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

Area of Science:

• Robotics
• Materials Science
• Sensor Technology

Background:

• Collaborative robots require advanced safety features.
• Existing sensors often lack the flexibility and durability needed for human-robot interaction.
• The integration of stretchable electronics is crucial for next-generation robotic skins.

Purpose of the Study:

• To design and validate a continuously stretchable and flexible skin sensor for collaborative robotic applications.
• To assess the sensor's accuracy in position and force detection under various conditions, including uniaxial stretch.
• To demonstrate the practical implementation of the sensor in real-world collaborative robotic scenarios.

Main Methods:

• Fabrication of a Poly(dimethylsiloxane) (PDMS) skin sensor doped with Carbon Nanotubes (CNTs).
• Integration of conductive fabric and a simplified five-wire connection to a microcontroller.
• Characterization of sensor accuracy for position estimation (Root Mean Square Error - RMSE) and force detection.
• Testing under uniaxial stretch conditions and evaluation in collaborative control experiments.

Main Results:

• The stationary position estimate achieved an RMSE of 7.02 mm.
• Sensor error remained within ±1.5 mm even under uniaxial stretch.
• The skin sensor consistently triggered an emergency stop command at forces as low as 0.5 N.
• Demonstrated maintenance of a 10 N collaboration force in a collaborative control experiment.

Conclusions:

• The developed stretchable and flexible skin sensor is suitable for collaborative robotic applications.
• The sensor exhibits high accuracy in position and force sensing, maintaining performance under stretch.
• The system offers reliable safety features, such as rapid emergency stop activation, enhancing human-robot collaboration safety.