This paper proposes a novel controller framework that provides trajectory tracking for an Aerial Manipulator (AM) while ensuring the safe operation of the system under unknown bounded disturbances. The AM considered here is a 2-DOF (degrees-of-freedom) manipulator rigidly attached to a UAV. Our proposed controller structure follows the conventional inner loop PID control for attitude dynamics and an outer loop controller for tracking a reference trajectory. The outer loop control is based on the Model Predictive Control (MPC) with constraints derived using the Barrier Lyapunov Function (BLF) for the safe operation of the AM. BLF-based constraints are proposed for two objectives, viz. 1) To avoid the AM from colliding with static obstacles like a rectangular wall, and 2) To maintain the end effector of the manipulator within the desired workspace. The proposed BLF ensures that the above-mentioned objectives are satisfied even in the presence of unknown bounded disturbances. The capabilities of the proposed controller are demonstrated through high-fidelity non-linear simulations with parameters derived from a real laboratory scale AM. We compare the performance of our controller with other state-of-the-art MPC controllers for AM.
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We are interested in neurosymbolic systems consisting of a high-level symbolic layer for explainable prediction in terms of human-intelligible concepts; and a low-level neural layer for extracting symbols required to generate the symbolic explanation. Real data is often imperfect meaning that even if the symbolic theory remains unchanged, we may still need to address the problem of mapping raw data to high-level symbols, each time there is a change in the data acquisition environment or equipment. Manual (re-)annotation of the raw data each time this happens is laborious and expensive; and automated labelling methods are often imperfect, especially for complex problems. NEUROLOG proposed the use of a semantic loss function that allows an existing feature-based symbolic model to guide the extraction of feature-values from raw data, using `abduction'. However, the experiments demonstrating the use of semantic loss through abduction appear to rely heavily on a domain-specific pre-processing step that enables a prior delineation of feature locations in the raw data. We examine the use of semantic loss in domains where such pre-processing is not possible, or is not obvious. We show that without any prior information about the features, the NEUROLOG approach can continue to predict accurately even with substantially incorrect feature predictions. We show also that prior information about the features in the form of even imperfect pre-training can help correct this situation. These findings are replicated on the original problem considered by NEUROLOG, without the use of feature-delineation. This suggests that symbolic explanations constructed for data in a domain could be re-used in a related domain, by `feature-adaptation' of pre-trained neural extractors using the semantic loss function constrained by abductive feedback.
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数据驱动的湍流建模正在经历数据科学算法和硬件开发后的兴趣激增。我们讨论了一种使用可区分物理范式的方法,该方法将已知的物理学与机器学习结合起来,以开发汉堡湍流的闭合模型。我们将1D汉堡系统视为一种原型测试问题,用于建模以对流为主的湍流问题中未解决的术语。我们训练一系列模型,这些模型在后验损失函数上结合了不同程度的物理假设,以测试模型在一系列系统参数(包括粘度,时间和网格分辨率)上的疗效。我们发现,以部分微分方程形式的归纳偏差的约束模型包含已知物理或现有闭合方法会产生高度数据效率,准确和可推广的模型,并且表现优于最先进的基准。以物理信息形式添加结构还为模型带来了一定程度的解释性,可能为封闭建模的未来提供了垫脚石。
