Claytronics Group Publications Listed by Topic

@inproceedings{bkirby-iros07,
  author = {Kirby, Brian and Aksak, Burak and Hoburg, James F. and
     Mowry, Todd C. and Pillai, Padmanabhan},
  title = {A Modular Robotic System Using Magnetic Force Effectors},
  booktitle = {In Proceedings of the IEEE International Conference on
     Intelligent Robots and Systems (IROS '07)},
  year = {2007},
  month = {October},
  abstract = {One of the primary impediments to building ensembles
     with many modular robots is the complexity and number of
     mechanical mechanisms used to construct the individual modules.
     As part of the Claytronics project---which aims to build very
     large ensembles of modular robots---we investigate how to
     simplify each module by eliminating moving parts and reducing the
     number of mechanical mechanisms on each robot by using
     force-at-a-distance actuators. Additionally, we are also
     investigating the feasibility of using these unary actuators to
     improve docking performance, implement intermodule adhesion,
     power transfer, communication, and sensing.},
  keywords = {Actuation, Adhesion},
  url = {http://www.cs.cmu.edu/~claytronics/papers/bkirby-iros07.pdf}
}

@article{campbell-ijrr-srmr,
  author = {Campbell, Jason D. and Pillai, Padmanabhan},
  title = {Collective Actuation},
  journal = {International Journal of Robotics Research},
  year = {2007},
  keywords = {Actuation, Controlling Ensembles},
  abstract = {Modular robot designers confront an inherent tradeoff
     between size and power: Smaller, more numerous modules increase
     the adaptability of a given volume or mass of robot---allowing
     the aggregate robot to take on a wider variety of
     configurations---but do so at a cost of reducing the power and
     complexity budget of each module. Fewer, larger modules can
     incorporate more powerful actuators and stronger hinges but at a
     cost of overspecializing the resulting robot in favor of
     corresponding uses. In the paper we describe a technique for
     coordinating the efforts of many tiny modules to achieve forces
     and movements larger than those possible for individual modules.
     In a broad sense, the question of actuator capacity and range
     thus may become one of software coding and ensemble topology as
     well as of hardware design. An important aspect of this technique
     is its ability to bend complex and large-scale structures and to
     realize the equivalent of large scale joints. Although our
     results do not suggest that modular robots will replace high
     power purpose-built robots, they do offer an increase in the
     plausible scalability of modular robot self-reconfiguration and
     facilitate a corresponding increase in adaptability.}
}

@inproceedings{karagozler-iros07,
  author = {Karagozler, Mustafa Emre and Campbell, Jason D. and
     Fedder, Gary K. and Goldstein, Seth Copen and Weller, Michael P.
     and Yoon, Byung W.},
  title = {Electrostatic Latching for Inter-module Adhesion, Power
     Transfer, and Communication in Modular Robots},
  booktitle = {Proceedings of the IEEE International Conference on
     Intelligent Robots and Systems IROS '07},
  see = {karagozler-msreport07},
  year = {2007},
  month = {October},
  abstract = {A simple and robust inter-module latch is possibly the
     most important component of a modular robotic system. This paper
     describes a latch based on capacitive coupling which not only
     provides significant adhesion forces, but can also be used for
     inter-module power transmission and communication. The key
     insight that enables electrostatic adhesion to be effective at
     the macroscale is to combine flexible electrodes with a geometery
     that uses shear forces to provide adhesion. To measure the
     effectiveness of our latch we incorporated it into a 28cm x 28cm
     x 28cm modular robot. The result is a latch which requires almost
     zero static power and yet can hold over 0.6N/cm^2 of latch
     area.},
  keywords = {Actuation, Adhesion},
  url = {http://www.cs.cmu.edu/~claytronics/papers/karagozler-iros07.pdf}
}

@inproceedings{Christensen-iros07,
  author = {Christensen, David Johan and Campbell, Jason D.},
  title = {From Roles to Anatomy to Scalable Modular
     Self-Reconfigurable Robots},
  booktitle = {Proceedings of the IEEE International Conference on
     Intelligent Robots and Systems {IROS '07}},
  keywords = {Biologically Inspired, Actuation, Controlling
     Ensembles},
  year = {2007}
}

@inproceedings{karagozler-msreport07,
  author = {Karagozler, Mustafa Emre},
  title = {Harnessing Capacitance for Inter-Robot Latching,
     Communication, and Power Transfer},
  booktitle = {MSc Report, Carnegie Mellon University, Department of
     Electrical and Computer Engineering},
  also = {Electrostatic Latching for Inter-module Adhesion, Power
     Transfer, and Communication in Modular Robots in IROS '07},
  month = {May},
  year = {2007},
  abstract = {A simple and robust inter-module latch is possibly the
     most important component of a modular robotic system. This report
     describes a latch based on capacitive coupling which not only
     provides significant adhesion forces, but can also be used for
     inter-module power transmission and communication. The key
     insight that enables electrostatic adhesion to be effective at
     the macro scale is to combine flexible electrodes with a geometry
     that uses shear forces to provide adhesion. To measure the
     effectiveness of our latch we incorporated it into a 28cm x 28cm
     x 28cm modular robot. The result is a latch which requires almost
     zero static power and yet can hold over 0.6N/cm2 of latch area.},
  keywords = {Actuation, Adhesion, Power Routing},
  url = {http://www.cs.cmu.edu/~claytronics/papers/karagozler-msreport07.pdf}
}

@inproceedings{Christensen-icra07,
  author = {Christensen, David Johan and Campbell, Jason D.},
  title = {Locomotion of Miniature Catom Chains: Scale Effects on Gait
     and Velocity},
  booktitle = {Proceedings of the IEEE International Conference on
     Robotics and Automation {ICRA '07}},
  month = {April},
  keywords = {Biologically Inspired, Actuation, Controlling
     Ensembles},
  year = {2007}
}

@inproceedings{campbell-rss06,
  author = {Campbell, Jason D. and Pillai, Padmanabhan},
  title = {Collective Actuation},
  booktitle = {RSS 2006 Workshop on Self-Reconfigurable Modular
     Robots},
  year = {2006},
  month = {August},
  keywords = {Actuation, Controlling Ensembles},
  url = {http://www.cs.cmu.edu/~claytronics/papers/campbell-rss06.pdf},
  abstract = {Modular robot designers confront an inherent tradeoff
     between size and power: Smaller, more numerous modules increase
     the adaptability of a given volume or mass of modules---allowing
     the aggregate robot to take on a wider variety of configurations
     – but do so at the expense of the power and complexity of each
     module. Fewer, larger modules can incorporate more powerful
     actuators, more powerful bonds, and stronger hinges but at a cost
     of overspecializing the resulting robot in favor of
     correspond-ing uses. We describe a technique for coordinating the
     efforts of many tiny modules to achieve forces and movements
     be-yond those possible for individual modules. Our approach is
     predominantly applicable to spherical and cylindrical modules and
     their faceted counterparts, but may apply to some chain-style
     modular robot systems. Thus actuator capacity and range becomes a
     function of software and dynamic topology as well as of hardware.
     An important aspect of this technique is its ability to bend
     complex and large-scale structures and to realize the equivalent
     of large scale joints.}
}

@inproceedings{bkirby-iros07,
  author = {Kirby, Brian and Aksak, Burak and Hoburg, James F. and
     Mowry, Todd C. and Pillai, Padmanabhan},
  title = {A Modular Robotic System Using Magnetic Force Effectors},
  booktitle = {In Proceedings of the IEEE International Conference on
     Intelligent Robots and Systems (IROS '07)},
  year = {2007},
  month = {October},
  abstract = {One of the primary impediments to building ensembles
     with many modular robots is the complexity and number of
     mechanical mechanisms used to construct the individual modules.
     As part of the Claytronics project---which aims to build very
     large ensembles of modular robots---we investigate how to
     simplify each module by eliminating moving parts and reducing the
     number of mechanical mechanisms on each robot by using
     force-at-a-distance actuators. Additionally, we are also
     investigating the feasibility of using these unary actuators to
     improve docking performance, implement intermodule adhesion,
     power transfer, communication, and sensing.},
  keywords = {Actuation, Adhesion},
  url = {http://www.cs.cmu.edu/~claytronics/papers/bkirby-iros07.pdf}
}

@article{aksak-jast07,
  author = {Murphy, M.P. and Aksak, Burak and Sitti, Metin},
  title = {Adhesion and Anisotropic Friction Enhancements of Angled
     Heterogeneous Micro-Fiber Arrays with Spherical and Spatula
     Tips},
  journal = {Journal of Adhesion Science and Technology},
  year = {2007},
  abstract = {Angled polyurethane fiber arrays are modified by adding
     soft spherical and spatula shaped tips by dipping. These fibers
     are characterized for adhesion and friction and compared with
     unmodified fibers and flat material samples. Sphere and spatula
     tip fiber samples demonstrate increased adhesion, with 10 and 23
     times the maximum adhesion of the unmodified fiber sample,
     respectively. The sphere and spatula tip fiber samples also show
     increased friction, with 1.6 and 4.7 times the maximum friction
     of the unmodified fiber sample, respectively. Simultaneous
     friction and adhesion is observed in a synthetic dry angled
     fibrillar adhesive sample (spatula tip fiber sample) for the
     first time. The direction dependent friction of angled fibers is
     investigated and observed. The adhesion and friction results
     reported in this paper suggest that fibers with negligible
     adhesion can be modified to exhibit significant adhesion and
     friction enhancement by the proposed fiber tip modifications.},
  keywords = {Gecko, Adhesion, Angled Fiber Array, Friction, Dry
     Adhesive, Bioinspired adhesive},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-jast07.pdf}
}

