Realization of Static Friction Sensing Mechanism by A Use of Artificial Skin

本研究的目的是通过开发具有机械结构和相当于人体皮肤的传感功能的人造皮肤来实现静摩擦感觉机制。首先，模仿人类手指的结构特征：在硅橡胶表面塑造脊，形成具有宏观曲率的形状。一对相对的PVDF或应变片作为人工迈斯纳小体嵌入脊状结构中。采用具有上述期货的人造皮肤进行以下研究。首先，研究了PVDF电路系统的幅值特性，发现其具有一阶（应力速率）和三阶（应力跳变）频率特性，并在两者之间有一个断点。其次，源自两种薄膜中的任意一种的差分PVDF电路输出产生低频信号波形模式，表示初始滑移的迹象，随后是更高频率的滑移序列信号。所得结果与有限元法对初滑动特性分析的仿真结果相一致。第三，验证了当物体在皮肤表面滚动时，不会出现这样的特征信号序列。此外，我们通过两指手的抓握力控制来证明早期滑移信息的有效性，无论物体的重量和表面粗糙度如何。从上述结果中，我们得出结论，一对人工迈斯纳小体的差分输出的早期滑移检测在静摩擦传感机制中发挥了主要作用。

The objective of the study was to realize static friction sensation mechanism by developing artificial skin with mechanical structure and a sensing function equivalent to those of human skin.To begin with, structural features of a human finger were imitated: Ridges were molded on a silicone rubber surface, and the shape was formed to have a macroscopic curvature. A pair of PVDF or strain gauge film sheets confronting each other were embedded in a ridge as artificial Meissner corpuscles. Artificial skin with the above futures was used to conduct the following studies.First, the amplitude characteristic of the PVDF circuit system was examined to have a combined first-order (stress-rate) and a third-order (stress-jerk) frequency characteristics with a breakpoint in between the two. Second, the differential PVDF circuit output originating in either one kind of two film sheets generated a low frequency signal wave form pattern indicating the sign of an incipient slip, which was followed by higher frequency slip sequence signals. The results cohered with a simulation result of dynamic behavior analysis for an incipient slip using FEM.Third, it was verified that such a characteristic sequence of signals did not appear when an object rolled on the skin surface. Moreover, we demonstrated the effectiveness of the incipient slip information through grasping force control of a two-fingered hand to hold an object regardless of the weight and the surface roughness.From the above results, we conclude that incipient slip detection with a differential output from a pair of artificial Meissner corpuscles fulfils a main role of the static friction sensing mechanism.