Dependent modal space control: Experimental test rig

Abstract

This article presents the experimental validation of a new control technique for reducing vibration in flexible structures: Dependent modal space control. While the classic independent modal space control allows only the frequency and the damping of the controlled modes to be changed, dependent modal space control can also impose the controlled mode shapes. Depending on the kind and number of sensors and actuators available for control, the mode shape can be imposed in both a direct and an indirect way. Owing to the need for modal sensors and actuators for direct mode shape imposition, the second methodology is often preferred in many engineering applications. In the indirect method, the optimal closed loop mode shapes set is computed with an optimization algorithm in order to minimize an Input-Output Performance Index. The worsening spillover effects due to errors in the estimates of the system state variables are considered when computing the gain matrix and play an important role in the entire control logic. Experimental validation on a cantilevered beam shows the effectiveness of the dependent modal space control and a good match between the numerical and the experimental results.