Experimental validation of a geometric method for the design of stable and broadband vibration controllers using a propeller blade test rig

A systematic geometric design methodology to generate a stable controller for simultaneous local and remote attenuation that was previously proposed is experimentally validated on a structure. The local control path transfer function for this experimental system is non-minimum phase due to which the original broadband controller design would yield an unstable controller. Here a modified procedure for systems with local non-minimum phase dynamics is used to generate a stable controller. According to this method, reduction in vibration at local and remote points on a structure can be parameterised in terms of the available design freedom and a controller is realised in terms of the optimal selection of this using the minimum phase counterpart of the local control path transfer function. The modified method results in a controller that is both stable and stabilizing and which achieves the desired vibration attenuation at the local and remote points on the structure. An experimental facility that replicates the vibration transmission through the shaft of a propeller blade rig system is used to demonstrate the method. Vibration for excitation near the first bending mode frequency of the resonating part of this structure is attenuated at the non-resonating part of the system without deteriorating vibration at the resonating end.