Prescribed Performance Consensus of Uncertain Nonlinear Strict-Feedback Systems With Unknown Control Directions

In this paper, a leader-following consensus scheme is presented for networked uncertain nonlinear strict-feedback systems with unknown control directions under directed graphs, which can achieve predefined synchronization error bounds. Fuzzy logic systems are employed to approximate system uncertainties. A specific Nussbaum-type function is introduced to solve the problem of unknown control directions. Using a dynamic surface control technique, distributed consensus controllers are developed to guarantee that the outputs of all followers synchronize with that of the leader with prescribed performance. Based on Lyapunov stability theory, it is proved that all signals in closed-loop systems are uniformly ultimately bounded and the outputs of all followers ultimately synchronize with that of the leader with bounded tracking errors. Simulation results are provided to demonstrate the effectiveness of the proposed consensus scheme.