ISOLATION DESIGN FOR A FLEXIBLE SYSTEM

It has been commonly assumed that the corner or mount frequency in an isolator should be designed as low as possible. This is one result of using a single-degree-of-freedom (SDOF) system to model isolation syst ems. However, for systems that have flexible or non-rigid foundations, a design point for the mount frequency can occur between the modes of the base. By implementing this type of design, a strong interaction w ill exist between the modes. When isolator damping is included, whethe r done passively or actively, more than one mode can be attenuated by this new mount design. Therefore, the effects of the mount frequency o n isolation designs are discussed as well as using both passive and ac tive damping in the isolator. For active damping, three commonly used control methodologies are discussed: a proportional-plus-integral-plus -derivative (PID) controller, a linear quadratic Gaussian (LQG) regula tor and a positive position feedback (PPF) controller. (C) 1998 Academ ic Press.