ABSTRACT
Many flexure designs necessarily include some form of drive mechanism. Of all type available, these can be split into two categories these being contact or noncontact. Non-contact drives are electromagnetic, electrostatic or hydrostatic. Contacting drives all consist of actuators designed to impose a force or strain in a solid body that is some way connected between two points in the flexure. Contacting drives can be motor driven micrometers, friction driven pushers, piezoelectric, magneto-strictive, electro-strictive, hydraulic piston, pressurized diaphragms, Poisson's ratio, shape memory, bimetallic and thermal expansion (for a rather fun version of this latter drive see Snyder, 1993). Some of the important attributes of these mechanisms are discussed in chapter 8 while the interested reader is referred to Smith and Chetwynd, 1991 for a more detailed discussion. Non-contact drives impose a force on the flexure without significantly effecting stiffness or adding mass. Contact drives however can be considered to add, often, significant stiffness at their point of application. In
general, the added mass of the actuator can be lumped into the 'stationary' link. For example, in the case of a micrometer the stationary link is the one to which the micrometer is rigidly secured while the moving link is attached to the anvil of the micrometer via some form of coupling. Consequently, the only additional mass on the moving link is that due only to the rigidly attached component of the coupling.
