Robots with silicone muscles could help disabled, elderly

Robots with muscle-like actuators made of silicone rubber elastomers have been created by roboticists in Switzerland.

The team from the École Polytechnique Fédérale de Lausanne (EPFL) is developing soft, flexible, and reconfigurable robots using the actuators. These would be used on the human body in order to help people suffering from impaired movement move around more easily.

Such malleable, air-actuated, materials could potentially be used in powered exoskeletons or exosuits, replacing rigid materials most often utilised.

According to researcher Matthew Robertson, "if you only deal with rigid materials or heavy metal materials, you can imagine having something like that tight against your body, it doesn't really give or take if you push against it too far. With these materials you can push without hurting yourself in the process. If it applies the force in the wrong direction then you don't cause any unwanted injury."

The 'robots' are controlled by changing the air pressure in specially designed 'soft balloons', which serve as the robot's body.

When the pressurised air fills each balloon it inflates in the direction required. A modular system, it can be moved around the body to where physical support is needed.

As part of their research the team has designed a belt made of multiple inflatable components for potential use on stroke patients, holding them upright during rehabilitation exercises and guiding their movements.

"For physical therapy and rehabilitation the belt acts as a wearable therapist, in a sense, to guide you through some exercises to help strengthen your upper body," Robertson told Reuters. "Stroke patients often have asymmetry where they lean towards one side and it could be used to correct that asymmetry. If you're using it to restore gait, the belt could do the job of providing the support for your upper body."

The belt's soft actuators consist of pink rubber and transparent fishing line. The placement of the latter guides the modules' deformation precisely when air is injected. Currently the belt is hooked up to a system of external pumps, but Robertson hopes it could soon become miniaturised and placed directly on the belt.

A predictive model designed by researcher Gunjan Agarwal can be used to carefully control the mechanical behaviour of the robots' various modules. Her research was published recently in Nature - Scientific Reports.

Director of EPFL's Reconfigurable Robotics Lab (RRL), Jamie Paik, said soft silicones were an ideal material for such products.

"Soft silicones allow us to address the difficulties when we cannot address active degrees of freedom on rigid robots. Instead of controlling them, because of the material characteristics they move as they are intended to," said Paik.

The potential for soft actuators doesn't rest solely with the infirm. Adaptable robots capable of navigating cramped, hostile environments, could be designed. On a more basic level, they could be used with people who suffer lower back pain.

According to Paik, "we can foresee a new type of technology being brought closer to our daily lives. When I say that, it's not us trying to bring in Terminator into everyone's home, but to bring in different types of technology that enable us to live healthier and with more comfort."

Paik believes that because the material and manufacturing process is mass produceable, the cost will be relatively low.

In a separate RRL project, using similar silicone material, pulsating actuator skin that provides haptic feedback to the user has been developed by researcher Harshal Sonar. This pneumatic silicone skin contains integrated electric sensors whose frequencies can be controlled by the user.

"We can use this kind of feedback for creating augmentary feedback for people who are suffering from stroke or paraplegia, so that they have information about something else happening on their wearable exoskeleton to the body parts where they have feelings," said Sonar. "The information can be incorporated in terms of the variation of frequency or amplitude, like a travelling wave. Apart from that we can generate a wearable glove for virtual reality platform, so that when you wear it you can not only hear or see whatever is happening in front of you, but you can actually feel them."

Various electronics companies are looking to tackle the problem of an ageing population. In 2014 Panasonic showed off its robot machine that literally lifts people up, via an attached vest worn by the user. The RRL team thinks its technology will give the elderly more autonomy than such products. — Reuters