Development of a Flexible 3-D Tactile Sensor System for Anthropomorphic Artificial Hand

Abstract

In this paper, we report a novel flexible tactile sensor array for an anthropomorphic artificial hand with the capability of measuring both normal and shear force distributions using quantum tunneling composite as a base material. There are four fan-shaped electrodes in a cell that decompose the contact force into normal and shear components. The sensor has been realized in a 2 × 6 array of unit sensors, and each unit sensor responds to normal and shear stresses in all three axes. By applying separated drops of conductive polymer instead of a full layer, cross-talk between the sensor cells is decreased. Furthermore, the voltage mirror method is used in this circuit to avoid crosstalk effect, which is based on a programmable system-on-chip. The measurement of a single sensor shows that the full-scale range of detectable forces are about 20, 8, and 8 N for the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> -, <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> -, and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> -directions, respectively. The sensitivities of a cell measured with a current setup are 0.47, 0.45, and 0.16 mV/mN for the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> -, <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> -, and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> -directions, respectively. The sensor showed a high repeatability, low hysteresis, and minimum tactile crosstalk. The proposed flexible three-axial tactile sensor array can be applied in a curved or compliant surface that requires slip detection and flexibility, such as a robotic finger.