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Robotics Institute
Seminar, May 5, 2006
Time and Place | Seminar Abstract | Speaker Biography | Speaker Appointments
Broadcast Feedback for Muscle Actuators
and Organic Robotics:
Biologically-Inspired
Cellular Actuators Using Distributed Stochastic Control
H. Harry Asada
Department of Mechanical Engineering
Massachusetts Institute of Technology
Mauldin
Auditorium (NSH 1305)
Refreshments 3:15 pm
Talk 3:30 pm
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Abstract |
A
biological muscle has an amazing structure consisting of a vast number of
discrete cellular units, which are highly coordinated, despite limited
communication and slow feedback control. This seminar presents a new framework
for communication and control of a vast number of independent cellular units, and
applies the concept to broad robotic systems, including artificial muscle
actuators. Over the years the robotics community has been striving to develop various
muscle-like actuators, ranging from PZT and SMA to conducting polymers and elastomers. These actuator materials, although an
order-of-magnitude higher in stress and energy density than electro-mechanical
actuators, are difficult to use due to prominent hysteresis, creep, and limited
life cycle. To cope with these difficulties, a new approach is explored by
dividing the actuator material into a vast number of small segments, each
taking a bi-stable ON-OFF state. As the size of cellular units becomes smaller,
the dynamic response gets faster, exhibiting the type of behavior of ON-OFF
finite state machine. Like a biological muscle, the aggregate effect of a vast
number of ON-OFF cellular units can be smooth and continuous with effective
coordination. To aggregate all the
cellular units, a new control method, called “broadcast feedback”,
will be developed based on stochastic control theory. In broadcast feedback,
only a few global output signals are “broadcasted” to all the
cellular units, which in turn make a probabilistic decision based on the
broadcast information and local state observation. Although there is no
deterministic coordination among the vast number of cellular units, the ensemble
of the cellular actuators can track a given trajectory accurately and robustly.
It will be shown that, although 30 percent of the cellular units are dead, the
system can still track the trajectory. This cellular architecture will be
applied to a five-fingered humanoid hand, and the potential of the broadcast
feedback for future “organic” robots will be addressed at the end.
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Speaker Biography |
H. Harry Asada is Ford Professor of Mechanical Engineering
and Director of the Brit and Alex d’Arbeloff
Laboratory for Information Systems and Technology in the Department of
Mechanical Engineering, Massachusetts Institute of Technology (MIT),
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Speaker Appointments |
For appointments,
please contact Janice Brochetti (janiceb@cs.cmu.edu)
The Robotics Institute is part of the School of Computer Science, Carnegie Mellon University.