Soft measurement of states of sandwich system with dead zone and its application

• Non-smooth observer was designed for a non-smooth sandwich system with dead zone.
• Estimation results were compared between non-smooth and conventional observers.
• Robust observer was designed for the system.
• Estimation results were compared between the robust and non-robust observers.

In this paper, a novel non-smooth observer is proposed to handle the soft measurement of the states of the sandwich system with dead zone. The convergence theorem of the non-smooth observer and its proof are given, respectively. After that, the experimental results are presented. The comparison between the proposed non-smooth scheme and the conventional method is illustrated. Finally, the robust observer is proposed for the sandwich system with dead zone and the states’ estimation results of the experimental equipment by the robust observer and the conventional non-robust observer have been compared in order to illustrate the necessity of proposing the robust one.