Performance enhancement of nonlinear drives by feedback linearization of linear-bilinear cascade models

Complex plants seldom fulfil the conditions required for the design of exact feedback linearizing controls. Using suitable approximate models, however, may allow the design of a feedback linearizing controller which, when applied to the true plant, leads to substantial performance enhancements provided the approximate model captures the essential characteristics of the plant. This paper discusses this issue in the case of an industrial hydrostatic gear. A linear-bilinear cascade model approximation is proposed, and a control law is derived to force such an approximation to behave like the “nearest” linear system, A simple, easily implementable form is obtained. The relevance of the approach is shown both by experimental results and by simulation studies to assess the optimization potential as well as the error sensitivity of the method