A Study on A Sensor Skin Using Wire-Free Tactile Sensing Elements Based on Optical Connection

本课题提出了一种新的触觉传感装置结构。触觉传感芯片通过光功率工作，并在芯片周围发送6个应力元件的光码。由于该传感装置不含金属导线，因此触觉传感元件与触觉传感本体的集成过程简单，可以在不损失传感装置弹性和韧性的前提下植入高密度的触觉传感元件。研究结果总结如下：1)给出了芯片设计和应力传感原理，并进行了实验验证。触觉传感芯片由超大规模集成电路芯片和附着在其上的弹性结构组成，该弹性结构受其周围的应力而变形。VLSI芯片通过弹性结构检测到达其上的光强，并从检测到的光强中检测到弹性结构的变形。利用其结构的对称性，通过在VLSI芯片上形成的8个光电探测器来检测应力张量的6个分量。2)将检测到的传感数据以光信号的数字编码发送。我们制作了具有通信功能的超大规模集成电路芯片，包括为每个传感芯片自动分配ID。基于CMOS 0.35 μm规则的电路在芯片上占据了1 mm × 1.4 mm，并确认了10mhz的工作频率。3)评估了具有足够触觉吞吐量的大量触觉传感元件的能耗。本研究暴露了无线连接不可避免的能量消耗，不适合实际的触觉传感器。这将激发传感芯片间通信的新研究领域。

In this project we proposed a new structure of tactile sensing device. The tactile sensing chip operates with optical power, and sends optical codes of 6 stress components around the chip. Since the sensing device includes no metal wire, the integration process of tactile sensing elements and a tactile sensor body is simple that enables us to implant high density of tactile sensing elements without loss of elasticity and toughness of the sensing device. The results of the study are summarized as follows.1) We showed the chip design and the 6 stress sensing principle, and examined it experimentally. The tactile sensing chip consists of a VLSI chip and an elastic structure attached on it that deforms by the stress around it. The VLSI chip detects the light intensity that reaches on it through the elastic structure, and it detects the deformation of the elastic structure from the detected light intensity. Using its symmetry of the structure it detects 6 components of stress tensor by the 8 photo-detectors formed on the VLSI chip.2) The detected sensing date are sent with digital codes of optical signal. We fabricated VLSI chip with communication functions including automatic ID assignment to each sensing chip. The circuit based on CMOS 0.35 μm rule occupied 1 mm by 1.4 mm on the chip, and we confirmed the 10 MHz operation.3) Energy consumption with large number of tactile sensing elements with sufficient throughput for tactile sensing was evaluated. This research exposed wireless connection requires inevitable energy consumption that is not suitable for practical tactile sensor. This will motivate a new research area of communication among sensing chips.