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Miniaturized positioning device for precise rotary motion by use of piezoelectric actuators

: Dörrer, P.

American Society for Precision Engineering -ASPE-:
American Society for Precision Engineering. Twelfth Annual Meeting 1997. Proceedings
Raleigh, NC: ASPE, 1997
ISBN: 1-887706-18-6
American Society for Precision Engineering (Annual Meeting) <12, 1997, Norfolk/Va.>
Fraunhofer IOF ()
Drehversteller; elastic hinge; Festkörpergelenk; miniaturized adjusting device; piezoelectric actuator; piezoelektrischer Aktuator; Positioniersystem; positioning system; rotary stage

With increasing miniaturisation of components which has to be handled and exactly examinated, the accuracy requirements of positioning systems are rising. Such high accuracy requirements can be meet by piezoelectric actuators, because it is easy to control their displacement on the order of submicrons by voltage control. However, in applying such actuators it is difficult to realize a rotary motion. At the Fraunhofer Institution in Jena the positioning device for precise rotary motion has been developed, which is driven by piezoelectric multilayer actuators. The deformation of one actuator generates a precise linear motion, which is transformed by an elastic hinge to the rotary motion. This elastic hinge constitutes the pivot point of the positioning system. The reachable angular resolution depends on the actuator, his distance to the pivot point and the control. The angular resolution of our new developed device with a volume of the whole lower than 3 cm3 is better than 0.4 seconds of arc. The generated rotary motion is transmitted to the rotor by the clamp mechanism. The clamp mechanism contains a further piezoelectric multilayer actuator, which is driven by a voltage up to 150 V. The motion generated in this way is transformed by elastic hinges, too. If the actuator is activated, the rotor is unclamped; if it is not driven, the clamps hold the rotor. There is no need for conventional bearing, whose production and assembly would be problematic in the miniaturized scale. To avoid complicated micro-assembly techniques in general, the mechanical body of the positioning device consists of only one part. Merely the actuators has to be arranged and attached. The simple structure of the miniaturized positioning device has the additional advantage, that the behaviour referring to vibrations is optimized. For this reason, considering the reachable angular resolution, a relative high speed is expected. The range of rotation is free. The miniaturized positioning device was d eveloped for high accuracy positioning of objects for handling and examination, for adjustment and quality control and for precise alignment of sensors. Due to the clamping without power consumption it is a long-time stable adjusting device. It can be coupled with linear positioning systems.