长期以来,Robotics一直是一个遍布复杂系统体系结构的领域,无论传统或基于学习的模块和联系都需要大量的人类专业知识和先验知识。受大型预训练语言模型的启发,这项工作引入了预先培训的通用表示范式,该范式可以作为给定机器人多个任务的起点。我们提出了感知性因果变压器(PACT),这是一种基于生成变压器的架构,旨在以自我监督的方式直接从机器人数据构建表示形式。通过对状态和行动的自动回归预测,我们的模型隐含地编码了特定机器人的动态和行为。我们的实验评估重点是移动药物的域,我们表明该机器人特定的表示可以作为单个起点,以实现不同的任务,例如安全导航,定位和映射。我们评估了两个形式:使用激光雷达传感器作为感知输入(MUSHR)的轮式机器人,以及使用第一人称RGB图像(栖息地)的模拟药物。我们表明,与训练单个模型的同时训练单个模型相比,对所有任务的单个模型进行训练,并且与独立培训单独的大型模型相当的性能,对每个任务的单个模型进行了可比的训练,则在较大的审计模型上进行了固定小型任务特异性网络,从而使性能明显提高。通过跨任务共享共同的优质表示,我们可以降低整体模型容量并加快此类系统的实时部署。
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本文涉及由马尔可夫噪声驱动的随机近似的收敛和渐近统计:$$ \ theta_ {n + 1} = \ theta_n + \ alpha_ {n + 1} f(\ theta_n,\ phi_ {n + 1})\, ,\ quad n \ ge 0,$$,其中每个$ \ theta_n \ in \ re ^ d $,$ \ {\ phi_n \} $是一般状态空间x上的马尔可夫链,静止分配$ \ pi $和$ f:\ re ^ d \ times \ text {x} \ to \ re ^ d $。除了在$ f $的标准lipschitz边界,以及消失的步骤大小序列$ \ {\ alpha_n \ \} $的条件外,假设相关ode是全局渐近稳定的静止点表示$ \ theta ^ * $ ,其中$ \ bar f(\ theta)= e [f(\ theta,\ phi)] $ with $ \ phi \ sim \ pi $。而且,ode @ $ \ infty $ virect with advoore字段,$$ \ bar f_ \ idty(\ theta):= \ lim_ {r \ to \ infty} r ^ { - 1} \ bar f(r \ theta)\ ,, \ qquad \ theta \ in \ re ^ d,$$是渐近稳定的。主要贡献总结如下:(i)如果$ \ phi $是几何ergodic,则序列$ \ theta $是融合的,并且在$ f $兼容兼容的界限。剩余的结果是在马尔可夫链的更强大假设下建立:Donsker-varadhan Lyapunov漂移条件的稍微弱版本(DV3)。 (ii)为联合过程$ \ {\ theta_n,\ phi_n \} $构建Lyapunov函数,这意味着$ \ {\ theta_n \} $ in $ l_4 $的融合。 (iii)建立了功能性CLT,以及归一化误差$ z_n:=(\ theta_n- \ theta ^ *)/ \ sqrt {\ alpha_n} $的常规一维CLT。时刻界限结合了CLT暗示了归一化协方差的收敛,$$ \ lim_ {n \ to \ infty} e [z_n z_n ^ t] = \ sigma_ \ theta,$$在$ \ sigma_ \ theta $ where asbptotic协方差出现在CLT中。 (iv)提供了一个例子,其中马尔可夫链$ \ phi $是几何ergodic,但它不满足(dv3)。虽然算法收敛,但第二个时刻是无限的。
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Open-ended text generation with autoregressive language models (LMs) is one of the core tasks in natural language processing. However, maximization-based decoding methods (e.g., greedy/beam search) often lead to the degeneration problem, i.e., the generated text is unnatural and contains undesirable repetitions. Existing solutions to this problem either introduce randomness prone to incoherence or require a look-ahead mechanism that demands extra computational overhead. In this study, we formulate open-ended text generation from a new perspective, i.e., we view it as an exploration process within a directed graph. Thereby, we understand the phenomenon of degeneration as circular loops within the directed graph. Based on our formulation, we propose a novel decoding method -- \textit{momentum decoding} -- which encourages the LM to \textit{greedily} explore new nodes outside the current graph. Meanwhile, it also allows the LM to return to the existing nodes with a momentum downgraded by a pre-defined resistance function. We extensively test our approach on three benchmarks from different domains through automatic and human evaluations. The results show that momentum decoding performs comparably with the current state of the art while enjoying notably improved inference speed and computation FLOPs. Furthermore, we conduct a detailed analysis to reveal the merits and inner workings of our approach. Our codes and other related resources are publicly available at https://github.com/gmftbyGMFTBY/MomentumDecoding.
