Feasibility of configuration-dependent substructure decoupling

Substructure decoupling allows identifying the unknown dynamic behavior of a subsystem starting from the dynamic behavior of the whole system and that of the residual part of the system. Recently, the coupling problem has been extended to deal with time or configuration-dependent coupling conditions. This approach is useful to numerically investigate the dynamics of a configuration-dependent system with a reduction of the computational burden. In this paper, we want to examine the feasibility of performing substructure decoupling when the coupling conditions among invariant mechanical subsystems are configuration-dependent. Typical examples of such systems could be a lifting crane or a Cartesian robot. Taking for granted that the dynamic behavior of the whole system must be known for each configuration, several further questions have to be addressed: if it is necessary to take FRF measurements on the connecting DoFs; if, for the residual system, it is necessary to consider a different set of FRF measurements for each configuration; if it is possible to take advantage of the redundancy of information provided by considering multiple configurations, i.e. multiple internal constraints. In the paper, we will try to answer these questions by starting from a well-known test bed, previously used for substructure decoupling.