Smith Predictors in Nonlinear Systems - Application to ISS-based Leader/follower Trailing Control

As in any control system, the presence of small delays in the feedback channel may severely affect the performance of the closed-loop system, and prevent a the successful application of established nonlinear control methodologies. In order to make a control law robust with respect to small time delay, we first extend input-to-state stability (ISS) concepts to encompass the effect of bounded delays and restrictions on the input. Then, a method is proposed to integrate the presence of a Smith predictor in a backstepping design based on nonlinear small gain assignment, when small time delays is present in the feedback loop. The method is applied to a leader-follower trailing control problem. Simulation results confirm the validity of the control design and the robustness analysis.