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卡尔曼滤波器广泛用于对象跟踪,其中过程和测量噪声通常被认为是准确的已知和恒定的。然而,确切的已知和常量假设并不总是在实践中保持。例如,当LIDAR用于跟踪非合作目标时,在不同距离和天气条件下测量噪声不同。另外,过程噪声随对象的运动状态而变化,尤其是当跟踪对象是行人时,并且过程噪声更频繁地改变。本文提出了一种新的估计校正校正闭环估计方法,用于在线估算卡尔曼滤波器过程和测量噪声协方差矩阵。首先,我们将噪声协方差矩阵分解为元素分布矩阵和噪声强度,并改善Sage滤波器以估计元素分布矩阵。其次,我们提出了一种校准方法来准确地诊断噪声强度偏差。然后,我们提出了一种正确的方法来在线自适应地校正噪声强度。第三,在假设系统是可检测的情况下,在数学上证明了所提出的方法的无偏偏差和收敛。仿真结果证明了所提出的方法的有效性和可靠性。最后,我们将建议的方法应用于多对LIDAR的跟踪并在官方Kitti服务器上进行评估。在基提步行者多元object跟踪排行榜上提出的方法(http://www.cvlibs.net/datasets /kitti/eval_tracking.php)超越了使用激光雷达的所有现有方法,证明了在实际应用中的方法的可行性。这项工作提供了一种提高卡尔曼滤波器和多功能跟踪性能的新方法。
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Model-based optimization methods and discriminative learning methods have been the two dominant strategies for solving various inverse problems in low-level vision. Typically, those two kinds of methods have their respective merits and drawbacks, e.g., model-based optimization methods are flexible for handling different inverse problems but are usually time-consuming with sophisticated priors for the purpose of good performance; in the meanwhile, discriminative learning methods have fast testing speed but their application range is greatly restricted by the specialized task. Recent works have revealed that, with the aid of variable splitting techniques, denoiser prior can be plugged in as a modular part of model-based optimization methods to solve other inverse problems (e.g., deblurring). Such an integration induces considerable advantage when the denoiser is obtained via discriminative learning. However, the study of integration with fast discriminative denoiser prior is still lacking. To this end, this paper aims to train a set of fast and effective CNN (convolutional neural network) denoisers and integrate them into model-based optimization method to solve other inverse problems. Experimental results demonstrate that the learned set of denoisers not only achieve promising Gaussian denoising results but also can be used as prior to deliver good performance for various low-level vision applications.
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Deep learning models can achieve high accuracy when trained on large amounts of labeled data. However, real-world scenarios often involve several challenges: Training data may become available in installments, may originate from multiple different domains, and may not contain labels for training. Certain settings, for instance medical applications, often involve further restrictions that prohibit retention of previously seen data due to privacy regulations. In this work, to address such challenges, we study unsupervised segmentation in continual learning scenarios that involve domain shift. To that end, we introduce GarDA (Generative Appearance Replay for continual Domain Adaptation), a generative-replay based approach that can adapt a segmentation model sequentially to new domains with unlabeled data. In contrast to single-step unsupervised domain adaptation (UDA), continual adaptation to a sequence of domains enables leveraging and consolidation of information from multiple domains. Unlike previous approaches in incremental UDA, our method does not require access to previously seen data, making it applicable in many practical scenarios. We evaluate GarDA on two datasets with different organs and modalities, where it substantially outperforms existing techniques.
