A microgripper using smart piezoelectric actuators

The manipulation of very small objects is one of the most important tasks in microrobotics. Micromanipulators are required in all fields where precise manipulation of very small objects must be performed like microsurgery or assembly of MEMS. It is well known that downsizing the tools used in the macroworld is not appropriate to achieve tasks in the microworld. In this paper we present a prototype of a microgripper made up of piezoelectric bending unimorphs. A dynamic model of the piezoelectric unimorphs is developed. Various identification methods have been applied in order to verify the validity of the model. An observer has been built in order to estimate the forces applied at the tip of the fingers. Knowing these forces is very important to avoid destruction of objects during manipulation. The microgripper is able to handle microobjects in a wide range of size by changing the initial distance between the fingers. The resolution of positioning obtained is better than 10 nm for each finger. Every finger can be actuated individually so that dexterous handling can be achieved. This system allows us to perform precise micromanipulation tasks