Pas de Deux avec les Microrobots (Video)

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Technical Report

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Technical Report Number



Video captured through an optical microscope, showing simultaneous control and operation of two stress-engineered microrobots. The dimensions of our microrobots are 260 x 60 x 10 micrometers; each robot consists of an unthetered scratch-drive actuator that provides forward motion, and a steering-arm actuator that controls whether the robot moves in a straight line or turns.

Our stress-engineered microrobots are electrostatically powered via a global control signal transmitted to all the robots regardless of the their position and orientation within their operating environment. Hence, a single control and power-delivery signal must be used to simultaneously control all robots within the same operating environment, resulting in a highly underactuated system. Despite this high level of underactution we are able to achieve independent control of the individual microrobots by designing their steering-arms to respond to different voltage levels of the supplied control signal.

This example uses nested hysteresis gaps. A hysteresis gap is the difference between the snap-down and release voltages for a steering-arm actuator. Nested hysteresis gaps allow us to set the states of the steering-arms (up or down) to any configuration. As shown in this video, all four states of the two microrobot steering-arms are used to choreograph their motion.

A disadvantage of nested hysteresis gaps is that they are control-voltage bandwidth intensive, limiting the number of simultaneously-controllable devices. An alternative multi-microrobot control scheme that minimizes control-bandwidth is described in [1].


[1] B. R. Donald, C. G. Levey and I. Paprotny. "Planar Microassembly by Parallel Actuation of MEMS Microrobots." Journal of Microelectromechanical Systems,2008, (Epub before print) Digital Object Identifier: 10.1109/JMEMS.2008.924251.

This technical report is a multimedia web page, available at http://www.cs.dartmouth.edu/reports/TR2008-631/ .