An actively controlled harmonic force generator

Low frequency harmonic force generators (HFG) are broadly utilized in a variety of applications, in some cases for generating desired harmonic force excitations and in others for canceling vibration caused by harmonic forces. Among various HFGs, those with rotating eccentric masses offer attractive weight-to-force ratios. This advantage becomes more pronounced especially when the operating frequencies are low (10–30 Hz) and the harmonic force amplitudes are high. A novel design is the topic of this paper which deploys four rotating eccentric masses, which are deployed to adjust the three key characteristics of the resultant harmonic force: the amplitude, the frequency and the phase angle.