Rigid robots can be precise in repetitive tasks but struggle in unstructured environments. Nature's versatility in such environments inspires researchers to develop biomimetic robots that incorporate compliant and contracting artificial muscles. Among the recently proposed artificial muscle technologies, electrohydraulic actuators are promising since they offer comparable performance to mammalian muscles in terms of speed and power density. However, they require high driving voltages and have safety concerns due to exposed electrodes. These high voltages lead to either bulky or inefficient driving electronics that make untethered, high-degree-of-freedom bio-inspired robots difficult to realize. Here, we present low voltage electrohydraulic actuators (LEAs) that match mammalian skeletal muscles in average power density (50.5 W/kg) and peak strain rate (971 percent/s) at a driving voltage of just 1100 V. This driving voltage is approx. 5 - 7 times lower compared to other electrohydraulic actuators using paraelectric dielectrics. Furthermore, LEAs are safe to touch, waterproof, and self-clearing, which makes them easy to implement in wearables and robotics. We characterize, model, and physically validate key performance metrics of the actuator and compare its performance to state-of-the-art electrohydraulic designs. Finally, we demonstrate the utility of our actuators on two muscle-based electrohydraulic robots: an untethered soft robotic swimmer and a robotic gripper. We foresee that LEAs can become a key building block for future highly-biomimetic untethered robots and wearables with many independent artificial muscles such as biomimetic hands, faces, or exoskeletons.

翻译：刚性机器人在重复性任务中可保持高精度，但在非结构化环境中表现欠佳。自然界在复杂环境中的适应能力启发研究人员开发兼具柔顺性与收缩特性的人工肌肉仿生机器人。在近期提出的人工肌肉技术中，电液驱动器因在速度与功率密度方面具备与哺乳动物肌肉相当的性能而备受关注。然而，此类技术需要高驱动电压，且裸露电极存在安全隐患。高电压会导致驱动电子设备体积庞大或效率低下，使得实现高自由度无束缚仿生机器人面临困难。本文提出一种低电压电液驱动器（LEAs），其在仅需1100 V驱动电压条件下，平均功率密度（50.5 W/kg）与峰值应变率（971%/s）可与哺乳动物骨骼肌媲美。该驱动电压较采用顺电介质的其他电液驱动器低约5-7倍。此外，LEAs具备可触碰安全、防水及自清除特性，便于在可穿戴设备与机器人中部署。我们通过表征、建模与物理验证了该驱动器的关键性能指标，并将其与当前最先进的电液设计方案进行对比。最终，我们通过两款基于肌肉电液驱动的机器人——无束缚软体游泳机器人与机器人夹具——展示了该驱动器的实用性。我们预见，LEAs将成为未来高仿生无束缚机器人及可穿戴设备（如仿生手、仿生面部或外骨骼）中集成大量独立人工肌肉的关键基础构件。