Collaborative Research: Use of Wearable Sensors to Track Muscle-Tendon Loading during Exosuit Assisted Locomotion

机器护甲技术的进步使得能够使用动力辅助来增强健康个体的行走性能，并辅助表现出步态病理的个体，例如中风个体。 与刚性外骨骼不同，外骨骼服重量轻，使用柔软的材料，提供与身体的舒适和不显眼的贴合。腰部的背包使用电池供电的马达产生的力传递到脚踝和臀部。 尽管在减少行走所需的能量方面已经证明是成功的，但是为个体用户调整机器护甲辅助模式仍然具有挑战性。因此，这项工作的长期目标是使个性化的援助，可以适应在真实的时间，以用户的独特的步态模式和环境。为此，将使用称为剪切波张力计的新型传感器来跟踪膝关节和踝关节肌肉负荷的适应性，这些适应性是在动力踝关节外装护具提供辅助时出现的。 将进行研究以确定不同的外装护具辅助控制模式如何在不同的步行条件下调节内部肌肉负荷，包括有和没有外装护具辅助，有和没有携带负载（背包）以及在户外/真实世界环境中行走（下降，倾斜和可变步行速度）。 这些研究将增强对机器人辅助的神经肌肉反应的基本理解，从而实现基于个人需求调整辅助的人在回路实现。教育和推广的影响将通过使用基础的机器人，生物力学和传感器技术在这个项目中开发作为一个平台，从事K-12学生在干实现。简化版的机器人和传感器将被纳入威斯康星大学麦迪逊分校的年度工程推广活动中，该活动每年都会吸引数千名K-12学生和他们的老师。此外，由哈佛主办的Soft Robotics Toolkit将用于创建描述人机交互、生物力学、生理学和步态的引人入胜的内容。该项目的目标是使用新型组织负荷传感器（称为剪切波张力计）来研究实验室环境内外对机器护甲辅助的生物力学适应性。 虽然目前的机器护甲技术已被证明可以降低健康受试者行走的代谢成本，并改善中风幸存者的推进力、离地间隙和对称性，但这些益处的程度在不同受试者之间差异很大。 该项目建立在实验室和实验室之间的新合作基础上，该实验室发明了张力计方法，通过测量剪切波沿着肌腱轴的传播速度来直接测量肌腱载荷（威斯康星大学麦迪逊分校），该实验室在开发下一代软式外装方面被公认为领导者（哈佛）。 研究计划分为三个目标，每个目标在10个人类受试者中进行评估。 第一个目标是开发一种可穿戴剪切波张力计，并将其纳入踝关节运动服中，以在长时间的跑步机行走试验期间连续监测跟腱负荷。通过张力计测量确定的踝关节扭矩将与基于运动捕捉的测量进行比较。 这一目标的结果将是一个有效的可穿戴传感器，用于量化由机器护甲辅助引起的肌腱组织负荷的变化。 第二个目的是评估踝关节机器护甲辅助幅度与在有和没有附加质量的情况下行走期间肌肉-肌腱负载变化之间的关系。 这一目标的结果将提供新的见解机器护甲辅助和生物软组织负荷之间的关系，与预期的测试变量（机器护甲力，机器护甲定时，和增加的质量）将有各种影响用户的肌肉肌腱负荷。第三个目标是评估踝关节外装护具辅助在户外电路中行走时对肌肉肌腱负荷的影响，所述户外电路包括倾斜、下降、舒适速度和快速行走。 测量包括使用移动的张力计进行的肌腱加载、使用超声进行的肌肉运动学、以及使用套装伊穆斯和称重传感器进行的生物力学和套装数据。这一目标的结果预计将证明，类似于在实验室环境中的运动捕捉和测力板设置如何允许估计关节力矩，西装传感器和张力计将允许评估户外环境中的关节运动学和肌腱动力学。该项目的成功有望带来带有集成张力计传感器的新型外装设计，对外装的生物力学产生新的理解，并可能为临床和/或老年人群优化个性化可穿戴外骨骼提供信息。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Advances in exosuit technologies are enabling the use of powered assistance to enhance walking performance in healthy individuals and assist individuals who exhibit gait pathologies, e.g. individuals with stroke. Unlike rigid exoskeletons, exosuits are lightweight and use soft materials that provide a comfortable and unobtrusive fit with the body. A pack worn at the waist uses battery-powered motors to generate forces that are transmitted to the ankle and hip. In spite of demonstrated success in decreasing the energy needed to walk, it remains challenging to tune exosuit assistance patterns for individual users. Thus, the long-term goal of this work is to enable individualized assistance that can adapt in real time to a user’s unique gait patterns and to the environment. To do this, novel sensors, termed shear wave tensiometers, will be used to track adaptations in knee and ankle muscle loading that arise when assistance is provided by a powered ankle exosuit. Studies will be performed to determine how different exosuit assistance control patterns modulate internal muscle loading under varied walking conditions, including with and without exosuit assistance, with and without carrying a load (backpack) and walking in an outdoor/real-world environment (declines, inclines and variable walking speeds.) Theses studies will enhance the fundamental understanding of neuromuscular responses to exosuit assistance and thus enable human-in-the-loop implementations that adapt assistance based on the needs of an individual. Educational and outreach impact will be achieved by using fundamentals underlying the robotic, biomechanics and sensor