Minimising the longest travel distance for a group of mobile robots with interchangeable goals requires knowledge of the shortest length paths between all robots and goal destinations. Determining the exact length of the shortest paths in an environment with obstacles is challenging and cannot be guaranteed in a finite time. We propose an algorithm in which the accuracy of the path planning is iteratively increased. The approach provides a certificate when the uncertainties on estimates of the shortest paths become small enough to guarantee the optimality of the goal assignment. To this end, we apply results from assignment sensitivity assuming upper and lower bounds on the length of the shortest paths. We then provide polynomial-time methods to find such bounds by applying sampling-based path planning. The upper bounds are given by feasible paths, the lower bounds are obtained by expanding the sample set and leveraging knowledge of the sample dispersion. We demonstrate the application of the proposed method with a multi-robot path-planning case study.
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The number of international benchmarking competitions is steadily increasing in various fields of machine learning (ML) research and practice. So far, however, little is known about the common practice as well as bottlenecks faced by the community in tackling the research questions posed. To shed light on the status quo of algorithm development in the specific field of biomedical imaging analysis, we designed an international survey that was issued to all participants of challenges conducted in conjunction with the IEEE ISBI 2021 and MICCAI 2021 conferences (80 competitions in total). The survey covered participants' expertise and working environments, their chosen strategies, as well as algorithm characteristics. A median of 72% challenge participants took part in the survey. According to our results, knowledge exchange was the primary incentive (70%) for participation, while the reception of prize money played only a minor role (16%). While a median of 80 working hours was spent on method development, a large portion of participants stated that they did not have enough time for method development (32%). 25% perceived the infrastructure to be a bottleneck. Overall, 94% of all solutions were deep learning-based. Of these, 84% were based on standard architectures. 43% of the respondents reported that the data samples (e.g., images) were too large to be processed at once. This was most commonly addressed by patch-based training (69%), downsampling (37%), and solving 3D analysis tasks as a series of 2D tasks. K-fold cross-validation on the training set was performed by only 37% of the participants and only 50% of the participants performed ensembling based on multiple identical models (61%) or heterogeneous models (39%). 48% of the respondents applied postprocessing steps.
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As a novel distributed learning paradigm, federated learning (FL) faces serious challenges in dealing with massive clients with heterogeneous data distribution and computation and communication resources. Various client-variance-reduction schemes and client sampling strategies have been respectively introduced to improve the robustness of FL. Among others, primal-dual algorithms such as the alternating direction of method multipliers (ADMM) have been found being resilient to data distribution and outperform most of the primal-only FL algorithms. However, the reason behind remains a mystery still. In this paper, we firstly reveal the fact that the federated ADMM is essentially a client-variance-reduced algorithm. While this explains the inherent robustness of federated ADMM, the vanilla version of it lacks the ability to be adaptive to the degree of client heterogeneity. Besides, the global model at the server under client sampling is biased which slows down the