Tactile Sensing For Sensible Robotics

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Grasping and manual interaction for robots so far has largely been approached with an emphasis on physics and control aspects. At the Center of Excellence “Cognitive Interaction Technology” (CITEC) we strive for a deeper understanding of the wider field of “manual intelligence” as a perspective for manual action research that brings the cognitive nature of human manual skills to the foreground. On the one hand we observe humans when manipulating objects in order to understand the underlying principles of manual motion generation. On the other hand we transfer the gained knowledge to artificial, bi-manual robot systems to validate our models and to endow robots with similar dexterous manipulation capabilities. A major prerequisite for successful object manipulation are highly sensitive tactile sensors providing force feedback at our fingertips, allowing us to sense incipient slippage of grasped objects and to distinguish textures and materials. Hence, it is a major research goal to develop “artificial skins”, i.e. flexible tactile sensing arrays, to imitate this major human sensor modality for robots. Our research into this direction follows two objectives: providing tactile sensors for (i) human motion analysis, thus augmenting classical motion tracking with force information, and for (ii) robotic usage to explore control mechanisms and feature extraction methods based on tactile feedback.

Myrmex: modular high speed sensor
• 16•16 arrays, sized 80•80mm • connectable to larger sensor areas • as end-effector: (large) fingertip • as tactile-sensitive book, table, … • 5mm spatial resolution • up to 1.9 kHz frame rate

Intelligent Object
• cylindrical object (like a soda can) • with motion and tactile sensors • 6D accelerometer, 3D compass • 10•2•11 tactile sensor array • 10mm spatial resolution • up to 250 Hz frame rate • Bluetooth wireless connection • modular tool attachment

Tactile Sensor Pen
• fabrics-based, flexible tactile sensor • measuring grip forces holding a pen • for ergotherapy of children improving stance and type face

Incipient Slip Detection and Grasp Force Adaptation
• incipient slippage generates micro-vibrations at ca. 400 Hz • further amplified by human papillary ridges • slip classificator can be trained based on Fourier Power Spectrum • provides basis for adaptive grasp force controller • increase grasp force at slippage • decrease slowly otherwise • results in grasp force at the edge of slippage and stable grasping

Tactile Sensor Properties
• resistive sensing principle • beneficial hyperbolic characteristic curve • high immunity to noise and abuse • various conductive sensor materials available: foam, fabrics, rubber • high sensitivity + wide measurement range

Contact:
Dr. Robert Haschke, CITEC, Bielefeld University