| Volume 26 Issue 11-12 - Publication Date: 1 November- December June 2007 |
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| Broadcast Feedback of Stochastic Cellular Actuators Inspired by Biological Muscle Control |
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| J. Ueda, d’Arbeloff Laboratory for Information Systems
and Technology, Department of Mechanical Engineering
Massachusetts Institute of Technology, Cambridge
MA 02139, and Graduate School
of Information Science, Nara Institute of Science
and Technology, Nara, 630-0192 L. Odhner, and H. H. Asada d’Arbeloff Laboratory for Information Systems
and Technology, Department of Mechanical Engineering
Massachusetts Institute of Technology, Cambridge MA 02139 |
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| This paper presents a broadcast feedback approach to the distributed
stochastic control of an actuator system consisting of many cellular
units. This control architecture was inspired by skeletal muscles comprising
a vast number of tiny functional units, called sarcomeres. The
output of the actuator system is an aggregate effect of numerous cellular
units, each taking a bistable ON–OFF state. A central controller
“broadcasts” the error between the aggregate output and a reference
input. Rather than ordering the individual units to take specific states,
the central controller merely broadcasts the overall error signal to
all the cellular units uniformly. In turn each cellular unit makes a
stochastic decision with a state transition probability, which is modulated
in relation to the broadcasted error. Stochastic properties of
both open-loop and closed-loop control systems are analyzed. Stability
conditions of the broadcast feedback system are obtained by using
a stochastic Lyapunov function. The proposed method is simulated for
an artificial cellular actuator, consisting of many segments of smart
actuator material. Theoretical results are verified through simulation.
It is demonstrated that, even in the absence of deterministic coordination,
the ensemble of the cellular units can track a given trajectory
stably and robustly. |
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