668272
First Results in the Coordination of Heterogeneous Robots for Large-Scale Assembly
While many multi-robot systems rely on fortuitous cooperation between agents, some tasks, such as the assembly of large structures, require tighter coordination. We present a general software architecture for coordinating heterogeneous robots that allows for both autonomy of the individual agents as well as explicit coordination. This paper presents recent results with three robots with very different configurations. Working as a team, these robots are able to perform a high-precision docking task that none could achieve individually.
3284353
Point-Based POMDP Algorithms: Improved Analysis and Implementation
Existing complexity bounds for point-based POMDP value iteration algorithms focus either on the curse of dimensionality or the curse of history. We derive a new bound that relies on both and uses the concept of discounted reachability; our conclusions may help guide future algorithm design. We also discuss recent improvements to our (point-based) heuristic search value iteration algorithm. Our new implementation calculates tighter initial bounds, avoids solving linear programs, and makes more effective use of sparsity.
1211760
Heuristic Search Value Iteration for POMDPs
We present a novel POMDP planning algorithm called heuristic search value iteration (HSVI). HSVI is an anytime algorithm that returns a policy and a provable bound on its regret with respect to the optimal policy. HSVI gets its power by combining two well-known techniques: attention-focusing search heuristics and piecewise linear convex representations of the value function. HSVI's soundness and convergence have been proven. On some bench-mark problems from the literature, HSVI displays speedups of greater than 100 with respect to other state-of-the-art POMDP value iteration algorithms. We also apply HSVI to a new rover exploration problem 10 times larger than most POMDP problems in the literature.
12515579
Supporting serendipitous integration in mobile computing environments
Abstract In the richly networked world of the near future, mobile computing users will be confronted with an ever-expanding array of devices and services accessible in their environments. In such a world, we cannot expect to have available to us specific applications that allow us to accomplish every conceivable combination of devices that we may wish. Instead, we believe that many of our interactions with the network will be characterized by the use of “general purpose” tools that allow us to discover, use, and integrate multiple devices around us. This paper lays out the case for why we believe that so-called “serendipitous integration” is a necessary fact that we will face in mobile computing, and explores a number of design experiments into supporting end user configuration and control of networked environments through general purpose tools. We present an iterative design approach to creating such tools and their user interfaces, discuss our observations about the challenges of designing for such a world, and then explore a number of tools that take differing design approaches to overcoming these challenges. We conclude with a set of reflections on the user experience issues that we believe are inherent in dealing with ad hoc mobile computing in richly networked environments.
16631800
Fast convergence with a greedy tag-phrase dictionary
Lexical categories have been shown to assist in giving good compression results when incorporated into context models. This paper describes a greedy dictionary-based model that maintains a dictionary of tag-phrases, along with separate lexicons for each unique tag. The text is tagged with part-of-speech (POS) labels and then given to the encoder, which uses the tags to construct the phrase dictionary in a manner similar to LZ78. The output is a sequence of arithmetically encoded phrase number coupled with the information needed to match the correct word with each tag in the phrase. Each unique word (defined as each novel word/tag pair) is transmitted once when it is first encountered, then retained in the appropriate dictionary and thereafter arithmetically encoded according to the empirical distribution for that dictionary whenever the word is encountered. We present results from some empirical tests showing that this "tag-phrase dictionary" technique achieves nearly identical compression as that obtainable using PPM, an explicit-context model. This goes against the widely held view that greedy dictionary schemes require much larger samples of text before they can compete with statistical context methods. Some interesting theoretical issues pertaining to text compression in general are implied, and these are also discussed.
1624330
Recipes for digital living [ubiquitous computing in consumer electronics]
As networked devices become increasingly ubiquitous, the potential benefits to users increase exponentially. However, this potential can't be fully realized if it is entirely up to developers and manufacturers to expose the combined functionality buried in the expanding network. Recipes for digital living - created and modified by users themselves - offer an easy-to-understand, logically consistent way to capture and share the various ensembles possible in the expanding world of networked components.
15703762
Armi: a High Level Communication Library for Stapl
ARMI is a communication library that provides a framework for expressing fine-grain parallelism and mapping it to a particular machine using shared-memory and message passing library calls. The library is an advanced implementation of the RMI protocol and handles low-level details such as scheduling incoming communication and aggregating outgoing communication to coarsen parallelism. These details can be tuned for different platforms to allow user codes to achieve the highest performance possible without manual modification. ARMI is used by STAPL, our generic parallel library, to provide a portable, user transparent communication layer. We present the basic design as well as the mechanisms used in the current Pthreads/OpenMP, MPI implementations and/or a combination thereof. Performance comparisons between ARMI and explicit use of Pthreads or MPI are given on a variety of machines, including an HP-V2200, Origin 3800, IBM Regatta and IBM RS/6000 SP cluster.
29526990
The orbital browser: composing ubicomp services using only rotation and selection
Most ubiquitous computing environments are designed as collections of highly distributed and heterogeneous services. In this paper we describe a user interface, the Orbital Browser, which reduces the complexity of ubicomp service composition to two simple end-user operations: rotation and selection. We discuss the design requirements imposed by service composition and how we addressed them with our system.