Durable and large-scale soft tactile sensor using CNT-coated porous elastomer and interference reduction Structure

Abstract

The needs of the whole-body soft tactile sensor is emerging as interest in human-robot interactions increase. The whole body soft tactile sensors should be able to cover large area or curved surface because the surface of robotic body can be wide and curved. The durability against to the external force is also required due to the unexpected collision or repeated usage. Many researches have been studied to make whole-body soft tactile sensor. Especially, the piezoresistive method is advantageous for the whole body tactile sensor because of scalability and easy working principle. For example, EIT or wire stitching methods have made it possible to achieve the scalability and durability of the sensor. The piezoresistive type soft sensor has many advantages for whole-body sensing, but it has not been used so much in real application due to bad performances such as large hysteresis and low repeatability. In this thesis, we aimed to make the whole-body soft tactile sensor by improving the performances of piezoresistive type soft tactile sensor with Carbon Nano tube (CNT) coated porous PDMS and interference reduction structure. The CNT-coated porous PDMS shows improved hysteresis, linearity, and repeatability compared with the polymer-conductive filler mixture. The offset drift phenomenon is investigated and its compensating algorithm is proposed. The trench-shape structures reduce the interference between the electrodes to allow for high sensor resolution and accuracy. The sensor was operated by array indexing, and the electrodes were made with conductive fabric to achieve the durability. As a result, it was possible to develop large-scale soft tactile sensor, which has low hysteresis, nonlinearity, and durability.