IIR?

The classical IIR filters, Butterworth, Chebyshev Types I and II, elliptic, and Bessel, all approximate the ideal “brick wall” filter in different ways.