  This paper presents an economic model predictive controller, under the
assumption that the only measurable signal of the plant is the economic cost to
be minimized. In order to forecast the evolution of this economic cost for a
given input trajectory, a prediction model with a NARX structure, the so-called
oracle, is proposed. Sufficient conditions to ensure the existence of such
oracle are studied, proving that it can be derived for a general nonlinear
system if the economic cost function is a Morse function. Based on this oracle,
economic model predictive controllers are proposed, and their stability is
demonstrated in nominal conditions under a standard dissipativity assumption.
The viability of these controllers in practical settings (where the oracle may
provide imperfect predictions for generic inputs) is proven by means of
input-to-state stability. These properties have been illustrated in a case
study based on a continuously stirred tank reactor.
