The current work examines the adverse effects of non-collocated sensors and actuators on the phase characteristics of flexible structures. The sensor location is allowed to sweep the entire length of a pinned-free flexible beam while the actuator is fixed at the pinned-end. The phase angle contour of the system has been generated as a function of the normalized sensor location and the excitation frequency. It clearly reveals the minimum and non-minimum phase regions of the system and illustrates the changes in the system’s zeros induced by varying the sensor location.
A basic sliding mode controller has been used to attenuate the unwanted vibrations of the beam. Based on the phase angle contours of the system, the structural controller has been modified to ensure a desirable controller performance irrespective of the sensor location with respect to the actuator. The simulation results demonstrate the efficacy of the modified controller in attenuating the overall transverse deformation of the beam irrespective of its phase characteristic.