Variable structure systems: research status and promise

Basic ideas in design of variable structure systems (VSS) at different stages of their development are considered. In design of control algorithms the dominating role is shown to be played by sliding modes; the mainstream of the VSS theory development is expected to be the decomposition principle with the use of this type of motion. The algorithmical and data processing aspects of designing VSS and ways of obtain invariance with the use of multidimensional sliding modes are analyzed. The promising lines of further research in the VSS theory are indicated.