practical convergence. To go beyond ADMM, we propose a novel primal-dual FL algorithm, termed FedVRA, that allows one to adaptively control the variance-reduction level and biasness of the global model. In addition, FedVRA unifies several representative FL algorithms in the sense that they are either special instances of FedVRA or are close to it. Extensions of FedVRA to semi/un-supervised learning are also presented. Experiments based on (semi-)supervised image classification tasks demonstrate superiority of FedVRA over the existing schemes in learning scenarios with massive heterogeneous clients and client sampling.
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在边缘计算中,必须根据用户移动性迁移用户的服务配置文件。已经提出了强化学习(RL)框架。然而,这些框架并不考虑偶尔的服务器故障,尽管很少会阻止Edge Computing用户的延迟敏感应用程序(例如自动驾驶和实时障碍物检测)的平稳和安全功能,因为用户的计算作业不再是完全的。由于这些故障的发生率很低,因此,RL算法本质上很难为数据驱动的算法学习针对典型事件和罕见事件方案的最佳服务迁移解决方案。因此,我们引入了罕见的事件自适应弹性框架火,该框架将重要性采样集成到加强学习中以放置备份服务。我们以与其对价值函数的贡献成正比的稀有事件进行采样,以学习最佳政策。我们的框架平衡了服务迁移和迁移成本之间的迁移权衡,与失败的成本以及备份放置和移民的成本。我们提出了一种基于重要性抽样的Q-学习算法,并证明其界限和收敛到最佳性。随后,我们提出了新的资格轨迹,我们的算法的线性函数近似和深Q学习版本,以确保其扩展到现实世界情景。我们扩展框架,以适应具有不同风险承受失败的用户。最后,我们使用痕量驱动的实验表明我们的算法在发生故障时会降低成本。
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多限制攀岩机器人的运动计划必须考虑机器人的姿势,联合扭矩,以及它如何使用接触力与环境相互作用。本文着重于使用非传统运动来探索不可预测的环境(例如火星洞穴)的机器人运动计划。我们的机器人概念Reachbot使用可扩展和可伸缩的动臂作为四肢,在攀爬时实现了大型可伸缩度工作区。每个可扩展的动臂都由旨在抓住岩石表面的微生物抓地力封顶。 Reachbot利用其大型工作空间来绕过障碍物,裂缝和挑战地形。我们的计划方法必须具有多功能性,以适应可变的地形特征和鲁棒性,以减轻用刺抓握随机性质的风险。在本文中,我们引入了一种图形遍历算法,以根据适用于握把的可用地形特征选择一个离散的grasps序列。该离散的计划是由一个解耦运动计划者互补的,该计划者使用基于抽样的计划和顺序凸面编程的组合来考虑身体运动和最终效应器运动的交替阶段,以优化单个阶段。我们使用运动规划师在模拟的2D洞穴环境中计划轨迹,至少有95%的成功概率,并在基线轨迹上表现出改善的鲁棒性。最后,我们通过对2D平面原型进行实验来验证运动计划算法。
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近年来,人们看到了新型神经网络体系结构的激增,用于整合多摩智数据以进行预测。大多数体系结构包括单独编码器或编码器和解码器,即各种自动编码器,以将多摩s数据转换为潜在表示。一个重要的参数是集成的深度:计算或合并潜在表示的点,可以是早期,中间或晚期。关于集成方法的文献正在稳步增长,但是,在公平的实验条件下这些方法的相对性能以及正在考虑不同用例的相对性能,几乎一无所知。我们开发了一个比较框架,该框架在均等条件下训练和优化了多摩斯集成方法。我们结合了早期整合,最近出版了四种深度学习方法:Moli,Super.felt,Omiembed和Moma。此外,我们设计了一种新颖的方法,即OMICS堆叠,结合了中间和晚期整合的优势。实验是在具有多个OMIC数据(体细胞突变,体拷贝数谱和基因表达谱)的公共药物反应数据集上进行的,该数据是从细胞系,患者衍生的异种移植物和患者样本中获得的。我们的实验证实,早期整合的预测性能最低。总体而言,整合三胞胎损失的体系结构取得了最佳的结果。总体而言,统计差异很少可以观察到方法的平均等级,而Super.FELT在交叉验证设置中始终保持最佳状态,并且在外部测试集设置中最好地堆叠OMICS。所有实验的源代码均可在\ url {https://github.com/kramerlab/multi-omics_analysis下获得。
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视频编码技术已不断改进,以更高的分辨率以更高的压缩比。但是,最先进的视频编码标准(例如H.265/HEVC和多功能视频编码)仍在设计中,该假设将被人类观看。随着深度神经网络在解决计算机视觉任务方面的巨大进步和成熟,越来越多的视频通过无人参与的深度神经网络直接分析。当计算机视觉应用程序使用压缩视频时,这种传统的视频编码标准设计并不是最佳的。尽管人类视觉系统对具有高对比度的内容一直敏感,但像素对计算机视觉算法的影响是由特定的计算机视觉任务驱动的。在本文中,我们探索并总结了计算机视觉任务的视频编码和新兴视频编码标准,机器的视频编码。
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社交机器人已被用来以各种方式来协助心理健康,例如帮助自闭症儿童改善其社交技能和执行功能,例如共同关注和身体意识。他们还用于通过减少孤立和孤独感,并支持青少年和儿童的心理健康来帮助老年人。但是,这一领域的现有工作仅通过社交机器人对人类活动的互动响应来帮助他们学习相关技能,从而通过社交机器人表现出对心理健康的支持。我们假设人类还可以通过与社交机器人释放或分享其心理健康数据来从社交机器人那里获得帮助。在本文中,我们提出了一项人类机器人相互作用(HRI)研究,以评估这一假设。在为期五天的研究中,共有五十五名(n = 55)的参与者与社交机器人分享了他们的内在情绪和压力水平。我们看到大多数积极的结果表明,值得在这个方向上进行未来的工作,以及社会机器人在很大程度上支持心理健康的潜力。
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根据诸如医疗条件,程序和药物使用之类的资格标准,识别患者队列对于临床试验的招募至关重要。这种标准通常是在自由文本中最自然地描述的,使用临床医生和研究人员熟悉的语言。为了大规模识别潜在参与者,必须首先将这些标准转换为临床数据库的查询,这可能是劳动密集型且容易出错的。自然语言处理(NLP)方法提供了一种可能自动转换为数据库查询的潜在手段。但是,必须首先使用Corpora对其进行培训和评估,该语料库详细列出临床试验标准。在本文中,我们介绍了叶片临床试验(LCT)语料库,该语料库是一种使用高度颗粒状结构化标签,捕获一系列生物医学现象的人类向超过1000个临床试验资格标准描述。我们提供了我们的模式,注释过程,语料库质量和统计数据的详细信息。此外,我们提出了该语料库的基线信息提取结果,作为未来工作的基准。
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在全球坐标系中,基于颜色的双手3D姿势估计在许多应用中至关重要。但是,很少有专门用于此任务的数据集,并且没有现有数据集支持在非实验室环境中的估计。这在很大程度上归因于3D手姿势注释所需的复杂数据收集过程,这也导致难以获得野生估计所需的视觉多样性水平的实例。为了实现这一目标,最近提出了一个大规模的数据集EGO2HANDS来解决野外双手分割和检测的任务。拟议的基于组成的数据生成技术可以创建具有质量,数量和多样性的双手实例,从而将其推广到看不见的域。在这项工作中,我们提出了EGO2Handspose,这是包含3D手姿势注释的EGO2HAND的扩展,并且是第一个在看不见域中启用基于颜色的两手3D跟踪的数据集。为此,我们开发了一组参数拟合算法以启用1)使用单个图像的3D手姿势注释,2)自动转换从2D到3D手势和3)具有时间一致性的准确双手跟踪。我们在多阶段管道上提供了增量的定量分析,并表明我们数据集中的培训达到了最新的结果,这些结果大大胜过其他数据集,以实现以自我为中心的双手全球3D姿势估计的任务。
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