Exact differentiation and sliding mode observers for switched Lagrangian systems

The main topic of this paper is the problem of constructing observers for switched mechanical systems, which includes, as a specific case, the design of observers based on the high order sliding mode technique. The high order sliding mode is used to overcome the chattering phenomena occurring, which induce some irrelevant and undesirable phenomena for mechanical systems. The proposed approach, based on the Fliess canonical form, also allows observers to give an estimate of the discrete location of the system, which indicates the dynamic evolution. The convergence of the observers is proved and a stick–mass–friction system is used to illustrate the efficiency of the proposed hybrid observers.