Abstract:

In this paper two sorts of hierarchical switching scheme for the variable structure control（VSC） of linear multivariable systems-the scheme in the fixed order and the scheme in the selected order, are suggested and the problems of their design methods are put forward. According to the reaching condition of the trajectories of VSS and the principle of Pole assignment of systems, the method on design of the switching functions and VSC of the systems in the two schemes are given respectively. The results have shown us that these design methods lead to a great simplification of the control law. The important practical features of the hierarchical switching scheme are that the VSS with this scheme in fixed order have the capability of fault tolerance; while the time of reaching the switching plane of the trajectories of the VSS with this scheme in selected order is reduced hence more adaptability of the systems is obtained.

Key words: linear multivariable system, variable structure control, hararchical switching scheme, control fault tolerance