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The development of social media user stance detection and bot detection methods rely heavily on large-scale and high-quality benchmarks. However, in addition to low annotation quality, existing benchmarks generally have incomplete user relationships, suppressing graph-based account detection research. To address these issues, we propose a Multi-Relational Graph-Based Twitter Account Detection Benchmark (MGTAB), the first standardized graph-based benchmark for account detection. To our knowledge, MGTAB was built based on the largest original data in the field, with over 1.55 million users and 130 million tweets. MGTAB contains 10,199 expert-annotated users and 7 types of relationships, ensuring high-quality annotation and diversified relations. In MGTAB, we extracted the 20 user property features with the greatest information gain and user tweet features as the user features. In addition, we performed a thorough evaluation of MGTAB and other public datasets. Our experiments found that graph-based approaches are generally more effective than feature-based approaches and perform better when introducing multiple relations. By analyzing experiment results, we identify effective approaches for account detection and provide potential future research directions in this field. Our benchmark and standardized evaluation procedures are freely available at: https://github.com/GraphDetec/MGTAB.
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As one of the prevalent methods to achieve automation systems, Imitation Learning (IL) presents a promising performance in a wide range of domains. However, despite the considerable improvement in policy performance, the corresponding research on the explainability of IL models is still limited. Inspired by the recent approaches in explainable artificial intelligence methods, we proposed a model-agnostic explaining framework for IL models called R2RISE. R2RISE aims to explain the overall policy performance with respect to the frames in demonstrations. It iteratively retrains the black-box IL model from the randomized masked demonstrations and uses the conventional evaluation outcome environment returns as the coefficient to build an importance map. We also conducted experiments to investigate three major questions concerning frames' importance equality, the effectiveness of the importance map, and connections between importance maps from different IL models. The result shows that R2RISE successfully distinguishes important frames from the demonstrations.
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Compressed videos often exhibit visually annoying artifacts, known as Perceivable Encoding Artifacts (PEAs), which dramatically degrade video visual quality. Subjective and objective measures capable of identifying and quantifying various types of PEAs are critical in improving visual quality. In this paper, we investigate the influence of four spatial PEAs (i.e. blurring, blocking, bleeding, and ringing) and two temporal PEAs (i.e. flickering and floating) on video quality. For spatial artifacts, we propose a visual saliency model with a low computational cost and higher consistency with human visual perception. In terms of temporal artifacts, self-attention based TimeSFormer is improved to detect temporal artifacts. Based on the six types of PEAs, a quality metric called Saliency-Aware Spatio-Temporal Artifacts Measurement (SSTAM) is proposed. Experimental results demonstrate that the proposed method outperforms state-of-the-art metrics. We believe that SSTAM will be beneficial for optimizing video coding techniques.
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We propose a distributionally robust return-risk model for Markov decision processes (MDPs) under risk and reward ambiguity. The proposed model optimizes the weighted average of mean and percentile performances, and it covers the distributionally robust MDPs and the distributionally robust chance-constrained MDPs (both under reward ambiguity) as special cases. By considering that the unknown reward distribution lies in a Wasserstein ambiguity set, we derive the tractable reformulation for our model. In particular, we show that that the return-risk model can also account for risk from uncertain transition kernel when one only seeks deterministic policies, and that a distributionally robust MDP under the percentile criterion can be reformulated as its nominal counterpart at an adjusted risk level. A scalable first-order algorithm is designed to solve large-scale problems, and we demonstrate the advantages of our proposed model and algorithm through numerical experiments.
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