Error due to two-force excitation in moment mobility measurement

In direct moment mobility measurement, one difficulty is the moment excitation. Two-force configuration excitation is widely used to generate moment in practice. Previous error analysis mainly focused on the initial load of exciters, the matching of the two forces, and the system resonance. In this paper, the distance requirement of two-force configuration in moment excitation is investigated. Based on the numerical calculation, other factors that affect the error in moment mobility measurement are discussed. The influence of the deduced distance requirement on moment mobility measurement is also explained.