@article{aksak-langmuir2007,
  author = {Aksak, Burak and Murphy, M.P. and Sitti, Metin},
  title = {Adhesion of Biologically Inspired Vertical and Angled
     Polymer Microfiber Arrays},
  journal = {Langmuir},
  year = {2007},
  month = {February},
  volume = {23},
  pages = {3322--32},
  number = {6},
  issn = {0743-7463},
  keywords = {Adhesion, Biologically Inspired},
  abstract = {This paper proposes an approximate adhesion model for
     fibrillar adhesives for developing a fibrillar adhesive design
     methodology and compares numerical simulation adhesion results
     with macroscale adhesion data from polymer microfiber array
     experiments. A technique for fabricating microfibers with a
     controlled angle is described for the first time. Polyurethane
     microfibers with different hardnesses, angles, and aspect ratios
     are fabricated using optical lithography and polymer micromolding
     techniques and tested with a custom tensile adhesion measurement
     setup. Macroscale adhesion and overall work of adhesion of the
     microfiber arrays are measured and compared with the models to
     observe the effect of fiber geometry and preload. The adhesion
     strength and work of adhesion behavior of short and long vertical
     and long angled fiber arrays have similar trends with the
     numerical simulations. A scheme is also proposed to aid in
     optimized fiber adhesive design.},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-langmuir2007.pdf}
}

@inproceedings{karagozler-iros07,
  author = {Karagozler, Mustafa Emre and Campbell, Jason D. and
     Fedder, Gary K. and Goldstein, Seth Copen and Weller, Michael P.
     and Yoon, Byung W.},
  title = {Electrostatic Latching for Inter-module Adhesion, Power
     Transfer, and Communication in Modular Robots},
  booktitle = {Proceedings of the IEEE International Conference on
     Intelligent Robots and Systems IROS '07},
  see = {karagozler-msreport07},
  year = {2007},
  month = {October},
  abstract = {A simple and robust inter-module latch is possibly the
     most important component of a modular robotic system. This paper
     describes a latch based on capacitive coupling which not only
     provides significant adhesion forces, but can also be used for
     inter-module power transmission and communication. The key
     insight that enables electrostatic adhesion to be effective at
     the macroscale is to combine flexible electrodes with a geometery
     that uses shear forces to provide adhesion. To measure the
     effectiveness of our latch we incorporated it into a 28cm x 28cm
     x 28cm modular robot. The result is a latch which requires almost
     zero static power and yet can hold over 0.6N/cm^2 of latch
     area.},
  keywords = {Actuation, Adhesion},
  url = {http://www.cs.cmu.edu/~claytronics/papers/karagozler-iros07.pdf}
}

@inproceedings{karagozler-msreport07,
  author = {Karagozler, Mustafa Emre},
  title = {Harnessing Capacitance for Inter-Robot Latching,
     Communication, and Power Transfer},
  booktitle = {MSc Report, Carnegie Mellon University, Department of
     Electrical and Computer Engineering},
  also = {Electrostatic Latching for Inter-module Adhesion, Power
     Transfer, and Communication in Modular Robots in IROS '07},
  month = {May},
  year = {2007},
  abstract = {A simple and robust inter-module latch is possibly the
     most important component of a modular robotic system. This report
     describes a latch based on capacitive coupling which not only
     provides significant adhesion forces, but can also be used for
     inter-module power transmission and communication. The key
     insight that enables electrostatic adhesion to be effective at
     the macro scale is to combine flexible electrodes with a geometry
     that uses shear forces to provide adhesion. To measure the
     effectiveness of our latch we incorporated it into a 28cm x 28cm
     x 28cm modular robot. The result is a latch which requires almost
     zero static power and yet can hold over 0.6N/cm2 of latch area.},
  keywords = {Actuation, Adhesion, Power Routing},
  url = {http://www.cs.cmu.edu/~claytronics/papers/karagozler-msreport07.pdf}
}

@article{aksak-jast07,
  author = {Murphy, M.P. and Aksak, Burak and Sitti, Metin},
  title = {Adhesion and Anisotropic Friction Enhancements of Angled
     Heterogeneous Micro-Fiber Arrays with Spherical and Spatula
     Tips},
  journal = {Journal of Adhesion Science and Technology},
  year = {2007},
  abstract = {Angled polyurethane fiber arrays are modified by adding
     soft spherical and spatula shaped tips by dipping. These fibers
     are characterized for adhesion and friction and compared with
     unmodified fibers and flat material samples. Sphere and spatula
     tip fiber samples demonstrate increased adhesion, with 10 and 23
     times the maximum adhesion of the unmodified fiber sample,
     respectively. The sphere and spatula tip fiber samples also show
     increased friction, with 1.6 and 4.7 times the maximum friction
     of the unmodified fiber sample, respectively. Simultaneous
     friction and adhesion is observed in a synthetic dry angled
     fibrillar adhesive sample (spatula tip fiber sample) for the
     first time. The direction dependent friction of angled fibers is
     investigated and observed. The adhesion and friction results
     reported in this paper suggest that fibers with negligible
     adhesion can be modified to exhibit significant adhesion and
     friction enhancement by the proposed fiber tip modifications.},
  keywords = {Gecko, Adhesion, Angled Fiber Array, Friction, Dry
     Adhesive, Bioinspired adhesive},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-jast07.pdf}
}

@inproceedings{pillai-iros06,
  author = {Pillai, Padmanabhan and Campbell, Jason D. and Kedia,
     Gautam and Moudgal, Shishir and Sheth, Kaushik},
  title = {A 3D Fax Machine based on Claytronics},
  booktitle = {2006 IEEE/RSJ International Conference on Intelligent
     Robots and Systems (IROS)},
  month = {October},
  year = {2006},
  keywords = {Applications of Claytronics},
  url = {http://www.cs.cmu.edu/~claytronics/papers/pillai-iros06.pdf},
  abstract = {This paper presents a novel application of modular
     robotic technology. Many researchers expect manufacturing
     technology will allow robot modules to be built at smaller and
     smaller scales, but movement and actuation are increasingly
     difficult as dimensions shrink. We describe an application --- a
     3D fax machine --- which exploits inter-module communication and
     computation without requiring self-reconfiguration. As a result,
     this application may be feasible sooner than applications which
     depend upon modules being able to move themselves. In our new
     approach to 3D faxing, a large number of sub-millimeter robot
     modules form an intelligent ``clay'' which can be reshaped via
     the external application of mechanical forces. This clay can act
     as a novel input device, using intermodule localization
     techniques to acquire the shape of a 3D object by casting. We
     describe software for such digital clay. We also describe how,
     when equipped with simple inter-module latches, such clay can be
     used as a 3D output device. Finally, we evaluate results from
     simulations which test how well our approach can replicate
     particular objects.}
}

@inproceedings{karagozler-rascal06,
  title = {Ultralight Modular Robotic Building blocks for the Rapid
     Deployment of Planetary Outposts},
  booktitle = {Revolutionary Aerospace Systems Concepts Academic
     Linkage (RASC-AL) Forum 2006},
  author = {Karagozler, Mustafa Emre and Kirby, Brian and Lee, W.J.
     and Marinelli, Eugene and Ng, T.C. and Weller, Michael P. and
     Goldstein, Seth Copen},
  year = {2006},
  month = {May},
  address = {Cape Canaveral, FL},
  url = {http://www.cs.cmu.edu/~claytronics/papers/karagozler-rascal06.pdf},
  keywords = {Applications of Claytronics, Robotics}
}

@misc{goldstein-popsci05,
  title = {2029 The 3-D Fax Machine Brings Back the House Call},
  howpublished = {Headline from the Future, Popular Science Magazine},
  author = {Goldstein, Seth Copen},
  year = {2005},
  url = {http://www.cs.cmu.edu/~claytronics/papers/goldstein-popsci05.pdf},
  month = {March},
  pages = {34},
  keywords = {Applications of Claytronics}
}

@article{aksak-jast07,
  author = {Murphy, M.P. and Aksak, Burak and Sitti, Metin},
  title = {Adhesion and Anisotropic Friction Enhancements of Angled
     Heterogeneous Micro-Fiber Arrays with Spherical and Spatula
     Tips},
  journal = {Journal of Adhesion Science and Technology},
  year = {2007},
  abstract = {Angled polyurethane fiber arrays are modified by adding
     soft spherical and spatula shaped tips by dipping. These fibers
     are characterized for adhesion and friction and compared with
     unmodified fibers and flat material samples. Sphere and spatula
     tip fiber samples demonstrate increased adhesion, with 10 and 23
     times the maximum adhesion of the unmodified fiber sample,
     respectively. The sphere and spatula tip fiber samples also show
     increased friction, with 1.6 and 4.7 times the maximum friction
     of the unmodified fiber sample, respectively. Simultaneous
     friction and adhesion is observed in a synthetic dry angled
     fibrillar adhesive sample (spatula tip fiber sample) for the
     first time. The direction dependent friction of angled fibers is
     investigated and observed. The adhesion and friction results
     reported in this paper suggest that fibers with negligible
     adhesion can be modified to exhibit significant adhesion and
     friction enhancement by the proposed fiber tip modifications.},
  keywords = {Gecko, Adhesion, Angled Fiber Array, Friction, Dry
     Adhesive, Bioinspired adhesive},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-jast07.pdf}
}

