A Modified Dynamic Surface Controller for Delayed Neuromuscular Electrical Stimulation.
A Modified Dynamic Surface Controller for Delayed Neuromuscular Electrical Stimulation.
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DOI：
10.1109/tmech.2017.2704915
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发表时间：
2017-08
期刊：
影响因子：
--
通讯作者：
Sharma N
中科院分区：
文献类型：
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作者：
Alibeji N;Kirsch N;Dicianno BE;Sharma N
神经肌肉电刺激（NMES）过程中肌肉力量产生的一个被广泛接受的模型是一个二阶非线性肌肉骨骼动力学级联延迟一阶肌肉激活动力学。然而，大多数非线性NMES控制方法要么忽略了肌肉激活动力学，要么使用一个特设的策略来解决肌肉激活动力学，这可能无法保证控制稳定性。我们假设，一个非线性控制设计，包括肌肉激活动力学可以提高控制性能。在本文中，一个动态表面控制（DSC）的方法被用来设计一个基于PID的NMES控制器，以补偿EMD的活化动力学。因为肌肉激活是不可测量的，所以使用基于模型的估计器来实时估计肌肉激活。李雅普诺夫稳定性分析证实，新开发的控制器实现半全局一致最终有界（SGUUB）跟踪的肌肉骨骼系统。实验进行了两个健全的主题和一个脊髓损伤的主题，使用修改后的腿伸展机。这些实验说明了新的控制器的性能，并将其与以前的PID-DC控制器进行比较，该控制器在控制设计中没有考虑肌肉激活动态。这些实验支持我们的假设，即控制设计，包括肌肉激活提高NMES控制性能。
A widely accepted model of muscle force generation during neuromuscular electrical stimulation (NMES) is a second-order nonlinear musculoskeletal dynamics cascaded to a delayed first-order muscle activation dynamics. However, most nonlinear NMES control methods have either neglected the muscle activation dynamics or used an ad hoc strategies to tackle the muscle activation dynamics, which may not guarantee control stability. We hypothesized that a nonlinear control design that includes muscle activation dynamics can improve the control performance. In this paper, a dynamic surface control (DSC) approach was used to design a PID-based NMES controller that compensates for EMD in the activation dynamics. Because the muscle activation is unmeasurable, a model based estimator was used to estimate the muscle activation in realtime. The Lyapunov stability analysis confirmed that the newly developed controller achieves semi-global uniformly ultimately bounded (SGUUB) tracking for the musculoskeletal system. Experiments were performed on two able-bodied subjects and one spinal cord injury subject using a modified leg extension machine. These experiments illustrate the performance of the new controller and compare it to a previous PID-DC controller that did not consider muscle activation dynamics in the control design. These experiments support our hypothesis that a control design that includes muscle activation improves the NMES control performance.