Combining the nonlinear control system theory and the aim of chaos synchronization, we designed a nonlinear feedback controller for synchronizing the scalar output signal of Chua's Circuits system.

The result of vector theory is far from that of the traditional scalar diffraction theory for a typical DVD system, so vector diffraction theory must be adopted.

Mathematical model of adaptive variable structure of control system for DC servo robot was established with nonlinear sliding mode formed with saturation type scalar functions.