Automatic Control of Standing Balance with Functional Neuromuscular Stimulation

描述(申请人提供)：该项目的目标是开发新的控制系统，以恢复站立功能，并增强脊髓损伤(SCI)瘫痪患者的姿势稳定性。通过自动调整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系统将在模拟中进行设计、优化，并在六名患有脊髓损伤的志愿者身上进行实验评估。该项目将产生一种独特的、全面的平衡控制系统，该系统扩展了目前所有可用的立式神经假体的功能并提高了安全性。第一个目标是设计、实现和测试“姿态跟随器”和“区域设定值”控制子系统。当使用者通过简单地拉或推步行器来改变他们的站立姿势时，姿势跟随者控制元件将自动改变刺激。这将确保当重心平稳地重新定位到新位置时，持续施加支持身体的最佳刺激。区域设定值控制元件将根据关节角度位置和质心加速度自动调整刺激以抵抗干扰并保持平衡。这个子系统将被优化，以跨越整个支撑基础，并保持姿势跟随者定义的所需姿势。这些新的控制元素将在模拟中单独设计和评估，随后将在患有脊髓损伤的志愿者中进行实验室演示和临床评估。然后，这些子系统将被整合起来，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促进站立伸展和日常生活的其他功能活动，需要更少的上肢努力来保持平衡，抵抗更大的应用扰动，并被认为比传统的站立方法更容易使用。第二个具体目标是发展执行“反应性步骤”的能力。这种新的控制元件将自动改变脚的位置，以充分扩大支撑底座，以保持站立状态，以应对大的、不稳定的干扰。这项工作将从全面描述电诱导的屈曲退缩反射开始，并评估其在足部位置产生快速变化的潜力。这些数据将被合并到计算机模拟中，以确定合适的触发因素并优化刺激模式，以产生可重复的步进运动。如果所施加的摄动超过设定点控制器有效抵抗的摄动，所产生的子系统将采取行动，从而避免即将到来的跌落。有效性将在模拟和实验室实验中得到充分评估，这些实验涉及应用可重复的外部扰动。最后，所有三个子系统将被集成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.