Hybrid neuroprosthesis with power assist for walking in SCI

本项目的目的是设计、制造和评估一种新的、肌肉驱动的步行辅助装置 适用于在家庭和社区环境中进行临床测试的系统， 运动性完全胸段脊髓损伤（SCI）患者的活动能力。SCI原因导致的瘫痪 几乎所有主要器官系统的迅速退化。市售外部动力机器人 外骨骼可以开始解决康复和监督环境中的这种不动性，但对于 抵消大下肢肌肉的废用性萎缩和随之而来的心血管失调。 使用这些装置实现的最大行走速度和距离远远低于 在社区中安全有效地使用。因此，患有SCI的退伍军人仍然无法获得许多 对不受限制地重新融入社会至关重要的实际地点和生活机会。 我们提出的“混合”方法与可穿戴步行机器人完全不同。我们的“肌肉第一” 策略通过引发相对较短的爆发来获得行走和其他机动的主要动力 通过电刺激使原本瘫痪的肌肉产生高强度收缩。内部化 主电源意味着外部组件只需锁定/解锁关节或塑造 由收缩的肌肉产生的弹道肢体轨迹，从而消除了对重型电机的需要， 并使使用者能够获得锻炼其下肢的相当大的生理益处 肌肉.我们的混合系统的植入神经肌肉组件也可持续用于 自发运动和短时间站立和踏步，即使不戴外部组件。 髋关节、膝关节和踝关节肌肉的刺激收缩通常会产生足够的力量， 完全负重几分钟，以及完成短距离的步进运动， 对动力外骨骼的需求然而，髋关节屈曲可能与单独的刺激不一致，特别是 当试图爬上台阶或走上坡道时。我们建议增加刺激收缩， 机械子系统由位于臀部的小型、轻型和高效的支架式电机组成。 当由收缩的肌肉提供动力时，这种新颖的配置将在站立时自由地稳定臀部。 在挥杆过程中旋转，并提供持续实现所需肢体所需的低水平扭矩 尽管行走表面或刺激反应存在变化，因为发动机只需要 提供必要的增量扭矩以增强受刺激的臀部肌肉并塑造肢体 轨道，整个外部结构可以显着更小，更轻，更安静，比商业 基于“电机优先”策略的可用动力外骨骼。主动膝关节伸展将由 刺激股神经，股神经通常产生足够的扭矩来站立和行走，而类似的 为髋关节提出的机构将在站立或站立中期锁定以使刺激的肌肉休息， 在挥杆和上楼梯时解锁，并在挥杆前立即辅助膝关节屈曲。余留机制将 缓冲脚与地板接触的冲击力，在下楼梯或从楼梯过渡时， 从站到坐。一个简单的弹簧辅助踝关节支架将保护脚，并提高脚趾在摆动， 而小腿肌肉的强烈刺激收缩提供推动力以驱动行走， 速度远远超过现有外骨骼的报道。 该项目将定义一种实用的临床干预措施，以恢复接近正常的长距离行走 速度适合日常活动和社区使用。经过实验室和实验室测试， 将尝试与混合系统协商不受限制的社区环境。所提出的混合 神经机械步态辅助系统应该使瘫痪的退伍军人恢复健康，生产力和 社会参与的生活方式，这将对生活质量和社会参与产生重大影响。

The objective of this project is to design, fabricate and evaluate a new, muscle-driven ambulatory assist system suitable for clinical testing in the home and community environments that maximizes the functional mobility of individuals with motor complete thoracic level spinal cord injury (SCI). Paralysis from SCI causes rapid degeneration of almost every major organ system. Commercially available externally powered robotic exoskeletons can begin to address such immobility in rehabilitation and supervised settings, but do nothing to counteract the disuse atrophy of the large lower extremity muscles and ensuing cardiovascular deconditioning. The maximal walking speeds and distances achieved with these devices fall far short of those necessary for safe and effective ambulation in the community. As a result, veterans with SCI are still unable to access many physical locations and life opportunities important for unrestricted reintegration into society. The “hybrid” approach we propose is radically different from wearable walking robots. Our “muscle first” strategy derives the primary motive power for walking and other maneuvers by eliciting relatively short bursts of high intensity contractions from the otherwise paralyzed muscles with electrical stimulation. Internalizing the primary power sources means the external components only have to lock/unlock the joints or shape the ballistic limb trajectories generated by the contracting muscles, thus eliminating the need for heavy motors at each joint and enabling users to reap the considerable physiological benefits of exercising their lower extremity muscles. The implanted neuromuscular component of our hybrid system is also continuously available for spontaneous exercise and short duration standing and stepping even without donning the external component. Stimulated contractions of the hip, knee and ankle muscles routinely generate sufficient power to maintain full weight bearing for several minutes, as well as to accomplish stepping motions for short distances without the need for powered exoskeletons. However, hip flexion can be inconsistent with stimulation alone, especially when attempting to climb steps or walk up ramps. We propose to augment stimulated contractions with a mechanical subsystem consisting of small, lightweight and efficient brace-mounted motors located at the hips. When powered by the contracting muscles, this novel configuration will stabilize the hips during stance, freely rotate during swing, and provide the low-level torques required to consistently achieve the desired limb movements in spite of variations in walking surfaces or stimulated responses. Since the motors only need to provide the incremental torques necessary to augment the stimulated hip muscles and shape the limb trajectories, the entire external structure can be significantly smaller, lighter, and quieter than commercially available powered exoskeletons based on a “motor-first” strategy. Active knee extension will be generated by exciting the femoral nerve which routinely generates sufficient torque to stand and walk, while a similar mechanism to that proposed for the hip will lock during standing or mid-stance to rest the stimulated muscles, unlock during swing and stair ascent, and assist knee flexion immediately prior to swing. The mechanism will damp the impact of foot-floor contact, and gently lower the body during stair descent or transitioning from standing to sitting. A simple spring-assisted ankle brace will protect the foot and raise the toes during swing, while strong stimulated contractions of the calf muscles provide the propulsive power to drive walking at speeds far beyond those reported for existing exoskeletons. This project will define a practical clinical intervention to restore long-distance walking at near normal speeds suitable for daily activities and community use. After benchtop and laboratory testing, selected users will attempt to negotiate unrestricted community environments with the hybrid system. The proposed hybrid neuromechanical gait assist system should enable paralyzed veterans to return to healthy, productive and socially engaged lifestyles which will have significant impacts on quality of life and societal participation.