@article{aksak-langmuir2007,
  author = {Aksak, Burak and Murphy, M.P. and Sitti, Metin},
  title = {Adhesion of Biologically Inspired Vertical and Angled
     Polymer Microfiber Arrays},
  journal = {Langmuir},
  year = {2007},
  month = {February},
  volume = {23},
  pages = {3322--32},
  number = {6},
  issn = {0743-7463},
  keywords = {Adhesion, Biologically Inspired},
  abstract = {This paper proposes an approximate adhesion model for
     fibrillar adhesives for developing a fibrillar adhesive design
     methodology and compares numerical simulation adhesion results
     with macroscale adhesion data from polymer microfiber array
     experiments. A technique for fabricating microfibers with a
     controlled angle is described for the first time. Polyurethane
     microfibers with different hardnesses, angles, and aspect ratios
     are fabricated using optical lithography and polymer micromolding
     techniques and tested with a custom tensile adhesion measurement
     setup. Macroscale adhesion and overall work of adhesion of the
     microfiber arrays are measured and compared with the models to
     observe the effect of fiber geometry and preload. The adhesion
     strength and work of adhesion behavior of short and long vertical
     and long angled fiber arrays have similar trends with the
     numerical simulations. A scheme is also proposed to aid in
     optimized fiber adhesive design.},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-langmuir2007.pdf}
}

@inproceedings{Christensen-iros07,
  author = {Christensen, David Johan and Campbell, Jason D.},
  title = {From Roles to Anatomy to Scalable Modular
     Self-Reconfigurable Robots},
  booktitle = {Proceedings of the IEEE International Conference on
     Intelligent Robots and Systems {IROS '07}},
  keywords = {Biologically Inspired, Actuation, Controlling
     Ensembles},
  year = {2007}
}

@inproceedings{Christensen-icra07,
  author = {Christensen, David Johan and Campbell, Jason D.},
  title = {Locomotion of Miniature Catom Chains: Scale Effects on Gait
     and Velocity},
  booktitle = {Proceedings of the IEEE International Conference on
     Robotics and Automation {ICRA '07}},
  month = {April},
  keywords = {Biologically Inspired, Actuation, Controlling
     Ensembles},
  year = {2007}
}

@article{aksak-apl07,
  author = {Aksak, Burak and Cassell, Alan and Li, Jun and Meyyappan,
     Meyya and Callen, Phillip and Sitti, Metin},
  title = {Friction of Partially Embedded Vertically Aligned Carbon
     Nanofibers Inside Elastomers},
  journal = {Applied Physics Letters},
  year = {2007},
  volume = {91},
  abstract = {Vertically aligned carbon nanofibers partially embedded
     inside polyurethane (eVACNFs) is proposed as a robust high
     friction fibrillar material with a compliant backing. Carbon
     nanofibers with 50-150 $nm$ in diameter and 20-30 $\mu$m in
     length are vertically grown on silicon and transferred completely
     inside an elastomer by vacuum molding. Using time controlled and
     selective oxygen plasma etching, fibers are partially released up
     to 5 $\mu$m length. Macroscale friction experiments show that
     eVACNFs exhibit reproducible effective friction coefficients up
     to 1. Besides high friction, the proposed fabrication method
     improves fiber-substrate bond strength, and enables uniform
     height nanofibers with a compliant backing.},
  keywords = {Nanofiber friction, compliant nanostructures, carbon
     nanofibers},
  originallink = {http://link.aip.org/link/?apl/91/061906},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-apl07.pdf}
}

@article{goldstein-computer05,
  author = {Goldstein, Seth Copen and Campbell, Jason D. and Mowry,
     Todd C.},
  title = {Programmable Matter},
  journal = {IEEE Computer},
  volume = {38},
  number = {6},
  pages = {99--101},
  year = {2005},
  month = {June},
  keywords = {Claytronics Overview},
  url = {http://www.cs.cmu.edu/~claytronics/papers/goldstein-computer05.pdf}
}

@inproceedings{goldstein-waci04,
  author = {Goldstein, Seth Copen and Mowry, Todd C.},
  title = {Claytronics: An Instance of Programmable Matter},
  booktitle = {Wild and Crazy Ideas Session of ASPLOS},
  year = {2004},
  month = {October},
  address = {Boston, MA},
  abstract = {Programmable matter refers to a technology that will
     allow one to control and manipulate three-dimensional physical
     artifacts (similar to how we already control and manipulate
     two-dimensional images with computer graphics). In other words,
     programmable matter will allow us to take a (big) step beyond
     virtual reality, to synthetic reality, an environment in which
     all the objects in a user's environment (including the ones
     inserted by the computer) are physically realized. Note that the
     idea is not to transport objects nor is it to recreate an objects
     chemical composition, but rather to create a physical artifact
     that will mimic the shape, movement, visual appearance, sound,
     and tactile qualities of the original object.},
  keywords = {Claytronics Overview},
  url = {http://www.cs.cmu.edu/~claytronics/papers/goldstein-waci04.pdf}
}

@article{aksak-apl07,
  author = {Aksak, Burak and Cassell, Alan and Li, Jun and Meyyappan,
     Meyya and Callen, Phillip and Sitti, Metin},
  title = {Friction of Partially Embedded Vertically Aligned Carbon
     Nanofibers Inside Elastomers},
  journal = {Applied Physics Letters},
  year = {2007},
  volume = {91},
  abstract = {Vertically aligned carbon nanofibers partially embedded
     inside polyurethane (eVACNFs) is proposed as a robust high
     friction fibrillar material with a compliant backing. Carbon
     nanofibers with 50-150 $nm$ in diameter and 20-30 $\mu$m in
     length are vertically grown on silicon and transferred completely
     inside an elastomer by vacuum molding. Using time controlled and
     selective oxygen plasma etching, fibers are partially released up
     to 5 $\mu$m length. Macroscale friction experiments show that
     eVACNFs exhibit reproducible effective friction coefficients up
     to 1. Besides high friction, the proposed fabrication method
     improves fiber-substrate bond strength, and enables uniform
     height nanofibers with a compliant backing.},
  keywords = {Nanofiber friction, compliant nanostructures, carbon
     nanofibers},
  originallink = {http://link.aip.org/link/?apl/91/061906},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-apl07.pdf}
}

@article{campbell-ijrr-srmr,
  author = {Campbell, Jason D. and Pillai, Padmanabhan},
  title = {Collective Actuation},
  journal = {International Journal of Robotics Research},
  year = {2007},
  keywords = {Actuation, Controlling Ensembles},
  abstract = {Modular robot designers confront an inherent tradeoff
     between size and power: Smaller, more numerous modules increase
     the adaptability of a given volume or mass of robot---allowing
     the aggregate robot to take on a wider variety of
     configurations---but do so at a cost of reducing the power and
     complexity budget of each module. Fewer, larger modules can
     incorporate more powerful actuators and stronger hinges but at a
     cost of overspecializing the resulting robot in favor of
     corresponding uses. In the paper we describe a technique for
     coordinating the efforts of many tiny modules to achieve forces
     and movements larger than those possible for individual modules.
     In a broad sense, the question of actuator capacity and range
     thus may become one of software coding and ensemble topology as
     well as of hardware design. An important aspect of this technique
     is its ability to bend complex and large-scale structures and to
     realize the equivalent of large scale joints. Although our
     results do not suggest that modular robots will replace high
     power purpose-built robots, they do offer an increase in the
     plausible scalability of modular robot self-reconfiguration and
     facilitate a corresponding increase in adaptability.}
}

@inproceedings{Christensen-iros07,
  author = {Christensen, David Johan and Campbell, Jason D.},
  title = {From Roles to Anatomy to Scalable Modular
     Self-Reconfigurable Robots},
  booktitle = {Proceedings of the IEEE International Conference on
     Intelligent Robots and Systems {IROS '07}},
  keywords = {Biologically Inspired, Actuation, Controlling
     Ensembles},
  year = {2007}
}

@inproceedings{Christensen-icra07,
  author = {Christensen, David Johan and Campbell, Jason D.},
  title = {Locomotion of Miniature Catom Chains: Scale Effects on Gait
     and Velocity},
  booktitle = {Proceedings of the IEEE International Conference on
     Robotics and Automation {ICRA '07}},
  month = {April},
  keywords = {Biologically Inspired, Actuation, Controlling
     Ensembles},
  year = {2007}
}

@inproceedings{campbell-rss06,
  author = {Campbell, Jason D. and Pillai, Padmanabhan},
  title = {Collective Actuation},
  booktitle = {RSS 2006 Workshop on Self-Reconfigurable Modular
     Robots},
  year = {2006},
  month = {August},
  keywords = {Actuation, Controlling Ensembles},
  url = {http://www.cs.cmu.edu/~claytronics/papers/campbell-rss06.pdf},
  abstract = {Modular robot designers confront an inherent tradeoff
     between size and power: Smaller, more numerous modules increase
     the adaptability of a given volume or mass of modules---allowing
     the aggregate robot to take on a wider variety of configurations
     – but do so at the expense of the power and complexity of each
     module. Fewer, larger modules can incorporate more powerful
     actuators, more powerful bonds, and stronger hinges but at a cost
     of overspecializing the resulting robot in favor of
     correspond-ing uses. We describe a technique for coordinating the
     efforts of many tiny modules to achieve forces and movements
     be-yond those possible for individual modules. Our approach is
     predominantly applicable to spherical and cylindrical modules and
     their faceted counterparts, but may apply to some chain-style
     modular robot systems. Thus actuator capacity and range becomes a
     function of software and dynamic topology as well as of hardware.
     An important aspect of this technique is its ability to bend
     complex and large-scale structures and to realize the equivalent
     of large scale joints.}
}

