Observer-based modal control of flexible systems using distributed sensing

We design a modal controller for conservative flexible systems that uses distributed sensing. A spatial filter design based on the eigenfunctions coupled with a velocity observer prevents spillover instabilities in the closed-loop system. The proposed control is proven to stabilize a discrete set of controlled modes without destabilizing the remaining, residual modes. We then apply the theory to a single flexible link robot arm and experimentally demonstrate the feasibility of the proposed control strategy. The experiments use high speed video feedback with image processing to determine the spatial beam curve. The controller quickly damps the first modal response without causing instability in the remaining modes.