In this work we introduce a non-planar soft high-resolution tactile sensor. An iteration of the GelSight sensors, it enables future GelSights to have more complicated form factors, such as a humanoid fingertip. To do this we introduce a novel method for achieving directional lighting along the entirety of a curved sensor using light piping. Light piping uses total internal reflection and a semi-specular membrane to constrain the path of the light inside the sensor until the sensing membrane is deformed. By using this new membrane and changing the geometry, we introduce a new bidirectional reflectance distribution function and new optics. This require new calibration procedures in the form of developing a fisheye projection model, and developing a neighborhood and location based continuous look-up table to map the relationship between RGB value and surface normal orientation of the membrane at a point. Finally we perform two dexterous manipulation task with feedback from the sensors in the form of controlled rolling of an object on a support surface, and lid removal off a jar. We also give instructions on how to manufacture the sensor as well as increasing the durability of the membrane for all GelSight sensors.

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We describe the grasping and manipulation strategy that we employed at the autonomous track of the Robotic Grasping and Manipulation Competition at IROS 2016. A salient feature of our architecture is the tight coupling between visual (Asus Xtion) and tactile perception (Robotic Materials), to reduce the uncertainty in sensing and actuation. We demonstrate the importance of tactile sensing and reactive control during the final stages of grasping using a Kinova Robotic arm. The set of tools and algorithms for object grasping presented here have been integrated into the open-source Robot Operating System (ROS).