Date of download: 11/4/2017 Copyright © ASME. All rights reserved. From: Position Control Using Acceleration-Based Identification and Feedback With Unknown Measurement Bias J. Dyn. Sys., Meas., Control. 2007;130(1):014501-014501-9. doi:10.1115/1.2807180 Figure Legend: Position-command following for the two-mass system using an LQG controller and a backward-path controller. The LQG controller Gc produces the control input u to track the position command r, while the backward-path controller with zero dc gain, that is, a zero at z=1, rejects the sensor bias.