With the wide application of various precision instruments and equipments in many scientific and engineering fields, vibration has been the main reason which influences the system performance and operating life. Thus, the problem of vibration control, especially vibration isolation must be fully taken into account. In general, vibration may come from different directions; that is, excitation force may have effect on the system in six degrees of freedom (DOFs). Therefore, in order to overcome the drawbacks of onventional passive vibration isolation, and achieve good vibration isolation performance in all six DOFs, active vibration isolation using a parallel mechanism, especially a Stewart parallel mechanism has been the focus of research recently. By taking the Stewart parallel mechanism based active vibration isolation platform as the research object, the research of this dissertation mainly focuses on some key problems of active vibration isolation, such as the optimal control of single-strut vibration isolation system, the dynamic modeling of active vibration isolation platform and the design of vibration controller, etc. Firstly, the characteristics of active vibration isolation are described. The previous research of general multi-DOF active vibration isolation platforms, as well as parallel mechanism based active vibration isolation platforms is surveyed. Furthermore, the actuator techniques are introduced. And the typical feedback control algorithms for vibration isolation are also reviewed. Secondly, the approximate dynamic programming (ADP) method is adopted to deal with the optimal control problem of the single-strut vibration isolation system. With the prior knowledge of the model, a dual heuristic programming (DHP) based active vibration isolation controller is proposed. Then, by fully considering the inherent complex nonlinear characteristics of the damping coefficient and the stiffness force in the system, an action dependent heuristic dynamic programming (ADHDP) based active vibration isolation controller is proposed. As the ADHDP approach is model free, only actual values of the inputs and outputs from the system are required in the process of controller design. The simulation results verify the vibration isolation performance of the aforementioned methods. Moreover, a voice coil actuator based experimental platform is constructed for the single-strut vibration isolation system. Thirdly, with consideration of the influence of vibratio...
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