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最近,电子学习平台已经发展为学生可以发表疑问(用智能手机拍摄的快照)并在几分钟内解决的地方。但是,这些平台的质量差异很大的学生寄出疑问的数量显着增加,这不仅给教师导航解决方案带来了挑战,还增加了每个疑问的分辨率时间。两者都是不可接受的,因为高度怀疑的时间阻碍了学生学习进度的学习。这需要方法来自动识别存储库中是否存在类似的疑问,然后将其作为验证和与学生沟通的合理解决方案。监督的学习技术(如暹罗建筑)需要标签来识别比赛,这是不可行的,因为标签稀缺且昂贵。因此,在这项工作中,我们基于通过自我监督技术学到的表示形式开发了符合范式的标签不足的疑问。在BYOL的先前理论见解(Bootstrap您自己的潜在空间)的基础上,我们提出了Custom Byol,将特定于域特异性的增强与对比目标结合在一起,而不是各种适当构建的数据视图。结果强调,与BYOL和监督学习实例相比,Custom Byol分别将TOP-1匹配精度提高了大约6 \%和5 \%。我们进一步表明,基于BYOL的学习实例在标准杆上的性能比人类标签更好。
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从简短的问题实例推断出较长的实例的能力是推理任务中分布概括的一种重要形式,并且在较长的问题实例很少见的数据集中学习时至关重要。这些包括定理证明,解决定量数学问题以及阅读/总结小说。在本文中,我们进行了仔细的经验研究,以探讨基于变压器的语言模型的长度概括能力。我们首先确定长度泛化任务上的天真固定变压器显示出与模型量表无关的显着泛化缺陷。然后,我们表明,将预处理的大语言模型与SCRATCHPAD提示(要求模型在产生答案之前输出解决方案步骤)相结合,从而巨大的长度概括改进。我们对每种学习方式进行了仔细的失败分析,并确定了常见的错误来源,这些错误来源突出了将语言模型的机会与更长的问题概括的能力。
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语言模型在需要自然语言理解的各种任务上取得了非凡的表现。然而,最先进的模型通常在需要定量推理的任务上挣扎,例如在大学一级解决数学,科学和工程问题。为了帮助缩小这一差距,我们介绍了Minerva,Minerva是一种在一般自然语言数据上鉴定的大型语言模型,并进一步培训了技术内容。该模型在不使用外部工具的情况下实现了技术基准测试的最新性能。我们还评估了我们在需要定量推理的物理学,生物学,化学,经济学和其他科学方面的200多个本科生问题上评估我们的模型,并发现该模型可以正确回答其中几乎三分之一。
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研究深度学习的鲁棒性的一个主要挑战是定义了给定神经网络(NN)不变的``毫无意义''扰动集。关于鲁棒性的大多数工作隐含地将人作为参考模型来定义这种扰动。我们的工作通过使用另一个参考NN来定义给定的NN应该不变,从而使对任何NN的依赖概述对任何NN的依赖。这使得衡量鲁棒性等同于衡量两个NN共享不稳定的程度,我们提出了一种称为搅拌的措施。搅拌重新调整现有的表示相似性措施,使其适合衡量共享的不稳定。使用我们的度量,我们能够深入了解共享的不断增长,随着重量初始化,体系结构,损失功能和培训数据集的变化如何变化。我们的实现可在:\ url {https://github.com/nvedant07/stir}中获得。
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语言模型既展示了定量的改进,又展示了新的定性功能,随着规模的增加。尽管它们具有潜在的变革性影响,但这些新能力的特征却很差。为了为未来的研究提供信息,为破坏性的新模型能力做准备,并改善社会有害的效果,至关重要的是,我们必须了解目前和近乎未来的能力和语言模型的局限性。为了应对这一挑战,我们介绍了超越模仿游戏基准(Big Bench)。 Big Bench目前由204个任务组成,由132家机构的442位作者贡献。任务主题是多样的,从语言学,儿童发展,数学,常识性推理,生物学,物理学,社会偏见,软件开发等等。 Big-Bench专注于被认为超出当前语言模型的功能的任务。我们评估了OpenAI的GPT型号,Google内部密集变压器体系结构和大型基础上的开关稀疏变压器的行为,跨越了数百万到数十亿个参数。此外,一个人类专家评估者团队执行了所有任务,以提供强大的基准。研究结果包括:模型性能和校准都随规模改善,但绝对的术语(以及与评估者的性能相比);在模型类中的性能非常相似,尽管带有稀疏性。逐渐和预测的任务通常涉及大量知识或记忆成分,而在临界规模上表现出“突破性”行为的任务通常涉及多个步骤或组成部分或脆性指标;社交偏见通常会随着含糊不清的环境而随着规模而增加,但这可以通过提示来改善。
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大型语言模型已被证明可以使用少量学习来实现各种自然语言任务的出色表现,这大大减少了将模型调整到特定应用程序所需的特定任务培训示例的数量。为了进一步了解量表对少量学习的影响,我们培训了一个5400亿个参数,密集激活的变压器语言模型,我们称之为“途径”语言模型棕榈。我们使用Pathways在6144 TPU V4芯片上训练了Palm,这是一种新的ML系统,可在多个TPU POD上进行高效的训练。我们通过在数百种语言理解和产生基准的基准方面实现最先进的学习结果来证明扩展的持续好处。在这些任务中,Palm 540B实现了突破性的表现,在一系列多步推理任务上表现出色,超过了最新的最新表现,并且在最近发布的Big Benchmark上表现优于平均人类表现。大量的大型基础任务显示出与模型量表的不连续改进,这意味着当我们扩展到最大模型时,性能急剧增加。 Palm在多语言任务和源代码生成方面也具有很强的功能,我们在各种基准测试中证明了这一点。我们还提供了有关偏见和毒性的全面分析,并研究了训练数据记忆的程度,相对于模型量表。最后,我们讨论与大语言模型有关的道德考虑,并讨论潜在的缓解策略。
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Online bipartite-matching platforms are ubiquitous and find applications in important areas such as crowdsourcing and ridesharing. In the most general form, the platform consists of three entities: two sides to be matched and a platform operator that decides the matching. The design of algorithms for such platforms has traditionally focused on the operator's (expected) profit. Since fairness has become an important consideration that was ignored in the existing algorithms a collection of online matching algorithms have been developed that give a fair treatment guarantee for one side of the market at the expense of a drop in the operator's profit. In this paper, we generalize the existing work to offer fair treatment guarantees to both sides of the market simultaneously, at a calculated worst case drop to operator profit. We consider group and individual Rawlsian fairness criteria. Moreover, our algorithms have theoretical guarantees and have adjustable parameters that can be tuned as desired to balance the trade-off between the utilities of the three sides. We also derive hardness results that give clear upper bounds over the performance of any algorithm.
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