DFL nonlinear control design and its application in water-level nonlinear plant

Designs of adaptive controllers to improve the performance of water-level nonlinear plants have been a topic of research for a long time. Few papers, however, have considered both the stability enhancement and speed increment of the dynamic response of the plant using adaptive controllers. The aim of this paper is to present the design of "direct feedback linearization" (DFL), which can solve the problems related to the nonlinear characteristic of the plant, and to apply the DFL method to a water-level nonlinear plant to improve its performance. The real time control experiments show that the DFL which linearizes the water-level nonlinear plant is valid in the large range, while the classical linearization method is valid only in the small range. Under the precondition of no steady-state error, there is no peak overshoot. Compared with the classical PID control method, the DFL method gives a satisfactory result.