We discover a robust self-supervised strategy tailored towards molecular representations for generative masked language models through a series of tailored, in-depth ablations. Using this pre-training strategy, we train BARTSmiles, a BART-like model with an order of magnitude more compute than previous self-supervised molecular representations. In-depth evaluations show that BARTSmiles consistently outperforms other self-supervised representations across classification, regression, and generation tasks setting a new state-of-the-art on 11 tasks. We then quantitatively show that when applied to the molecular domain, the BART objective learns representations that implicitly encode our downstream tasks of interest. For example, by selecting seven neurons from a frozen BARTSmiles, we can obtain a model having performance within two percentage points of the full fine-tuned model on task Clintox. Lastly, we show that standard attribution interpretability methods, when applied to BARTSmiles, highlight certain substructures that chemists use to explain specific properties of molecules. The code and the pretrained model are publicly available.

We seek methods to model, control, and analyze robot teams performing environmental monitoring tasks. During environmental monitoring, the goal is to have teams of robots collect various data throughout a fixed region for extended periods of time. Standard bottom-up task assignment methods do not scale as the number of robots and task locations increases and require computationally expensive replanning. Alternatively, top-down methods have been used to combat computational complexity, but most have been limited to the analysis of methods which focus on transition times between tasks. In this work, we study a class of nonlinear macroscopic models which we use to control a time-varying distribution of robots performing different tasks throughout an environment. Our proposed ensemble model and control maintains desired time-varying populations of robots by leveraging naturally occurring interactions between robots performing tasks. We validate our approach at multiple fidelity levels including experimental results, suggesting the effectiveness of our approach to perform environmental monitoring.

Any strategy used to distribute a robot ensemble over a set of sequential tasks is subject to inaccuracy due to robot-level uncertainties and environmental influences on the robots' behavior. We approach the problem of inaccuracy during task allocation by modeling and controlling the overall ensemble behavior. Our model represents the allocation problem as a stochastic jump process and we regulate the mean and variance of such a process. The main contributions of this paper are: Establishing a structure for the transition rates of the equivalent stochastic jump process and formally showing that this approach leads to decoupled parameters that allow us to adjust the first- and second-order moments of the ensemble distribution over tasks, which gives the flexibility to decrease the variance in the desired final distribution. This allows us to directly shape the impact of uncertainties on the group allocation over tasks. We introduce a detailed procedure to design the gains to achieve the desired mean and show how the additional parameters impact the covariance matrix, which is directly associated with the degree of task allocation precision. Our simulation and experimental results illustrate the successful control of several robot ensembles during task allocation.

This paper focuses on the broadcast of information on robot networks with stochastic network interconnection topologies. Problematic communication networks are almost unavoidable in areas where we wish to deploy multi-robotic systems, usually due to a lack of environmental consistency, accessibility, and structure. We tackle this problem by modeling the broadcast of information in a multi-robot communication network as a stochastic process with random arrival times, which can be produced by irregular robot movements, wireless attenuation, and other environmental factors. Using this model, we provide and analyze a receding horizon control strategy to control the statistics of the information broadcast. The resulting strategy compels the robots to re-direct their communication resources to different neighbors according to the current propagation process to fulfill global broadcast requirements. Based on this method, we provide an approach to compute the expected time to broadcast the message to all nodes. Numerical examples are provided to illustrate the results.

Transfer operators offer linear representations and global, physically meaningful features of nonlinear dynamical systems. Discovering transfer operators, such as the Koopman operator, require careful crafted dictionaries of observables, acting on states of the dynamical system. This is ad hoc and requires the full dataset for evaluation. In this paper, we offer an optimization scheme to allow joint learning of the observables and Koopman operator with online data. Our results show we are able to reconstruct the evolution and represent the global features of complex dynamical systems.

Document images are a ubiquitous source of data where the text is organized in a complex hierarchical structure ranging from fine granularity (e.g., words), medium granularity (e.g., regions such as paragraphs or figures), to coarse granularity (e.g., the whole page). The spatial hierarchical relationships between content at different levels of granularity are crucial for document image understanding tasks. Existing methods learn features from either word-level or region-level but fail to consider both simultaneously. Word-level models are restricted by the fact that they originate from pure-text language models, which only encode the word-level context. In contrast, region-level models attempt to encode regions corresponding to paragraphs or text blocks into a single embedding, but they perform worse with additional word-level features. To deal with these issues, we propose MGDoc, a new multi-modal multi-granular pre-training framework that encodes page-level, region-level, and word-level information at the same time. MGDoc uses a unified text-visual encoder to obtain multi-modal features across different granularities, which makes it possible to project the multi-granular features into the same hyperspace. To model the region-word correlation, we design a cross-granular attention mechanism and specific pre-training tasks for our model to reinforce the model of learning the hierarchy between regions and words. Experiments demonstrate that our proposed model can learn better features that perform well across granularities and lead to improvements in downstream tasks.

