我们提出了一种新的方法，可以通过具有relu，sigmoid或双曲线切线激活功能的神经网络有效地计算图像的紧密非凸面。特别是，我们通过多项式近似来抽象每个神经元的输入输出关系，该近似是使用多项式界定的基于设定的方式进行评估的。我们提出的方法特别适合于对神经网络控制系统的可及性分析，因为多项式地位型能够捕获两者中的非共鸣性，通过神经网络以及可触及的集合。与各种基准系统上的其他最新方法相比，我们证明了方法的卓越性能。

目的：开发基于深度学习的图像重建框架，以在MRI中可复制研究。方法：Bart Toolbox提供了丰富的校准和重建算法的实现，用于并行成像和压缩传感。在这项工作中，BART由非线性操作员框架扩展，该框架提供了自动差异以允许计算梯度。 BART的现有特定于MRI的操作员，例如非均匀的快速傅立叶变换，直接集成到该框架中，并与神经网络中使用的常见构件相辅相成。为了评估用于先进的基于深度学习的重建框架的使用，实现了两个最先进的展开的重建网络，即变异网络[1]和MODL [2]。结果：可以使用BART的基于BART的优化算法来构建和训练最新的深层图像重建网络。与基于TensorFlow的原始实现相比，BART实施在训练时间和重建质量方面具有相似的性能。结论：通过将非线性操作员和神经网络整合到BART中，我们为MRI中的深度学习重建提供了一个一般框架。

我们研究了具有神经网络控制器（NNC）的闭环动态系统的验证问题。此问题通常还原为计算可达状态集。在考虑动态系统和神经网络的隔离时，基于分别称为泰勒模型和Zonotopes的集合表示，该任务存在精确的方法。然而，这些方法对NNC的组合是非微不足道的，因为当在集合表示之间转换时，依赖性信息在每个控制周期中丢失，并且累积的近似误差快速使结果呈现。我们提出了一种基于泰勒模型和ZONotopes的链接近算法，得到了NNC的精确可达性算法。因为该算法仅在孤立方法的界面上起作用，所以适用于一般动态系统和神经网络，可以从这些领域的未来进展中受益。我们的实施提供了最先进的绩效，是第一个成功分析NNC年可达性竞争的所有基准问题。

当预测它们被训练以识别时的输入类时，神经网络分类器可以实现高精度。在动态环境中保持这种准确性，其中输入经常掉落在最初已知的类的固定集合之外，仍然是一个挑战。典型方法是检测新颖类别的输入，并在增强的数据集上重新转回分类器。但是，不仅是分类器还是检测机制也需要适应以区分新学习和尚未未知的输入类。为了解决这一挑战，我们介绍了一个算法框架，用于神经网络的主动监控。在我们的框架中包装的监视器与神经网络并行运行，并通过一系列可解释的标记查询与人类用户进行交互，以增量适应。此外，我们提出了一种自适应定量监测，以提高精度。具有不同数量的类别的多种基准测试的实验评估证实了我们在动态方案中的主动监测框架的好处。

Robotic teleoperation is a key technology for a wide variety of applications. It allows sending robots instead of humans in remote, possibly dangerous locations while still using the human brain with its enormous knowledge and creativity, especially for solving unexpected problems. A main challenge in teleoperation consists of providing enough feedback to the human operator for situation awareness and thus create full immersion, as well as offering the operator suitable control interfaces to achieve efficient and robust task fulfillment. We present a bimanual telemanipulation system consisting of an anthropomorphic avatar robot and an operator station providing force and haptic feedback to the human operator. The avatar arms are controlled in Cartesian space with a direct mapping of the operator movements. The measured forces and torques on the avatar side are haptically displayed to the operator. We developed a predictive avatar model for limit avoidance which runs on the operator side, ensuring low latency. The system was successfully evaluated during the ANA Avatar XPRIZE competition semifinals. In addition, we performed in lab experiments and carried out a small user study with mostly untrained operators.

