Pas de Deux avec les Microrobots
Bruce R. Donalda,b,*, Christopher Leveyc, and Igor Paprotnyd,a
aDepartment of Computer Science, Duke University, Durham NC 27708
bDepartment of Biochemistry, Duke University Medical Center, Durham NC 27708
cThayer School of Engineering, Dartmouth College, Hanover NH 03755
dDepartment of Computer Science, Dartmouth College, Hanover NH 03755
Bruce R. Donald
Department of Computer Science
Department of Biochemistry
Duke University Medical Center
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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 .
 B. R. Donald, C. G. Levey and I. Paprotny.
"Planar Microassembly by Parallel
Actuation of MEMS Microrobots." Journal of Microelectromechanical Systems,
2008; 17(4): 789-808.