国家估计是许多机器人应用中的重要方面。在这项工作中，我们考虑通过增强状态估计算法中使用的动力学模型来获得机器人系统的准确状态估计的任务。现有的框架，例如移动视野估计（MHE）和无气味的卡尔曼过滤器（UKF），为合并非线性动力学和测量模型提供了灵活性。但是，这意味着这些算法中的动力学模型必须足够准确，以保证状态估计的准确性。为了增强动力学模型并提高估计准确性，我们利用了一个深度学习框架，称为基于知识的神经普通微分方程（KNODES）。 KNODE框架将先验知识嵌入到训练过程中，并通过将先前的第一原理模型与神经普通微分方程（NODE）模型融合来合成精确的混合模型。在我们提出的最新框架中，我们将数据驱动的模型集成到两种基于新型模型的状态估计算法中，它们表示为Knode-Mhe和Knode-UKF。在许多机器人应用中，将这两种算法与它们的常规对应物进行了比较。使用部分测量值，地面机器人的定位以及四型二次估计的状态估计。通过使用现实世界实验数据的模拟和测试，我们证明了所提出的学习增强状态估计框架的多功能性和功效。

在本文中，我们为具有异质传感器的机器人团队提供了在线自适应计划策略，以使用学习的模型进行决策模型从潜在空间领域进行采样。当前的机器人抽样方法试图收集有关可观察到的空间场的信息。但是，许多应用程序，例如环境监测和精确农业，都涉及不直接观察或衡量昂贵的现象，称为潜在现象。在我们的方法中，我们试图通过使用具有异质传感器的机器人团队有效地采样可观察到的空间场来实时推理潜在现象，在这种空间场中，每个机器人都有一个独特的传感器来测量不同可观察的场。信息增益是使用从可观察到的空间场映射到潜在现象的学习模型来估计的。该模型捕获了关系中的不确定性，以允许信息理论措施。此外，我们明确考虑可观察到的空间场之间的相关性，从而捕获了观察结果并非独立的传感器类型之间的关系。我们表明，可以学习这些相关性，并研究学习相关模型对我们采样方法性能的影响。通过我们的定性和定量结果，我们说明了经验学习的相关性提高了团队的整体抽样效率。我们使用在魁北克的Lac Hertel上收集的传感器测量数据集模拟我们的方法，我们可以公开使用。

在这项工作中，我们考虑了在线环境中提高模型预测控制（MPC）动态模型准确性的任务。即使可以学习预测模型并将其应用于基于模型的控制器，但这些模型也经常离线学习。在此离线环境中，首先收集培训数据，并通过详细的培训程序来学习预测模型。将模型训练至所需的精度后，然后将其部署到模型预测控制器中。但是，由于模型是离线学习的，因此它不适合部署过程中观察到的干扰或模型错误。为了提高模型和控制器的适应性，我们提出了一个在线动力学学习框架，该框架不断提高部署过程中动态模型的准确性。我们采用基于知识的神经普通微分方程（KNODE）作为动态模型，并使用受转移学习启发的技术来不断提高模型的准确性。我们通过四型机器人证明了框架的功效，并在模拟和物理实验中验证框架。结果表明，所提出的方法能够说明可能段时间变化的干扰，同时保持良好的轨迹跟踪性能。

多机器人自适应抽样问题旨在为机器人团队找到轨迹，以有效地对机器人的给定耐力预算中的感兴趣现象进行采样。在本文中，我们使用分散的多代理增强学习来提出一种可靠，可扩展的方法，用于准静态环境过程的合作自适应采样（MARLAS）。鉴于该领域的先验采样，该提议的方法学习了一个机器人团队的分散政策，以在固定预算范围内采样高实现区域。多机器人自适应采样问题要求机器人彼此协调，以避免重叠的采样轨迹。因此，我们编码机器人之间的邻居位置和间歇性通信在学习过程中的估计值。我们评估了Marlas对多个性能指标的评估，发现它的表现优于其他基线多机器人采样技术。我们进一步证明了与机器人团队的大小和所采样区域的大小相对于通信失败和可伸缩性的鲁棒性。实验评估既是对真实数据的模拟，又在演示环境设置的实际机器人实验中进行的。