Dynamic compensation and homeostasis: a feedback control perspective

\"Dynamic compensation\" is a robustness property where a perturbed biological circuit maintains a suitable output [Karin O., Swisa A., Glaser B., Dor Y., Alon U. (2016). Mol. Syst. Biol., 12: 886]. In spite of several attempts, no fully convincing analysis seems now to be on hand. This communication suggests an explanation via \"model-free control\" and the corresponding \"intelligent\" controllers [Fliess M., Join C. (2013). Int. J. Contr., 86, 2228-2252], which are already successfully applied in many concrete situations. As a byproduct this setting provides also a slightly different presentation of homeostasis, or \"exact adaptation,\" where the working conditions are assumed to be \"mild.\" Several convincing, but academic, computer simulations are provided and discussed.