@inproceedings{bhat06,
  author = {Bhat, Preethi Srinivas and Kuffner, James and Goldstein,
     Seth Copen and Srinivasa, Siddhartha S.},
  title = {Hierarchical Motion Planning for Self-reconfigurable
     Modular Robots},
  booktitle = {2006 IEEE/RSJ International Confernce on Intelligent
     Robots and Systems (IROS)},
  year = {2006},
  month = {October},
  keywords = {Planning, Controlling Ensembles, Hierarchical
     Algorithms},
  url = {http://www.cs.cmu.edu/~claytronics/papers/bhat06.pdf},
  abstract = {Motion planning for a self-reconfigurable robot involves
     coordinating the movement and connectivity of each of its
     homogeneous modules. Reconfiguration occurs when the shape of the
     robot changes from some initial configuration to a target
     configuration. Finding an optimal solution to reconfiguration
     problems involves searching the space of possible robot
     configurations. As this space grows exponentially with the number
     of modules, optimal planning becomes intractable. We propose a
     hierarchical planning approach that computes heuristic global
     reconfiguration strategies efficiently. Our approach consists of
     a base planner that computes an optimal solution for a few
     modules and a hierarchical planner that calls this base planner
     or reuses pre-computed plans at each level of the hierarchy to
     ultimately compute a global suboptimal solution. We present
     results from a prototype implementation of the method that
     efficiently plans for self-reconfigurable robots with several
     thousand modules.We also discuss tradeoffs and performance issues
     including scalability, heuristics and plan optimality.}
}

@inproceedings{derosa-icra06,
  author = {De Rosa, Michael and Goldstein, Seth Copen and Lee, Peter
     and Campbell, Jason D. and Pillai, Padmanabhan},
  title = {Scalable Shape Sculpting via Hole Motion: Motion Planning
     in Lattice-Constrained Module Robots},
  month = {May},
  booktitle = {Proceedings of the 2006 {IEEE} International Conference
     on Robotics and Automation (ICRA '06)},
  year = {2006},
  keywords = {Planning, Controlling Ensembles, Stochastic Algorithms},
  url = {http://www.cs.cmu.edu/~claytronics/papers/derosa-icra06.pdf},
  abstract = {We describe a novel shape formation algorithm for
     ensembles of 2-dimensional lattice-arrayed modular robots, based
     on the manipulation of regularly shaped voids within the lattice
     (``holes''). The algorithm is massively parallel and fully
     distributed. Constructing a goal shape requires time proportional
     only to the complexity of the desired target geometry.
     Construction of the shape by the modules requires no global
     communication nor broadcast floods after distribution of the
     target shape. Results in simulation show 97.3\% shape compliance
     in ensembles of approximately 60,000 modules, and we believe that
     the algorithm will generalize to 3D and scale to handle millions
     of modules.}
}

@inproceedings{ashish-iros07,
  author = {Deshpande, Ashish and Srinivasa, Siddhartha S. and Pillai,
     Padmanabhan},
  title = {Control Strategies and Design Guidelines for Planar
     Latch-less Metamorphic RobotsBased on Analysis of Dynamics},
  booktitle = {In Proceedings of the IEEE International Conference on
     Intelligent Robots and Systems IROS '07, 2007},
  year = {2007},
  month = {October},
  abstract = {Modular robotic systems with no fixed mechanical
     contacts are have the ability to adopt and reconfigure very
     rapidly, but are very difficult to control dynamically. Moving
     module solely with electro-magnetic or -static forces can lead to
     unwanted slipping or even loss of contact. This paper presents a
     strategy to design controller for such modules based on the
     limits derived by combining the contact constraints and the
     actuator saturation. We demonstrate the design of a simple but
     effective controller for two module motions. We also present
     guidelines for the design of the modules based on the controller
     limitations.},
  keywords = {Controlling Nodes}
}

@inproceedings{derosa2007-icra07,
  abstract = {Tightly-coupled multi-agent systems such as modular
     robots frequently exhibit properties of interest that span
     multiple modules. These properties cannot easily be detected from
     any single module, though they might readily be detected by
     combining the knowledge of multiple modules. Testing for
     distributed conditions is especially important in debugging or
     verifying the correctness of software for modular robots. We have
     developed a technique we call distributed watchpoint triggers
     which can efficiently recognize such distributed conditions. Our
     watchpoint description language can handle a variety of temporal,
     spatial, and logical properties spanning multiple robots. This
     paper presents that language, describes our fully-distributed,
     online mechanism for detecting distributed conditions in a
     running system, and evaluates the performance of our
     implementation. We found that the performance of the system is
     highly dependent on the program being debugged, scales linearly
     with ensemble size, and is small enough to make the system
     practical in all but the worst case scenarios.},
  author = {De Rosa, Michael and Goldstein, Seth Copen and Lee, Peter
     and Campbell, Jason D. and Pillai, Padmanabhan and Mowry, Todd
     C.},
  booktitle = {Proceedings of the IEEE International Conference on
     Robotics and Automation {ICRA '07}},
  title = {Distributed Watchpoints: Debugging Large Multi-Robot
     Systems},
  year = {2007},
  month = {April},
  keywords = {Debugging, Distributed Algorithms},
  url = {http://www.cs.cmu.edu/~claytronics/papers/derosa2007-icra07.pdf}
}

@article{mderosa-ijrr-2007,
  also = {Distributed Watchpoints: Debugging Large Multi-Robot
     Systems, icra07)},
  abstract = {Distributed systems frequently exhibit properties of
     interest which span multiple entities. These properties cannot
     easily be detected from any single entity, but can be readily be
     detected by combining the knowledge of multiple entities. Testing
     for distributed properties is especially important in debugging
     or verifying software for modular robots. We have developed a
     technique we call distributed watchpoint triggers which can
     efficiently recognize distributed conditions. Our watchpoint
     description language can handle a variety of temporal, spatial,
     and logical properties spanning multiple robots. This paper
     presents the specification language, describes the distributed
     online mechanism for detecting distributed conditions in a
     running system, and evaluates the performance of our
     implementation.},
  author = {De Rosa, Michael and Goldstein, Seth Copen and Lee, Peter
     and Campbell, Jason D. and Pillai, Padmanabhan and Mowry, Todd
     C.},
  journal = {International Journal of Robotics Research},
  keywords = {Debugging, Distributed Systems},
  title = {Distributed Watchpoints: Debugging Large Multi-Robot
     Systems},
  year = {2007}
}

@inproceedings{rister-icra07,
  author = {Rister, Benjamin D. and Campbell, Jason D. and Pillai,
     Padmanabhan and Mowry, Todd C.},
  title = {Integrated Debugging of Large Modular Robot Ensembles},
  booktitle = {Proceedings of the IEEE International Conference on
     Robotics and Automation {ICRA '07}},
  keywords = {Debugging, Distributed Systems},
  month = {April},
  abstract = {Creatively misquoting Thomas Hobbes, the process of
     software debugging is nasty, brutish, and all too long. This
     holds all the more true in robotics, which frequently involves
     concurrency, extensive nondeterminisism, event-driven components,
     complex state machines, and difficult platform limitations.
     Inspired by the challenges we have encountered while attempting
     to debug software on simulated ensembles of tens of thousands of
     modular robots, we have developed a new debugging tool
     particularly suited to the characteristics of highly parallel,
     event- and state-driven robotics software. Our state capture and
     introspection system also provides data that may be used in
     higher-level debugging tools as well. We report on the design of
     this promising debugging system, and on our experiences with it
     so far.},
  year = {2007},
  url = {http://www.cs.cmu.edu/~claytronics/papers/rister-icra07.pdf}
}

@inproceedings{derosa-rss06,
  author = {De Rosa, Michael and Goldstein, Seth Copen and Lee, Peter
     and Campbell, Jason D. and Pillai, Padmanabhan},
  booktitle = {Robotics: Science and Systems Workshop on
     Self-Reconfigurable Modular Robots},
  title = {Distributed Watchpoints: Debugging Very Large Ensembles of
     Robots},
  see = {derosa2007-icra07},
  month = {August},
  year = {2006},
  keywords = {Debugging, Distributed Systems},
  address = {Philadelphia, PA},
  url = {http://www.cs.cmu.edu/~claytronics/papers/derosa-rss06.pdf},
  abstract = {We describe a debugging tool for modular robotics that
     introduces the concept of distributed watchpoint triggers. This
     technique can initiate debugging actions (system halt, global
     snapshot, logging, etc.) in an ensemble of robots based on
     temporal, physical, and logical conditions distributed over
     multiple robots. Our technique is specifically designed to be
     effective in debugging modular robotic ensembles, where many
     important types of failure conditions can be detected within
     small, physically connected subsets of the total ensemble.}
}

@inproceedings{aksak-sensys06,
  author = {Pillai, Padmanabhan and Campbell, Jason D.},
  title = {Demo Abstract: Sensing and Reproducing the Shapes of 3D
     Objects Using Claytronics},
  booktitle = {Proceedings of the 4rd international conference on
     Embedded networked sensor systems (SenSys)},
  year = {2006},
  month = {October},
  keywords = {Demos}
}

