P. Minotti

New multi-degree of freedom piezoelectric micromotors for micromanipulator applications

The authors have developed new multidegrees of freedom (d.o.f.) piezoelectric micromotors using both stationary bending modes and traveling wave technology. These devices are respectively based on the conversion, through frictional contact, of bending vibrations sustained in one or several vibrators into rigid body displacements of a moving element. They have allowed the design and the development of a micromanipulator with five degrees of freedom composed of stationary wave type linear translators (2 d.o.f.) and traveling wave type spherical micromotors (3 d.o.f.). These two motors can be driven reversibly in both directions with linear speeds between one mm. s/sup -1/ and few cm. s/sup -1/. The paper shows however that micrometer steps can be activated for micropositioning applications without displacement limitations.

Interferometry system for out-of-plane microdisplacement measurement: application to mechanical expertise of scratch drive actuators

The material properties of silicon, as well as the planar and monolithic nature of the microstructures make electrostatic field energy conversion the most suitable driving principle on the micrometer scale. Moreover, compared with most other actuation principles, the scaling of electrostatic forces is particularly suitable for actuator downsizing. In spite of the advantages, it is still difficult to obtain appropriate driving characteristics because of silicon based actuator limitations such as small structural height, micrometer gap requirements and material limitations in the shaping process. Actuators require specific tools to verify that their mechanical properties and motions obey the designers intent. In this paper capabilities of future direct-drive electrostatic actuators SDA (Scratch Drive Actuators) are investigated through the characterisation of their out-of-plane displacements by interferometry. The actuation involves contact interactions by using flexible polysilicon elementary actuator plate. The region of the physical contact is measured using Twyman-Green interferometer incorporated within a metallurgical microscope. The shapes and out-of-plane displacements of microstructures are extracted from interferograms by temporal phase shift method (TPS). Additionally, the results from interferometric method are compared with numerical simulations given by finite elements software - ANSYS.

Fully integrated on-chip laboratories for MEMS-based material and structure mechanical analysis

Industrialization of MEMS devices such as silicon-based sensors and actuators requires specific tools to verify that their mechanical properties and/or motions obey the designerss intent. Accordingly, this paper investigates new on-chip laboratories that will allow systematic mechanical analysis of MEMS-based structures and materials.

A Two-Degrees of Freedom Speed Control of a Revolving Travelling Wave Piezomotor

Abstract A newly-developed servo-control system using two feedback control loops based on sensorless technique have been demonstrated by the authors. The schemes using an instantaneous control and average value control processing strategies are based upon loadadaptative resonant frequency and constant velocity amplitude schemes. Its control schemes are theoretically considered and its experimental results are demonstrated and evaluated in practice.