In this article, we present the design of a powered knee–ankle prosthetic leg, which implements high-torque actuators with low-reduction transmissions. The transmission coupled with a high-torque and low-speed motor creates an actuator with low mechanical impedance and high backdrivability. This style of actuation presents several possible benefits over modern actuation styles in emerging robotic prosthetic legs, which include free-swinging knee motion, compliance with the ground, negligible unmodeled actuator dynamics, less acoustic noise, and power regeneration. Benchtop tests establish that both joints can be backdriven by small torques ($\sim$1–3 N$\cdot$m) and confirm the small reflected inertia. Impedance control tests prove that the intrinsic impedance and unmodeled dynamics of the actuator are sufficiently small to control joint impedance without torque feedback or lengthy tuning trials. Walking experiments validate performance under the designed loading conditions with minimal tuning. Finally, the regenerative abilities, low friction, and small reflected inertia of the presented actuators reduced power consumption and acoustic noise compared to state-of-the-art powered legs.

中文翻译：

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具有高扭矩、低阻抗致动器的动力膝-踝假肢的设计和验证

在本文中，我们展示了动力膝-踝假肢的设计，它实现了具有低减速传输的高扭矩执行器。传动装置与高扭矩和低速电机相结合，形成具有低机械阻抗和高反向驱动能力的执行器。在新兴的机器人假腿中，这种驱动方式与现代驱动方式相比有几个可能的好处，包括自由摆动的膝盖运动、与地面的顺应性、可忽略的未建模的驱动器动力学、更少的噪音和能量再生。台式测试表明，两个关节都可以通过小扭矩反向驱动（$\sim$1–3 N$\cdot$m) 并确认反射惯量小。阻抗控制测试证明，执行器的固有阻抗和未建模的动力学足够小，无需扭矩反馈或长时间的调谐试验即可控制关节阻抗。步行实验验证了设计负载条件下的性能，并进行了最少的调整。最后，与最先进的动力腿相比，所提出的执行器的再生能力、低摩擦和小反射惯性降低了功耗和噪音。