Observer based robust control

This paper presents an original contribution to the field of robust control. Plant order uncertainty as well as parametric uncertainty is catered for while guaranteeing not only closed loop stability but also a precisely prescribed closed loop dynamic response to the reference inputs. The method extends to nonlinear multivariable plants. Its ability to control plants having different orders without adjustment and yielding the same closed-loop dynamics is demonstrated by simulation of its application to speed control and position control of a permanent magnet synchronous motor drive. The model of the plant used in the observer can simply be a chain of integrators driven by each control variable, at least equal in number to the rank of the plant with respect to the associated controlled output. The controller is simple, requires no adjustment and requires little more computational power than a typical classical PID controller.