脊髓反射对姿势稳定性的影响效果

发布时间：2018-03-14 01:37

本文选题：神经运动控制　切入点：建模与仿真　出处：《上海交通大学》2012年硕士论文　论文类型：学位论文

【摘要】：姿势的稳定性在上肢的运动行为中是非常重要的,因为神经运动系统时刻都面临着内部或者外部的不稳定因素的干扰。刚度是一个常常用来刻画上肢姿势稳定性的物理量,它由三个部分组成:内部主动分量、被动分量、和反射引起的刚度。反射对刚度有重要的贡献,前面的实验已经证明,由反射活动产生的刚度可以根据运动任务的特点和环境做出相应的改变,改变的最终目的都是通过增大刚度来减小不稳定性。然而,受技术限制,实验方法至今不能对反射活动对上肢端点刚度的影响方式这一问题做出深入的研究。本文中,我们在一个已经建好的开环的虚拟上臂模型的基础上加入脊髓反射网络模型,完成了一个闭环的虚拟上臂模型。用这两个模型进行的仿真实验可以帮助我们将反射活动引起的刚度分离出来进行研究。为了使仿真更接近真实情况,在模型的控制信号中加入了随机噪声。本研究中采用和实验方法相似的加入干扰力的方法来估计上肢端点刚度,上肢端点刚度用刚度椭圆表示。另外一个漂移椭圆用来表示上肢端点在神经噪声影响下的分布范围。用开环和闭环模型分别做14组仿真实验。实验结果显示,反射活动可以使刚度的幅度平均增大18.37%,这个和实验方法的估计值一致。它还可以使漂移椭圆的幅度平均减小35%。同时,刚度椭圆和漂移椭圆的形状和方向不发生变化。这说明前向控制信号决定上臂的阻抗特性,反射只是起到增大阻抗的幅度的作用。另外,本文还对反射增益值对上臂的稳定性的影响进行了研究,结论是牵张反射的增益最容易引起不稳定,腱反射的增益最不容易引起不稳定。
[Abstract]:The stability of posture is very important in the movement behavior of upper limb, because the neural motor system always faces the disturbance of internal or external unstable factors. Stiffness is a physical quantity which is often used to describe the stability of upper limb posture. It consists of three parts: the internal active component, the passive component, and the stiffness caused by reflection, which makes an important contribution to stiffness, as has been demonstrated by previous experiments. The stiffness generated by the reflection activity can be changed accordingly according to the characteristics of the motion task and the environment. The ultimate purpose of the change is to reduce the instability by increasing the stiffness. In this paper, we add a spinal cord reflex network model based on an open loop virtual upper arm model. A closed loop virtual upper arm model is completed. The simulation experiments with these two models can help us to separate the stiffness caused by the reflection activities. In order to make the simulation more close to the real situation, Random noise is added to the control signal of the model. In this study, the stiffness of upper extremities is estimated by adding interference force similar to the experimental method. The stiffness of upper extremities is expressed by stiffness ellipse. Another drift ellipse is used to describe the distribution range of upper extremities under the influence of neural noise. Fourteen groups of simulation experiments are done with open loop and closed loop models respectively. The experimental results show that, The reflection activity can increase the stiffness amplitude by 18.37 on average, which is consistent with the experimental method. It can also reduce the average amplitude of the drift ellipse by 35 percent. The shape and direction of the stiffness ellipse and the drift ellipse do not change. This indicates that the forward control signal determines the impedance characteristics of the upper arm, and the reflection only increases the amplitude of the impedance. The effect of reflection gain on the stability of upper arm is also studied. It is concluded that the gain of stretch reflex is the most likely to cause instability, and the gain of tendon reflex is the least to cause instability.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.0

【共引文献】