生物医学图像分析算法验证取决于参考数据集的高质量注释,标记指令是关键。尽管它们的重要性,但他们的优化仍然没有得到探索。在这里,我们介绍了对标签指令及其对该领域注释质量的影响的首次系统研究。通过对Miccai协会注册的专业实践和国际比赛的全面检查,我们发现了注释者对标签说明的标签需求及其当前质量和可用性之间的差异。基于对156家专业公司的156个注释者和708个亚马逊机械土耳其人(MTURK)人群的注释者的14040张图像的分析,使用具有不同信息密度级别的说明,我们进一步发现,包括示例性图像与文本描述,唯一的描述,示例性图像显着增强了注释性能,虽然仅扩展文本说明并非如此。最后,专业注释者不断优于mturk人群。我们的研究提高了对生物医学图像分析标签指令中质量标准的需求的认识。
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自动生物医学图像分析的领域至关重要地取决于算法验证的可靠和有意义的性能指标。但是,当前的度量使用通常是不明智的,并且不能反映基本的域名。在这里,我们提出了一个全面的框架,该框架指导研究人员以问题意识的方式选择绩效指标。具体而言,我们专注于生物医学图像分析问题,这些问题可以解释为图像,对象或像素级别的分类任务。该框架首先编译域兴趣 - 目标结构 - ,数据集和算法与输出问题相关的属性的属性与问题指纹相关,同时还将其映射到适当的问题类别,即图像级分类,语义分段,实例,实例细分或对象检测。然后,它指导用户选择和应用一组适当的验证指标的过程,同时使他们意识到与个人选择相关的潜在陷阱。在本文中,我们描述了指标重新加载推荐框架的当前状态,目的是从图像分析社区获得建设性的反馈。当前版本是在由60多个图像分析专家的国际联盟中开发的,将在社区驱动的优化之后公开作为用户友好的工具包提供。
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尽管自动图像分析的重要性不断增加,但最近的元研究揭示了有关算法验证的主要缺陷。性能指标对于使用的自动算法的有意义,客观和透明的性能评估和验证尤其是关键,但是在使用特定的指标进行给定的图像分析任务时,对实际陷阱的关注相对较少。这些通常与(1)无视固有的度量属性,例如在存在类不平衡或小目标结构的情况下的行为,(2)无视固有的数据集属性,例如测试的非独立性案例和(3)无视指标应反映的实际生物医学领域的兴趣。该动态文档的目的是说明图像分析领域通常应用的性能指标的重要局限性。在这种情况下,它重点介绍了可以用作图像级分类,语义分割,实例分割或对象检测任务的生物医学图像分析问题。当前版本是基于由全球60多家机构的国际图像分析专家进行的关于指标的Delphi流程。
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This paper expounds the design and control of a new Variable Stiffness Series Elastic Actuator (VSSEA). It is established by employing a modular mechanical design approach that allows us to effectively optimise the stiffness modulation characteristics and power density of the actuator. The proposed VSSEA possesses the following features: i) no limitation in the work-range of output link, ii) a wide range of stiffness modulation (~20Nm/rad to ~1KNm/rad), iii) low-energy-cost stiffness modulation at equilibrium and non-equilibrium positions, iv) compact design and high torque density (~36Nm/kg), and v) high-speed stiffness modulation (~3000Nm/rad/s). Such features can help boost the safety and performance of many advanced robotic systems, e.g., a cobot that physically interacts with unstructured environments and an exoskeleton that provides physical assistance to human users. These features can also enable us to utilise variable stiffness property to attain various regulation and trajectory tracking control tasks only by employing conventional controllers, eliminating the need for synthesising complex motion control systems in compliant actuation. To this end, it is experimentally demonstrated that the proposed VSSEA is capable of precisely tracking desired position and force control references through the use of conventional Proportional-Integral-Derivative (PID) controllers.
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Animals run robustly in diverse terrain. This locomotion robustness is puzzling because axon conduction velocity is limited to a few ten meters per second. If reflex loops deliver sensory information with significant delays, one would expect a destabilizing effect on sensorimotor control. Hence, an alternative explanation describes a hierarchical structure of low-level adaptive mechanics and high-level sensorimotor control to help mitigate the effects of transmission delays. Motivated by the concept of an adaptive mechanism triggering an immediate response, we developed a tunable physical damper system. Our mechanism combines a tendon with adjustable slackness connected to a physical damper. The slack damper allows adjustment of damping force, onset timing, effective stroke, and energy dissipation. We characterize the slack damper mechanism mounted to a legged robot controlled in open-loop mode. The robot hops vertically and planar over varying terrains and perturbations. During forward hopping, slack-based damping improves faster perturbation recovery (up to 170%) at higher energetic cost (27%). The tunable slack mechanism auto-engages the damper during perturbations, leading to a perturbation-trigger damping, improving robustness at minimum energetic cost. With the results from the slack damper mechanism, we propose a new functional interpretation of animals' redundant muscle tendons as tunable dampers.
