We present Recurrent Vision Transformers (RVTs), a novel backbone for object detection with event cameras. Event cameras provide visual information with sub-millisecond latency at a high-dynamic range and with strong robustness against motion blur. These unique properties offer great potential for low-latency object detection and tracking in time-critical scenarios. Prior work in event-based vision has achieved outstanding detection performance but at the cost of substantial inference time, typically beyond 40 milliseconds. By revisiting the high-level design of recurrent vision backbones, we reduce inference time by a factor of 5 while retaining similar performance. To achieve this, we explore a multi-stage design that utilizes three key concepts in each stage: First, a convolutional prior that can be regarded as a conditional positional embedding. Second, local- and dilated global self-attention for spatial feature interaction. Third, recurrent temporal feature aggregation to minimize latency while retaining temporal information. RVTs can be trained from scratch to reach state-of-the-art performance on event-based object detection - achieving an mAP of 47.5% on the Gen1 automotive dataset. At the same time, RVTs offer fast inference (13 ms on a T4 GPU) and favorable parameter efficiency (5 times fewer than prior art). Our study brings new insights into effective design choices that could be fruitful for research beyond event-based vision.
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In recent decades, several assistive technologies for visually impaired and blind (VIB) people have been developed to improve their ability to navigate independently and safely. At the same time, simultaneous localization and mapping (SLAM) techniques have become sufficiently robust and efficient to be adopted in the development of assistive technologies. In this paper, we first report the results of an anonymous survey conducted with VIB people to understand their experience and needs; we focus on digital assistive technologies that help them with indoor and outdoor navigation. Then, we present a literature review of assistive technologies based on SLAM. We discuss proposed approaches and indicate their pros and cons. We conclude by presenting future opportunities and challenges in this domain.
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Recently, learning-based controllers have been shown to push mobile robotic systems to their limits and provide the robustness needed for many real-world applications. However, only classical optimization-based control frameworks offer the inherent flexibility to be dynamically adjusted during execution by, for example, setting target speeds or actuator limits. We present a framework to overcome this shortcoming of neural controllers by conditioning them on an auxiliary input. This advance is enabled by including a feature-wise linear modulation layer (FiLM). We use model-free reinforcement-learning to train quadrotor control policies for the task of navigating through a sequence of waypoints in minimum time. By conditioning the policy on the maximum available thrust or the viewing direction relative to the next waypoint, a user can regulate the aggressiveness of the quadrotor's flight during deployment. We demonstrate in simulation and in real-world experiments that a single control policy can achieve close to time-optimal flight performance across the entire performance envelope of the robot, reaching up to 60 km/h and 4.5g in acceleration. The ability to guide a learned controller during task execution has implications beyond agile quadrotor flight, as conditioning the control policy on human intent helps safely bringing learning based systems out of the well-defined laboratory environment into the wild.
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Double-blind peer review is considered a pillar of academic research because it is perceived to ensure a fair, unbiased, and fact-centered scientific discussion. Yet, experienced researchers can often correctly guess from which research group an anonymous submission originates, biasing the peer-review process. In this work, we present a transformer-based, neural-network architecture that only uses the text content and the author names in the bibliography to atttribute an anonymous manuscript to an author. To train and evaluate our method, we created the largest authorship-identification dataset to date. It leverages all research papers publicly available on arXiv amounting to over 2 million manuscripts. In arXiv-subsets with up to 2,000 different authors, our method achieves an unprecedented authorship attribution accuracy, where up to 95% of papers are attributed correctly. Thanks to our method, we are not only able to predict the author of an anonymous work but we also identify weaknesses of the double-blind review process by finding the key aspects that make a paper attributable. We believe that this work gives precious insights into how a submission can remain anonymous in order to support an unbiased double-blind review process.
