On the use of a multivariable frequency response estimation method for closed loop identification
Erik Wernholt, Svante Gunnarsson · 2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601) · 2004
A method for estimating the multivariable frequency response function using closed loop data is studied. An approximate expression for the estimation error is derived, and using this expression some properties of the estimation error can be explained. The properties of the disturbances, the choice of excitation signal in the different input channels, the feedback, and the properties of the system itself affect the model quality. The expression is illustrated by simulation data from an industrial robot.