用于截瘫FES行走的三维上肢力动态测量系统

A Dynamic Measurement System for 3-D Upper-limb Forces during Paraplegic FES-assisted Walking

功能性电刺激(FES)技术已被广泛用于截瘫病人行走能力的恢复,但作为评估截瘫FES行走效率的重要指标,三维上肢力状况的研究至今仍十分有限,亟待深入开展。本文研制出了一套可用于截瘫FES行走的三维上肢力动态测量系统,该系统在一个标准步行器框架上装备有 12个应力应变片电桥,通过专用的隔离放大及A/D转换装置与计算机相连,经过标定后,截瘫FES行走时的上肢支撑力数据就可以被系统实时获得并显示。测力系统在应变片位置的确定以及“冗余-优化”方法的采用等多个方面保证了测量的可靠性和准确性,后续的校准实验显示系统的非线性、交互干扰和力学精度误差分别小于 2. 901%, 3. 188%和 1. 01%。研究中,一例截瘫患者作为志愿者按照正常的FES行走训练程序进行了相关测试,以验证新系统在行走能力评估方面的临床前景,结果表明其可用于: 1)截瘫FES行走效率的评估; 2)病人自我训练的控制指导; 3)作为反馈信号选择一种有效的FES模式和阵列。

Functional electrical stimulation (FES) was commonly prescribed to resume paraplegic patient walking ability. Up to now, as an important index for paraplegic walking efficiency evaluation, the research on 3-D upper-limb forces was limited and starved for development. This paper suggested a new dynamic measurement system for 3-D upper-limb forces during FES-assisted paraplegic walking, in which a standard walker based on 12 string-gauge bridges was tethered to a computer through a dedicated isolation amplifier and A-D converter. Then after calibration, upper limb forces data could be real-time monitored and displayed. The dynamometer system adopted some special designs, e.g. string-gauge allocation and redundant-optimized method, to guarantee the reliability and precision of measurements. In this design, force accuracy is higher than 1.01%, nonlinearity is less than 2.901%, and crosstalk is less than 3.188%. A pilot trial from a paraplegic volunteer undergoing normal walking training protocol with FES was given in this study to demonstrate the potential clinical usefulness of this method. The results show that this system may be used as 1) an evaluation index of FES-assisted paraplegic walking efficiency, 2) a control indicator during FES-assisted paraplegic walking training and 3) a feed-back signal to choose an efficient FES pattern and sequence.