Actuator systems for precision motion control

Piezoelectric actuators have gained widespread used in the aerospace industry. They possess the desirable qualities of high force, high bandwidth, and extremely precise positioning capabilities, making them ideal for precision motion control for both dynamic and static applications. However, piezoelectric materials have a very low stroke, about 0.1% strain. Also, the high density of piezoelectrics makes large actuators undesirable for applications with strict weight restrictions. Amplification mechanisms are needed to expand the versatility of such actuators. Garman Systems, Inc., and the Smart Structures Lab at Vanderbilt University, have developed two novel amplification mechanisms, the flat plate actuator, and the BOA (Bi-directional Operating Actuator) to amplify the stroke of piezoelectric actuators. Both mechanisms amplify the 18-20 mu m displacement of a 20 mm long piezoelectric stack nearly five times. The flat plate actuator achieves a full scale displacement of over 100 mu m, and the BOA achieves a full scale displacement of approximately 90 mu m. These actuators have limitless uses in optical applications, and many other situations in which precision motion is needed. Also developed are two novel mechanisms for vibration suppression. These devices operate as proof mass actuators, to damp out the vibrations of the structure on which they are mounted. These actuators can be used to damp out mechanical vibrations in large optical arrays and other structures. The devices can also be used as active vibration mounts, to isolate structures from vibrations.