A New Silicone Structure for uSkin—A Soft, Distributed, Digital 3-Axis Skin Sensor and Its Integration on the Humanoid Robot iCub

Abstract

Tactile sensing is one important element that can enable robots to interact with an unstructured world. By having tactile perception, a robot can explore its environment by touching objects. Like human skin, a tactile sensor that can provide rich information such as distributed normal and shear forces with high density can help the robot to recognize objects. In previous work, we introduced uSkin, a soft skin with distributed 3-axis force-sensitive elements and a center-to-center distance between the 3-axis load cells of 4.7 mm for the flat version. This letter presents a new structure for the distributed soft force transducer that reduces the crosstalk between the components of the 3-axis force measurements. Three dimensionally (3-D) printing the silicone structure eased the prototype production. However, the 3-D printed material has a higher hysteresis than the previously used Ecoflex. Microcontroller boards originally developed for the skin of iCub were implemented for uSkin, increasing the readout frequency and reducing the space requirements and number of wires. The sensor was installed on iCub and successfully used for shape exploration.