Legacy IP routing restricts the efficacy of traffic engineering solutions. This restriction stems from the constraint that traffic at a node must be uniformly split across all next-hop nodes corresponding to equal cost shortest path to a destination. Proposals that alleviate this constraint either completely overhaul legacy IP routing, or introduce complex control and/or forwarding plane components. This additional complexity departs from the elegant simplicity of legacy routing protocols where statically optimized link weights embed all traffic engineering semantics.
We present Interface Split Routing (ISR), which retains the basic forwarding and control mechanism of legacy IP routing. Furthermore, a set of link weights embed all traffic engineering semantics in ISR. However, ISR makes possible finer-grained traffic engineering by configuring independent sets of next-hops to a destination at each incoming interface. This lends itself well to modern router architectures where each incoming interface has its own forwarding table. Consequently, at the aggregated node level, traffic to a particular destination may be non-uniformly distributed across next-hop nodes. Hence, ISR allows additional flexibility in routing traffic as compared to default IP routing while retaining its simplicity. We conduct simulation studies on representative ISP topologies to compare ISR with traditional link-weight-optimized routing. ISR reduces the difference between optimal routing and weight-optimized routing by 50%. 相似文献
This article describes a prototype autonomous mobile robot, KANTARO, designed for inspecting sewer pipes. It is able to move
autonomously in 200–300-mm-diameter sewer pipes, to turn smoothly through 90° at a junction, and to go down a 5-cm step. KANTARO
carries all the resources required, such as a control unit, a camera, a 2D laser, and an IR sensor. Damage or abnormalities
in sewer pipes are detected based on recorded sensory data. KANTARO has demonstrated its effectiveness in inspection and in
autonomous navigation in a dry sewer test field at the FAIS–Robotics Development Support Office (FAIS–RDSO).
This work was presented in part at the 11th International Symposium on Artificial Life and Robotics, Oita, Japan, January
23–25, 2006 相似文献
This paper describes theoretical and experimental results using the SmartNav rule-free fuzzy rover navigation system. SmartNav
divides the terrain perceived by the rover into a number of circular sectors, and evaluates each sector using goal and safety
preference factors to differentiate between preferred and unpreferred terrain sectors. The goal-preference factor is used
to make sector evaluation based on the sector orientation relative to the designated goal position. The safety-preference
factors are used to make sector evaluations on the basis of the sector local and regional terrain hazards. Three methods are
developed to blend the three sector evaluations in order to find the effective preference factor for each sector. Two sector
selection methods are then described in which the sector preference factors are used to find the heading command for the rover.
The rover speed command is also computed based on the goal distance and safety-preference factor of the chosen sector. The
above navigation steps are continuously repeated throughout the rover motion. Experimental results are presented to demonstrate
the navigational capabilities of SmartNav using a commercial Pioneer 2AT rover traversing a simulated Martian terrain at the
JPL Mini Mars Yard.
相似文献
Mobile devices are becoming increasingly integrated into our society. In addition to entertaining people with applications
like pervasive games, mobile devices can also help to address cognitive challenges people face in the real world. This paper,
by drawing on research findings from cognitive psychology and geography, explores a design to use mobile VR to help people
overcome one cognitive barrier in navigation, which is to establish the correspondence between 2D spatial information found
in maps and 3D entities they perceive from the real world. The design offers users multi-format, multi-scale, and semantic
(M2S) maps, ranging from 2D maps to 3D immersive environments, and helps users to connect 2D maps to the real world through 3D
environments which are equipped with semantic representation and animation techniques. Consequently, users can apply various
kinds of spatial knowledge, 2D or 3D, in understanding the real world as well as assisting in navigation. This research enhances
the design repertoire of mobile VR, and suggests a way to integrate virtual environments into people’s real-world life by
examining the cognitive implications of 3D models on users’ activities. 相似文献
In this paper, we generalize the notion of persistence, which has been originally introduced for two-dimensional formations, to Rd for d?3, seeking to provide a theoretical framework for real world applications, which often are in three-dimensional space as opposed to the plane. Persistence captures the desirable property that a formation moves as a cohesive whole when certain agents maintain their distances from certain other agents. We verify that many of the properties of rigid and/or persistent formations established in R2 are also valid for higher dimensions. Analysing the closed subgraphs and directed paths in persistent graphs, we derive some further properties of persistent formations. We also provide an easily checkable necessary condition for persistence. We then turn our attention to consider some practical issues raised in multi-agent formation control in three-dimensional space. We display a new phenomenon, not present in R2, whereby subsets of agents can behave in a problematic way. When this behaviour is precluded, we say that the graph depicting the multi-agent formation has structural persistence. In real deployment of controlled multi-agent systems, formations with underlying structurally persistent graphs are of interest. We analyse the characteristics of structurally persistent graphs and provide a streamlined test for structural persistence. We study the connections between the allocation of degrees of freedom (DOFs) across agents and the characteristics of persistence and/or structural persistence of a directed graph. We also show how to transfer DOFs among agents, when the formation changes with new agent(s) added, to preserve persistence and/or structural persistence. 相似文献
Increased flexibility and modularisation in higher education complicates the process of learners finding their way through the offerings of higher education institutions. In lifelong learning, where learning opportunities are diverse and reach beyond institutional boundaries, it becomes even more complex to decide on a learning path. However, efficient and effective lifelong learning requires that learners can make well informed decisions. Drawing on principles of self-organisation and indirect social interaction, this article suggests solving the problem by analysing the paths followed by learners and feeding this information back as advice to learners facing navigational decisions. This article starts by introducing the principles of self-organisation and indirect social interaction. It describes how we expect the use of indirect social interaction using collaborative filtering to enhance effectiveness (completion rates and amount of progress) and efficiency (time taken to complete) in lifelong learning. The effects were tested in a controlled experiment, with the results showing effects on effectiveness though not on efficiency. The study shows that indirect feedback is a promising line of enquiry for navigational support in lifelong learning. 相似文献
We describe our development of Cobot, a novel software agent who lives in LambdaMOO, a popular virtual world frequented by
hundreds of users. Cobot’s goal was to become an actual part of that community. Here, we present a detailed discussion of
the functionality that made him one of the objects most frequently interacted with in LambdaMOO, human or artificial. Cobot’s
fundamental power is that he has the ability to collect social statistics summarizing the quantity and quality of interpersonal
interactions. Initially, Cobot acted as little more than a reporter of this information; however, as he collected more and
more data, he was able to use these statistics as models that allowed him to modify his own behavior. In particular, cobot
is able to use this data to “self-program,” learning the proper way to respond to the actions of individual users, by observing
how others interact with one another. Further, Cobot uses reinforcement learning to proactively take action in this complex
social environment, and adapts his behavior based on multiple sources of human reward. Cobot represents a unique experiment
in building adaptive agents who must live in and navigate social spaces. 相似文献