All-in-type optical three-axis tactile sensor

The optical three-axis tactile sensor was developed to allow a robot to sense three-axis force distribution caused by touch. Although we have accomplished several manipulation tasks using a robot equipped with optical three-axis tactile sensors, the sensor has some problems related to compactness and insensible zone. The former problem is more serious for robotic manipulation and is caused by usage of external devices. In this study, we designed and developed an all-in-type three-axis tactile sensor, which includes all devices required for this sensor in its casing. Furthermore, this sensor features a rubber dome structure rather than the previous aluminum dome. Not only is this tactile sensor equipped with all devices on the inside, it also reduces the insensible zone and enlarges measurable range of force. In the design of the tactile sensor, we miniaturized its whole structure through adoption of a CMOS board camera equipped with LEDs. Since a USB is installed in the CMOS camera as an interface, an additional image processing board is not required. In evaluation experiments, although this sensor shows considerable non-linear characteristics, it possesses sufficient sensitivity and acceptable force range for both normal and tangential forces.