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Generative models learned from training using deep learning methods can be used as priors in inverse under-determined inverse problems, including imaging from sparse set of measurements. In this paper, we present a novel hierarchical deep-generative model MrSARP for SAR imagery that can synthesize SAR images of a target at different resolutions jointly. MrSARP is trained in conjunction with a critic that scores multi resolution images jointly to decide if they are realistic images of a target at different resolutions. We show how this deep generative model can be used to retrieve the high spatial resolution image from low resolution images of the same target. The cost function of the generator is modified to improve its capability to retrieve the input parameters for a given set of resolution images. We evaluate the model's performance using the three standard error metrics used for evaluating super-resolution performance on simulated data and compare it to upsampling and sparsity based image sharpening approaches.
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由于卷积神经网络(CNN)在过去的十年中检测成功,多对象跟踪(MOT)通过检测方法的使用来控制。随着数据集和基础标记网站的发布,研究方向已转向在跟踪时在包括重新识别对象的通用场景(包括重新识别(REID))上的最佳准确性。在这项研究中,我们通过提供专用的行人数据集并专注于对性能良好的多对象跟踪器的深入分析来缩小监视的范围)现实世界应用的技术。为此,我们介绍SOMPT22数据集;一套新的,用于多人跟踪的新套装,带有带注释的简短视频,该视频从位于杆子上的静态摄像头捕获,高度为6-8米,用于城市监视。与公共MOT数据集相比,这提供了室外监视的MOT的更为集中和具体的基准。我们分析了该新数据集上检测和REID网络的使用方式,分析了将MOT跟踪器分类为单发和两阶段。我们新数据集的实验结果表明,SOTA远非高效率,而单一跟踪器是统一快速执行和准确性的良好候选者,并具有竞争性的性能。该数据集将在以下网址提供:sompt22.github.io
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人类的腿部运动受人体和神经控制的自然动态的控制。假定有助于人类行走效率高的一种机制是冲动的脚踝推断,它可能为挥杆腿弹射器提供动力。然而,尚不清楚人类下腿的机制,其复杂的肌肉弯曲单元跨越了单个关节和多个关节。腿部机器人允许在实际步行步态中测试复杂的腿力学,控制和环境之间的相互作用。我们开发了一个高0.49m,2.2千克的拟人化型双足机器人,带有比目鱼和甲壳虫肌肉弯曲单元,由线性弹簧代表,在机器人的踝关节和膝关节周围充当单型和二子弹性结构。我们测试了三个比目鱼和胃弹簧螺旋形构型对踝关节功率曲线的影响,踝关节和膝关节运动的协调,总运输成本和步行速度。我们用前馈中央模式发生器控制了机器人,在1.0Hz运动频率下,步行速度在0.35m/s和0.57m/s之间,腿长为0.35m。我们发现所有三种配置之间的差异。比目鱼弹簧刺刺调节机器人的速度和能量效率可能是通过踝关节放大的,而胃刺的弹簧螺旋体在推下时改变了脚踝和膝关节之间的运动配位。
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我们提出了一种新颖的基于变压器的架构,用于3D人类运动的生成建模任务。以前的工作通常依赖于基于RNN的模型,考虑到更短的预测视野迅速达到静止和通常难以置信的状态。最近的研究表明,频域中的隐式时间表示也是有效地制定预定地平线的预测。我们的重点是学习自向学习时空陈述,从而在短期和长期生成合理的未来发展。该模型学习骨骼关节的高尺寸嵌入,以及如何通过去耦的时间和空间自我关注机制来组成时间相干的姿势。我们的双重关注概念允许模型直接访问电流和过去信息,并明确捕获结构和时间依赖项。我们凭经验显示,这有效地了解潜在的运动动态,并减少自动回归模型中观察到的误差累积。我们的模型能够在长视程中产生准确的短期预测和产生合理的运动序列。我们在HTTPS://github.com/eth-Ation-Transformer中公开公开提供我们的代码。
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Variational inference uses optimization, rather than integration, to approximate the marginal likelihood, and thereby the posterior, in a Bayesian model. Thanks to advances in computational scalability made in the last decade, variational inference is now the preferred choice for many high-dimensional models and large datasets. This tutorial introduces variational inference from the parametric perspective that dominates these recent developments, in contrast to the mean-field perspective commonly found in other introductory texts.
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