The frequency-response and the root-locus methods，which are the care of classical theory, lead to systems that are stable and satisfy a set of more or less arbitrary performance requirements.Such systems are, in general,not optimal in any meaningful sense.Since the late 1950's,the emphasis in control design problems has been shifted from the design of one of many systems that work to the design of one optimal system in some meaningful sense.
As modern plants with many inputs and outputs become more and more complex, the description of a modern control system requires a large number of equations. Classical control theory, which deals only with single-input-single-output systems,becomes entirely powerless for multiple-input-multiple-output system.Since about 1960,modern control theory has been developed to cope with the increased complexity of modern plants and the stringent requirements on accuracy,weight,and industrial application.
），不過太巧了，這篇文章我曾經看過，所以就挺好的
，下來是口頭作文依舊讓你準備一會，然后就問你專業問題了。