@inproceedings{aksak-sensys05,
  author = {Aksak, Burak and Bhat, Preethi Srinivas and Campbell,
     Jason D. and De Rosa, Michael and Funiak, Stanislav and Gibbons,
     Phillip B. and Goldstein, Seth Copen and Guestrin, Carlos and
     Gupta, Ashish and Helfrich, Casey and Hoburg, James F. and Kirby,
     Brian and Kuffner, James and Lee, Peter and Mowry, Todd C. and
     Pillai, Padmanabhan and Ravichandran, Ram and Rister, Benjamin D.
     and Seshan, Srinivasan and Sitti, Metin and Yu, Haifeng},
  title = {Demo Abstract: Claytronics---highly scalable
     communications, sensing, and actuation networks.},
  booktitle = {Proceedings of the 3rd international conference on
     Embedded networked sensor systems (SenSys)},
  year = {2005},
  pages = {299},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-sensys05.pdf},
  doi = {http://doi.acm.org/10.1145/1098918.1098964},
  keywords = {Demos},
  abstract = {We propose a demonstration of extremely scalable modular
     robotics algorithms developed as part of the Claytronics Project
     (http://www-2.cs.cmu.edu/~claytronics/), as well as a
     demonstration of proof-of-concept prototypes. Our effort
     envisions multi-million-module robot ensembles able to morph into
     three-dimensional scenes, eventually with sufficient fidelity so
     as to convince a human observer the scenes are real. Although
     this work is potentially revolutionary in the sense that it holds
     out the possibility of radically altering the relationship
     between computation, humans, and the physical world, many of the
     research questions involved are similar in flavor to more
     mainstream systems research, albeit larger in scale. For
     instance, as in sensor networks, each robot will incorporate
     sensing, computation, and communications components. However,
     unlike most sensor networks each robot will also include
     mechanisms for actuation and motion. Many of the key challenges
     in this project involve coordination and communication of sensing
     and actuation across such large ensembles of independent units.}
}

@inproceedings{derosa2007-icra07,
  abstract = {Tightly-coupled multi-agent systems such as modular
     robots frequently exhibit properties of interest that span
     multiple modules. These properties cannot easily be detected from
     any single module, though they might readily be detected by
     combining the knowledge of multiple modules. Testing for
     distributed conditions is especially important in debugging or
     verifying the correctness of software for modular robots. We have
     developed a technique we call distributed watchpoint triggers
     which can efficiently recognize such distributed conditions. Our
     watchpoint description language can handle a variety of temporal,
     spatial, and logical properties spanning multiple robots. This
     paper presents that language, describes our fully-distributed,
     online mechanism for detecting distributed conditions in a
     running system, and evaluates the performance of our
     implementation. We found that the performance of the system is
     highly dependent on the program being debugged, scales linearly
     with ensemble size, and is small enough to make the system
     practical in all but the worst case scenarios.},
  author = {De Rosa, Michael and Goldstein, Seth Copen and Lee, Peter
     and Campbell, Jason D. and Pillai, Padmanabhan and Mowry, Todd
     C.},
  booktitle = {Proceedings of the IEEE International Conference on
     Robotics and Automation {ICRA '07}},
  title = {Distributed Watchpoints: Debugging Large Multi-Robot
     Systems},
  year = {2007},
  month = {April},
  keywords = {Debugging, Distributed Algorithms},
  url = {http://www.cs.cmu.edu/~claytronics/papers/derosa2007-icra07.pdf}
}

@inproceedings{funiak-nips06,
  title = {Distributed Inference in Dynamical Systems},
  author = {Funiak, Stanislav and Guestrin, Carlos and Paskin, Mark
     and Sukthankar, Rahul},
  booktitle = {Advances in Neural Information Processing Systems 19},
  editor = {B. Scholkopf and J. Platt and T. Hoffman},
  publisher = {MIT Press},
  address = {Cambridge, MA},
  pages = {433--440},
  year = {2006},
  month = {December},
  url = {http://www.cs.cmu.edu/~claytronics/papers/funiak-nips06.pdf},
  keywords = {Probabilistic Inference, Sensing, Distributed
     Algorithms, Graphical Models},
  abstract = {We present a robust distributed algorithm for
     approximate probabilistic inference in dynamical systems, such as
     sensor networks and teams of mobile robots. Using assumed density
     filtering, the network nodes maintain a tractable representation
     of the belief state in a distributed fashion. At each time step,
     the nodes coordinate to condition this distribution on the
     observations made throughout the network, and to advance this
     estimate to the next time step. In addition, we identify a
     significant challenge for probabilistic inference in dynamical
     systems: message losses or network partitions can cause nodes to
     have inconsistent beliefs about the current state of the system.
     We address this problem by developing distributed algorithms that
     guarantee that nodes will reach an informative consistent
     distribution when communication is re-established. We present a
     suite of experimental results on real-world sensor data for two
     real sensor network deployments: one with 25 cameras and another
     with 54 temperature sensors.}
}

@inproceedings{funiak-ipsn06,
  author = {Funiak, Stanislav and Guestrin, Carlos and Sukthankar,
     Rahul and Paskin, Mark},
  title = {Distributed Localization of Networked Cameras},
  booktitle = {Fifth International Conference on Information
     Processing in Sensor Networks (IPSN'06)},
  month = {April},
  pages = {34--42},
  year = {2006},
  keywords = {Probabilistic Inference, Sensing, Distributed
     Algorithms, Graphical Models, Localization},
  url = {http://www.cs.cmu.edu/~claytronics/papers/funiak-ipsn06.pdf},
  abstract = {Camera networks are perhaps the most common type of
     sensor network and are deployed in a variety of real-world
     applications including surveillance, intelligent environments and
     scientific remote monitoring. A key problem in deploying a
     network of cameras is calibration, i.e., determining the location
     and orientation of each sensor so that observations in an image
     can be mapped to locations in the real world. This paper proposes
     a fully distributed approach for camera network calibration. The
     cameras collaborate to track an object that moves through the
     environment and reason probabilistically about which camera poses
     are consistent with the observed images. This reasoning employs
     sophisticated techniques for handling the difficult
     nonlinearities imposed by projective transformations, as well as
     the dense correlations that arise between distant cameras. Our
     method requires minimal overlap of the cameras' fields of view
     and makes very few assumptions about the motion of the object. In
     contrast to existing approaches, which are centralized, our
     distributed algorithm scales easily to very large camera
     networks. We evaluate the system on a real camera network with 25
     nodes as well as simulated camera networks of up to 50 cameras
     and demonstrate that our approach performs well even when
     communication is lossy.}
}

@article{mderosa-ijrr-2007,
  also = {Distributed Watchpoints: Debugging Large Multi-Robot
     Systems, icra07)},
  abstract = {Distributed systems frequently exhibit properties of
     interest which span multiple entities. These properties cannot
     easily be detected from any single entity, but can be readily be
     detected by combining the knowledge of multiple entities. Testing
     for distributed properties is especially important in debugging
     or verifying software for modular robots. We have developed a
     technique we call distributed watchpoint triggers which can
     efficiently recognize distributed conditions. Our watchpoint
     description language can handle a variety of temporal, spatial,
     and logical properties spanning multiple robots. This paper
     presents the specification language, describes the distributed
     online mechanism for detecting distributed conditions in a
     running system, and evaluates the performance of our
     implementation.},
  author = {De Rosa, Michael and Goldstein, Seth Copen and Lee, Peter
     and Campbell, Jason D. and Pillai, Padmanabhan and Mowry, Todd
     C.},
  journal = {International Journal of Robotics Research},
  keywords = {Debugging, Distributed Systems},
  title = {Distributed Watchpoints: Debugging Large Multi-Robot
     Systems},
  year = {2007}
}

@inproceedings{rister-icra07,
  author = {Rister, Benjamin D. and Campbell, Jason D. and Pillai,
     Padmanabhan and Mowry, Todd C.},
  title = {Integrated Debugging of Large Modular Robot Ensembles},
  booktitle = {Proceedings of the IEEE International Conference on
     Robotics and Automation {ICRA '07}},
  keywords = {Debugging, Distributed Systems},
  month = {April},
  abstract = {Creatively misquoting Thomas Hobbes, the process of
     software debugging is nasty, brutish, and all too long. This
     holds all the more true in robotics, which frequently involves
     concurrency, extensive nondeterminisism, event-driven components,
     complex state machines, and difficult platform limitations.
     Inspired by the challenges we have encountered while attempting
     to debug software on simulated ensembles of tens of thousands of
     modular robots, we have developed a new debugging tool
     particularly suited to the characteristics of highly parallel,
     event- and state-driven robotics software. Our state capture and
     introspection system also provides data that may be used in
     higher-level debugging tools as well. We report on the design of
     this promising debugging system, and on our experiences with it
     so far.},
  year = {2007},
  url = {http://www.cs.cmu.edu/~claytronics/papers/rister-icra07.pdf}
}

@inproceedings{derosa-rss06,
  author = {De Rosa, Michael and Goldstein, Seth Copen and Lee, Peter
     and Campbell, Jason D. and Pillai, Padmanabhan},
  booktitle = {Robotics: Science and Systems Workshop on
     Self-Reconfigurable Modular Robots},
  title = {Distributed Watchpoints: Debugging Very Large Ensembles of
     Robots},
  see = {derosa2007-icra07},
  month = {August},
  year = {2006},
  keywords = {Debugging, Distributed Systems},
  address = {Philadelphia, PA},
  url = {http://www.cs.cmu.edu/~claytronics/papers/derosa-rss06.pdf},
  abstract = {We describe a debugging tool for modular robotics that
     introduces the concept of distributed watchpoint triggers. This
     technique can initiate debugging actions (system halt, global
     snapshot, logging, etc.) in an ensemble of robots based on
     temporal, physical, and logical conditions distributed over
     multiple robots. Our technique is specifically designed to be
     effective in debugging modular robotic ensembles, where many
     important types of failure conditions can be detected within
     small, physically connected subsets of the total ensemble.}
}

