W. Brenner

The transfer function of a new disc-type ultrasonic motor

Abstract This paper deals with the transfer functions of a new disc-type ultrasonic motor: stator and stator–rotor energy transformation. The objective is to initiate a mode that can produce certain relative dynamic responses in the proposed motor. The performance will be parameterized by system inputs in an attempt to obtain an optimal operational configuration. The transfer function model of the piezoelectric ultrasonic stator based on the lateral elliptical motion is derived for the control application and certification of its load-characteristic parameters and also predicts the motor performance. On this basis, we can determine whether the output of the motor will be stable. The contact-dynamics behaviors of the stator are also studied. These derived formulations in this paper are based on the general concept of the constitutive laws governing piezoelectric materials which permit the introduction of kinetic energy, electrical energy, and geometric constraints relating to the deformation variables.

Gripping tools for handling and assembly of microcomponents

In this paper a vacuum gripper for handling of microstructures in MST will be presented as well as the design, production and testing of two types of mechanical micro-grippers used for handling and assembly of microcomponents. One of them is with the possibility of optical force sensing.

Development of a totally implantable hearing aid

In this paper we described briefly the activities done in the frame of development of a system for contactless detection of the vibrations of the middle ear ossicle. The system has been constructed in the form of a fiber-optic vibrometer, which can be used as the microphone of a totally implantable hearing aid. The current state of the art is described and the initial measurements are presented and commented upon.

Micro torque measurement based on the cable brake principle

This paper describes a micro torque measurement device based on the cable brake principle. The miniature cable brake permits the measurement of torque produced by miniature motors in the /spl mu/Nm range with a resolution of 0.1 /spl mu/Nm and rotational speeds up to 50,000 rpm. The relative error is about 7.5 %. Work on further system miniaturization for application on micromotors is in progress.

The measurement of minimotors and micromotors torque characteristic

Two miniaturized torque sensors, based on cable brake principle and so-called measurement cross principle, have been developed. Design principles and the production process are described. Experimental results show fair conformity with technical data for minimotors.

Principles of torque measurement for rotating microactuators

Different micromotors and other rotating microsystems like gearboxes with dimensions of a few millimeters have been developed during the last years. Applications of such micromotors can be found in sensors and actuators for example in medical equipment. These components offer the possibility of extreme miniaturization of mechanical systems with driven rotating parts. The characterization of rotating microsystems is necessary during the state of development as well as for quality control in production. The minimum requirement for the characterization of a motor is the measurement of torque and of rotational speed The measurement of rotational speed is a relative simple task, even for miniaturized systems, but the measurement of torque is much more complicated. Most of the well-known methods and sensors for measurement of torque are not suitable for micromotors. A sensor unit based on a spring-element using optoelectronic methods for measuring the small deformation of the spring has been developed to cover the requirements for torque measurement of rotating microsystems. Within the European project HAFAM (Handling and Assembly of Functionally Adapted Microcomponents) a complete testing stage for characterizing rotating microsystems using this sensor has been developed. The objective of this micro torque testing stage is to provide a flexible and modular means for assessing the performance and the quality of both active and passive microsystems, e.g. micromotors or micro ball bearings.

Principles of Torque Measurements for Rotating Microsystems

In this paper, the torque-rotational speed characteristics of rotating iicrosystems and the principles involved are examined. Furthermore, some devices on the market and some realisations in the scope of TMR-proiect “Handling and Assembly of Functionally Adapted Microcomponents, HAFAM” are presented.

Vibration characteristic identification by experiment of a new disc-type ultrasonic stator

The objective of this paper is to gain a deeper understanding of the vibration characteristics on the surface of a new disc-type ultrasonic stator for possible application to a moving object. By using the laser heterodyne technique, we can identify the vibration displacement and velocity patterns of the stator. Furthermore, the sensitivity is acquired from the measurement data. As a result, we find that the stator can produce a levitation motion on the surface of the stator. However, this is better for a lateral motion than a planar levitation.

New types of silicon torsion microspring and their characterization

A number of methods for torque measurements in the macro domain exist, but only some of them can be scaled down to micro dimensions. This paper describes one method for measuring very small moments which is based on the measurement of torque by using silicon micro springs. Three different designs of torsion micro springs have been produced. The experimentally measured results show the possibility of torque measurement in the sub-(mu) Nm range.

Development of microactuators for tactile graphic displays (State of the art and recent efforts)

An overview of the state of the art principles that can be used for actuators in high-resolution tactile graphic displays is presented. Existing actuators used in commercially available tactile displays (electromagnetic or piezoelectric) have several disadvantages, and are not suitable for high resolution graphic displays. The actuators based on some of the presented, non-conventional principles in this paper can be smaller, cheaper, and more reliable.