Automatic Control of Standing Balance with Functional Neuromuscular Stimulation

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.第一个目标是设计、实施和测试“姿势跟随器”和“区域设定点”控制子系统。 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.这将确保当质心平稳地重新定位到新位置时，持续施加支撑身体的最佳刺激。区域设定点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。该子系统将被优化以跨越整个支撑底座并维持由姿势跟随器定义的所需姿势。 These new control elements will be designed and evaluated individually in simulation, followed by laboratory demonstration and clinical assessment in volunteers with SCI.然后，这些子系统将被整合，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助于站立伸展和日常生活的其他功能性活动，需要更少的上肢力量来保持平衡，抵抗更大的施加扰动，并且被认为比传统的站立方法更容易使用。第二个具体目标是发展执行“反应步骤”的能力。 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.工作将首先全面描述电诱导的屈曲撤退反射的特征，并评估其产生足部放置快速变化的潜力。这些数据将被纳入计算机模拟中，以识别适当的触发器并优化刺激模式，以生成可重复的步进运动。 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.有效性将在涉及应用可重复外部扰动的模拟和实验室实验中得到充分评估。 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.

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.