A Standalone Capacitive Tactile Fingertip Module for Multi-Point Contact Sensing in Robotic Grasping

Area of Science:

• Robotics
• Sensors and Actuators
• Human-Robot Interaction

Background:

• Tactile sensing significantly improves robotic grasping capabilities by offering contact details beyond vision or control signals.
• Integrating tactile sensing into robotic hands faces challenges like wiring, hardware, power, and space limitations.

Purpose of the Study:

• To develop a self-contained, wireless capacitive tactile fingertip module for robotic grippers.
• To enable multi-point contact sensing independent of the robotic hand controller.

Main Methods:

• A 3x1 array of flexible capacitive sensors, a capacitance-to-digital converter, a Bluetooth microcontroller, and a battery were integrated into a fingertip housing.
• Sensors were characterized for linearity and durability over 100 compression cycles up to 2.5 N.
• Proof-of-concept grasping tests were performed with various objects.

Main Results:

• Individual sensors showed near-linear response to normal compression (R² = 0.99) with ~8% capacitance change at 2.5 N.
• The module successfully detected distinguishable capacitance changes indicating contact location and local loading during grasping.
• The system operated wirelessly and independently of the main robotic controller.

Conclusions:

• The developed module demonstrates the feasibility of implementing wireless tactile sensing in robotic grippers.
• This compact, standalone solution addresses limitations of traditional tactile sensing systems.
• The technology offers a pathway to more sophisticated and adaptable robotic manipulation.