ISSN   1004-0595

CN  62-1224/O4

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仿生六边形精细纹理的触感深度阈值研究

Depth Recognition Thresholds of Tactile Perception for Fine Texture of Bionic Hexagonal

  • 摘要: 六边形纹理是自然界中动物体表常见的1种纹理形式,具有良好的摩擦学性能. 本文中利用认知行为学、摩擦学和脑电图法从皮肤的“感”到大脑的“知”,系统研究了微米级仿生六边形纹理深度和方向特征对触觉感知深度阈值的影响,利用单通道触感神经元群模型初步验证了纹理刺激强度和神经元兴奋性对触觉感知的影响. 研究结果表明:随着纹理深度的增大,六边形纹理的主观纹理感和识别率提高、黏着摩擦分量减小、形变摩擦分量增大、振动信号频谱主频和主频最大振幅增大,当纹理深度达到触感阈值时,形变摩擦比例和振动信号主频振幅显著增大;纹理深度达到触感阈值深度后才能激发脑电事件相关电位(Event-related potentials, ERP)的P100和P200早期成分. 从平端方向触摸产生的形变摩擦力分量和振动信号的主频幅值大于尖端方向触摸,平端方向触摸更容易感知到纹理. 平端方向触摸激发触感脑电ERP曲线的P300成分幅值较沿尖端触摸更高,潜伏期更短. 单通道神经元模型结果显示沿平端方向触摸的仿真脑电信号输入函数均值和信号幅值均高于沿尖端方向触摸,说明平端触摸产生的触感机械刺激增强是脑电信号主频幅值增大的原因之一.

     

    Abstract: Appropriate design of surface texture can contribute to the sensitivity of tactile perception, grasp reliability and touch comfort. Hexagonal texture is a common texture found on animal body surfaces in nature. The bionic hexagonal textures exhibited good tribological and adhesion properties. At present, the formation and conduction pathways of human tactile sensation as well as the tactile perception of textured surface have been systematically studied. However, little studies elucidated the correlation between skin friction as well as vibration features and brain activity during tactile perception of fine textures. Therefore, in this paper, the effects of depth and touching direction of micron-sized bionic hexagonal textures on the depth recognition threshold of tactile perception were systematically investigated based on subjective evaluation, skin friction and vibrations, and neurophysiological response of the brain. The influence of intensity of texture stimuli and neuronal excitability on tactile perception were verified using a single-channel neural mass model. The results showed that as the texture depth increased, the subjective texture sense and recognition rate of the hexagonal texture increased. Also, the adhesive friction component decreased and deformation friction component increased with the increase of texture depth. The vibration features during tactile friction were extracted, and the results showed that the dominant frequency of the vibration signal spectrum and the maximum amplitude increased with the increase of texture depth. As the texture depth reached the recognition threshold for tactile perception, the deformation friction component and the amplitude of the dominant frequency was increased significantly. The texture depth reached the tactile recognition threshold depth before the P100 and P200 components of the ERP curves were excited. The depth of bionic hexagonal texture was observed significantly positively correlated with P300 amplitude and negatively correlated with P300 latency. The dominant frequency amplitude of vibration signals and the deformation friction component generated from touching along the flat direction was larger than that of touching along the tip direction. It suggested that the bionic hexagonal texture was more easily perceived during touching along the flat direction. The P300 amplitude of ERP curves excited by touching along the flat direction was higher, and the latency was shorter. It indicated that the process of brain was faster and more attentional resources were involved in tactile perception during touching along the flat direction. The neural mass model showed that the input and amplitude of the simulated EEG signals for touching along the flat direction were lager than those for touching along the tip direction, suggesting that the enhancement of tactile stimulation produced by touching along the flat direction is one of the reasons for the increase in the amplitude of the dominant frequency of the EEG signals.

     

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