Hybrid Electric-Pneumatic Actuator (EPA) for legged locomotion

更好地理解执行器设计如何支持运动功能可能
有助于设计和开发新颖和功能更强的动力辅助或机器人腿
系统。腿部运动可以描述为运动
子功能的组成，即轴向腿功能、腿摆动和平衡。在这个
项目中，我们将重点放在轴向腿功能（例如，弹簧式跳跃）上，该功能基于混合电动-气动执行器（EPA）的新概念。这个主要的运动子功能决定
身体质心的运动。我们将设计和制造EPA原型
作为增强型可变阻抗执行器（VIA）。与其他过孔相比，EPA不仅提供了适应性适应性（例如可调节弹簧）
，而且还提供了气动人造肌肉（PAM）
，这是一个具有类似肌肉特性的额外强大的致动器，可以
以不同的配置（例如，串联或并联）安排到电动机（EM）。这种新型的混合执行器
分享了EM和PAM的优点，结合了精确的控制和兼容的
能量存储，需要通过简单的控制
定律来实现高效，稳健和通用的类人腿部运动。基于人体实验，EPA设计将被优化，以最小化
能量消耗，并在
期望的操作范围内最大化抗扰动的鲁棒性。我们认为人类原地跳跃是一个简单的运动，集中在轴向腿的功能。通过“逆
最优控制”，建立人体肌肉-骨骼功能模拟模型，再现人体跳跃实验结果，确定生物执行器（肌肉）的目标函数。这种受生物学启发的成本函数将帮助我们
确定最合适的EPA执行器设计。MARCO-2跳跃机器人的机器人装置将配备EPA来演示和评估执行器的设计和控制。基于其机械性能及其在
多段系统中的灵活安排，EPA提供了一种模仿人类
肌肉功能的新型执行器，并且能够机械地适应不同的步态和
条件（例如运动速度）。我们小组的初步实验和模拟
研究表明，将PAM添加到EM中具有预期的优势。我们预计，在不同的运动子功能控制器之间，只需要有限的感觉信息交换，就可以实现运动控制系统的模块化架构。随着EPA技术，新的多功能，高效和强大的运动
系统广泛的应用可以设计。

A better understanding of how actuator design supports locomotor function may 
help design and develop novel and more functional powered assistive or robotic legged
 systems. Legged locomotion can be described as a composition of locomotor
 sub-functions, namely axial leg function, leg swinging and balancing. In this 
project, we focus on the axial leg function (e.g., spring-like hopping) based on a novel concept of a hybrid electric-pneumatic actuator (EPA). This principal locomotor sub-function determines 
the movement of the body center of mass. We will design and manufacture EPA prototypes 
as enhanced variable impedance actuators (VIA). In contrast to other VIAs, the EPA provides not only adaptable compliance (e.g. an adjustable spring) 
but with the pneumatic artificial muscle (PAM) also 
an additional powerful actuator with muscle-like properties, which can be
arranged in different configurations (e.g., in series or parallel) to the electric motor (EM). This novel hybrid actuator
 shares the advantages of EM and PAM combining precise control with compliant
 energy storage required for efficient, robust and versatile human-like leg motions via simple control 
laws. Based on human experiments, the EPA design will be optimized to minimize
 energy consumption and maximize robustness against perturbations within a
 desired operational range. We consider human hopping in place as a simple movement concentrating on the axial leg function. A simulation model of human muscle-skeletal function reproducing human hopping experiment results will be used to identify the objective function for the biological actuators (muscles) through "inverse
 optimal control". This biologically inspired cost function will then help us to 
identify the most appropriate EPA actuator design. A robotic setup of the MARCO-2 hopping robot will be equipped with EPA to demonstrate and evaluate the actuator design and control. Based on its mechanical properties and its flexible arrangement in 
multi-segment-systems, the EPA provides a novel actuator that mimics human 
muscle function and is able to mechanically adapt to different gaits and 
conditions (e.g. locomotion speed). Preliminary experimental and simulation
 studies in our group show evidence of expected advantages of adding PAM to EM. We expect that only limited exchange of sensory information between the different locomotor sub-function controllers will be required enabling the envisioned modular architecture of the locomotor control system. With EPA technology, new versatile, efficient and robust locomotor
 systems for a wide range of applications can be designed.