A systematic single-range controller synthesis procedure for nonlinear and multivariable liquid propellant engines

A new systematic single-range controller synthesis procedure for use with nonlinear, multivariable, and time-varying liquid propellant engines is developed. The developed procedure is based on one describing function model of the nonlinear plant coupled with two different linear algebraic controller design procedures; one of the algebraic procedures is to achieve decoupling, and the second one is to achieve command following. The developed procedure is demonstrated by solving an example problem comparing the results using a H ∞ controller design procedure.