This paper summarizes a feedback stability theory developed by the author during 1959-64. It introduces the concept of an extended space, and establishes three equivalent principles for input-outputâ€¦ (More)

This paper deals with the design of feedback controllers which minimize the HÂ¿-norm of the sensitivity function, suitably weighted. This approach to the theory of feedback design was introduced byâ€¦ (More)

In this note we discuss the HÂ¿-sensitivity minimitization problem for linear time-invariant delay systems. While the unweighted case reduces to simple Nevanlinna-Pick interpolation, the weighted caseâ€¦ (More)

The optimal worst-case uncertainty that can be achieved by identification depends on the observation time. In the first part of the paper, this dependence is evaluated for selected linear timeâ€¦ (More)

Mi~ed sensitivity optimization was considered! by Kwakernaak [9]. Francis et al. [5,4,6] gave various characterizations of the problem, e.g., in terms of the distance from [0 w] to [vM]H Â°Â°, where W,â€¦ (More)

A tutorial account is given of Hâˆž theory for the design of controllers which optimize the weighted sensitivity matrix. Linear multi-input, multi-output discrete time systems are considered.

A servoanalysis of the feedback control system for lens accommodation has been based upon experimental evidence designed to explore the nonlinear properties. Because these nonlinearities areâ€¦ (More)