@article{aksak-jast07,
  author = {Murphy, M.P. and Aksak, Burak and Sitti, Metin},
  title = {Adhesion and Anisotropic Friction Enhancements of Angled
     Heterogeneous Micro-Fiber Arrays with Spherical and Spatula
     Tips},
  journal = {Journal of Adhesion Science and Technology},
  year = {2007},
  abstract = {Angled polyurethane fiber arrays are modified by adding
     soft spherical and spatula shaped tips by dipping. These fibers
     are characterized for adhesion and friction and compared with
     unmodified fibers and flat material samples. Sphere and spatula
     tip fiber samples demonstrate increased adhesion, with 10 and 23
     times the maximum adhesion of the unmodified fiber sample,
     respectively. The sphere and spatula tip fiber samples also show
     increased friction, with 1.6 and 4.7 times the maximum friction
     of the unmodified fiber sample, respectively. Simultaneous
     friction and adhesion is observed in a synthetic dry angled
     fibrillar adhesive sample (spatula tip fiber sample) for the
     first time. The direction dependent friction of angled fibers is
     investigated and observed. The adhesion and friction results
     reported in this paper suggest that fibers with negligible
     adhesion can be modified to exhibit significant adhesion and
     friction enhancement by the proposed fiber tip modifications.},
  keywords = {Gecko, Adhesion, Angled Fiber Array, Friction, Dry
     Adhesive, Bioinspired adhesive},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-jast07.pdf}
}

@inproceedings{kirby05,
  author = {Kirby, Brian and Campbell, Jason D. and Aksak, Burak and
     Pillai, Padmanabhan and Hoburg, James F. and Mowry, Todd C. and
     Goldstein, Seth Copen},
  title = {Catoms: Moving Robots Without Moving Parts},
  url = {http://www.cs.cmu.edu/~claytronics/papers/kirby05.pdf},
  booktitle = {AAAI (Robot Exhibition)},
  pages = {1730--1},
  year = {2005},
  month = {July},
  address = {Pittsburgh, PA},
  keywords = {Ensemble Principle},
  abstract = {We demonstrate modular robot prototypes developed as
     part of the Claytronics Project (Goldstein et al. 2005). Among
     the novel features of these robots (“catoms”) is their ability to
     reconfigure (move) relative to one another without moving parts.
     The absence of moving parts is central to one key aim of our
     work, namely, plausible manufacturability at smaller and smaller
     physical scales using high-volume, low-unit-cost techniques such
     as batch photolithography, multi-material submicron 3D
     lithographic processing, and self assembly. Claytronics envisions
     multi-million-module robot ensembles able to form into three
     dimensional scenes, eventually with sufficient fidelity so as to
     convince a human observer the scenes are real. This work presents
     substantial challenges in mechanical and electronic design,
     control, programming, reliability, power delivery, and motion
     planning (among other areas), and holds the promise of radically
     altering the relationship between computation, humans, and the
     physical world.}
}

@inproceedings{goldstein05,
  author = {Goldstein, Seth Copen and Mowry, Todd C. and Campbell,
     Jason D. and Lee, Peter and Pillai, Padmanabhan and Hoburg, James
     F. and Gibbons, Phillip B. and Guestrin, Carlos and Kuffner,
     James and Kirby, Brian and Rister, Benjamin D. and De Rosa,
     Michael and Funiak, Stanislav and Aksak, Burak and Sukthankar,
     Rahul},
  title = {The Ensemble Principle},
  booktitle = {13th Foresight Conference of Advanced Nanotechnogy},
  url = {http://www.cs.cmu.edu/~claytronics/papers/goldstein05.pdf},
  year = {2005},
  month = {October},
  address = {San Francisco, CA},
  keywords = {Ensemble Principle}
}

@article{aksak-jast07,
  author = {Murphy, M.P. and Aksak, Burak and Sitti, Metin},
  title = {Adhesion and Anisotropic Friction Enhancements of Angled
     Heterogeneous Micro-Fiber Arrays with Spherical and Spatula
     Tips},
  journal = {Journal of Adhesion Science and Technology},
  year = {2007},
  abstract = {Angled polyurethane fiber arrays are modified by adding
     soft spherical and spatula shaped tips by dipping. These fibers
     are characterized for adhesion and friction and compared with
     unmodified fibers and flat material samples. Sphere and spatula
     tip fiber samples demonstrate increased adhesion, with 10 and 23
     times the maximum adhesion of the unmodified fiber sample,
     respectively. The sphere and spatula tip fiber samples also show
     increased friction, with 1.6 and 4.7 times the maximum friction
     of the unmodified fiber sample, respectively. Simultaneous
     friction and adhesion is observed in a synthetic dry angled
     fibrillar adhesive sample (spatula tip fiber sample) for the
     first time. The direction dependent friction of angled fibers is
     investigated and observed. The adhesion and friction results
     reported in this paper suggest that fibers with negligible
     adhesion can be modified to exhibit significant adhesion and
     friction enhancement by the proposed fiber tip modifications.},
  keywords = {Gecko, Adhesion, Angled Fiber Array, Friction, Dry
     Adhesive, Bioinspired adhesive},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-jast07.pdf}
}

@article{aksak-jast07,
  author = {Murphy, M.P. and Aksak, Burak and Sitti, Metin},
  title = {Adhesion and Anisotropic Friction Enhancements of Angled
     Heterogeneous Micro-Fiber Arrays with Spherical and Spatula
     Tips},
  journal = {Journal of Adhesion Science and Technology},
  year = {2007},
  abstract = {Angled polyurethane fiber arrays are modified by adding
     soft spherical and spatula shaped tips by dipping. These fibers
     are characterized for adhesion and friction and compared with
     unmodified fibers and flat material samples. Sphere and spatula
     tip fiber samples demonstrate increased adhesion, with 10 and 23
     times the maximum adhesion of the unmodified fiber sample,
     respectively. The sphere and spatula tip fiber samples also show
     increased friction, with 1.6 and 4.7 times the maximum friction
     of the unmodified fiber sample, respectively. Simultaneous
     friction and adhesion is observed in a synthetic dry angled
     fibrillar adhesive sample (spatula tip fiber sample) for the
     first time. The direction dependent friction of angled fibers is
     investigated and observed. The adhesion and friction results
     reported in this paper suggest that fibers with negligible
     adhesion can be modified to exhibit significant adhesion and
     friction enhancement by the proposed fiber tip modifications.},
  keywords = {Gecko, Adhesion, Angled Fiber Array, Friction, Dry
     Adhesive, Bioinspired adhesive},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-jast07.pdf}
}

@inproceedings{funiak-nips06,
  title = {Distributed Inference in Dynamical Systems},
  author = {Funiak, Stanislav and Guestrin, Carlos and Paskin, Mark
     and Sukthankar, Rahul},
  booktitle = {Advances in Neural Information Processing Systems 19},
  editor = {B. Scholkopf and J. Platt and T. Hoffman},
  publisher = {MIT Press},
  address = {Cambridge, MA},
  pages = {433--440},
  year = {2006},
  month = {December},
  url = {http://www.cs.cmu.edu/~claytronics/papers/funiak-nips06.pdf},
  keywords = {Probabilistic Inference, Sensing, Distributed
     Algorithms, Graphical Models},
  abstract = {We present a robust distributed algorithm for
     approximate probabilistic inference in dynamical systems, such as
     sensor networks and teams of mobile robots. Using assumed density
     filtering, the network nodes maintain a tractable representation
     of the belief state in a distributed fashion. At each time step,
     the nodes coordinate to condition this distribution on the
     observations made throughout the network, and to advance this
     estimate to the next time step. In addition, we identify a
     significant challenge for probabilistic inference in dynamical
     systems: message losses or network partitions can cause nodes to
     have inconsistent beliefs about the current state of the system.
     We address this problem by developing distributed algorithms that
     guarantee that nodes will reach an informative consistent
     distribution when communication is re-established. We present a
     suite of experimental results on real-world sensor data for two
     real sensor network deployments: one with 25 cameras and another
     with 54 temperature sensors.}
}

@inproceedings{funiak-ipsn06,
  author = {Funiak, Stanislav and Guestrin, Carlos and Sukthankar,
     Rahul and Paskin, Mark},
  title = {Distributed Localization of Networked Cameras},
  booktitle = {Fifth International Conference on Information
     Processing in Sensor Networks (IPSN'06)},
  month = {April},
  pages = {34--42},
  year = {2006},
  keywords = {Probabilistic Inference, Sensing, Distributed
     Algorithms, Graphical Models, Localization},
  url = {http://www.cs.cmu.edu/~claytronics/papers/funiak-ipsn06.pdf},
  abstract = {Camera networks are perhaps the most common type of
     sensor network and are deployed in a variety of real-world
     applications including surveillance, intelligent environments and
     scientific remote monitoring. A key problem in deploying a
     network of cameras is calibration, i.e., determining the location
     and orientation of each sensor so that observations in an image
     can be mapped to locations in the real world. This paper proposes
     a fully distributed approach for camera network calibration. The
     cameras collaborate to track an object that moves through the
     environment and reason probabilistically about which camera poses
     are consistent with the observed images. This reasoning employs
     sophisticated techniques for handling the difficult
     nonlinearities imposed by projective transformations, as well as
     the dense correlations that arise between distant cameras. Our
     method requires minimal overlap of the cameras' fields of view
     and makes very few assumptions about the motion of the object. In
     contrast to existing approaches, which are centralized, our
     distributed algorithm scales easily to very large camera
     networks. We evaluate the system on a real camera network with 25
     nodes as well as simulated camera networks of up to 50 cameras
     and demonstrate that our approach performs well even when
     communication is lossy.}
}

