Reduced order robust controllers for an experimental flexible grid

S. Vittal Rao, M. Westerheide, Alok Das

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


A procedure for the design and implementation of reduced-order robust controllers for active vibration control on an experimental flexible grid structure is presented. The experimental structure consists of a 5-ft × 5-ft grid made of 2-in-wide, 1/8-in-thick aluminum strips. The grid hangs vertically, being cantilevered at the top to a large T-beam anchored to a cinder block wall. The grid structure is represented by a 75-degree-of-freedom finite-element model, and the controller uses three piezoelectric accelerometer sensors to command three noncollocated DC motor torquers. The modified balance-truncation model-reduction method is used to derive a control synthesis model. These reduced-order models preserve stabiilty, controllability, and observability, and have a good frequency response match at low frequencies. A 10-mode mathematical representation of the experimental grid structure has non-minimum-phase zeros. The effects of non-minimum-phase zeros on the performance of a closed-loop LQG/LTR controller are investigated. The reduced-order controllers are implemented on the structure using an ISI Max 100 computer. Experimental closed-loop performance of the grid is obtained for various parameter variations.

Original languageEnglish
Pages (from-to)356-361
Number of pages6
JournalProceedings of the American Control Conference
StatePublished - 1990
EventProceedings of the 1990 American Control Conference - San Diego, CA, USA
Duration: May 23 1990May 25 1990


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