Human balancing of an inverted pendulum with a compliant linkage: neural control by anticipatory intermittent bias
Human balancing of an inverted pendulum with a compliant linkage: neural control by anticipatory intermittent bias
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DOI：
10.1113/jphysiol.2002.036939
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发表时间：
2003-08-15
影响因子：
5.5
通讯作者：
Loram, ID
中科院分区：
文献类型：
--
作者：
Lakie, M;Caplan, N;Loram, ID
这些实验是由最近的发现推动的，即脚踝的固有刚度不足以被动地稳定站立时的身体。我们希望通过展示如何手动平衡大型倒立摆和低固有刚度来阐明人类站立的主动控制。结果表明，当固有刚度较低时，摆可以令人满意地稳定。对摇摆尺寸的分析表明，内在刚度实际上对稳定性影响不大。摇摆持续时间也基本上与固有刚度无关。这表明摆的特征摆动可能是由手部运动的控制模式引起的，而不是由刚度和惯性决定的。这些实验揭示的关键点是，在固有刚度较低的情况下，手通过间歇性改变弹簧的偏置来提供摆稳定性，并且平均而言，手与负载相反地移动。结果得出了一个新的、可检验的假设；即站立时，小腿肌肉随着身体向前摆动而缩短，随着身体向后摆动而延长。这些发现很难与钟摆的牵张反射控制相一致，并且与站立特别相关。当中枢神经系统控制通过顺应性连杆操作的肌肉时，它们通常也可能与姿势维持相关。结果还表明，在站立时，内在的刚度不是提供被动稳定性，而是充当节能缓冲器，提供肌肉和身体之间的解耦。
These experiments were prompted by the recent discovery that the intrinsic stiffness of the ankle is inadequate to stabilise passively the body in standing. Our hope was that showing how a large inverted pendulum was manually balanced with low intrinsic stiffness would elucidate the active control of human standing. The results show that the pendulum can be satisfactorily stabilised when intrinsic stiffness is low. Analysis of sway size shows that intrinsic stiffness actually plays little part in stabilisation. The sway duration is also substantially independent of intrinsic stiffness. This suggests that the characteristic sway of the pendulum, rather than being dictated by stiffness and inertia, may result from the control pattern of hand movements. The key points revealed by these experiments are that with low intrinsic stiffness the hand provides pendulum stability by intermittently altering the bias of the spring and, on average, the hand moves in opposition to the load. The results lead to a new and testable hypothesis; namely that in standing, the calf muscle shortens as the body sways forward and lengthens as it sways backwards. These findings are difficult to reconcile with stretch reflex control of the pendulum and are of particular relevance to standing. They may also be relevant to postural maintenance in general whenever the CNS controls muscles which operate through compliant linkages. The results also suggest that in standing, rather than providing passive stability, the intrinsic stiffness acts as an energy efficient buffer which provides decoupling between muscle and body.