Control engineering practice vol:7 issue:11 pages:1333-1341
In this paper, an electro-hydraulic control system for a vibration-isolating platform that must behave like a band-pass filter and display robustness against mass variations, is designed. A good estimation of the frequency response is obtained by performing an identification on the low- and high-frequency band. The poor conditioning of the H-infinity algorithm caused by poles and zeros at the origin is solved by adding uncertainty. Conflicting constraints during the controller design are handled by the appropriate selection of weighting functions. Practical implementation issues which arise from numerical problems are tackled. Finally, the performance and the robustness are evaluated experimentally. (C) 1999 Elsevier Science Ltd. All rights reserved.