Preliminary experimental study on the sensing performance of a capacitive tactile sensor array mounted on curved surfaces

In real applications, the capacitive tactile sensor array usually needs to be mounted on curved surfaces. To study the effect of curved surfaces on the sensing performance of the sensor array, we have fabricated the sensor array with 4 × 4 sensor units. Four types of rigid and flexible curved surfaces are selected to mount the sensor array, with radius of curvature of +∞, 40 mm, 30 mm, and 20 mm. The initial capacitances of the sensor array increase as the radius of the surfaces decrease. By applying normal and shear forces to the sensor unit mounted on the curved surfaces, we have found that as the radius of the surface decrease, the capacitance increases faster when the sensor is mounted on 40 mm curved surfaces, and increases slower on 30 mm and 20 mm curved surfaces. The shear forces in the x- and y-axes cause symmetric and asymmetric capacitance changes to the sensor unit, respectively. The flexible curved surfaces can induce larger capacitance changes to the sensor unit, compared with the rigid ones.