This paper deals with a procedure to perform the identification of the probabilistic model of uncertainties for the bit-rock interaction model of a drill-string system. The bit-rock interaction model is represented by a nonlinear constitutive equation, whose uncertainties are modeled using the nonparametric probabilistic approach. The identification of the parameter of this probabilistic model is carried out using the Maximum Likelihood method together with a statistical reduction in the frequency domain using the Principal Component Analysis. This is the first time that a procedure is proposed to identify the probabilistic model, in the context of drill-string dynamics.
