I. Introduction
Tactile sensors, which can be used to recognize various object properties such as material, roughness, texture, friction, or compliance, play very important role for robot perception and manipulation in dynamic or unknown environment [33], [46], [52]. There was a lot of work which adopted the tactile sensors for robotic applications, such as grasp stability judgement [4], slippage detection [12], object localization [23], [44], tactile serving [57], and 3-D reconstruction [54]. For a detailed survey, please refer to [28].