CiteULike: J0y's library [15 articles]

A Survey of Mobility Models for Ad Hoc Network Research

T Camp — 2006-06-26T09:49:38-00:00

Wireless Communications & Mobile Computing (WCMC): Special issue on Mobile Ad Hoc Networking: Research, Trends and Applications, Vol. 2, No. 5. (2002), pp. 483-502.

In the performance evaluation of a protocol for an ad hoc network, the protocol should be tested under realistic conditions including, but not limited to, a sensible transmission range, limited buffer space for the storage of messages, representative data traffic models, and realistic movements of the mobile users (i.e., a mobility model). This paper is a survey of mobility models that are used in the simulations of ad hoc networks. We describe several mobility models that represent mobile...

A Group Mobility Model for Ad Hoc Wireless Networks

X Hong — 2006-10-08T11:12:50-00:00

(1999)

In this paper, we present a survey of various mobility models in both cellular networks and multi-hop networks. We show that group motion occurs frequently in ad hoc networks, and introduce a novel group mobility model - Reference Point Group Mobility (RPGM) - to represent the relationship among mobile hosts. RPGM can be readily applied to many existing applications. Moreover, by proper choice of parameters, RPGM can be used to model several mobility models which were previously proposed. One...

One-Phase Commit: Does it make sense

M Abdallah — 2006-11-13T19:44:05-00:00

(1998)

Although widely used in distributed transactional systems, the so-called Two-Phase Commit (2PC) protocol introduces a substantial delay in transaction processing, even in the absence of failures. This has led several researchers to look for alternative commit protocols that minimize the time cost associated with coordination messages and forced log writes in 2PC. In particular, variations of a One-Phase Commit (1PC) protocol have recently been proposed. Although efficient, 1PC is however rarely ...

Teleo-reactive programs and the triple-tower architecture

N Nilsson — 2006-10-29T13:44:16-00:00

(2001)

I describe an architecture for linking perception and action in a robot. It consists of three "towers" of layered components. The "perception tower" contains rules that create increasingly abstract descriptions of the current environmental situation starting with the primitive predicates produced by the robot's sensory apparatus. These descriptions are deposited in a "model tower" which is continuously kept faithful to the current environmental situation by a "truthmaintenance " system. The...

Spatio-Temporal Case-Based Reasoning for Behavioral Selection

M Likhachev — 2006-10-24T08:14:56-00:00

(2001)

This paper presents the application of a Case-Based Reasoning approach to the selection and modification of behavioral assemblage parameters. The goal of this research is to achieve an optimal parameterization of robotic behaviors in run-time. This increases robot performance and makes a manual configuration of parameters unnecessary. The case-based reasoning module selects a set of parameters for an active behavioral assemblage in real-time. This set of parameters fits the environment better...

Motor schema based navigation for a mobile robot: An approach to programming by behavior

R Arkin — 2006-05-23T20:21:25-00:00

Robotics and Automation. Proceedings. 1987 IEEE International Conference on, Vol. 4 (1987), pp. 264-271.

Motor schemas are proposed as a basic unit of behavior specification for the navigation of a mobile robot. These are multiple concurrent processes which operate in conjunction with associated perceptual schemas and contribute independently to the overall concerted action of the vehicle. The motivation behind the use of schemas for this domain is drawn from neuroscientific, psychological and robotic sources. A variant of the potential field method is used to produce the appropriate velocity and steering commands for the robot. An implementation strategy based on available tools at UMASS is described. Simulation results show the feasibility of this approach.

Patterns of Intelligent and Mobile Agents

Elizabeth Kendall — 2006-10-23T20:22:38-00:00

(~September--JanuaryMarch, 1998), pp. 92-99.

Agent systems must have a strong foundation; one approach that has been successfully applied to other kinds of software is patterns. This paper presents a collection of patterns for agents. 2. MOTIVATION Almost all agent development to date has been "home grown" [4] and done from scratch, independently, by each development team. This has led to the following problems: . Lack of an agreed definition: Agents built by different teams have different capabilities. . Duplication of effort: There has...

Is it an Agent, or just a Program?: A Taxonomy for Autonomous Agents

S Franklin — 2006-10-17T13:25:19-00:00

Vol. 1193 (1996)

The advent of software agents gave rise to much discussion of just what such an agent is, and of how they differ from programs in general. Here we propose a formal definition of an autonomous agent which clearly distinguishes a software agent from just any program. We also offer the beginnings of a natural kinds taxonomy of autonomous agents, and discuss possibilities for further classification. Finally, we discuss subagents and multiagent systems. Introduction On meeting a friend or...

Mission-Directed Behaviour-Based Robots for Planetary Exploration

Andrei Rotenstein — 2006-10-12T21:02:38-00:00

This paper argues that the S* robot control architecture of Tsotsos [1997] is well-suited to intelligent control of planetary rovers. Behaviour-based systems operate well in unknown environments, but cannot support deliberative functionality. Hybrid systems resolve this issue, but introduce the potential for other problems. S* is a non-hybrid approach that supports deliberation but also attentive vision. As well, S* includes a missionspecification language that permits behaviour ...

