Cylindrical tactile sensor for a robot hand using position sensitive detectors on a suspension shell

In this paper, we propose a cylindrical tactile sensor for robot hands that can simultaneously detect the contact angle, contact location, and magnitude of the contact force. This sensor consists of an inner frame with light sources and an outer shell to which two position sensitive detectors (PSDs) are fixed; the concentric outer shell and inner frame are separated by two elastic rings. Since each two-dimensional PSD is installed on the same cross section as an elastic ring, the output of a PSD directly corresponds to displacement of an elastic ring. Based on experiments performed on a prototype, we found that values for contact angle, contact location, and magnitude of the contact force could be obtained with good accuracy from simple mathematical expressions. Consequently, this cylindrical tactile sensor is considered to be effective as a tactile sensor for robot hands.