On the Robust Quantized Sampled-Data Leaderless Consensus Tracking of Nonlinear Multi-Agent Systems

This paper deals with the robust quantized sampled-data leaderless consensus tracking problem for nonlinear multi-agent systems (MASs), affected by actuation disturbances and observation errors, over strongly connected networks. The input-to-state stability redesign methodology is used in order to design a new quantized sampled-data control term able to arbitrarily attenuate the effects of bounded actuation disturbances and bounded observation errors. The quantization of both input/output channels is simultaneously considered. It is proved that, by suitably fast sampling and accurately quantizing the continuous-time protocol at hand, the leaderless consensus tracking is ensured, regardless of the above disturbances and errors provided that: (i) the bounds of the actuation disturbances and of the observation errors are a-priori known; (ii) the observation errors do not affect or affect marginally the new added control term. Possible discontinuities in the function describing the protocol are also managed. The cases of time-varying sampling intervals and of non-uniform quantization in the input/output channels are included in the theory here developed. Furthermore, the stability analysis of the inter-sampling system behaviour is performed. The stabilization in the sample-and-hold sense theory is used as a tool for proving the results. The provided results are validated through an application concerning the formation control problem of unmanned aerial vehicles.