These 3D-Printed TPU "Soft Skin" Pads Give Robots a Low-Cost, Highly-Sensitive Sense of Touch

Researchers from the University of Illinois Urbana-Champaign have come up with a low-cost way to give robots a human-like sense of touch: 3D-printed soft skin pads that double as mechanical pressure sensors.

"Tactile robotic sensors usually contain very complicated arrays of electronics and are quite expensive, but we have shown that functional, durable alternatives can be made very cheaply," explains Joohyung Kim, project lead and professor of electrical and computer engineering, of the team's breakthrough. "Moreover, since it's just a question of reprogramming a 3D printer, the same technique can be easily customized to different robotic systems."

"Robotic hardware can involve large forces and torques, so it needs to be made quite safe if it's going to either directly interact with humans or be used in human environments," Kim adds. "It's expected that soft skin will play an important role in this regard since it can be used for both mechanical safety compliance and tactile sensing."

The team's sensor is made using pads printed from thermoplastic urethane (TPU) on an off-the-shelf Raise3D E2 3D printer. The soft outer layer covers a hollow infill section, and as the outer layer is compressed the air pressure inside alters accordingly — allowing a Honywell ABPDANT005 pressure sensor connected to a Teensy 4.0 microcontroller to detect vibration, touch, and increasing pressure.

"Imagine you want to use soft-skinned robots to assist in a hospital setting," Kim supposes of a potential use-case for the technology. “They would need to be regularly sanitized, or the skin would need to be regularly replaced. Either way, there's a huge cost. However, 3D printing is a very scalable process, so interchangeable parts can be inexpensively made and easily snapped on and off the robot body."

The team's work has been published in the IEEE Transactions on Robotics under open-access terms.