在线调整对到达运动中人体上肢刚性特性的影响

The effect of on-line correction on stiffness of human upper limb during goal-directed movement

目的研究在线调整与运动中人体上肢刚性值之间的关系,提高人体刚性值测量的精度以及评判在线调整能力。方法设计5类不同类型的上肢平面到达运动,通过施加快速扰动的方法,对运动过程的前期、前中期、中期、中后期和后期共5个位置的刚性值进行测量,探讨刚性值在受到在线调整影响时的变化规律,以及刚性幅值与运动精度之间的关系。结果运动过程中刚性一直变化,而且刚性值的变化影响了最终的运动误差。运动过程中在线调整的发生会引起刚性幅值的改变,尤其是运动后期的刚性幅值,但是目前没有发现这一变化与在线调整发生的时间或者内容存在密切的联系。结论在线调整在到达运动中扮演了重要的角色。考虑到在线调整的发生会引起刚性幅值的变化,在临床上,通过对患者在特定实验中刚性幅值的测量,结合其他医学诊断方法,可以更精确地表明患者当前在线调整功能的状况。

Objective To study the relationship between on-line correction and stiffness of the upper limb during human movements, so as to improve the measurement accuracy of stiffness and to assess the on-line correction capability. Methods Five kinds of upper limb goal-directed movements in a horizontal plane were designed. The stiffness values at 5 different positions, i.e. in the early period, early to mid period, mid period, mid to late period and late period separately during the movements with sudden perturbation were measured to investigate the regu- lar pattern of human hand stiffness influenced by such on-line correction, as well as the relationship between the movement accuracy and hand stiffness. Results The stiffness was always varying during the movements, and the variation of the stiffness would influence the movement error. On-line correction during the movements could induce an increase in the value of stiffness amplitude, especially at the position in late period of the movement. However, no significant linkage was found between the change of stiffness and the occurrence time or content of on-line correction. Conclusions On-line correction plays an important role in goal-directed movements. Consider- ing that on-line correction may cause a change in the amplitude of the stiffness, the on-line correction function of patients can be more accurately assessed by measuring stiffness value in specific experiments, combined with other medical diagnosis methods in clinic.