Passivity motivated controller design for flexible structures

When actuators and sensors on a controlled mechanical structure form naturally passive pairs, which usually requires physical collocation, very robust stabilizing controllers can be constructed. If the number of such naturally passive pairs is small, the closed loop performance may not be satisfactory. This motivates the incorporation of additional sensors in the control design. However, the passivity property no longer holds for these sensors. Some thoughts are presented on extending the passivity based design to incorporate these non-collocated sensors by using some nominal model information to synthesize a fictitious strictly passive output. Simulation and experimental studies are presented to show the merits of this approach.<>