人工电触觉反馈对手抓握力的影响

目的:为了给受试者提供触觉反馈来完成抓取力的闭环控制,提出各种方法和相应的控制策略,以探究触觉反馈对手抓握力的影响,为假肢手的研究提供参考。方法:主要根据动态系统的输出特性提出了四类考察变量(三种失败次数、完成时间、握力的均值和握力的标准差),以及稳定性、快速性和经济性指标,依据上述准则来比较基于经皮电刺激的触觉反馈和无反馈对于控制握力的影响。结果:对于三种失败次数,无反馈模式下的表现均高于触觉反馈模式,尤其是在由摔碎和捏碎引起的失败次数上,无反馈模式下的结果分别为4.3次和4.9次,而电触觉反馈模式下的结果仅为0.6次和0.5次。对于反映时间,无反馈模式下的受试者完成实验的时间为26.4s,而在电触觉反馈模式下,受试者仅用17.7s。在对6个物体的抓取中,电触觉反馈下的握力始终小于无反馈模式下的结果。触觉反馈模式下的等效握力的稳定性要高于无反馈模式下的结果。结论:经皮电刺激的触觉反馈在四类考察变量以及3种目标上均优于无反馈,提示经皮电刺激的触觉反馈对于假肢手握力控制的重要性。随着物体重量的增加,无反馈和经皮电刺激的触觉反馈下抓取力的经济性和稳定性差异逐渐的减小。

Influence of artificial electrotactile feedback on hand grasping closed-loop control

Abstract Objective: To provide subjects with tactile feedback to perform the grasping closed-loop control, by various methods and control strategies, to provide the reference for the study on prosthetics. Method: Based on the output characteristics of dynamical systems, four types of assessment variables were proposed, including failure numbers, duration time, average grasping force and its standard deviation. Besides, three goals were also set, which were grasping stability, grasping rapidity and economical grasping force. According to the assessment variables and goals, difference between the influences of tactile feedback on grasping force and that of non-feedback were investigated. Result: The failure number in the modalities of non-feedback were always higher than that in the modalities of tactile feedback. Specially, for the number of broken objects and crushed objects, the modalities of non-feedback were 4.3 and 4.9, respectively, but the modalities of tactile feedback were 0.6 and 0.5, respectively. For the duration time, it were 26.4s in modalities of non-feedback and 17.7s in modalities of tactile feedback. For the six objects, the grasping force in the modalities of tactile feedback were always lower than that in the modalities of non-feedback. And the standard deviation of grasping force in the modalities of tactile feedback were also lower than that in the modality of non-feedback. Conclusion: For the 4 kinds of assessment variables, the performance of tactile feedback is better than that of non-feedback. It means that tactile feedback plays an important role in the grasping closed-loop control. Besides, the difference of grasping stability and economical grasping between tactile feedback and non-feedback show steady decrease.