论文标题

对最大链形成问题的离散和连续研究

A Discrete and Continuous Study of the Max-Chain-Formation Problem

论文作者

Castenow, Jannik, Kling, Peter, Knollmann, Till, der Heide, Friedhelm Meyer auf

论文摘要

大多数现有的机器人形成问题寻求某个\ emph {minimal}的目标形成,从而是有效的结构。例子包括聚会和链形成问题。在这项工作中,我们研究了试图达到\ emph {Maximal}结构的编队问题,例如在探索方案中支持有效的覆盖范围。 NASA Shapeshifter项目最近的一个例子是,该项目描述了机器人如何形成一个继电器链,该链中可以将收集的数据从外星洞穴探索中收集到家庭基地。 作为理解此类最大化任务的第一步,我们介绍并研究了最大链形成问题,其中$ n $ n $机器人沿着蜿蜒的,潜在的自我截断链订购,必须形成连接的最大长度,连接其两个端点。我们在离散和连续的时间模型中提出和分析策略。在离散的情况下,如果所有机器人最初都是共线,我们就会给出一个完整的分析,这表明达到$ \ varepsilon $ -Approximation的最糟糕的时间是由$ \ Mathcal {o}(n^2 \ cdot \ log(N/\ varepsilon)$和下部限制的$ \ mathcal {o}(n^2 \ cdot \ log and dog)的限制。 (1/\ varepsilon))$。如果链的一个端点保持静止,则可以将此结果扩展到非共线情况。如果两个端点都移动,我们将确定一个实例家庭的运行时家族。对于连续模型,我们给出了$θ(n)$的最佳运行时限制的策略。避免与离散案例类似的无界运行时,至关重要的是策略的违反直觉方面:放慢端点,而所有其他机器人都以全速移动。令人惊讶的是,我们可以证明类似的技巧在离散模型中不起作用。

Most existing robot formation problems seek a target formation of a certain \emph{minimal} and, thus, efficient structure. Examples include the Gathering and the Chain-Formation problem. In this work, we study formation problems that try to reach a \emph{maximal} structure, supporting for example an efficient coverage in exploration scenarios. A recent example is the NASA Shapeshifter project, which describes how the robots form a relay chain along which gathered data from extraterrestrial cave explorations may be sent to a home base. As a first step towards understanding such maximization tasks, we introduce and study the Max-Chain-Formation problem, where $n$ robots are ordered along a winding, potentially self-intersecting chain and must form a connected, straight line of maximal length connecting its two endpoints. We propose and analyze strategies in a discrete and in a continuous time model. In the discrete case, we give a complete analysis if all robots are initially collinear, showing that the worst-case time to reach an $\varepsilon$-approximation is upper bounded by $\mathcal{O}(n^2 \cdot \log (n/\varepsilon))$ and lower bounded by $Ω(n^2 \cdot~\log (1/\varepsilon))$. If one endpoint of the chain remains stationary, this result can be extended to the non-collinear case. If both endpoints move, we identify a family of instances whose runtime is unbounded. For the continuous model, we give a strategy with an optimal runtime bound of $Θ(n)$. Avoiding an unbounded runtime similar to the discrete case relies crucially on a counter-intuitive aspect of the strategy: slowing down the endpoints while all other robots move at full speed. Surprisingly, we can show that a similar trick does not work in the discrete model.

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