Automatic Control of Standing Balance with FNS

本研究的目的是提供有意义的站立功能的个人与运动完全 胸脊髓损伤通过一种新的16通道植入神经假体，并量化其临床和 与现有8通道植入系统相比的技术优势。常设职能将在 通过躯干、髋关节和膝关节的持续超最大激活， 伸肌沿着与选定的踝跖肌/背屈肌和髋AB肌/内收肌以开环方式连接。的 由新植入的刺激遥测仪提供的额外刺激通道将改善几个 与现有系统相比，临床相关的站立性能指标。此外，我们将 开发一种新的控制系统，自动调节姿势，主动恢复站立平衡， 在实验室环境控制良好。因此，我们将开始解决 所有其他植入式功能性神经肌肉刺激（FNS）系统，以备开发传感器- 驱动控制系统，将主动监测姿态，预计扰动，以平衡和自动 调节刺激以保持用户直立。这将通过结合创新的饲料- 在三维和基于全局的多个关节处的前向、反馈和预测控制元件 变量来自少量简单但信息丰富的身体安装传感器。动态 通过使用躯干的加速度来预测和快速响应预期的 扰动的影响，而静态稳定性将通过调整基地内的压力中心来实现 支持使用反馈控制。将采用基于模型的控制器开发方法， 包括计算机模拟和实验室测试， 系统新的控制系统在痉挛和肌肉变化的情况下执行的能力 由于疲劳的性质，以及其对控制参数选择和传感器精度的敏感性，将被 在模拟中评估。这种新的控制系统应该减少对上肢的依赖， 在实验室中使用FNS，从而推进最终提供神经假体的目标。 用户可以更自由地使用他们的手来操纵环境中的物体， 在存在内在和外在干扰时的平衡。

The purpose of this study is to provide meaningful standing function to individuals with motor complete thoracic spinal cord injuries via a new 16-channel implanted neuroprosthesis, and quantify its clinical and technical benefits over existing 8-channel implanted systems. Standing function will be achieved in the home and community environments through continuous supramaximal activation of the trunk, hip and knee extensors along with selected ankle plantar/dorsiflexors and hip ab/adductors in an open-loop manner. The additional channels of stimulation afforded by the new implanted stimulator-telemeter will improve several clinically relevant measures of standing performance over currently available systems. In addition, we will develop a novel control system to automatically regulate posture and actively restore standing balance to individuals in the well-controlled laboratory environment. Thus, we will begin to address the shortcomings of all other implanted functional neuromuscular stimulation (FNS) systems for standing by developing a sensor- driven control system that will actively monitor posture, anticipate perturbations to balance and automatically modulate stimulation to keep the user upright. This will be accomplished by combining innovative feed- forward, feedback and predictive control elements in three dimensions and at multiple joints based on global variables derived from a small number of simple, but information-rich, body-mounted sensors. Dynamic stability will be achieved by using accelerations of the trunk to predict and rapidly respond to the anticipated effects of perturbations, while static stability will be achieved by regulating center of pressure within the base of support using feedback control. A model-based approach to controller development will be adopted that involves computer simulation and laboratory testing with recipients of the 16-channel implanted stimulation system. The ability of the new control system to perform in the presence of spasms and changing muscle properties due to fatigue, as well as its sensitivity to control parameter selection and sensor accuracy, will be evaluated in simulation. This new control system should reduce reliance on the upper extremities while standing with FNS in the laboratory, thereby advancing the goal of eventually providing neuroprosthesis users with freer use of their hands to manipulate objects in the environment by automatically maintaining balance in the presence of intrinsic and extrinsic disturbances.