title: Analysis of exclusively kinetic two-link underactuated mechanical systems
abstract: Analysis of exclusively kinetic two-link underactuated mechanical systems is undertaken. It is first shown that such systems are not full-state feedback linearizable around any equilibrium point. Also, the equilibrium points for which the system is small-time locally controllable (STLC) is at most a one-dimensional submanifold. A concept less restrictive than STLC, termed the small-time local output controllability (STLOC) is introduced, the satisfaction of which guarantees that a chosen configuration output can be controlled at its desired value. It is shown that the class of systems considered is STLOC, if the inertial coupling between the input and output is nonzero. Also, in such a case, the system is nonminimum phase. An example section illustrates all the results presented
keyphrases: exclusively kinetic two-link underactuated mechanical systems equilibrium points one-dimensional submanifold small-time local output controllability nonminimum phase small-time locally controllable system