Just like in humans vision plays a fundamental role in guiding adaptive locomotion, when designing the control strategy for a walking assistive technology, Computer Vision may bring substantial improvements when performing an environment-based assistance modulation. In this work, we developed a hip exosuit controller able to distinguish among three different walking terrains through the use of an RGB camera and to adapt the assistance accordingly. The system was tested with seven healthy participants walking throughout an overground path comprising of staircases and level ground. Subjects performed the task with the exosuit disabled (Exo Off), constant assistance profile (Vision Off ), and with assistance modulation (Vision On). Our results showed that the controller was able to promptly classify in real-time the path in front of the user with an overall accuracy per class above the 85%, and to perform assistance modulation accordingly. Evaluation related to the effects on the user showed that Vision On was able to outperform the other two conditions: we obtained significantly higher metabolic savings than Exo Off, with a peak of about -20% when climbing up the staircase and about -16% in the overall path, and than Vision Off when ascending or descending stairs. Such advancements in the field may yield to a step forward for the exploitation of lightweight walking assistive technologies in real-life scenarios.

Deep learning models for learning analytics have become increasingly popular over the last few years; however, these approaches are still not widely adopted in real-world settings, likely due to a lack of trust and transparency. In this paper, we tackle this issue by implementing explainable AI methods for black-box neural networks. This work focuses on the context of online and blended learning and the use case of student success prediction models. We use a pairwise study design, enabling us to investigate controlled differences between pairs of courses. Our analyses cover five course pairs that differ in one educationally relevant aspect and two popular instance-based explainable AI methods (LIME and SHAP). We quantitatively compare the distances between the explanations across courses and methods. We then validate the explanations of LIME and SHAP with 26 semi-structured interviews of university-level educators regarding which features they believe contribute most to student success, which explanations they trust most, and how they could transform these insights into actionable course design decisions. Our results show that quantitatively, explainers significantly disagree with each other about what is important, and qualitatively, experts themselves do not agree on which explanations are most trustworthy. All code, extended results, and the interview protocol are provided at https://github.com/epfl-ml4ed/trusting-explainers.

Student success models might be prone to develop weak spots, i.e., examples hard to accurately classify due to insufficient representation during model creation. This weakness is one of the main factors undermining users' trust, since model predictions could for instance lead an instructor to not intervene on a student in need. In this paper, we unveil the need of detecting and characterizing unknown unknowns in student success prediction in order to better understand when models may fail. Unknown unknowns include the students for which the model is highly confident in its predictions, but is actually wrong. Therefore, we cannot solely rely on the model's confidence when evaluating the predictions quality. We first introduce a framework for the identification and characterization of unknown unknowns. We then assess its informativeness on log data collected from flipped courses and online courses using quantitative analyses and interviews with instructors. Our results show that unknown unknowns are a critical issue in this domain and that our framework can be applied to support their detection. The source code is available at https://github.com/epfl-ml4ed/unknown-unknowns.

Time series is the most prevalent form of input data for educational prediction tasks. The vast majority of research using time series data focuses on hand-crafted features, designed by experts for predictive performance and interpretability. However, extracting these features is labor-intensive for humans and computers. In this paper, we propose an approach that utilizes irregular multivariate time series modeling with graph neural networks to achieve comparable or better accuracy with raw time series clickstreams in comparison to hand-crafted features. Furthermore, we extend concept activation vectors for interpretability in raw time series models. We analyze these advances in the education domain, addressing the task of early student performance prediction for downstream targeted interventions and instructional support. Our experimental analysis on 23 MOOCs with millions of combined interactions over six behavioral dimensions show that models designed with our approach can (i) beat state-of-the-art educational time series baselines with no feature extraction and (ii) provide interpretable insights for personalized interventions. Source code: https://github.com/epfl-ml4ed/ripple/.

事实证明，联邦学习（FL）是利用分布式资源的最有希望的范式之一，使一组客户能够协作培训机器学习模型，同时保持数据分散。对该主题兴趣的爆炸性增长导致了几个核心方面的快速发展，例如沟通效率，处理非IID数据，隐私和安全能力。但是，假设客户的培训集被标记，大多数FL仅处理监督任务。为了利用分布式边缘设备上的巨大未标记数据，我们旨在通过解决分散设置中的异常检测问题来扩展FL范式到无监督任务。特别是，我们提出了一种新颖的方法，在这种方法中，通过预处理阶段，客户分组为社区，每个社区都具有相似的多数（即近距离）模式。随后，每个客户社区都以联合方式训练相同的异常检测模型（即自动编码器）。然后共享所得模型并用于检测加入相应联合过程的同一社区客户端内的异常情况。实验表明我们的方法是强大的，它可以检测到与理想分区一致的社区，在这种分区中，知道具有相同近距离模式的客户组。此外，性能要比客户专门培训模型在本地数据上训练，并且与理想社区分区的联合模型相当的性能要好得多。

