A High-Gain Observer for a Class of Cascade-Feedback-Connected Nonlinear Systems With Application to Injection Molding

Design complexity becomes an issue for nonlinear observers when dimension of the dynamic system is high. Exploiting the inherent structure of the dynamic system, a high-gain nonlinear observer for a class of cascade-feedback-connected systems is presented. Instead of a single observer for the entire system with high dimension, a family of observers, one corresponding to a dynamic subsystem with lower dimension, is designed. The nonlinear high-gain technique is utilized to ensure the estimation convergence of the observer. Evaluation on a commercial injection-molding machine demonstrates the performance and applicability of this design.