Application of improved DFD method based on finite element theory in detection of depth information of tactile sensing

Abstract. Current traditional tactile sensors based on the principles of capacitance or piezoelectricity have complex structures and difficulty in obtaining tactile information. A tactile sensor is introduced which can measure depth information through vision in this paper. The tactile sensor is mainly composed of an elastomer embedded with marker point array, a transparent acrylic plate, 8 LED lamps and a micro monocular camera. The elastomer deforms when the tactile sensor touches an object, and the micro camera is used to capture the elastomer deformation and transmits it to the computer in the form of image. After processed the image, the improved DFD method is used to obtain the depth information. In order to more accurately recover the missing scale information in the depth information detection of the monocular camera, an improved DFD (Depth from Defocus) method based on finite element theory was proposed in this paper. It was verified by comparative experiments that the improved DFD method proposed in this paper can measure the depth information of the marker points embedded in the elastomer more accurately compared with the traditional DFD method. The experimental results show that the depth information measurement method of the marker points proposed in this paper can provide technical support for the design and development of tactile sensors.