Active Isolation and Damping of Vibrations via Stewart Platform

Acknowledgements In the beginning, I would like to express my sincere gratitude to my supervisor professor André Preumont, the head of the Active Structures Laboratory for his patience, wise advices, brilliant ideas and suggestions and for his strong insistance and high pressure to achieve better work. I would like to thank my colleagues: Frédéric Bossens for putting my feet on the right way, Mihaita Horodinca for his big efforts in manufacturing the Stewart platform, Vin-cent Piefort for his advices in the finite element modelling, Ioanica Burda and Salvator Dusabimana for their efforts in building the electronics needed for the flight test, Pierre De Man, Arnaud François, Ioan Doroftei and Xavier Pitoiset for their help and friendship. Special thanks to Mihaita and Ioanica for their support and participation in the parabolic flight test. I am grateful to the team of Micromega Dynamics, in particular, Nicolas Loix, Jean Phillippe Verschueren and Serge Cattoul for their continuous help and cooperation and for their endless industrial and practical advices specially in the electronics. I am also grateful to the other space and vibration isolation research groups who provided us with helpful ideas in the construction of the Stewart platform. I am deeply thankful to my family in Palestine, particularly, my beloved mother and I send a ray of love and blessing to the memory of my father who died during the period of this work. The words are too little to describe my thanks to my wife and children for their patience and endless support to withstand the challenges of life and work. i Summary In this work, we investigate the active vibration isolation and damping of sensitive equipment. Several single-axis isolation techniques are analyzed and tested. A comparison between the sky-hook damper, integral force feedback, inertial velocity feedback and Lag-Lead control techniques is conducted using several practical examples. The study of single-axis systems has been developed and used to build a six-axis isola-tor. A six degrees of freedom active isolator based on Stewart platform has been designed manufactured and tested for the purpose of active vibration isolation of sensitive payloads in space applications. This six-axis hexapod is designed according to the cubic configuration ; it consists of two triangular parallel plates connected to each other by six active legs orhtogonal to each other; each leg consists of a voice coil actuator, a force sensor and two flexible joints. Two different control techniques have …