这项工作引入了一种数据驱动的控制方法,用于从稀缺数据中稳定高维动力系统。提出的上下文感知控制器推断方法基于这样的观察,即控制器只需要在不稳定的动态上进行本地行动才能稳定系统。这意味着仅仅学习不稳定的动力学就足够了,通常将其限制在所有系统动力学的高维状态空间中,尺寸要少得多,因此很少有数据示例足以识别它们。数值实验表明,与传统的数据驱动的控制技术和增强学习的变体相比,从数量级的数据样本中学习了上下文感知的控制器的推理,从数量级的稳定控制器学习。该实验进一步表明,上下文感知的控制器推断的数据需求较低,在复杂物理学的数据筛分工程问题中尤其有益,在该数据和培训成本方面,学习完整的系统动态通常是棘手的。
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从数据稳定动力学系统的数据中学习控制器通常遵循首先识别模型然后基于确定模型构建控制器的两步过程。但是,学习模型意味着确定系统动力学的通用描述,这些描述可能需要大量数据并提取对稳定的特定任务不必要的信息。这项工作的贡献是表明,如果线性动力学系统具有尺寸(McMillan学位)$ n $,那么总是存在$ n $状态,可以从中构建稳定反馈控制器,而与表示的尺寸无关观察到的状态和输入的数量。通过基于先前的工作,这一发现意味着,与学习动力学模型所需的最少状态相比,观察到的状态较少的任何线性动力系统都可以稳定。通过数值实验证明了理论发现,这些实验表明了圆柱体后面的流动稳定,从学习模型的数据少于数据。
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While the capabilities of autonomous systems have been steadily improving in recent years, these systems still struggle to rapidly explore previously unknown environments without the aid of GPS-assisted navigation. The DARPA Subterranean (SubT) Challenge aimed to fast track the development of autonomous exploration systems by evaluating their performance in real-world underground search-and-rescue scenarios. Subterranean environments present a plethora of challenges for robotic systems, such as limited communications, complex topology, visually-degraded sensing, and harsh terrain. The presented solution enables long-term autonomy with minimal human supervision by combining a powerful and independent single-agent autonomy stack, with higher level mission management operating over a flexible mesh network. The autonomy suite deployed on quadruped and wheeled robots was fully independent, freeing the human supervision to loosely supervise the mission and make high-impact strategic decisions. We also discuss lessons learned from fielding our system at the SubT Final Event, relating to vehicle versatility, system adaptability, and re-configurable communications.
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Recent advances in upper limb prostheses have led to significant improvements in the number of movements provided by the robotic limb. However, the method for controlling multiple degrees of freedom via user-generated signals remains challenging. To address this issue, various machine learning controllers have been developed to better predict movement intent. As these controllers become more intelligent and take on more autonomy in the system, the traditional approach of representing the human-machine interface as a human controlling a tool becomes limiting. One possible approach to improve the understanding of these interfaces is to model them as collaborative, multi-agent systems through the lens of joint action. The field of joint action has been commonly applied to two human partners who are trying to work jointly together to achieve a task, such as singing or moving a table together, by effecting coordinated change in their shared environment. In this work, we compare different prosthesis controllers (proportional electromyography with sequential switching, pattern recognition, and adaptive switching) in terms of how they present the hallmarks of joint action. The results of the comparison lead to a new perspective for understanding how existing myoelectric systems relate to each other, along with recommendations for how to improve these systems by increasing the collaborative communication between each partner.
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With the rise in high resolution remote sensing technologies there has been an explosion in the amount of data available for forest monitoring, and an accompanying growth in artificial intelligence applications to automatically derive forest properties of interest from these datasets. Many studies use their own data at small spatio-temporal scales, and demonstrate an application of an existing or adapted data science method for a particular task. This approach often involves intensive and time-consuming data collection and processing, but generates results restricted to specific ecosystems and sensor types. There is a lack of widespread acknowledgement of how the types and structures of data used affects performance and accuracy of analysis algorithms. To accelerate progress in the field more efficiently, benchmarking datasets upon which methods can be tested and compared are sorely needed. Here, we discuss how lack of standardisation impacts confidence in estimation of key forest properties, and how considerations of data collection need to be accounted for in assessing method performance. We present pragmatic requirements and considerations for the creation of rigorous, useful benchmarking datasets for forest monitoring applications, and discuss how tools from modern data science can improve use of existing data. We list a set of example large-scale datasets that could contribute to benchmarking, and present a vision for how community-driven, representative benchmarking initiatives could benefit the field.
