Biological systems can achieve scalable and adaptive
group behaviors, such as animal flocking, through local interactions
amongst a vast network of unreliable agents. In these systems, each
agent acts autonomously and interacts only with its neighbors, yet the
global system exhibits coordinated behavior. Large-scale multi-agent
systems, e.g. distributed robot systems, are similar to these
biological systems, in that their overall tasks must be achieved by
coordinating many independent agents. One important question to ask
is: How can we program large networks of agents to achieve
collective tasks, and at the same time adapt to dynamic conditions
like living systems?
Our group has developed a biologically-inspired
control framework for multi-agent networks to achieve coordinated
tasks in a scalable, robust, and analyzable manner. We focus on a type
of tasks, called distributed homeostasis, in
which agents must use distributed sensing to solve
collective tasks and to cope with changing
environments. This task space can be formulated more generally
as distributed constraint-maintenance on a networked multi-agent
system, and this approach allows us to capture various multi-agent
scenarios and tasks. We show how one can exploit the locality of this
formulation to design nearest-neighbor agent control, based on simple
sensing, actuation and local communication.
The main contributions and directions of this project
are:
Simple Decentralized Algorithms for Various Self-Adaptive
Tasks: We formulate this problem more generally as distributed
constraint maintenance on a networked multiagent system. Such a
formulation allows the framework to model and simplify tasks on a
variety of distributed agent applications. It also allows us to
exploit locality of the task to derive decentralized agent control
that is based on a simple sensing and actuation strategy.
Theoretical Analysis and Understanding of the Approach: We
analyze important aspects of this decentralized approach, including
convergence, scalability, and robustness. We also outline sufficient
conditions that guarantee agent control laws' correctness for
different networked multiagent systems. This analytical framework
allows one to have a concrete understanding of the strengths,
limitations, and scope of this class of decentralized
approaches.
Many Application Areas: This framework has wide
applicability to autonomous systems that exploit sensor-actuator
networks as underlying architectures, including modular robots,
adaptive architecture, multi-robot cooperation, and adaptive
medical devices. We have designed and demonstrated a number of
different hardware prototype systems, using both chain-style and
link-style modular robots, based on this theoretical approach.
Movies of (1) Self-adapting Modular Robot Table, and
other examples (2) Narrated Overview with many types of Self-adapting
Modular Robots (3) Amorphous and Collective Locomotion using a
link-based "deformable" robot. For more movies, see our movie page and
Youtube channel.
Biologically-Inspired
Control for Self-Adaptive Multiagent Systems
Chih-Han Yu.
Doctoral Thesis, Harvard University, Apr 2010. (pdf)
Biologically-Inspired
Control for Multi-Agent Self-Adaptive Tasks
Chih-Han Yu, Radhika Nagpal.
Twenty-Fourth AAAI Conference on Artificial Intelligence (AAAI),
2010. (pdf)
New scientific and technical advances in research (Nectar)
Track
Algorithms and Theories:
Collective
Decision-Making in Multi-Agent Systems by Implicit Leadership
Chih-Han Yu, Justin Werfel, Radhika Nagpal.
Intl. Conf on Autonomous Agents and Multi-Agent
Systems (AAMAS), 2010. (pdf)
Sensing-based Shape
Formation Tasks on Modular
Multi-Robot Systems: A Theoretical Study
Chih-Han Yu, Radhika Nagpal,
Intl. Conf on Autonomous Agents and Multi-Agent
Systems (AAMAS),
2008. (pdf) Nominated for Pragnesh Jay Modi Best Student Paper
Award.
Applications:
Coordinating Collective
Locomotion in an Amorphous Modular Robot
Chih-Han Yu, Justin Werfel, Radhika Nagpal.
IEEE International Conference on Robotics and Automation (ICRA), 2010. (pdf)
Self-Adapting Modular
Robotics: A Generalized Distributed Consensus Framework
Chih-Han Yu, Radhika Nagpal.
IEEE International Conference
on Robotics and Automation (ICRA),
2009. (pdf)
Also see Video Paper, IROS 2009 (Video, youtube link)(pdf)
Self-organizing
Environmentally-adaptive Shapes on
a Modular Robot
Chih-Han Yu, FX Williems, Donald Ingber,
Radhika Nagpal
IEEE Conference on Intelligent Robots
and Systems (IROS),
Oct, 2007 (pdf)
Robot Hardware:
Mechanical Design and
Locomotion of Modular-Expanding Robots
Rebecca Belisle, Chih-Han Yu, Radhika Nagpal.
Modular Robotics Workshop,
IEEE Intl. Conf. on Robotics and Automation (ICRA), 2010. (pdf)
Morpho: A
Self-Deformable Modular Robot Inspired By
Cellular Structure
Chih-Han Yu, Kristina Haller, Donald Ingber, Radhika Nagpal.
IEEE Intl. Conference on Intelligent Robots and Systems (IROS), 2008. (pdf)