Automatic Control of Standing Balance with Functional Neuromuscular Stimulation

描述（由申请人提供）：该项目的目标是开发新的控制系统，以恢复因脊髓损伤（SCI）而瘫痪的个体的站立功能并增强其姿势稳定性。该系统通过自动调节对瘫痪肌肉的刺激来提供站立、改变站立姿势和保持平衡的能力，将在模拟中进行设计、优化，并在6名脊髓损伤志愿者中进行实验评估。该项目将产生一个独特的、全面的平衡控制系统，扩展所有目前可用的站立神经假体的能力并提高其安全性。第一个目标是设计、实现和测试“姿态跟随”和“区域设定点”控制子系统。当用户通过简单地拉动或推动助行器来改变他们的站立姿势时，姿势跟随控制元件将自动改变刺激。这将确保在重心平稳移动到新的位置时，持续施加最佳的刺激来支撑身体。区域设定点控制元件根据关节角度位置和质心加速度自动调节刺激，抵抗干扰，保持平衡。该子系统将被优化，以跨越整个支撑基础，并维持由姿势跟随者定义的所需姿势。这些新的控制元件将在模拟中单独设计和评估，然后在脊髓损伤志愿者中进行实验室演示和临床评估。然后，子系统将被整合并与瘫痪肌肉的持续激活进行比较。由此产生的控制器应该有利于站立和其他日常生活功能活动，需要更少的上肢努力来保持平衡，抵抗更大的应用扰动，并且被认为比传统的站立方法更容易使用。第二个具体目标是开发执行“反应步骤”的能力。这种新的控制元件将自动改变脚的位置，以扩大支撑的基础，以保持站立，以应对大的，不稳定的干扰。工作将从充分描述电诱导的屈曲退缩反射开始，并评估其产生足部位置快速变化的潜力。这些数据将纳入计算机模拟，以确定适当的触发和优化刺激模式，以产生可重复的步进运动。如果施加的扰动超过设定值控制器有效抵抗的扰动，则产生的子系统将采取行动，从而避免即将发生的下降。有效性将在涉及应用可重复的外部扰动的模拟和实验室实验中充分评估。最后，所有三个子系统将整合到一个全面的平衡控制系统中，并与先进的手术植入16通道刺激器的接受者进行彻底评估。

DESCRIPTION (provided by applicant): The goal of this project is to develop new control systems to restore standing function and enhance the postural stability of individuals paralyzed by spinal cord injuries (SCI). Systems that provide the ability to stand, alter standing posture, and maintain balance by automatically adjusting stimulation to the paralyzed muscles will be designed, optimized in simulation, and evaluated experimentally in six volunteers with SCI. The project will result in a unique, comprehensive balance control system that extends the capabilities and improves the safety of all currently available standing neuroprostheses. The first aim is to design, implement and test "posture-follower" and "regional set-point" control sub- systems. The posture-follower control element will automatically alter stimulation as users vary their standing postures about the nominal erect position by simply pulling or pushing against a walker. This will ensure that the optimal stimulation to support the body is applied continuously as the center of mass is smoothly relocated to a new location. The regional set-point control element will automatically adjust stimulation to resist disturbances and maintain balance based on joint angle position and center of mass acceleration. This sub-system will be optimized to span the entire base of support and sustain the desired posture defined by the posture-follower. These new control elements will be designed and evaluated individually in simulation, followed by laboratory demonstration and clinical assessment in volunteers with SCI. The sub-systems will then be integrated and compared to constant activation of the paralyzed muscles. The resulting controller should facilitate standing reach and other functional activities of daily living, require less upper extremity effort to maintain balance, resist larger applied perturbations, and be perceived as easier to use than conventional methods of standing. The second specific aim is to develop the capability to execute a "reactive step". This new control element will automatically change foot position to expand the base of support sufficiently to remain standing in response to large, destabilizing disturbances. Work will begin by fully characterizing the electrically-induced flexion withdrawal reflex and evaluating its potential for generating a rapid change in foot placement. These data will be incorporated into computer simulations to identify an appropriate trigger and optimize patterns of stimulation to generate reproducible stepping motion. The resulting sub-system will take action if the applied perturbations exceed those effectively resisted by the set-point controller, and thus avoid impending falls. Effectiveness will be fully assessed in simulation and laboratory experiments involving application of repeatable external perturbations. Finally, all three sub-systems will be integrated into a comprehensive balance control system and thoroughly assessed with recipients of advanced surgically-implanted 16-channel stimulators.