A comparison between the IMSC and the DMSC for vibration suppression of smart flexible structures

The proposed article deals with a new control technique for the vibration reduction of flexible structures based on modal approach and named Dependent Modal Space Control (DMSC). The well-known Independent Modal Space Control (IMSC), devised in the '80 s, by using diagonal control gain matrices, allows changing the frequency and the damping of the controlled modes leaving the mode shapes unaltered. The DMSC, instead, besides frequency and damping, can also impose the controlled mode shapes by making use of full control gain matrices. This will be the first way in which the DMSC can be applied allowing the creation of virtual nodes in desired point of the structure with consequent advantages in many applications. In the majority of control problems, due to the limited number of sensors-actuators available and the worsening spillover effects, the generic eigenvector imposition is not possible thus the same method is applied in a different way. Imposed the desired controlled poles, the optimal eigenstructure assignment can be suitably computed through a Genetic Algorithm in order to reduce the structure vibration by minimizing an Input-Output performance index in a desired frequency range depending on the physics of the problem. In this second application of the DMSC the stability of a determined number of modes in closed loop can be ensured constraining the optimization. In order to prove the advantages of this new method, a comparison of the IMSC and DMSC using a numerical and experimental simulation on a cantilevered beam Finite Element Method (FEM) model is provided. © 2013 SPIE.