The design and validation of a continuously stretchable and flexible skin sensor for collaborative robotic applications is outlined. The skin consists of a PDMS skin doped with Carbon Nanotubes and the addition of conductive fabric, connected by only five wires to a simple microcontroller. The accuracy is characterized in position as well as force, and the skin is also tested under uniaxial stretch. There are also two examples of practical implementations in collaborative robotic applications. The stationary position estimate has an RMSE of 7.02 mm, and the sensor error stays within 2.5±1.5 mm even under stretch. The skin consistently provides an emergency stop command at only 0.5 N of force and is shown to maintain a collaboration force of 10 N in a collaborative control experiment.
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Acknowledgments: The authors would like to thank Wade Eichhorn and 7-SIGMA Inc. (Minneapolis, MN, USA) for donating their CNT-PDMS conformable sensor technology and related supplies. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. We are indebted to Chris Frethem for his invaluable assistance at this facility. John O’Neill and Rodney Dockter were supported by the University of Minnesota Informatics Institute Graduate Fellowship under Minnesota’s Discovery, Research, and InnoVation Economy (MnDRIVE) program. Rodney Dockter was also supported by the University of Minnesota’s Interdisciplinary Doctoral Fellowship.
- Collaborative control