在本文中，我们提出了一个新颖的解释性框架，旨在更好地理解面部识别模型作为基本数据特征的表现（受保护的属性：性别，种族，年龄；非保护属性：面部毛发，化妆品，配件，脸部，面部，面部，面部，面部，面部，它们被测试的变化的方向和阻塞，图像失真，情绪）。通过我们的框架，我们评估了十种最先进的面部识别模型，并在两个数据集上的安全性和可用性方面进行了比较，涉及基于性别和种族的六个小组。然后，我们分析图像特征对模型性能的影响。我们的结果表明，当考虑多归因组时，单属分析中出现的趋势消失或逆转，并且性能差异也与非保护属性有关。源代码：https：//cutt.ly/2xwrlia。

在过去的十年中，通过深度学习方法取得了杰出的结果，对单一语言的语音情感识别（SER）取得了显着的结果。但是，由于（i）源和目标域分布之间的巨大差异，（ii）少数标记和许多未标记的新语言的话语，跨语言SER仍然是现实世界中的挑战。考虑到以前的方面，我们提出了一种半监督学习方法（SSL）方法，用于跨语性情感识别时，当有一些新语言的标签可用时。基于卷积神经网络（CNN），我们的方法通过利用伪标记的策略来适应新语言。特别是，研究了使用硬和软伪标签方法的使用。我们在源和新语言上均独立于语言的设置中彻底评估了该方法的性能，并在属于不同语言菌株的五种语言中显示出其稳健性。

互动模拟使学生可以通过自己的探索来发现科学现象的基本原理。不幸的是，学生经常在这些环境中有效地学习。根据他们的预期表现对学生的互动数据进行分类，有可能实现自适应指导并因此改善学生的学习。该领域的先前研究主要集中于A-tosteriori分析或研究限于一个特定的预测模型和仿真。在本文中，我们研究了模型的质量和普遍性，以根据跨交互式仿真的学生的点击数据进行概念性理解的早期预测。我们首先通过他们的任务表现来衡量学生的概念理解。然后，我们建议一种新型的功能，该功能从ClickStream数据开始，既编码仿真的状态和学生执行的动作。我们最终建议将这些功能馈送到基于GRU的模型中，有或没有注意力进行预测。在两个不同的模拟上进行的实验和两个不同的人群表明，我们提出的模型的表现优于浅层学习基准，并更好地推广到不同的学习环境和人群。将注意力包括在模型中可以提高有效的查询。源代码可在GitHub（https://github.com/epfl-ml4ed/beerslaw-lab.git）上获得。

神经网络无处不在用于教育的应用机器学习。他们在预测性能方面的普遍成功伴随着严重的弱点，缺乏决策的解释性，尤其是在以人为中心的领域中。我们实施了五种最先进的方法，用于解释黑盒机器学习模型（Lime，PermiputationShap，kernelshap，dice，CEM），并检查每种方法的优势在学生绩效预测的下游任务上，用于五个大规模开放的在线在线公开培训班。我们的实验表明，解释者的家属在与同一代表学生集的同一双向LSTM模型中相互重要性不同意。我们使用主成分分析，詹森 - 香农距离以及Spearman的等级相关性，以跨方法和课程进行定量的盘问解释。此外，我们验证了基于课程的先决条件之间的解释器表现。我们的结果得出的结论是，解释器的选择是一个重要的决定，实际上对预测结果的解释至关重要，甚至比模型的课程更重要。源代码和模型在http://github.com/epfl-ml4ed/evaluating-explainers上发布。

虚拟助手利用自动语音识别（ASR）来帮助用户回答以实体为中心的查询。但是，由于大量经常变化的命名实体，口语实体识别是一个困难的问题。此外，当ASR在设备上执行ASR时，可供识别的资源受到限制。在这项工作中，我们研究了概率语法作为有限状态传感器（FST）框架中的语言模型的使用。我们向概率语法引入了确定性近似，该语法避免了在模型创建时间上的非末端的显式扩展，直接与FST框架集成，并与N-Gram模型互补。与在没有我们的方法的情况下使用类似大小的N-Gram模型相比，我们在长尾部实体查询上获得了10％的相对单词错误率提高。