The purpose of this work was to tackle practical issues which arise when using a tendon-driven robotic manipulator with a long, passive, flexible proximal section in medical applications. A separable robot which overcomes difficulties in actuation and sterilization is introduced, in which the body containing the electronics is reusable and the remainder is disposable. A control input which resolves the redundancy in the kinematics and a physical interpretation of this redundancy are provided. The effect of a static change in the proximal section angle on bending angle error was explored under four testing conditions for a sinusoidal input. Bending angle error increased for increasing proximal section angle for all testing conditions with an average error reduction of 41.48% for retension, 4.28% for hysteresis, and 52.35% for re-tension + hysteresis compensation relative to the baseline case. Two major sources of error in tracking the bending angle were identified: time delay from hysteresis and DC offset from the proximal section angle. Examination of these error sources revealed that the simple hysteresis compensation was most effective for removing time delay and re-tension compensation for removing DC offset, which was the primary source of increasing error. The re-tension compensation was also tested for dynamic changes in the proximal section and reduced error in the final configuration of the tip by 89.14% relative to the baseline case.

Learning enabled autonomous systems provide increased capabilities compared to traditional systems. However, the complexity of and probabilistic nature in the underlying methods enabling such capabilities present challenges for current systems engineering processes for assurance, and test, evaluation, verification, and validation (TEVV). This paper provides a preliminary attempt to map recently developed technical approaches in the assurance and TEVV of learning enabled autonomous systems (LEAS) literature to a traditional systems engineering v-model. This mapping categorizes such techniques into three main approaches: development, acquisition, and sustainment. We review the latest techniques to develop safe, reliable, and resilient learning enabled autonomous systems, without recommending radical and impractical changes to existing systems engineering processes. By performing this mapping, we seek to assist acquisition professionals by (i) informing comprehensive test and evaluation planning, and (ii) objectively communicating risk to leaders.

In inverse reinforcement learning (IRL), a learning agent infers a reward function encoding the underlying task using demonstrations from experts. However, many existing IRL techniques make the often unrealistic assumption that the agent has access to full information about the environment. We remove this assumption by developing an algorithm for IRL in partially observable Markov decision processes (POMDPs). We address two limitations of existing IRL techniques. First, they require an excessive amount of data due to the information asymmetry between the expert and the learner. Second, most of these IRL techniques require solving the computationally intractable forward problem -- computing an optimal policy given a reward function -- in POMDPs. The developed algorithm reduces the information asymmetry while increasing the data efficiency by incorporating task specifications expressed in temporal logic into IRL. Such specifications may be interpreted as side information available to the learner a priori in addition to the demonstrations. Further, the algorithm avoids a common source of algorithmic complexity by building on causal entropy as the measure of the likelihood of the demonstrations as opposed to entropy. Nevertheless, the resulting problem is nonconvex due to the so-called forward problem. We solve the intrinsic nonconvexity of the forward problem in a scalable manner through a sequential linear programming scheme that guarantees to converge to a locally optimal policy. In a series of examples, including experiments in a high-fidelity Unity simulator, we demonstrate that even with a limited amount of data and POMDPs with tens of thousands of states, our algorithm learns reward functions and policies that satisfy the task while inducing similar behavior to the expert by leveraging the provided side information.

Speech-driven 3D facial animation has been widely explored, with applications in gaming, character animation, virtual reality, and telepresence systems. State-of-the-art methods deform the face topology of the target actor to sync the input audio without considering the identity-specific speaking style and facial idiosyncrasies of the target actor, thus, resulting in unrealistic and inaccurate lip movements. To address this, we present Imitator, a speech-driven facial expression synthesis method, which learns identity-specific details from a short input video and produces novel facial expressions matching the identity-specific speaking style and facial idiosyncrasies of the target actor. Specifically, we train a style-agnostic transformer on a large facial expression dataset which we use as a prior for audio-driven facial expressions. Based on this prior, we optimize for identity-specific speaking style based on a short reference video. To train the prior, we introduce a novel loss function based on detected bilabial consonants to ensure plausible lip closures and consequently improve the realism of the generated expressions. Through detailed experiments and a user study, we show that our approach produces temporally coherent facial expressions from input audio while preserving the speaking style of the target actors.

We study the problem of graph clustering under a broad class of objectives in which the quality of a cluster is defined based on the ratio between the number of edges in the cluster, and the total weight of vertices in the cluster. We show that our definition is closely related to popular clustering measures, namely normalized associations, which is a dual of the normalized cut objective, and normalized modularity. We give a linear time constant-approximate algorithm for our objective, which implies the first constant-factor approximation algorithms for normalized modularity and normalized associations.