@inproceedings{bhat06,
  author = {Bhat, Preethi Srinivas and Kuffner, James and Goldstein,
     Seth Copen and Srinivasa, Siddhartha S.},
  title = {Hierarchical Motion Planning for Self-reconfigurable
     Modular Robots},
  booktitle = {2006 IEEE/RSJ International Confernce on Intelligent
     Robots and Systems (IROS)},
  year = {2006},
  month = {October},
  keywords = {Planning, Controlling Ensembles, Hierarchical
     Algorithms},
  url = {http://www.cs.cmu.edu/~claytronics/papers/bhat06.pdf},
  abstract = {Motion planning for a self-reconfigurable robot involves
     coordinating the movement and connectivity of each of its
     homogeneous modules. Reconfiguration occurs when the shape of the
     robot changes from some initial configuration to a target
     configuration. Finding an optimal solution to reconfiguration
     problems involves searching the space of possible robot
     configurations. As this space grows exponentially with the number
     of modules, optimal planning becomes intractable. We propose a
     hierarchical planning approach that computes heuristic global
     reconfiguration strategies efficiently. Our approach consists of
     a base planner that computes an optimal solution for a few
     modules and a hierarchical planner that calls this base planner
     or reuses pre-computed plans at each level of the hierarchy to
     ultimately compute a global suboptimal solution. We present
     results from a prototype implementation of the method that
     efficiently plans for self-reconfigurable robots with several
     thousand modules.We also discuss tradeoffs and performance issues
     including scalability, heuristics and plan optimality.}
}

@inproceedings{funiak-ipsn06,
  author = {Funiak, Stanislav and Guestrin, Carlos and Sukthankar,
     Rahul and Paskin, Mark},
  title = {Distributed Localization of Networked Cameras},
  booktitle = {Fifth International Conference on Information
     Processing in Sensor Networks (IPSN'06)},
  month = {April},
  pages = {34--42},
  year = {2006},
  keywords = {Probabilistic Inference, Sensing, Distributed
     Algorithms, Graphical Models, Localization},
  url = {http://www.cs.cmu.edu/~claytronics/papers/funiak-ipsn06.pdf},
  abstract = {Camera networks are perhaps the most common type of
     sensor network and are deployed in a variety of real-world
     applications including surveillance, intelligent environments and
     scientific remote monitoring. A key problem in deploying a
     network of cameras is calibration, i.e., determining the location
     and orientation of each sensor so that observations in an image
     can be mapped to locations in the real world. This paper proposes
     a fully distributed approach for camera network calibration. The
     cameras collaborate to track an object that moves through the
     environment and reason probabilistically about which camera poses
     are consistent with the observed images. This reasoning employs
     sophisticated techniques for handling the difficult
     nonlinearities imposed by projective transformations, as well as
     the dense correlations that arise between distant cameras. Our
     method requires minimal overlap of the cameras' fields of view
     and makes very few assumptions about the motion of the object. In
     contrast to existing approaches, which are centralized, our
     distributed algorithm scales easily to very large camera
     networks. We evaluate the system on a real camera network with 25
     nodes as well as simulated camera networks of up to 50 cameras
     and demonstrate that our approach performs well even when
     communication is lossy.}
}

@mastersthesis{reshko04,
  author = {Reshko, Greg},
  title = {Localization Techniques for Synthetic Reality},
  school = {Carnegie Mellon University},
  keywords = {Localization},
  year = {2004}
}

@article{aksak-apl07,
  author = {Aksak, Burak and Cassell, Alan and Li, Jun and Meyyappan,
     Meyya and Callen, Phillip and Sitti, Metin},
  title = {Friction of Partially Embedded Vertically Aligned Carbon
     Nanofibers Inside Elastomers},
  journal = {Applied Physics Letters},
  year = {2007},
  volume = {91},
  abstract = {Vertically aligned carbon nanofibers partially embedded
     inside polyurethane (eVACNFs) is proposed as a robust high
     friction fibrillar material with a compliant backing. Carbon
     nanofibers with 50-150 $nm$ in diameter and 20-30 $\mu$m in
     length are vertically grown on silicon and transferred completely
     inside an elastomer by vacuum molding. Using time controlled and
     selective oxygen plasma etching, fibers are partially released up
     to 5 $\mu$m length. Macroscale friction experiments show that
     eVACNFs exhibit reproducible effective friction coefficients up
     to 1. Besides high friction, the proposed fabrication method
     improves fiber-substrate bond strength, and enables uniform
     height nanofibers with a compliant backing.},
  keywords = {Nanofiber friction, compliant nanostructures, carbon
     nanofibers},
  originallink = {http://link.aip.org/link/?apl/91/061906},
  url = {http://www.cs.cmu.edu/~claytronics/papers/aksak-apl07.pdf}
}

@inproceedings{bhat06,
  author = {Bhat, Preethi Srinivas and Kuffner, James and Goldstein,
     Seth Copen and Srinivasa, Siddhartha S.},
  title = {Hierarchical Motion Planning for Self-reconfigurable
     Modular Robots},
  booktitle = {2006 IEEE/RSJ International Confernce on Intelligent
     Robots and Systems (IROS)},
  year = {2006},
  month = {October},
  keywords = {Planning, Controlling Ensembles, Hierarchical
     Algorithms},
  url = {http://www.cs.cmu.edu/~claytronics/papers/bhat06.pdf},
  abstract = {Motion planning for a self-reconfigurable robot involves
     coordinating the movement and connectivity of each of its
     homogeneous modules. Reconfiguration occurs when the shape of the
     robot changes from some initial configuration to a target
     configuration. Finding an optimal solution to reconfiguration
     problems involves searching the space of possible robot
     configurations. As this space grows exponentially with the number
     of modules, optimal planning becomes intractable. We propose a
     hierarchical planning approach that computes heuristic global
     reconfiguration strategies efficiently. Our approach consists of
     a base planner that computes an optimal solution for a few
     modules and a hierarchical planner that calls this base planner
     or reuses pre-computed plans at each level of the hierarchy to
     ultimately compute a global suboptimal solution. We present
     results from a prototype implementation of the method that
     efficiently plans for self-reconfigurable robots with several
     thousand modules.We also discuss tradeoffs and performance issues
     including scalability, heuristics and plan optimality.}
}

@inproceedings{derosa-icra06,
  author = {De Rosa, Michael and Goldstein, Seth Copen and Lee, Peter
     and Campbell, Jason D. and Pillai, Padmanabhan},
  title = {Scalable Shape Sculpting via Hole Motion: Motion Planning
     in Lattice-Constrained Module Robots},
  month = {May},
  booktitle = {Proceedings of the 2006 {IEEE} International Conference
     on Robotics and Automation (ICRA '06)},
  year = {2006},
  keywords = {Planning, Controlling Ensembles, Stochastic Algorithms},
  url = {http://www.cs.cmu.edu/~claytronics/papers/derosa-icra06.pdf},
  abstract = {We describe a novel shape formation algorithm for
     ensembles of 2-dimensional lattice-arrayed modular robots, based
     on the manipulation of regularly shaped voids within the lattice
     (``holes''). The algorithm is massively parallel and fully
     distributed. Constructing a goal shape requires time proportional
     only to the complexity of the desired target geometry.
     Construction of the shape by the modules requires no global
     communication nor broadcast floods after distribution of the
     target shape. Results in simulation show 97.3\% shape compliance
     in ensembles of approximately 60,000 modules, and we believe that
     the algorithm will generalize to 3D and scale to handle millions
     of modules.}
}

@inproceedings{karagozler-msreport07,
  author = {Karagozler, Mustafa Emre},
  title = {Harnessing Capacitance for Inter-Robot Latching,
     Communication, and Power Transfer},
  booktitle = {MSc Report, Carnegie Mellon University, Department of
     Electrical and Computer Engineering},
  also = {Electrostatic Latching for Inter-module Adhesion, Power
     Transfer, and Communication in Modular Robots in IROS '07},
  month = {May},
  year = {2007},
  abstract = {A simple and robust inter-module latch is possibly the
     most important component of a modular robotic system. This report
     describes a latch based on capacitive coupling which not only
     provides significant adhesion forces, but can also be used for
     inter-module power transmission and communication. The key
     insight that enables electrostatic adhesion to be effective at
     the macro scale is to combine flexible electrodes with a geometry
     that uses shear forces to provide adhesion. To measure the
     effectiveness of our latch we incorporated it into a 28cm x 28cm
     x 28cm modular robot. The result is a latch which requires almost
     zero static power and yet can hold over 0.6N/cm2 of latch area.},
  keywords = {Actuation, Adhesion, Power Routing},
  url = {http://www.cs.cmu.edu/~claytronics/papers/karagozler-msreport07.pdf}
}

@inproceedings{campbell05,
  author = {Campbell, Jason D. and Pillai, Padmanabhan and Goldstein,
     Seth Copen},
  title = {The Robot is the Tether: Active, Adaptive Power Routing for
     Modular Robots With Unary Inter-robot Connectors},
  booktitle = {IEEE/RSJ International Conference on Intelligent Robots
     and Systems (IROS 2005)},
  pages = {4108--15},
  year = {2005},
  address = {Edmonton, Alberta Canada},
  month = {August},
  keywords = {Power Routing},
  url = {http://www.cs.cmu.edu/~claytronics/papers/campbell05.pdf}
}

