System identification and control: A fruitful cooperation over half a century, and more

Control science is basically a model based discipline. The performance of control is determined by the accuracy of the model representing data. Therefore the successes of identification reflects into the successes of control. This is why identification and control have had a never-ending interplay over so many decades. In this paper we try to outline such interplay by making reference to one of the main problems encountered in control engineering modeling: the estimation of unknown or uncertain parameters in the plant equations.