Control of linear plants with zeros and slowly varying parameters

A reduction of order technique is developed which is useful in controller design for single-input, single-output, linear plants which have transfer functions with zeros and parameters which vary slowly compared to the response time of the plant. The controller design is based on a Liapunov-like method and employs a model reference. The reduction of order technique allows the control signal to be generated from the plant output and only its first derivatives if the plant transfer function has an th order denominator and an th order numerator and if the transfer function has known fixed poles.