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Summary This paper develops a filtered high‐gain output feedback controller for a class of nonlinear systems in the presence of unknown state‐dependent and time‐varying nonlinearities. It considers that the nonlinearities satisfy a semiglobal Lipschitz condition. The presence of high‐gain observer in the adaptive law delivers a good property of disturbance rejection at the cost of peaking phenomenon as well as reduced robustness. The addition of filtering mechanism in the control law overcomes the cons of high‐gain observer and makes it robust to uncertainties in modeling the nonlinear functions. In this way, the filtered high‐gain output feedback controller realizes nonlinear time‐varying uncertainty cancelation and good tracking delivering with guaranteed robustness. The simulation results demonstrate the high efficiency of our novel design for handling of a class of nonlinear systems in the presence of time‐varying uncertainty when compared with saturated control signal.

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This paper deals with uncertainties problem in multi-agent systems with novel cooperative adaptation approach. Since uncertainties in multi-agent systems are interconnected, local agent often faces uncertainties not only from itself but also from neighbors. The proposed approach is that a local agent estimates uncertainties from itself and neighboring agents and then changes control strategy. The uncertainties or the equivalences of neighbors can be estimated based on their available outputs; thus, the local agent can adapt to them to cancel out these effects. Stability analysis is also derived that characterizes the transient and steady state performance of multi-agent system. The simulation presents the details of the proposed cooperative adaptation mechanism by compared typical cooperative control.