Design, modeling and control of microrobotic systems

Advances in microtechnology over the past three decades have led to the creation of increasingly integrated systems of ever smaller dimensions. Intervening directly on these "microscopic" elements using macroscopic processes is extremely delicate. The difficulty of manipulating microscopic objects using macroscopic actuators was already highlighted by W.S.N. Trimmer in a visionary article published several decades ago (1989). This article described very well the difficulties of manipulating millimeter-sized objects – in this case electronic chips – using a metric-sized robot:

"This thousand-fold difference between the size of a macro-robot and the chip is equivalent to using a bulldozer to move a lump of sugar. The corresponding precision required is equivalent to positioning this lump of sugar with a precision the thickness of a hair".

This comparison illustrates that using handling systems of an order of magnitude comparable to the object being manipulated is often desirable, or even necessary, for certain microrobotic applications. The expected gains are not only in terms of precision, but also in terms of price, consumption/performance, as well as in terms of the space to be gained in "host environments", notably in clean rooms where microsystems are built, or in the chambers of scanning electron microscopes (SEM) where certain micromanipulation applications are carried out.

Numerous research laboratories embarked on the adventure of microrobotics in the mid-1990s, and the many advances made since then have made microrobotics a relatively mature science. This article describes the main elements of the field and some of its most emblematic achievements worldwide. After presenting the issues specific to microrobotics in relation to conventional robotics, this article will describe the main architectures and components making up a microrobotic station. In particular, elements of design, modeling and operation will be presented, with a focus on microrobotic structures and actuation. Finally, the problem of integration and control will be addressed. These themes will be illustrated by examples from the micro robotics industry and academic research.