This paper expounds the design and control of a new Variable Stiffness Series Elastic Actuator (VSSEA). It is established by employing a modular mechanical design approach that allows us to effectively optimise the stiffness modulation characteristics and power density of the actuator. The proposed VSSEA possesses the following features: i) no limitation in the work-range of output link, ii) a wide range of stiffness modulation (~20Nm/rad to ~1KNm/rad), iii) low-energy-cost stiffness modulation at equilibrium and non-equilibrium positions, iv) compact design and high torque density (~36Nm/kg), and v) high-speed stiffness modulation (~3000Nm/rad/s). Such features can help boost the safety and performance of many advanced robotic systems, e.g., a cobot that physically interacts with unstructured environments and an exoskeleton that provides physical assistance to human users. These features can also enable us to utilise variable stiffness property to attain various regulation and trajectory tracking control tasks only by employing conventional controllers, eliminating the need for synthesising complex motion control systems in compliant actuation. To this end, it is experimentally demonstrated that the proposed VSSEA is capable of precisely tracking desired position and force control references through the use of conventional Proportional-Integral-Derivative (PID) controllers.

最近，人们对基于变压器的模型产生有意义的文本嵌入的能力越来越兴趣，例如文本相似性。尽管该领域取得了重大进展，但相似性预测的解释仍然具有挑战性，尤其是在无监督的环境中。在这项工作中，我们提出了一种无监督的技术，用于解释预先训练的BERT模型推断出的段落相似性。通过查看一对段落，我们的技术确定了决定每个段落的语义的重要单词，在这两个段落中的单词之间匹配，并检索解释两者之间相似性的最重要对。该方法已通过广泛的人类评估进行了评估，并在包含长期复杂段落的数据集中证明了这一方法，已显示出巨大的希望，提供了与人类看法更好相关的准确解释。

我们提出了Metricbert，这是一个基于BERT的模型，该模型学会了以明确的相似性度量嵌入文本，同时遵守``传统''蒙面语言任务。我们专注于学习相似之处的下游任务，以表明公制表现优于最先进的替代方案，有时要大幅度。我们对我们的方法及其不同的变体进行了广泛的评估，这表明我们的训练目标对传统的对比损失，标准余弦相似性目标和其他六个基线非常有益。作为另一个贡献，我们发布了视频游戏描述的数据集，以及由域专家制作的一系列相似性注释。