  Base inertial parameters constitute a minimal inertial parametrization of
mechanical systems that is of interest, for example, in parameter estimation
and model reduction. Numerical and symbolic methods are available to determine
their expressions. In this paper the problems associated with the numerical
determination of the base inertial parameters expressions in the context of low
mobility mechanisms are analyzed and discussed through and example. To
circumvent these problems two alternatives are proposed: a variable precision
arithmetic implementation of the customary numerical algorithm and the
application of a general symbolic method. Finally, the advantages of both
approaches compared to the numerical one are discussed in the context of the
proposed low mobility example.
