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

在本计画中，我们提出一种新的触觉感测装置结构。触觉传感芯片以光功率工作，并在芯片周围发送6个应力分量的光代码。由于感测装置不包括金属线，触觉感测元件和触觉传感器主体的集成过程简单，使得我们能够植入高密度的触觉感测元件，而不会损失感测装置的弹性和韧性。主要研究成果如下：1）介绍了芯片设计和6种应力传感原理，并进行了实验验证。触觉传感芯片由VLSI芯片和附着在其上的弹性结构组成，弹性结构通过其周围的应力而变形。VLSI芯片检测通过弹性结构到达其上的光强度，并且其根据检测到的光强度来检测弹性结构的变形。利用其结构的对称性，通过在VLSI芯片上形成的8个光电探测器检测应力张量的6个分量。2）检测的传感数据用光信号的数字编码发送。我们制作了具有通信功能的VLSI芯片，包括自动为每个传感芯片分配ID。基于CMOS 0.35 μm规则的电路在芯片上占用1mm × 1.4mm，我们确认了10MHz的操作。3）评估了具有足够吞吐量的大量触觉传感元件的能耗。该研究暴露了无线连接需要不可避免的能量消耗，这不适合实际的触觉传感器。这将激发一个新的研究领域的传感芯片之间的通信。

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.