Stretchable, Flexible, Scalable Smart Skin Sensors for Robotic Position and Force Estimation

John O'Neill; Jason Lu; Rodney Dockter; Timothy Kowalewski

doi:10.3390/s18040953

Stretchable, Flexible, Scalable Smart Skin Sensors for Robotic Position and Force Estimation

Sensors (Basel). 2018 Mar 23;18(4):953. doi: 10.3390/s18040953.

Authors

John O'Neill¹, Jason Lu², Rodney Dockter³, Timothy Kowalewski⁴

Affiliations

¹ Department of Mechanical Engineering, University of Minnesota, 111 Church St SE, Minneapolis, MN 55401, USA. oneil463@umn.edu.
² Department of Mechanical Engineering, University of Minnesota, 111 Church St SE, Minneapolis, MN 55401, USA. luxxx544@umn.edu.
³ Department of Mechanical Engineering, University of Minnesota, 111 Church St SE, Minneapolis, MN 55401, USA. dockt036@umn.edu.
⁴ Department of Mechanical Engineering, University of Minnesota, 111 Church St SE, Minneapolis, MN 55401, USA. timk@umn.edu.

Abstract

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.

Keywords: collaborative control; robotics; skin; stretchable.