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This paper describes important considerations and challenges associated with online reinforcement-learning based waveform selection for target identification in frequency modulated continuous wave (FMCW) automotive radar systems. We present a novel learning approach based on satisficing Thompson sampling, which quickly identifies a waveform expected to yield satisfactory classification performance. We demonstrate through measurement-level simulations that effective waveform selection strategies can be quickly learned, even in cases where the radar must select from a large catalog of candidate waveforms. The radar learns to adaptively select a bandwidth for appropriate resolution and a slow-time unimodular code for interference mitigation in the scene of interest by optimizing an expected classification metric.
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The NASA Astrophysics Data System (ADS) is an essential tool for researchers that allows them to explore the astronomy and astrophysics scientific literature, but it has yet to exploit recent advances in natural language processing. At ADASS 2021, we introduced astroBERT, a machine learning language model tailored to the text used in astronomy papers in ADS. In this work we: - announce the first public release of the astroBERT language model; - show how astroBERT improves over existing public language models on astrophysics specific tasks; - and detail how ADS plans to harness the unique structure of scientific papers, the citation graph and citation context, to further improve astroBERT.
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我们引入了一种新的文化学习范式,以测量在推理过程中学习新颖单词的大型语言模型(LLMS)。特别是,我们通过用一个合成但合理的词代替关键概念词来重写Winograd风格的共同参考分辨率问题,该词必须理解该模型以完成任务。解决此任务需要模型来利用提示中给出的新单词的字典定义。这个基准介绍了单词获取,这是折磨llms已知的历时降解的一个重要方面。由于LLM在训练的那一刻及时被冻结,因此通常无法反映语言随着时间的变化方式。我们表明,与原始Winograd任务相比,LLM的准确性在我们的基准测试中从根本上降低,从而确定了当前模型的局限性,并提供了基准来衡量LLMS的未来改善LLMS进行内在学习的能力。
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现有的数据驱动和反馈流量控制策略不考虑实时数据测量的异质性。此外,对于缺乏数据效率,传统的加固学习方法(RL)方法通常会缓慢收敛。此外,常规的最佳外围控制方案需要对系统动力学的精确了解,因此对内源性不确定性会很脆弱。为了应对这些挑战,这项工作提出了一种基于不可或缺的增强学习(IRL)的方法来学习宏观交通动态,以进行自适应最佳周边控制。这项工作为运输文献做出了以下主要贡献:(a)开发连续的时间控制,并具有离散增益更新以适应离散时间传感器数据。 (b)为了降低采样复杂性并更有效地使用可用数据,将体验重播(ER)技术引入IRL算法。 (c)所提出的方法以“无模型”方式放松模型校准的要求,该方式可以稳健地进行建模不确定性,并通过数据驱动的RL算法增强实时性能。 (d)通过Lyapunov理论证明了基于IRL的算法和受控交通动力学的稳定性的收敛性。最佳控制定律被参数化,然后通过神经网络(NN)近似,从而缓解计算复杂性。在不需要模型线性化的同时,考虑了状态和输入约束。提出了数值示例和仿真实验,以验证所提出方法的有效性和效率。
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ICECUBE是一种用于检测1 GEV和1 PEV之间大气和天体中微子的光学传感器的立方公斤阵列,该阵列已部署1.45 km至2.45 km的南极的冰盖表面以下1.45 km至2.45 km。来自ICE探测器的事件的分类和重建在ICeCube数据分析中起着核心作用。重建和分类事件是一个挑战,这是由于探测器的几何形状,不均匀的散射和冰中光的吸收,并且低于100 GEV的光,每个事件产生的信号光子数量相对较少。为了应对这一挑战,可以将ICECUBE事件表示为点云图形,并将图形神经网络(GNN)作为分类和重建方法。 GNN能够将中微子事件与宇宙射线背景区分开,对不同的中微子事件类型进行分类,并重建沉积的能量,方向和相互作用顶点。基于仿真,我们提供了1-100 GEV能量范围的比较与当前ICECUBE分析中使用的当前最新最大似然技术,包括已知系统不确定性的影响。对于中微子事件分类,与当前的IceCube方法相比,GNN以固定的假阳性速率(FPR)提高了信号效率的18%。另外,GNN在固定信号效率下将FPR的降低超过8(低于半百分比)。对于能源,方向和相互作用顶点的重建,与当前最大似然技术相比,分辨率平均提高了13%-20%。当在GPU上运行时,GNN能够以几乎是2.7 kHz的中位数ICECUBE触发速率的速率处理ICECUBE事件,这打开了在在线搜索瞬态事件中使用低能量中微子的可能性。
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