Experimental study of active vibration control for suppressing impact or moving disturbance-induced vibrations with polyvinylidene fluoride and fiber Bragg grating sensors

In this work, we experimentally study active vibration control of a smart cantilever beam and focus on influences of disturbances to the vibrations and corresponding control performances. The smart cantilever beam is subjected to impacts or moving mass loadings and robust positive position feedback (PPF) control is implemented to suppress the disturbance-induced vibrations. Specifically, we employ high sensitive polyvinylidene fluoride (PVDF) and fiber Bragg grating (FBG) sensors to capture dynamic characteristics of the disturbances. To allow repeatable and controllable experimental conditions for the prescribed disturbances, steel balls or a steel rod are used as the sources of the disturbances applied on the cantilever beam, on which a rail is cut out to guide the motions of the steel ball. Before designing PPF, finite element simulations are carried out to numerically compare sensing performances of the PVDF and FBG sensors. Resonant frequencies of the cantilever beam, including bending, torsional, and lateral modes, are also obtained beforehand numerically and experimentally for understanding behaviors of the disturbance-induced vibrations. By performing fast Fourier transform (FFT) and short-time Fourier transform (STFT) on the detected transient responses, characteristics of the disturbances and their suppressions with the PPF controllers are demonstrated and discussed. The proposed smart cantilever beam with the prescribed repeatable and controllable disturbances serves as a very suitable model in laboratory confirmations for active controller designs. In addition, our experimental work provides suggestions for sensor selections in active vibration control of flexible structures, especially in environments involving impact or moving disturbances.