... differ-ential equations. Unfortunately, these equations cannot be treated by the methodsof modern nonlinear control theory since the latter assumes that the control signalenters the state space ... linearization and shows (using the Fokker-Planck equation and the filter hypothesis) that the errorbetween the standard deviation of the plant output and its quasilinearization (i.e., σy and σˆy) ... reference, disturbance, error, controller output, actuatoroutput, plant output, and measured output, respectively. These notations are usedthroughout this book. In the framework of the system of Figure...