technologies developed in this project as a platform for engaging K-12 students in STEM. Simplified versions of the exosuits and sensors will be incorporated into the annual engineering outreach event at the University of Wisconsin-Madison which reaches thousands of K-12 students and their teachers every year. Also, the Soft Robotics Toolkit hosted by Harvard will be used to create engaging content that describes human-machine interaction, biomechanics, physiology and gait.The goal of this project is to use novel tissue load sensors, termed shear wave tensiometers, to investigate biomechanical adaptations to exosuit assistance within and beyond the laboratory environment. Though current exosuit technologies have been shown to lower the metabolic cost of walking in healthy subjects and improve propulsion, ground clearance, and symmetry in stroke survivors, the extent of these benefits varies widely across subjects. The project builds on a new collaboration between the lab that invented the tensiometer method to directly gauge tendon loading by measuring the propagation speed of shear waves along the tendon’s axis (University of Wisconsin-Madison) and a lab that is recognized for leadership in developing the next generation of soft exosuits (Harvard.) The Research Plan is organized under three aims, with each aim being evaluated in 10 human subjects. The FIRST Aim is to develop and incorporate a wearable shear wave tensiometer into an ankle exosuit to continuously monitor Achilles tendon loading during prolonged treadmill walking trials. Ankle joint torque determined from tensiometer measurements will be compared to measurements based on motion capture. The result of this aim will be a validated wearable sensor for quantifying changes in tendon tissue loading induced by exosuit assistance. The SECOND Aim is to evaluate relationship between ankle exosuit assistance magnitude and change in muscle-tendon loading during walking with and without added mass. Results of this aim will provide novel insights into the relationship between exosuit assistance and biological soft tissue loads, with expectations that the tested variables (exosuit force, exosuit timing, and added mass) will have various effects on the user’s muscle-tendon load. The THIRD Aim is to evaluate the effect of ankle exosuit assistance on muscle-tendon loading while walking in an outdoor circuit that includes inclines, declines, comfortable speed and fast walking. Measurements include tendon loading with the mobile tensiometer, muscle kinematics with ultrasound, and biomechanics and suit data with suit IMUs and load cells. Results of this aim are expected to demonstrate that, similar to how a motion capture and force plate setup in a lab environment allows for estimating joint moments, the suit sensors and tensiometer will allow for evaluating joint kinematics and tendon kinetics in outdoor environments. Success of the project is expected to lead to a new design of exosuits with integrated tensiometer sensors, produce new understanding of biomechanics with exosuits, and potentially inform optimization of personalized wearable exoskeletons for clinical and/or aged populations.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.