由于基本的非线性,混合和本质上不稳定的动力学,需要通过有限的接触力来稳定,因此为腿部机器人生成强大的轨迹仍然是一项具有挑战性的任务。此外,由于与环境和模型不匹配的未建模接触相互作用引起的干扰会阻碍计划轨迹的质量,从而导致不安全的运动。在这项工作中,我们建议使用随机轨迹优化来生成健壮的质心动量轨迹,以说明模型动力学和触点位置上的参数不确定性上的加法不确定性。通过强大的质心和全身轨迹优化之间的交替,我们生成了健壮的动量轨迹,同时与全身动力学保持一致。我们在四倍的机器人上执行了一组大量的模拟,这表明我们的随机轨迹优化问题减少了不同步态的脚部滑倒量,同时在确定性计划上实现了更好的性能。
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最先进的腿机器人可以在其驱动系统的输出处测量扭矩,或者具有透明的驱动系统,从而能够从电动电流计算关节扭矩。无论哪种情况,这种传感器模式很少用于状态估计。在本文中,我们建议使用关节扭矩测量值来估计腿部机器人的质心状态。为此,我们将腿部机器人的全身动力学投射到接触约束的无空间中,从而使动力学的表达独立于接触力。使用受约束的动力学和质心动量矩阵,我们能够直接将关节扭矩和质心态动力学联系起来。使用结果模型作为扩展卡尔曼滤波器(EKF)的过程模型,我们将扭矩测量融合在质心状态估计问题中。通过在具有不同步态的四倍机器人上进行的实际实验,我们证明,与直接计算相比,基于扭矩的EKF的估计质心状态大大改善了这些数量的回收率。
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由于机器人动力学中的固有非线性,腿部机器人全身动作的在线计划具有挑战性。在这项工作中,我们提出了一个非线性MPC框架,该框架可以通过有效利用机器人动力学结构来在线生成全身轨迹。Biconmp用于在真正的四倍机器人上生成各种环状步态,其性能在不同的地形上进行了评估,对抗不同步态之间的不可预见的推动力并在线过渡。此外,提出了双孔在机器人上产生非平凡无环的全身动态运动的能力。同样的方法也被用来在人体机器人(TALOS)上产生MPC的各种动态运动,并在模拟中产生另一个四倍的机器人(Anymal)。最后,报告并讨论了对计划范围和频率对非线性MPC框架的影响的广泛经验分析。
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模型预测控制(MPC)表明了控制诸如腿机器人等复杂系统的巨大成功。然而,在关闭循环时,在每个控制周期解决的有限范围最佳控制问题(OCP)的性能和可行性不再保证。这是由于模型差异,低级控制器,不确定性和传感器噪声的影响。为了解决这些问题,我们提出了一种修改版本,该版本的标准MPC方法用于带有活力的腿运动(弱向不变性)保证。在这种方法中,代替向问题添加(保守)终端约束,我们建议使用投影到在每个控制周期的OCP中的可行性内核中投影的测量状态。此外,我们使用过去的实验数据来找到最佳成本重量,该重量测量性能,约束满足鲁棒性或稳定性(不变性)的组合。这些可解释的成本衡量了稳健性和性能之间的贸易。为此目的,我们使用贝叶斯优化(BO)系统地设计实验,有助于有效地收集数据以了解导致强大性能的成本函数。我们的模拟结果具有不同的现实干扰(即外部推动,未铭出的执行器动态和计算延迟)表明了我们为人形机器人创造了强大的控制器的方法的有效性。
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We study the relationship between adversarial robustness and differential privacy in high-dimensional algorithmic statistics. We give the first black-box reduction from privacy to robustness which can produce private estimators with optimal tradeoffs among sample complexity, accuracy, and privacy for a wide range of fundamental high-dimensional parameter estimation problems, including mean and covariance estimation. We show that this reduction can be implemented in polynomial time in some important special cases. In particular, using nearly-optimal polynomial-time robust estimators for the mean and covariance of high-dimensional Gaussians which are based on the Sum-of-Squares method, we design the first polynomial-time private estimators for these problems with nearly-optimal samples-accuracy-privacy tradeoffs. Our algorithms are also robust to a constant fraction of adversarially-corrupted samples.
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A major challenge in machine learning is resilience to out-of-distribution data, that is data that exists outside of the distribution of a model's training data. Training is often performed using limited, carefully curated datasets and so when a model is deployed there is often a significant distribution shift as edge cases and anomalies not included in the training data are encountered. To address this, we propose the Input Optimisation Network, an image preprocessing model that learns to optimise input data for a specific target vision model. In this work we investigate several out-of-distribution scenarios in the context of semantic segmentation for autonomous vehicles, comparing an Input Optimisation based solution to existing approaches of finetuning the target model with augmented training data and an adversarially trained preprocessing model. We demonstrate that our approach can enable performance on such data comparable to that of a finetuned model, and subsequently that a combined approach, whereby an input optimization network is optimised to target a finetuned model, delivers superior performance to either method in isolation. Finally, we propose a joint optimisation approach, in which input optimization network and target model are trained simultaneously, which we demonstrate achieves significant further performance gains, particularly in challenging edge-case scenarios. We also demonstrate that our architecture can be reduced to a relatively compact size without a significant performance impact, potentially facilitating real time embedded applications.
