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 submillimeter 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. I.

Claytronics is a form a programmable matter that takes the concept of modular robots to a new extreme. The concept of modular robots has been around for some time. (See [14] for a survey.) Previous approaches to modular robotics sought to create an ensemble of tens or even hundreds of small autonomous robots which could, through coordination, achieve a global effect not possible by any single unit. In general the goal of these projects was to adapt to the environment to facilitate, for example, improved locomotion. Our work on claytronics departs from previous work in several important ways. One of the primary goals of claytronics is to form the basis for a new media type, pario. Pario, a logical extension of audio and video, is a media type used to reproduce moving 3D objects in the real world. A direct result of our goal is that claytronics must scale to millions of micron-scale units. Having scaling (both in number and size) as a primary design goal impacts the work significantly.

Abstract — Internal localization, the problem of estimating relative pose for each module (part) of a modular robot is a prerequisite for many shape control, locomotion, and actuation algorithms. In this paper, we propose a robust hierarchical approach that uses normalized cut to identify dense subregions with small mutual localization error, then progressively merges those subregions to localize the entire ensemble. Our method works well in both 2D and 3D, and requires neither exact measurements nor rigid inter-module connectors. Most of the computations in our method can be effectively distributed. The result is a robust algorithm that scales to large, non-homogeneous ensembles. We evaluate our algorithm in accurate 2D and 3D simulations of scenarios with up to 10,000 modules. I.

Abstract — LDP (Locally Distributed Predicates) is a distributed, high-level language for programming modular reconfigurable robot systems (MRRs). In this paper we present the implementation of two motion-planning algorithms in LDP, and analyze both their performance and ease of implementation. We present multiple variations of one planner, including a novel resource allocation algorithm. We then draw conclusions about both the utility of the motion-planning algorithms and the suitability of LDP to the problem space. Our experiments suggest that metamodule-based planning approaches have a cost in time and/or energy terms, but that the cost can be worth paying in exchange for the additional generality and separationof-concerns offered by these techniques. The particular tradeoff for a given system will depend upon its goals and the details of the underlying modules.

Distributed systems frequently exhibit properties of interest which span multiple entities. These properties cannot easily be recognized from any single entity, but can be readily 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. In this paper we present the specification language, describe the distributed online mechanism for detecting distributed conditions in a running system and evaluate the performance of our implementation. KEY WORDS—cellular and modular robotics, distributed robot systems, programming environment

This thesis examines reasoning under uncertainty in distributed systems. Unlike in centralized systems, where the observations reside in a single location, the observations in distributed systems are often scattered across the network. To reason accurately, a networked device often needs to incorporate observations from other nodes and must do so with limited computation and communication even for large problems. The reasoning is further complicated by unstable network conditions, characteristic to many real-world networks: the nodes may fail, communication links may become unreliable, and the entire network may get fragmented into several components that cannot communicate with each other. These aspects make distributed inference very challenging. We consider one general problem of distributed filtering for estimating the state of a dynamical system and three independent applications: simultaneous localization and tracking, where a camera network localizes itself by observing a moving object, internal localization of large-scale modular robots, where a robot determines the relative poses of its internal parts,