%0 Journal Article %T Model-free control and intelligent PID controllers: towards a possible trivialization of nonlinear control? %A Michel Fliess %A C¨¦dric Join %J Mathematics %D 2009 %I arXiv %X We are introducing a model-free control and a control with a restricted model for finite-dimensional complex systems. This control design may be viewed as a contribution to "intelligent" PID controllers, the tuning of which becomes quite straightforward, even with highly nonlinear and/or time-varying systems. Our main tool is a newly developed numerical differentiation. Differential algebra provides the theoretical framework. Our approach is validated by several numerical experiments. %U http://arxiv.org/abs/0904.0322v1