Modeling and control of nonlinear systems with input monotonic gains

In this paper, an identification scheme is designed to determine the system dynamics which has static nonlinearity in its input. The procedure has obtained one limit cycle data from a symmetrical relay test to identify both structure and parameters of the model. The static nonlinearity block is represented by a memoryless and monotonic function while the linear subsystem by a second order transfer function model. First, the nonlinear static function is estimated without any iterative procedures and then linear subsystem model from explicit analytical expressions in terms of a few measurements on the plots. Nonlinear controller is designed to linearize the nonlinear dynamics using the inverse of the nonlinear static function and it can be tuned by usual tuning rules developed for linear processes. Simulation study shows the simplicity of the proposed approach.