Experimental investigation of performances of different optimal controllers in active vibration control of a cantilever beam

Active vibration control using smart materials has been a subject of research for about 2 decades. In active vibration control, the controller plays an important role in attenuating vibration of the flexible structure. In the present study, a cantilever beam structure is used to study the effect of various optimal controllers using a single pair of actuator and sensor which is placed in a collocated manner at the root of the beam. Simulation and experimental studies are carried out using three optimal controllers, viz. Linear quadratic regulator (LQR), linear quadratic Gaussian (LQG) and H-infinity. The simulation study is carried out using ANSYS© and MATLAB© for all the three controllers. The experimental results are obtained using LabVIEW© programs developed by the authors. The LQR optimal control gain is calculated using state and output feedback control laws. Considering the process and measurement noises the Kalman gain is calculated and the LQG regulator is obtained further by combining the LQR and Kalman gains. The H-infinity controller is designed by considering weighting function which maintains system response and error signals within the prescribed tolerances. In the present study, H-infinity control is found to be giving robust and better performance.