Rejecting disturbances to flexible structures using PI Kalman filters

The proportional Kalman filter (PKF) is formulated with integral action and generalized to the proportional-integral Kalman filter (PIKF). The PIKF can be utilized to improve the disturbance rejection property of the Kalman filter-based controller. Through extensive simulations, as applied to the lightly damped flexible structure of the 1992 ACC Benchmark, we show that the integral term of the PIKF allows effective estimation and rejection of arbitrary disturbances. As a result, a single PIKF-based controller robustly achieves full loop transfer recovery even when perturbed by an unknown shaped disturbance.