Fingertip Tactile Sensor With Single Sensing Element Based on FSR and PVDF

The fingertip sensor is essential for the closed loop control of prosthetic hand, while the development of a tactile sensor with a balance in the cost and performance is still a challenge. This paper presents the development of an anthropomorphic fingertip sensor for prosthetic hands. The structure of our sensor mainly consists of a force sensing resistor (FSR) sensor module and a polyvinylidene fluoride (PVDF) sensor module. The PVDF sensor module is made up of a circular truncated cone shaped PVDF film that wrapped in a polydimethylsiloxane (PDMS) substrate. The PVDF sensor module plays two roles in the tactile sensing task. First, the dynamic low frequency response of the PVDF is used for dynamic contact point estimation. Second, the high frequency response of the PVDF is used for texture recognition. An FSR sensor module is used for static force measuring. Experimental results show that the sensor has a good performance in contact force measuring, contact point estimation, and texture recognition. The force measurement error of normal force is less than 5% at the most sensitive subareas, and the sensor is capable of distinguishing five subareas of the sensitive part at an accuracy over 96%. It also can recognize five different textures with an accuracy of 94.1%±0.7%.