<title>Adaptive devices for precise position control</title>

Abstract

While many new smart materials have been developed over the last few years, the integration of these materials into useful systems must be exploited if this emerging technology is to become viable. Two applications of piezoelectric and electrostricüve materials are proposed that generate both micro and macro positioning control. Additionally, an overview of these smart materials and their properties will be given.Precise micro positioning devices have applications to adaptive optical systems. A NASA project called Space Laser Energy (SELENE) involves such a system. This project proposes to control the surface of a power transmission dish comprised of several thousands of small lenses or lenslets. A major objective of the dish is to increase efficiency by compensating for atmospheric disturbances. Success of this objective requires high-speed precision control of individual and overall lenslet motion in three degrees of freedom (two rotation and one translation). A discussion of system requirements will be given. Analysis of issues such as linearity, hysteretic compensation, actuator and sensor integration issues will be discussed. A summary of performance predictions will be given for piezoelectric and electrostrictive materials.A second application of piezoelectric materials will be presented for micro and macroscopic one dimensional motion. Specifically, a novel design of an inchworm device will be presented. This device will have the ability to generate macroscopic motion from microscopic piezoelectric expansions and contractions, the frequency of these expansion/contraction cycles should allow the motor to move for significant distances as well as provide incremental micro positioning. The design of the inchworm drive should allow considerable forces, and hence work, to be performed by the device. The design of the inchworm motor will be performed using a combination of FEA and dynamic simulations on Simulab. Predictions regarding the performance of the actuator will be presented.

Design and Testing of a Mesoscale Piezoelectric Inchworm Actuator with Microridges

“…A CTIVE materials are being used in a wide range of applications including vibration reduction [1][2][3][4][5][6], noise suppression [7], adaptive optics [8][9][10], and solid-state motors [11][12][13][14][15][16]. For example, vibration in rotorcraft is a major problem resulting in fatigue, poor ride quality, high noise levels, deficiencies in handling qualities, and reduction of weapons system effectiveness [1][2][3][4].…”

<title>Self-sensing control as applied to a PZT stack actuator used as a micropositioner</title>

“…Thus, piezoelectrics can act as both an actuator and a sensor [4]. Conversely, the material has the unique ability to strain upon the application of an electric field.…”