Levels of causal understanding in chimpanzees and children

David Premack — 2005-05-26T07:24:53-00:00

Cognition, Vol. 50, No. 1-3. ( 1994), pp. 347-362.

We compare three levels of causal understanding in chimpanzees and children: (1) causal reasoning, (2) labelling the components (actor, object, and instrument) of a causal sequence, and (3) choosing the correct alternative for an incomplete representation of a causal sequence. We present two tests of causal reasoning, the first requiring chimpanzees to read and use as evidence the emotional state of a conspecific. Despite registering the emotion, they failed to use it as evidence. The second test, comparing children and chimpanzees, required them to infer the location of food eaten by a trainer. Children and, to a lesser extent, chimpanzees succeeded. When given information showing the inference to be unsound - physically impossible - 4-year-old children abandoned the inference but younger children and chimpanzees did not. Children and chimpanzees are both capable of labelling causal sequences and completing incomplete representations of them. The chimpanzee Sarah labelled the components of a causal sequence, and completed incomplete representations of actions involving multiple transformations. We conclude the article with a general discussion of the concept of cause, suggesting that the concept evolved far earlier in the psychological domain than in the physical.

Robot Learning with Parallel Genetic Algorithms on Networked Computers

J Grefenstette — 2006-01-26T13:35:29-00:00

(1995)

This work explores the use of machine learning methods for extracting knowledge from simulations of complex systems. In particular, we use genetic algorithms to learn rule-based strategies used by autonomous robots. The evaluation of a given strategy may require several executions of a simulation to produce a meaningful estimate of the quality of the strategy. As a consequence, the evaluation of a single individual in the genetic algorithm requires a fairly substantial amount of computation....

Computational approaches to motor learning by imitation.

S Schaal — 2005-12-19T22:21:31-00:00

Philos Trans R Soc Lond B Biol Sci, Vol. 358, No. 1431. (29 March 2003), pp. 537-547.

Movement imitation requires a complex set of mechanisms that map an observed movement of a teacher onto one's own movement apparatus. Relevant problems include movement recognition, pose estimation, pose tracking, body correspondence, coordinate transformation from external to egocentric space, matching of observed against previously learned movement, resolution of redundant degrees-of-freedom that are unconstrained by the observation, suitable movement representations for imitation, modularization of motor control, etc. All of these topics by themselves are active research problems in computational and neurobiological sciences, such that their combination into a complete imitation system remains a daunting undertaking-indeed, one could argue that we need to understand the complete perception-action loop. As a strategy to untangle the complexity of imitation, this paper will examine imitation purely from a computational point of view, i.e. we will review statistical and mathematical approaches that have been suggested for tackling parts of the imitation problem, and discuss their merits, disadvantages and underlying principles. Given the focus on action recognition of other contributions in this special issue, this paper will primarily emphasize the motor side of imitation, assuming that a perceptual system has already identified important features of a demonstrated movement and created their corresponding spatial information. Based on the formalization of motor control in terms of control policies and their associated performance criteria, useful taxonomies of imitation learning can be generated that clarify different approaches and future research directions.

A case study in the behavior-oriented design of autonomous agents

L Steels — 2006-01-23T08:36:40-00:00

The paper documents a case study in the design and implementation of a robotic multi-agent system. It illustrates known design guidelines, namely that the physics of the environment must be exploited, that behavior is the result from the interaction dynamics between the agent and the environment, and that emergent behavior can and must be utilised whenever possible. But the case study also challenges certain views, such as the subsumption architecture, the need for an action selection...

Hierarchical segmentation schemes for function evaluation

DU Lee — 2006-05-26T13:44:45-00:00

Field-Programmable Technology (FPT), 2003. Proceedings. 2003 IEEE International Conference on (2003), pp. 92-99.

This paper presents a method for evaluating functions based on piecewise polynomial approximation with a novel hierarchical segmentation scheme. The use of a novel hierarchy scheme of uniform segments and segments with size varying by powers of two enables us to approximate non-linear regions of a function particularly well. This partitioning is automated: efficient look-up tables and their coefficients are generated for a given function, input range, order of the polynomials, desired accuracy and finite precision constraints. We describe an algorithm to find the optimum number of segments and the placement of their boundaries, which is used to analyze the properties of a function and to benchmark out approach. Our method is illustrated using three non-linear compound functions, /spl radic/-log(x), x log(x) and a high order rational function. We present results for various operand sizes between 8 and 24 bits for first and second order polynomial approximations.

Behavior-Grounded Representation of Tool Affordances

A Stoytchev — 2006-04-07T21:03:43-00:00

Robotics and Automation, 2005. Proceedings of the 2005 IEEE International Conference on (2005), pp. 3060-3065.

This paper introduces a novel approach to representing and learning tool affordances by a robot. The tool representation described here uses a behavior-based approach to ground the tool affordances in the behavioral repertoire of the robot. The representation is learned during a behavioral babbling stage in which the robot randomly chooses different exploratory behaviors, applies them to the tool, and observes their effects on environmental objects. The paper shows how the autonomously learned affordance representation can be used to solve tool-using tasks by dynamically sequencing the exploratory behaviors based on their expected outcomes. The quality of the learned representation was tested on extension-of-reach tool-using tasks.