Capacitive Tactile Sensor for Angle Detection and Its Accuracy Study

This paper proposes a capacitive tactile sensor for applications in normal force, shear force, and xy-plane shear angle sensing. This tactile sensor enabled shear force angle detection with less than 3° tolerance to be realized for the first time. The average sensitivity when applying the normal force was 4.43 pF/N, and the average sensitivity when applying the shear force ranged between 0.13 and 0.85 pF/N, depending on the angle. Angle detection errors caused by planar-, rotational-, and vertical-pattern shifts during the lamination process and operation are detailed. The results of an analysis indicated that both the planar and rotational shift greatly contributed to detection errors, whereas the contribution of the vertical shift was negligible. In addition to the experiment and analysis, simulations were performed to prove that the angle detection methodology yields consistent results in theory and in practice.