Estimate based H∞ compensator: Application to robust automatic steering

Using the results of the linear sub-state estimation and of the linear matrix inequality (LMI), we develop a Luenberger low — order unknown input observer/controller, which gives full unbiased state estimation and H∞ disturbance attenuation. This method is designed in a nonstandard case: an output-disturbance free system, it's based on the bounded real lemma, and the resultant design algorithms are two Riccati inequalities.