CAREER: Highly Underactuated Lower-Body Exoskeletons and the Dynamics of Walking

该学院早期职业发展计划(Career)奖支持将促进对人类行走的理解的研究，并创造一种新型的下半身外骨骼，以减轻残疾和增强人类表现。当人们正常行走时，两个因素在很大程度上决定了他们的平衡和前进速度：每个脚步的位置，以及站立时每条腿在地面上的推力。一般来说，当外骨骼产生的力与佩戴它的人的预期或想要的略有不同时，它会影响人如何采取下一步行动，进而影响未来外骨骼的反应。该项目研究的外骨骼通过增加行走时的支撑力来补充佩戴者的自然肌肉力量。系统地改变外骨骼的力量并测量反应将揭示行走过程中平衡和运动的动态图，包括这些变化在上坡和下坡上的变化。这种对行走的新的基本理解可以被外骨骼用来适应任何用户的个体特征，并从那里刺激所需的行走模式，同时降低摔倒的可能性。这项研究将得到教育宣传的补充，包括通过社交媒体上的科学视频向更广泛的公众宣传机器人和人与机器人的互动，以及让大学预科学生参加生物力学和外骨骼控制的研讨会。这个项目的中心是一种新型的外骨骼，这种外骨骼在每条腿上使用一个单一的棱柱致动器，从地面上直接向佩戴者的重心施加力。在行走过程中，该执行器可以提供高达80%的无辅助地面反作用力。外骨骼髋部是非致动的，可以自由旋转，这使得佩戴者可以选择他们的足迹位置，就像没有外骨骼一样。人体实验将研究在不同速度和坡度等不同条件下，人体运动学、肌肉活动、代谢成本、脚部位置和稳定性如何受到人体质心的不同力的影响--本质上完成人-机器人耦合系统的系统识别。这些系统识别结果，与运动发散分量(DCM)框架和机器学习一起，将定义外骨骼控制器，以根据佩戴者的当前状态和预期的未来足迹位置提供优化的行走辅助力量。该项目随后将研究人类和外骨骼之间的双向适应：人类如何适应外骨骼力量，他们随后的足迹位置如何受到这些力量的影响，以及外骨骼如何最好地适应个人及其个人运动模式和足迹位置。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Faculty Early Career Development Program (CAREER) award supports research that will advance understanding of human walking and create a new type of lower-body exoskeleton for mitigation of disability and augmentation of human performance. When people walk normally, two factors largely determine their balance and forward progress: the location of each footstep, and how hard each leg in stance pushes on the ground. In general, when an exoskeleton produces forces that are slightly different from what the person wearing it expects or wants, it affects how the person takes their next step, which in turn affects the future exoskeleton response. The exoskeletons studied in this project supplement the natural muscular strength of their wearers by adding to the support forces during walking. Systematically varying the exoskeleton force and measuring the response will reveal a map of the dynamics of balance and movement during walking, including how these change on uphill and downhill slopes. This new fundamental understanding of walking can then be used by the exoskeleton to adapt to individual characteristics of any user, and from there to stimulate desired walking patterns while decreasing the likelihood of a fall. This research will be complemented by educational outreach, including informing the broader public about robotics and human-robot interaction via science videos on social media, and engaging pre-college students with workshops on biomechanics and exoskeleton control. This project is centered on a new type of exoskeleton that uses a single prismatic actuator on each leg to apply force from the ground next to a planted foot, directly to the wearer's center of mass. The actuator can provide up to 80 percent of the unassisted ground reaction force during walking. The exoskeleton hip is unactuated and free to rotate, which allows the wearer to choose their footstep locations as though the exoskeleton was absent. Human subject experiments will study how the human kinematics, muscle activity, metabolic cost, foot placement, and stability are affected by different forces on the person's center of mass under various conditions including varying speeds and slopes -- essentially accomplishing system identification of the coupled human-robot system. These system identification results, together with the divergent component of motion (DCM) framework and machine learning, will define an exoskeleton controller to provide optimized walking assist forces based on the wearer's current state and expected future footstep locations. The project will subsequently investigate the bi-directional adaptation between the human and exoskeleton: how humans adapt to the exoskeleton forces, how their subsequent footstep locations are affected by these forces, and how the exoskeleton can best adapt to an individual human and their personal locomotion patterns and footstep placements.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.