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机器人系统的控制设计很复杂,通常需要解决优化才能准确遵循轨迹。在线优化方法(例如模型预测性控制(MPC))已被证明可以实现出色的跟踪性能,但需要高计算能力。相反,基于学习的离线优化方法,例如加固学习(RL),可以在机器人上快速有效地执行,但几乎不匹配MPC在轨迹跟踪任务中的准确性。在具有有限计算的系统(例如航空车)中,必须在执行时间有效的精确控制器。我们提出了一种分析策略梯度(APG)方法来解决此问题。 APG通过在跟踪误差上以梯度下降的速度训练控制器来利用可区分的模拟器的可用性。我们解决了通过课程学习和实验经常在广泛使用的控制基准,Cartpole和两个常见的空中机器人,一个四极管和固定翼无人机上进行的训练不稳定性。在跟踪误差方面,我们提出的方法优于基于模型和无模型的RL方法。同时,它达到与MPC相似的性能,同时需要少于数量级的计算时间。我们的工作为APG作为机器人技术的有前途的控制方法提供了见解。为了促进对APG的探索,我们开放代码并在https://github.com/lis-epfl/apg_traightory_tracking上提供。
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我们提出了一种系统解决方案,以实现使用热图像和惯性测量的飞行机器人团队的数据效率,分散的状态估计。每个机器人可以独立飞行,并在可能的情况下交换数据以完善其状态估计。我们的系统前端应用在线光度校准以完善热图像,从而增强功能跟踪并放置识别。我们的系统后端使用协方差融合策略来忽略代理之间的互相关,以降低内存使用和计算成本。通信管道使用本地汇总的描述符(VLAD)的向量来构建需要较低带宽使用情况的请求响应策略。我们在合成数据和现实世界数据上测试我们的协作方法。我们的结果表明,相对于个人代理方法,该提出的方法最多可提高46%的轨迹估计,同时减少多达89%的通信交换。数据集和代码将发布给公众,扩展了已经发布的JPL XVIO库。
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从理想图像中估算神经辐射场(NERF)已在计算机视觉社区中进行了广泛的研究。大多数方法都采用最佳照明和缓慢的相机运动。这些假设通常在机器人应用中违反,其中图像包含运动模糊,场景可能没有合适的照明。这可能会给下游任务(例如导航,检查或可视化场景)带来重大问题。为了减轻我们提出的E-NERF的这些问题,这是第一种方法,该方法以快速移动的事件摄像机的形式估算了以NERF的形式进行体积的场景表示形式。我们的方法可以在非常快速的运动和高动态范围条件下恢复NERF,而基于框架的方法失败。我们证明,仅提供事件流作为输入,可以渲染高质量的帧。此外,通过结合事件和框架,我们可以在严重的运动模糊下估计比最先进的方法更高的质量。我们还表明,将事件和帧组合可以克服在只有很少的输入视图的情况下,无需额外正则化的方案中的NERF估计案例。
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同时本地化和映射(SLAM)正在现实世界应用中部署,但是在许多常见情况下,许多最先进的解决方案仍然在困难。进步的SLAM研究的关键是高质量数据集的可用性以及公平透明的基准测试。为此,我们创建了Hilti-Oxford数据集,以将最新的SLAM系统推向其极限。该数据集面临着各种挑战,从稀疏和常规的建筑工地到17世纪的新古典建筑,并具有细节和弯曲的表面。为了鼓励多模式的大满贯方法,我们设计了一个具有激光雷达,五个相机和IMU(惯性测量单元)的数据收集平台。为了对精度和鲁棒性至关重要的任务进行基准测试量算法,我们实施了一种新颖的地面真相收集方法,使我们的数据集能够以毫米精度准确地测量SLAM姿势错误。为了进一步确保准确性,我们平台的外部设备通过微米精确的扫描仪进行了验证,并使用硬件时间同步在线管理时间校准。我们数据集的多模式和多样性吸引了大量的学术和工业研究人员进入第二版《希尔蒂·斯拉姆挑战赛》,该挑战于2022年6月结束。挑战的结果表明,尽管前三名团队可以实现准确性在某些序列中的2厘米或更高的速度中,性能以更困难的序列下降。
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由于它们对运动模糊和在弱光和高动态范围条件下的高度鲁棒性的韧性,事件摄像机有望成为对未来火星直升机任务的基于视觉探索的传感器。但是,现有的基于事件的视觉惯性进程(VIO)算法要么患有高跟踪误差,要么是脆弱的,因为它们无法应对由于无法预料的跟踪损失或其他效果而导致的显着深度不确定性。在这项工作中,我们介绍了EKLT-VIO,该工作通过将基于事件的最新前端与基于过滤器的后端相结合来解决这两种限制。这使得不确定性的准确和强大,超过了基于事件和基于框架的VIO算法在挑战性基准上的算法32%。此外,我们在悬停的条件(胜过现有事件的方法)以及新近收集的类似火星和高动态范围的新序列中表现出准确的性能,而现有的基于框架的方法失败了。在此过程中,我们表明基于事件的VIO是基于视觉的火星探索的前进道路。
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我们解决了在存在障碍物的情况下,通过一系列航路点来解决四肢飞行的最低时间飞行问题,同时利用了完整的四型动力学。早期作品依赖于简化的动力学或多项式轨迹表示,而这些动力学或多项式轨迹表示,这些表示没有利用四四光的全部执行器电位,因此导致了次优溶液。最近的作品可以计划最小的时间轨迹;然而,轨迹是通过无法解释障碍的控制方法执行的。因此,由于模型不匹配和机上干扰,成功执行此类轨迹很容易出现错误。为此,我们利用深厚的强化学习和经典的拓扑路径计划来训练强大的神经网络控制器,以在混乱的环境中为最少的四型四型飞行。由此产生的神经网络控制器表现出比最新方法相比,高达19%的性能要高得多。更重要的是,博学的政策同时在线解决了计划和控制问题,以解决干扰,从而实现更高的鲁棒性。因此,提出的方法在没有碰撞的情况下实现了100%的最低时间策略的成功率,而传统的计划和控制方法仅获得40%。所提出的方法在模拟和现实世界中均已验证,四速速度高达42公里/小时,加速度为3.6g。
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