@inproceedings{funiak-nips06,
  title = {Distributed Inference in Dynamical Systems},
  author = {Funiak, Stanislav and Guestrin, Carlos and Paskin, Mark
     and Sukthankar, Rahul},
  booktitle = {Advances in Neural Information Processing Systems 19},
  editor = {B. Scholkopf and J. Platt and T. Hoffman},
  publisher = {MIT Press},
  address = {Cambridge, MA},
  pages = {433--440},
  year = {2006},
  month = {December},
  url = {http://www.cs.cmu.edu/~claytronics/papers/funiak-nips06.pdf},
  keywords = {Probabilistic Inference, Sensing, Distributed
     Algorithms, Graphical Models},
  abstract = {We present a robust distributed algorithm for
     approximate probabilistic inference in dynamical systems, such as
     sensor networks and teams of mobile robots. Using assumed density
     filtering, the network nodes maintain a tractable representation
     of the belief state in a distributed fashion. At each time step,
     the nodes coordinate to condition this distribution on the
     observations made throughout the network, and to advance this
     estimate to the next time step. In addition, we identify a
     significant challenge for probabilistic inference in dynamical
     systems: message losses or network partitions can cause nodes to
     have inconsistent beliefs about the current state of the system.
     We address this problem by developing distributed algorithms that
     guarantee that nodes will reach an informative consistent
     distribution when communication is re-established. We present a
     suite of experimental results on real-world sensor data for two
     real sensor network deployments: one with 25 cameras and another
     with 54 temperature sensors.}
}

@inproceedings{funiak-ipsn06,
  author = {Funiak, Stanislav and Guestrin, Carlos and Sukthankar,
     Rahul and Paskin, Mark},
  title = {Distributed Localization of Networked Cameras},
  booktitle = {Fifth International Conference on Information
     Processing in Sensor Networks (IPSN'06)},
  month = {April},
  pages = {34--42},
  year = {2006},
  keywords = {Probabilistic Inference, Sensing, Distributed
     Algorithms, Graphical Models, Localization},
  url = {http://www.cs.cmu.edu/~claytronics/papers/funiak-ipsn06.pdf},
  abstract = {Camera networks are perhaps the most common type of
     sensor network and are deployed in a variety of real-world
     applications including surveillance, intelligent environments and
     scientific remote monitoring. A key problem in deploying a
     network of cameras is calibration, i.e., determining the location
     and orientation of each sensor so that observations in an image
     can be mapped to locations in the real world. This paper proposes
     a fully distributed approach for camera network calibration. The
     cameras collaborate to track an object that moves through the
     environment and reason probabilistically about which camera poses
     are consistent with the observed images. This reasoning employs
     sophisticated techniques for handling the difficult
     nonlinearities imposed by projective transformations, as well as
     the dense correlations that arise between distant cameras. Our
     method requires minimal overlap of the cameras' fields of view
     and makes very few assumptions about the motion of the object. In
     contrast to existing approaches, which are centralized, our
     distributed algorithm scales easily to very large camera
     networks. We evaluate the system on a real camera network with 25
     nodes as well as simulated camera networks of up to 50 cameras
     and demonstrate that our approach performs well even when
     communication is lossy.}
}

@inproceedings{beckman-sdir07,
  author = {Beckman, Nels and Aldrich, Jonathan},
  title = {A Programming Model for Failure-Prone, Collaborative
     Robots},
  booktitle = {Workshop on Software Development and Integration in
     Robotics (SDIR)},
  year = {2007},
  month = {April},
  keywords = {Programming Models},
  url = {http://www.cs.cmu.edu/~claytronics/papers/beckman-sdir07.pdf},
  abstract = {A major problem in programming failure-prone
     collaborative robots is liveness. How do we ensure that the
     failure of one robot does not cause other robots to be
     permanently unavailable if, for example, that robot was a leader
     of others? In this paper, we propose a general mechanism which
     could be added to existing RPC libraries that allows applications
     to detect failure and execute programmer-specified recovery
     code.}
}

@inproceedings{karagozler-rascal06,
  title = {Ultralight Modular Robotic Building blocks for the Rapid
     Deployment of Planetary Outposts},
  booktitle = {Revolutionary Aerospace Systems Concepts Academic
     Linkage (RASC-AL) Forum 2006},
  author = {Karagozler, Mustafa Emre and Kirby, Brian and Lee, W.J.
     and Marinelli, Eugene and Ng, T.C. and Weller, Michael P. and
     Goldstein, Seth Copen},
  year = {2006},
  month = {May},
  address = {Cape Canaveral, FL},
  url = {http://www.cs.cmu.edu/~claytronics/papers/karagozler-rascal06.pdf},
  keywords = {Applications of Claytronics, Robotics}
}

@inproceedings{goldstein-robosphere04,
  author = {Goldstein, Seth Copen and Mowry, Todd C.},
  title = {Claytronics: A scalable basis for future robots},
  booktitle = {RoboSphere 2004},
  address = {Moffett Field, CA},
  month = {November},
  year = {2004},
  keywords = {Robotics},
  url = {http://www.cs.cmu.edu/~claytronics/papers/goldstein-robosphere04.pdf}
}

@inproceedings{funiak-nips06,
  title = {Distributed Inference in Dynamical Systems},
  author = {Funiak, Stanislav and Guestrin, Carlos and Paskin, Mark
     and Sukthankar, Rahul},
  booktitle = {Advances in Neural Information Processing Systems 19},
  editor = {B. Scholkopf and J. Platt and T. Hoffman},
  publisher = {MIT Press},
  address = {Cambridge, MA},
  pages = {433--440},
  year = {2006},
  month = {December},
  url = {http://www.cs.cmu.edu/~claytronics/papers/funiak-nips06.pdf},
  keywords = {Probabilistic Inference, Sensing, Distributed
     Algorithms, Graphical Models},
  abstract = {We present a robust distributed algorithm for
     approximate probabilistic inference in dynamical systems, such as
     sensor networks and teams of mobile robots. Using assumed density
     filtering, the network nodes maintain a tractable representation
     of the belief state in a distributed fashion. At each time step,
     the nodes coordinate to condition this distribution on the
     observations made throughout the network, and to advance this
     estimate to the next time step. In addition, we identify a
     significant challenge for probabilistic inference in dynamical
     systems: message losses or network partitions can cause nodes to
     have inconsistent beliefs about the current state of the system.
     We address this problem by developing distributed algorithms that
     guarantee that nodes will reach an informative consistent
     distribution when communication is re-established. We present a
     suite of experimental results on real-world sensor data for two
     real sensor network deployments: one with 25 cameras and another
     with 54 temperature sensors.}
}

@inproceedings{funiak-ipsn06,
  author = {Funiak, Stanislav and Guestrin, Carlos and Sukthankar,
     Rahul and Paskin, Mark},
  title = {Distributed Localization of Networked Cameras},
  booktitle = {Fifth International Conference on Information
     Processing in Sensor Networks (IPSN'06)},
  month = {April},
  pages = {34--42},
  year = {2006},
  keywords = {Probabilistic Inference, Sensing, Distributed
     Algorithms, Graphical Models, Localization},
  url = {http://www.cs.cmu.edu/~claytronics/papers/funiak-ipsn06.pdf},
  abstract = {Camera networks are perhaps the most common type of
     sensor network and are deployed in a variety of real-world
     applications including surveillance, intelligent environments and
     scientific remote monitoring. A key problem in deploying a
     network of cameras is calibration, i.e., determining the location
     and orientation of each sensor so that observations in an image
     can be mapped to locations in the real world. This paper proposes
     a fully distributed approach for camera network calibration. The
     cameras collaborate to track an object that moves through the
     environment and reason probabilistically about which camera poses
     are consistent with the observed images. This reasoning employs
     sophisticated techniques for handling the difficult
     nonlinearities imposed by projective transformations, as well as
     the dense correlations that arise between distant cameras. Our
     method requires minimal overlap of the cameras' fields of view
     and makes very few assumptions about the motion of the object. In
     contrast to existing approaches, which are centralized, our
     distributed algorithm scales easily to very large camera
     networks. We evaluate the system on a real camera network with 25
     nodes as well as simulated camera networks of up to 50 cameras
     and demonstrate that our approach performs well even when
     communication is lossy.}
}

@inproceedings{derosa-icra06,
  author = {De Rosa, Michael and Goldstein, Seth Copen and Lee, Peter
     and Campbell, Jason D. and Pillai, Padmanabhan},
  title = {Scalable Shape Sculpting via Hole Motion: Motion Planning
     in Lattice-Constrained Module Robots},
  month = {May},
  booktitle = {Proceedings of the 2006 {IEEE} International Conference
     on Robotics and Automation (ICRA '06)},
  year = {2006},
  keywords = {Planning, Controlling Ensembles, Stochastic Algorithms},
  url = {http://www.cs.cmu.edu/~claytronics/papers/derosa-icra06.pdf},
  abstract = {We describe a novel shape formation algorithm for
     ensembles of 2-dimensional lattice-arrayed modular robots, based
     on the manipulation of regularly shaped voids within the lattice
     (``holes''). The algorithm is massively parallel and fully
     distributed. Constructing a goal shape requires time proportional
     only to the complexity of the desired target geometry.
     Construction of the shape by the modules requires no global
     communication nor broadcast floods after distribution of the
     target shape. Results in simulation show 97.3\% shape compliance
     in ensembles of approximately 60,000 modules, and we believe that
     the algorithm will generalize to 3D and scale to handle millions
     of modules.}
}