Collaborative Research: Legible Co-Adaptation of Wearable Devices for As-Needed Assistance of Arm Motion

对于那些移动手臂或抓取物体有困难的人来说，外骨骼可以用来增强他们的能力，在某些情况下，还可以提供康复服务。手臂外骨骼可以采用从手部到肘部以上佩戴的支架的形式，带有马达来辅助运动并提供额外的力量。现有的商业外骨骼系统有控制参数的软件，可以根据个人的能力、需求和舒适度进行调整，但这些设置在设备使用过程中不会自动修改。在某些情况下，一个人可能会在长时间工作的过程中感到疲劳，因此在任务结束时需要外骨骼的帮助比任务开始时更多。在其他情况下，一个人可能会获得更多的能力，因为他们在几天或几周的活动中得到帮助，允许外骨骼开始提供更少的帮助。本研究的激励目标是实现手臂外骨骼的协同适应，其中外骨骼的控制参数随着时间的推移适应人的变化能力，在人类外骨骼团队之间产生协同协调运动。该项目通过开发一种自适应外骨骼控制器来促进科学进步，促进国家健康、繁荣和福利，该控制器旨在根据用户不断变化的肌肉疲劳程度和能力提供所需的运动辅助。这项研究考虑了增强健康参与者的能力，这与减少工业或军事应用中肌肉骨骼的风险是一致的，以及为老年人提供运动辅助，这可以帮助他们解决因衰老而导致的感觉运动缺陷。该项目解决了疲劳检测、易读通知和设备辅助，以实现人与智能外骨骼机器之间的协同物理和认知契合。这一融合性研究汇集了计算机科学、人为因素、机器人、物理治疗和运动机能学的理论，以促进对人机交互的基本理解。该项目还包括通过面向中学女生的STEM活动以及面向老年人的终身学习活动开展公众参与。该算法的函数可以用动力系统理论的原理来表示。该算法将使外骨骼控制器在参数动态级别（描述与完成任务相关的参数的时间尺度）适应指定的图形动态（描述代表系统的连接架构的更长的时间尺度）。该算法采用易读方案，提高了图形动态的稳定性。项目团队将使用市售的Myomo MyoPro动力矫形器作为评估人类外骨骼团队共同适应的平台。项目团队计划一个控制易读性方案，该方案将向用户传达一系列通知，告知她/他MyoPro正在做什么。易读性方案旨在使用户对设备的校准信任保持一致，并防止图形动态中的分叉。该研究的具体目标是：(1)将肌肉疲劳的测量纳入易读的协同自适应外骨骼控制器中；(2)评估协同自适应控制器在健康青年人群疲劳状态下改善人体外骨骼任务性能的假设；(3)检验该控制器在老年人群中的泛化性。所有研究的主要任务都是一个“捡放”任务，参与者从桌子上抓起一个物体（例如，一本书，一支笔，篮子，杯子），把它放在书架上，然后把物体放回桌子上。不同对象大小和权重的使用增加了数据集中抓取类型的数量，以及所需的电机控制策略，从而提高了算法在抓取任务中的泛化性。参与者将同时执行认知任务，这些任务将用于评估主要拾取和放置任务期间的认知负荷。为了增加疲劳率，主要任务与疲劳任务交替进行。这些研究的结果将通过在外骨骼控制政策内考虑人类适应的自然形式来提高外骨骼系统的可用性，使外骨骼能够应用于支持原位老化和减轻损伤的长期应用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

For people who have difficulties moving their arms or grasping objects, an exoskeleton can be used to augment a person’s capabilities and, in some cases, to provide rehabilitation. An arm exoskeleton can take the form of a brace worn from the hand to above the elbow, with motors to assist movement and to provide additional strength. Existing commercial exoskeleton systems have software with control parameters that can be adjusted to an individual’s capabilities, needs, and comfort, but these settings are not modified automatically while the device is being used. In some cases, a person could fatigue over the course of a long task, thus requiring the exoskeleton to help more at the end of a task than at the beginning. In other cases, a person might gain more ability as they are assisted in movements over days or weeks, allowing the exoskeleton to start providing less assistance. The motivating objective of this research is to enable co-adaptation of an arm-worn exoskeleton, where the control parameters of the exoskeleton adapt over time to the person’s changing capabilities, generating synergistic coordinated motion between the human-exoskeleton team. This project promotes the progress of science and advances the national health, prosperity and welfare through the development of an adaptive exoskeleton controller designed to provide as-needed motion assistance based on the user's changing level of muscular fatigue and capabilities. The research considers augmenting the abilities of healthy participants, which aligns with reducing musculoskeletal risk for an industrial or military application, as well as motion assistance for older populations, which can aid with sensorimotor deficits due to aging. The project addresses fatigue detection, legible notifications, and device assistance to enable synergistic physical and cognitive fit between the human and intelligent exoskeleton machine. This convergent research brings together theories from computer science, human factors, robotics, physical therapy, and kinesiology to advance a fundamental understanding of human-robot interactions. The project also includes public engagement through STEM activities for middle school girls, as well as through activities for life-long learning for older adults.The function of the co-adaptive algorithm can be expressed using principles motivated by dynamical systems theory. The algorithm will adapt the exoskeleton controller at the parameter dynamics level (a time scale describing parameters associated with completing the task) for a specified graph dynamics (a longer time scale describing the connectivity architecture representing the system). The algorithm encourages stability of the graph dynamics using a legibility scheme. The project team will use the commercially available Myomo MyoPro powered orthosis as a platform to evaluate co-adaptation of a human-exoskeleton team. The project team plans a control legibility scheme that will convey a series of notifications to the user to inform her/him about what the MyoPro is doing. The legibility scheme is designed to align with enabling a calibrated trust of the user with respect to the device and to prevent bifurcations in the graph dynamics. The specific objectives of the research are: (1) to incorporate measures of muscle fatigue in a legible co-adaptive exoskeleton controller; (2) to evaluate the hypothesis that a co-adaptive controller can improve human-exoskeleton task performance in the presence of fatigue in a healthy young adult population; and (3) to examine the generalizability of the co-adaptive controller to an older adult population. The primary task across all studies is a pick-and-place task where participants grasp an object (e.g., a book, pen, basket, cup) from a table and place it on a bookshelf, then return the object to the table. The use of different object sizes and weights increases the number of grasp types in the dataset, as well as the motor control strategies required, providing increased generalizability of the algorithms across grasping tasks. Participants will perform concurrent cognitive tasks that will be used to assess cognitive load during the primary pick-and-place task. To increase the rate of fatigue, the primary task is alternated with a fatiguing task. Results from these studies will advance the usability of exoskeleton systems by accounting for natural forms of human adaptation within the exoskeleton control policy, enabling exoskeletons to be applied for longer-duration applications that support aging in place and the mitigation of injury.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.