Two rank hybrid iterative quasi-sliding mode control strategy

A novel two rank hybrid iterative quasi-sliding mode control strategy is present for a class of uncertain nonlinear systems. In the first rank of sliding mode switch function, a reference trending function is introduced, which eliminated the reaching stage of sliding mode controller; The second rank of sliding mode switch function iterate based on the first one, and a hyperbolic tangent function is introduced to form nonlinear integral term. The proposed strategy inherits the merits of the method of global dynamic sliding mode control and integral sliding mode control. The approach guarantees global robust performance of the whole response process, and provides better transient response performances while maintaining the tracking accuracy as the integral sliding mode control. Theory has proved that the proposed approach can full-scale suppress constant disturbance and get arbitrarily small steady state tracking error by setting control parameters for dynamic disturbances.