在自动驾驶的背景下,车辆本质上肯定会遇到更多的极端天气,在此期间必须确保公共安全。随着气候迅速变化,大暴风雪的频率有望增加,并成为安全导航的主要威胁。尽管有许多文献旨在提高对冬季条件的导航弹性,但缺乏标准指标来量化与降水有关的LIDAR传感器的可见性丧失。本章提出了一个新颖的指标,以实时量化LIDAR可见性损失,并依赖气象研究领域的可见性概念。我们在加拿大不良驾驶条件(CADC)数据集上评估了该指标,将其与基于最先进的激光雷达的本地化算法的性能相关联,并评估在本地化过程之前过滤点云的好处。我们表明,迭代最接近的点(ICP)算法令人惊讶地抵抗降雪,但是突然的事件(例如雪地)可以极大地阻碍其准确性。我们讨论了此类事件,并证明需要更好地关注这些极端事件以量化其效果。
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定义:“雪和冰中的机器人技术”术语是指在可以在其固态中找到水的地区进行研究,开发和使用的机器人系统。这个专业的现场机器人分支研究了与冷环境有关的极端条件对自动驾驶汽车的影响。
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本文通过讨论参加了为期三年的SubT竞赛的六支球队的不同大满贯策略和成果,报道了地下大满贯的现状。特别是,本文有四个主要目标。首先,我们审查团队采用的算法,架构和系统;特别重点是以激光雷达以激光雷达为中心的SLAM解决方案(几乎所有竞争中所有团队的首选方法),异质的多机器人操作(包括空中机器人和地面机器人)和现实世界的地下操作(从存在需要处理严格的计算约束的晦涩之处)。我们不会回避讨论不同SubT SLAM系统背后的肮脏细节,这些系统通常会从技术论文中省略。其次,我们通过强调当前的SLAM系统的可能性以及我们认为与一些良好的系统工程有关的范围来讨论该领域的成熟度。第三,我们概述了我们认为是基本的开放问题,这些问题可能需要进一步的研究才能突破。最后,我们提供了在SubT挑战和相关工作期间生产的开源SLAM实现和数据集的列表,并构成了研究人员和从业人员的有用资源。
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森林中自主冬季导航所固有的挑战包括缺乏可靠的全球导航卫星系统(GNSS)信号,低特征对比度,高照明变化和变化环境。这种类型的越野环境是一个极端的情况,自治车可能会在北部地区遇到。因此,了解对自动导航系统对这种恶劣环境的影响非常重要。为此,我们介绍了一个现场报告分析亚曲率区域中的教导和重复导航,同时受到气象条件的大变化。首先,我们描述了系统,它依赖于点云注册来通过北方林地定位移动机器人,同时构建地图。我们通过在教学和重复模式下在自动导航中进行了在实验中评估了该系统。我们展示了密集的植被扰乱了GNSS信号,使其不适合在森林径中导航。此外,我们突出了在森林走廊中使用点云登记的定位相关的不确定性。我们证明它不是雪降水,而是影响我们系统在环境中定位的能力的积雪。最后,我们从我们的实地运动中揭示了一些经验教训和挑战,以支持在冬季条件下更好的实验工作。
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在自治机器人的背景下,最重要的任务之一是在导航期间防止对机器人的潜在损坏。为此目的,通常认为必须处理已知的概率障碍,然后计算与每个障碍物碰撞的概率。然而,在复杂的场景或非结构化环境中,可能难以检测这种障碍。在这些情况下,使用公制地图,其中每个位置存储占用的信息。最常见的公制地图类型是贝叶斯占用地图。然而,由于其离散性,这种类型的地图对计算持续路径的风险评估不太适合。因此,我们介绍了一种名为Lambda领域的新型地图,专门用于风险评估。我们首先提出了一种方法来计算这样的地图和对路径的通用风险的期望。然后,我们用一个用例展示了我们的通用配方的益处,该用例将风险定义为路径上的预期碰撞力。使用这种风险定义和Lambda领域,我们表明我们的框架能够在具有物理度量的同时进行经典路径规划。此外,Lambda领域为处理非结构化环境(如高草)提供了一种自然的方式。如果标准环境表示始终会产生围绕此类障碍的轨迹,我们的框架允许机器人在意识到所采取的风险时穿过草地。
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For long-term simultaneous planning, localization and mapping (SPLAM), a robot should be able to continuously update its map according to the dynamic changes of the environment and the new areas explored. With limited onboard computation capabilities, a robot should also be able to limit the size of the map used for online localization and mapping. This paper addresses these challenges using a memory management mechanism, which identifies locations that should remain in a Working Memory (WM) for online processing from locations that should be transferred to a Long-Term Memory (LTM). When revisiting previously mapped areas that are in LTM, the mechanism can retrieve these locations and place them back in WM for online SPLAM. The approach is tested on a robot equipped with a short-range laser rangefinder and a RGB-D camera, patrolling autonomously 10.5 km in an indoor environment over 11 sessions while having encountered 139 people.
