Robohub.org
 

Creating a synthetic “second skin” with soft pneumatic actuators


by
17 February 2016



share this:
Print

Photos courtesy: RRL, EPFL and NCCR Robotics

Soft pneumatic actuators (SPAs) are an up and coming solution to the contradictory design criteria that many robotic systems have – high torque/force often means greater weight and volume, which is impractical and often specifically against the purpose of wearable robots. Taking the principles of pneumatic artificial muscles (PAMs) which have been used for powering orthoses since the 1960s, SPAs are a soft solution for creating a bending motion while not being limited to a single direction of movement, and as such can be used for a wider range of applications.

Orthoses (exoekeletons) used for training to regain movement in patients after stroke suffer from a number of common problems; they are uncomfortable and bulky and thus have not yet been integrated into common usage. To make a truly practical device that is useable on a day-to-day basis, tactile interfaces on the surface need to be lightweight, compliant, safe and have multiple points of sensing and actuation. A team from RRL, EPFL and NCCR Robotics presents a Soft Pneumatic Actuator (SPA)-skin embedded with piezo electric (PZT) sensors to tackle these problems and provide vibrotactile feedback.

SPA-based skin allows bidirectional tactile information transfer to facilitate simpler and responsive wearable interface. By creating an interface made from SPAs and designed to be worn over the skin, it is possible to create a synthetic “second skin” that is thin, lightweight and flexible, meaning that sensors can be placed across all points of the hand (like nerves across your skin) but when the wearer bends their hand, the skin and the integrated tactile feedback system both follow it.

Print

Photos courtesy: RRL, EPFL and NCCR Robotics

SPA-skin is made of two layers, a lower sensor layer and an upper actuator layer. The actuator layer is made of two silicone sheets with a mask between them to prevent the layers sticking. The final design is 1.4 mm-thick including the integrated sensor layer. To create actuation (or movement) air is pumped into a 3-4mm diameter bubble between the layers, which creates forces of up to 0.3N, which may sound small, but is comparable to pressures experienced by the human hand on a daily basis. The sensor layer is created using piezoelectric ceramic elements embedded into silicone sheets which convert mechanical stress (the pressure exerted by touching something) into an electrical voltage. This voltage is then used to measure the strength of vibrations that come from both the actuator and the external interaction forces faced by SPA skin.

Print

Photos courtesy: RRL, EPFL and NCCR Robotics

The presented SPA-skin produces vibrotactile feedback (a vibration is initiated to facilitate haptic feedback) over a range of frequencies. Sensors embedded inside can detect vibrations from actuators at the same time as external interaction forces applied by something touching the skin. This measured sensor information is then used to actively control vibration strength from the actuators. In other words, the “skin” can detect that it is touching something, and also, modulate the vibration accordingly so that the sense of feeling (the haptic sensation) is consistent.

SPA-skin provides a highly customisable and a wearable physical interface with facility of the closed-loop control for multiple vibrotactile signals. It may find uses anywhere that requires a wearable device for vibrotactile feedback across the human body. As described above, it can be used as a plug and play component for a feedback mechanism in rehabilitation devices for training patients with loss of movement e.g. after stroke, or for providing a sense of touch in virtual reality games.

Reference

H.A. Sonar and J. Paik, “Soft Pneumatic Actuator Skin with Piezoelectric Sensors for Vibrotactile Feedback“, Frontiers in Robotics and AI, doi:10.3389/frobt.2015.00038



tags: ,


NCCR Robotics





Related posts :



Robot Talk Episode 126 – Why are we building humanoid robots?

  20 Jun 2025
In this special live recording at Imperial College London, Claire chatted to Ben Russell, Maryam Banitalebi Dehkordi, and Petar Kormushev about humanoid robotics.

Gearing up for RoboCupJunior: Interview with Ana Patrícia Magalhães

and   18 Jun 2025
We hear from the organiser of RoboCupJunior 2025 and find out how the preparations are going for the event.

Robot Talk Episode 125 – Chatting with robots, with Gabriel Skantze

  13 Jun 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Gabriel Skantze from KTH Royal Institute of Technology about having natural face-to-face conversations with robots.

Preparing for kick-off at RoboCup2025: an interview with General Chair Marco Simões

and   12 Jun 2025
We caught up with Marco to find out what exciting events are in store at this year's RoboCup.

Interview with Amar Halilovic: Explainable AI for robotics

  10 Jun 2025
Find out about Amar's research investigating the generation of explanations for robot actions.

Robot Talk Episode 124 – Robots in the performing arts, with Amy LaViers

  06 Jun 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Amy LaViers from the Robotics, Automation, and Dance Lab about the creative relationship between humans and machines.

Robot Talk Episode 123 – Standardising robot programming, with Nick Thompson

  30 May 2025
In the latest episode of the Robot Talk podcast, Claire chatted to Nick Thompson from BOW about software that makes robots easier to program.

Congratulations to the #AAMAS2025 best paper, best demo, and distinguished dissertation award winners

  29 May 2025
Find out who won the awards presented at the International Conference on Autonomous Agents and Multiagent Systems last week.



 

Robohub is supported by:




Would you like to learn how to tell impactful stories about your robot or AI system?


scicomm
training the next generation of science communicators in robotics & AI


©2025.05 - Association for the Understanding of Artificial Intelligence


 












©2025.05 - Association for the Understanding of Artificial Intelligence