High precision intelligent flexible grasping front-end with CMOS interface for robots application

Abstract

This paper presents a high-precision intelligent flexible robot grasping front-end with an integrated capacitive tactile sensor array and a conditioning chip. The capacitive tactile sensor is the primary part of the front-end, it determines the overall performance. The micro-needle array sandwich structure in the tactile sensor increases the repeatability and stability, and ensures the sensitivity. The assembled sensor exhibits a saturation at 10.53 N (421 kPa) with a sensitivity of 1.9%/kPa. Furthermore, a conditioning chip is utilized in a custom readout interface to achieve better performance by reducing signal attenuation, and to increase the compatibility of the front-end. The chip is optimized for the parasitic shunt capacitance in the capacitor array. A dual bidirectional charge-discharge conversion method and a two-port detection method are matched to achieve the goal of reducing the shunting influence, and attenuating the offset voltage or the noise input effects. A prototype of the interface has been fabricated using 180-nm CMOS technology. Sensor with the value of 0.5 pF shunted by capacitors of 47 pF has been detected with an error of 1% within 100 μs.

摘要

创新点

本文提出了一种应用于高精机器人应用的高灵敏度的柔性抓握前端。 该前端集成了电容传感器和调理芯片。 其中, 电容传感器是柔性抓握前端的主体, 它决定了整体的性能。 夹杂在两电容极板间的微针阵列结构提升了器件的可重复性、稳定性和灵敏度。 键合后的器件在10.53N(421kPa)压力输入时呈现饱和, 灵敏度为1.9%/kPa。 同时, 前端中搭配了专用的调理芯片以达到更好的性能和更高的集成度。 芯片针对电容阵列中不可消除的寄生电容效应做了专门处理。 本文中将双模双向充-放电方法和两端检测方式匹配, 来实现寄生电容的消减。 该方案对输入失调电压和输入噪声电压的消减也十分有效。 芯片在180 nm CMOS工艺条件下流片验证。测试结果显示, 0.5pF的电容在47pF寄生电容的影响下误差仅为1%。