逆运动学（IK）系统通常相对于其输入特征很僵硬，因此需要将用户干预适应新骨架。在本文中，我们旨在创建一个适用于各种人类形态的灵活的，学到的IK求解器。我们扩展了最先进的机器学习IK求解器，以在众所周知的皮肤多人线性模型（SMPL）上运行。我们称我们的模型SMPL-IK，并表明当集成到实时3D软件中时，该扩展系统为定义新型AI-Asissist Animation Workfrows提供了机会。例如，通过允许用户在摆姿势的同时修改性别和身体形状，可以使姿势创作更加灵活。此外，当使用现有姿势估计算法链接时，SMPL-IK通过允许用户从2D图像引导3D场景来加速摆姿势，同时允许进一步编辑。最后，我们提出了一种新颖的SMPL形状反转机制（SMPL-SI），将任意类人形特征映射到SMPL空间，使艺术家能够在自定义字符上利用SMPL-IK。除了显示拟议工具的定性演示外，我们还介绍了H36M和Amass数据集上的定量SMPL-IK基准。
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我们表明，如果基于深度学习的插值器使用球形线性插值器作为基线，可以更准确，有效地求解在一组关键帧上进行人类运动的任务。我们从经验上证明了我们在实现最新性能的公开数据集上的方法的实力。我们通过证明$ \ delta $ - 优势相对于最后已知帧（也称为零速度模型）的参考，进一步概括了这些结果。这支持了一个更一般的结论，即在参考框架本地对输入帧的工作比以前的工作中主张的全球（世界）参考框架更准确，更强大。我们的代码可在https://github.com/boreshkinai/delta-interpolator上公开获取。
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我们的工作重点是开发人类姿势的可学习神经代表，用于先进的AI辅助动画工具。具体而言，我们解决了基于稀疏和可变的用户输入（例如，身体关节子集的位置和/或方向）构建完整静态人姿势的问题。为了解决这个问题，我们提出了一种新型的神经结构，将残留连接与部分指定姿势编码的原型结合在一起，以从学习的潜在空间中创建一个新的完整姿势。我们表明，在准确性和计算效率方面，我们的体系结构的表现优于基准基线。此外，我们开发了一个用户界面，以将我们的神经模型集成到Unity，这是一个实时3D开发平台。此外，我们基于高质量的人类运动捕获数据，介绍了代表静态人类姿势建模问题的两个新数据集，该数据将与模型代码一起公开发布。
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Accomplishing safe and efficient driving is one of the predominant challenges in the controller design of connected automated vehicles (CAVs). It is often more convenient to address these goals separately and integrate the resulting controllers. In this study, we propose a controller integration scheme to fuse performance-based controllers and safety-oriented controllers safely for the longitudinal motion of a CAV. The resulting structure is compatible with a large class of controllers, and offers flexibility to design each controller individually without affecting the performance of the others. We implement the proposed safe integration scheme on a connected automated truck using an optimal-in-energy controller and a safety-oriented connected cruise controller. We validate the premise of the safe integration through experiments with a full-scale truck in two scenarios: a controlled experiment on a test track and a real-world experiment on a public highway. In both scenarios, we achieve energy efficient driving without violating safety.
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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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Attention mechanisms form a core component of several successful deep learning architectures, and are based on one key idea: ''The output depends only on a small (but unknown) segment of the input.'' In several practical applications like image captioning and language translation, this is mostly true. In trained models with an attention mechanism, the outputs of an intermediate module that encodes the segment of input responsible for the output is often used as a way to peek into the `reasoning` of the network. We make such a notion more precise for a variant of the classification problem that we term selective dependence classification (SDC) when used with attention model architectures. Under such a setting, we demonstrate various error modes where an attention model can be accurate but fail to be interpretable, and show that such models do occur as a result of training. We illustrate various situations that can accentuate and mitigate this behaviour. Finally, we use our objective definition of interpretability for SDC tasks to evaluate a few attention model learning algorithms designed to encourage sparsity and demonstrate that these algorithms help improve interpretability.
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Recent advances in deep learning have enabled us to address the curse of dimensionality (COD) by solving problems in higher dimensions. A subset of such approaches of addressing the COD has led us to solving high-dimensional PDEs. This has resulted in opening doors to solving a variety of real-world problems ranging from mathematical finance to stochastic control for industrial applications. Although feasible, these deep learning methods are still constrained by training time and memory. Tackling these shortcomings, Tensor Neural Networks (TNN) demonstrate that they can provide significant parameter savings while attaining the same accuracy as compared to the classical Dense Neural Network (DNN). In addition, we also show how TNN can be trained faster than DNN for the same accuracy. Besides TNN, we also introduce Tensor Network Initializer (TNN Init), a weight initialization scheme that leads to faster convergence with smaller variance for an equivalent parameter count as compared to a DNN. We benchmark TNN and TNN Init by applying them to solve the parabolic PDE associated with the Heston model, which is widely used in financial pricing theory.
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Artificial neural networks can learn complex, salient data features to achieve a given task. On the opposite end of the spectrum, mathematically grounded methods such as topological data analysis allow users to design analysis pipelines fully aware of data constraints and symmetries. We introduce a class of persistence-based neural network layers. Persistence-based layers allow the users to easily inject knowledge about symmetries (equivariance) respected by the data, are equipped with learnable weights, and can be composed with state-of-the-art neural architectures.
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KL-regularized reinforcement learning from expert demonstrations has proved successful in improving the sample efficiency of deep reinforcement learning algorithms, allowing them to be applied to challenging physical real-world tasks. However, we show that KL-regularized reinforcement learning with behavioral reference policies derived from expert demonstrations can suffer from pathological training dynamics that can lead to slow, unstable, and suboptimal online learning. We show empirically that the pathology occurs for commonly chosen behavioral policy classes and demonstrate its impact on sample efficiency and online policy performance. Finally, we show that the pathology can be remedied by non-parametric behavioral reference policies and that this allows KL-regularized reinforcement learning to significantly outperform state-of-the-art approaches on a variety of challenging locomotion and dexterous hand manipulation tasks.
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Three main points: 1. Data Science (DS) will be increasingly important to heliophysics; 2. Methods of heliophysics science discovery will continually evolve, requiring the use of learning technologies [e.g., machine learning (ML)] that are applied rigorously and that are capable of supporting discovery; and 3. To grow with the pace of data, technology, and workforce changes, heliophysics requires a new approach to the representation of knowledge.
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