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Traditional approaches to RL have focused on learning decision policies directly from episodic decisions, while slowly and implicitly learning the semantics of compositional representations needed for generalization. While some approaches have been adopted to refine representations via auxiliary self-supervised losses while simultaneously learning decision policies, learning compositional representations from hand-designed and context-independent self-supervised losses (multi-view) still adapts relatively slowly to the real world, which contains many non-IID subspaces requiring rapid distribution shift in both time and spatial attention patterns at varying levels of abstraction. In contrast, supervised language model cascades have shown the flexibility to adapt to many diverse manifolds, and hints of self-learning needed for autonomous task transfer. However, to date, transfer methods for language models like few-shot learning and fine-tuning still require human supervision and transfer learning using self-learning methods has been underexplored. We propose a self-supervised loss policy called contrastive distillation which manifests latent variables with high mutual information with both source and target tasks from weights to tokens. We show how this outperforms common methods of transfer learning and suggests a useful design axis of trading off compute for generalizability for online transfer. Contrastive distillation is improved through sampling from memory and suggests a simple algorithm for more efficiently sampling negative examples for contrastive losses than random sampling.
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As of 2022, greenhouse gases (GHG) emissions reporting and auditing are not yet compulsory for all companies and methodologies of measurement and estimation are not unified. We propose a machine learning-based model to estimate scope 1 and scope 2 GHG emissions of companies not reporting them yet. Our model, specifically designed to be transparent and completely adapted to this use case, is able to estimate emissions for a large universe of companies. It shows good out-of-sample global performances as well as good out-of-sample granular performances when evaluating it by sectors, by countries or by revenues buckets. We also compare our results to those of other providers and find our estimates to be more accurate. Thanks to the proposed explainability tools using Shapley values, our model is fully interpretable, the user being able to understand which factors split explain the GHG emissions for each particular company.
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In intensively managed forests in Europe, where forests are divided into stands of small size and may show heterogeneity within stands, a high spatial resolution (10 - 20 meters) is arguably needed to capture the differences in canopy height. In this work, we developed a deep learning model based on multi-stream remote sensing measurements to create a high-resolution canopy height map over the "Landes de Gascogne" forest in France, a large maritime pine plantation of 13,000 km$^2$ with flat terrain and intensive management. This area is characterized by even-aged and mono-specific stands, of a typical length of a few hundred meters, harvested every 35 to 50 years. Our deep learning U-Net model uses multi-band images from Sentinel-1 and Sentinel-2 with composite time averages as input to predict tree height derived from GEDI waveforms. The evaluation is performed with external validation data from forest inventory plots and a stereo 3D reconstruction model based on Skysat imagery available at specific locations. We trained seven different U-net models based on a combination of Sentinel-1 and Sentinel-2 bands to evaluate the importance of each instrument in the dominant height retrieval. The model outputs allow us to generate a 10 m resolution canopy height map of the whole "Landes de Gascogne" forest area for 2020 with a mean absolute error of 2.02 m on the Test dataset. The best predictions were obtained using all available satellite layers from Sentinel-1 and Sentinel-2 but using only one satellite source also provided good predictions. For all validation datasets in coniferous forests, our model showed better metrics than previous canopy height models available in the same region.
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Purpose: The purpose of this paper is to present a method for real-time 2D-3D non-rigid registration using a single fluoroscopic image. Such a method can find applications in surgery, interventional radiology and radiotherapy. By estimating a three-dimensional displacement field from a 2D X-ray image, anatomical structures segmented in the preoperative scan can be projected onto the 2D image, thus providing a mixed reality view. Methods: A dataset composed of displacement fields and 2D projections of the anatomy is generated from the preoperative scan. From this dataset, a neural network is trained to recover the unknown 3D displacement field from a single projection image. Results: Our method is validated on lung 4D CT data at different stages of the lung deformation. The training is performed on a 3D CT using random (non domain-specific) diffeomorphic deformations, to which perturbations mimicking the pose uncertainty are added. The model achieves a mean TRE over a series of landmarks ranging from 2.3 to 5.5 mm depending on the amplitude of deformation. Conclusion: In this paper, a CNN-based method for real-time 2D-3D non-rigid registration is presented. This method is able to cope with pose estimation uncertainties, making it applicable to actual clinical scenarios, such as lung surgery, where the C-arm pose is planned before the intervention.
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