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Existing metrics for evaluating the quality of automatically generated questions such as BLEU, ROUGE, BERTScore, and BLEURT compare the reference and predicted questions, providing a high score when there is a considerable lexical overlap or semantic similarity between the candidate and the reference questions. This approach has two major shortcomings. First, we need expensive human-provided reference questions. Second, it penalises valid questions that may not have high lexical or semantic similarity to the reference questions. In this paper, we propose a new metric, RQUGE, based on the answerability of the candidate question given the context. The metric consists of a question-answering and a span scorer module, in which we use pre-trained models from the existing literature, and therefore, our metric can be used without further training. We show that RQUGE has a higher correlation with human judgment without relying on the reference question. RQUGE is shown to be significantly more robust to several adversarial corruptions. Additionally, we illustrate that we can significantly improve the performance of QA models on out-of-domain datasets by fine-tuning on the synthetic data generated by a question generation model and re-ranked by RQUGE.
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The meaningful use of electronic health records (EHR) continues to progress in the digital era with clinical decision support systems augmented by artificial intelligence. A priority in improving provider experience is to overcome information overload and reduce the cognitive burden so fewer medical errors and cognitive biases are introduced during patient care. One major type of medical error is diagnostic error due to systematic or predictable errors in judgment that rely on heuristics. The potential for clinical natural language processing (cNLP) to model diagnostic reasoning in humans with forward reasoning from data to diagnosis and potentially reduce the cognitive burden and medical error has not been investigated. Existing tasks to advance the science in cNLP have largely focused on information extraction and named entity recognition through classification tasks. We introduce a novel suite of tasks coined as Diagnostic Reasoning Benchmarks, DR.BENCH, as a new benchmark for developing and evaluating cNLP models with clinical diagnostic reasoning ability. The suite includes six tasks from ten publicly available datasets addressing clinical text understanding, medical knowledge reasoning, and diagnosis generation. DR.BENCH is the first clinical suite of tasks designed to be a natural language generation framework to evaluate pre-trained language models. Experiments with state-of-the-art pre-trained generative language models using large general domain models and models that were continually trained on a medical corpus demonstrate opportunities for improvement when evaluated in DR. BENCH. We share DR. BENCH as a publicly available GitLab repository with a systematic approach to load and evaluate models for the cNLP community.
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与其2D图像对应物相比,3D点云数据上的零射击学习是一个相关的未置换问题。 3D数据由于不可用的预训练特征提取模型而带来了ZSL的新挑战。为了解决这个问题,我们提出了一种及时引导的3D场景生成和监督方法,该方法可以增强3D数据以更好地学习网络,从而探索可见和看不见的对象的复杂相互作用。首先,我们以提示描述的某些方式合并了两个3D模型的点云。提示的行为就像描述每个3D场景的注释一样。后来,我们进行对比学习,以端到端的方式培训我们所提出的建筑。我们认为,与单​​个对象相比,3D场景可以更有效地关联对象,因为当对象出现在上下文中时,流行的语言模型(如Bert)可以实现高性能。我们提出的及时引导场景生成方法封装了数据扩展和基于及时的注释/字幕,以提高3D ZSL性能。我们已经在合成(ModelNet40,ModelNet10)和实扫描(ScanoJbectnn)3D对象数据集上实现了最新的ZSL和广义ZSL性能。
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VQ(供应商资格)和IOQ(安装和操作资格)审核在仓库中实施,以确保在履行网络中翻转所有设备都符合质量标准。如果在短时间内进行许多检查,则可能会跳过审核检查。此外,探索性数据分析揭示了对相同资产进行类似检查的几个实例,从而重复了这项工作。在这项工作中,通过识别相似性和重复项,将自然语言处理和机器学习应用于仓库网络的大型清单数据集,并预测具有较高传递率的非批评性数据集。该研究建议ML分类器识别具有IOQ和VQ的高传递概率的检查,并将优先级分配给检查,以便在无法执行所有检查的时间时优先考虑。这项研究建议使用基于NLP的BLAZINGTEXT分类器以高速率进行清单,这可以降低检查的10%-37%,并大大降低成本。应用的算法超过了随机森林和神经网络分类器,并在90%的曲线下达到了一个区域。由于数据不平衡,使用F1分数对模型的准确性产生了积极影响,从8%提高到75%。此外,提出的重复检测过程确定要修剪的17%可能的冗余支票。
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