German researchers tap smart elastomers to develop soft robots 

Saarland, Germany – Researchers from Saarland University are developing a new generation of robotic tools that employ smart elastomers for intelligent, flexible movements.

The collaborative robot (cobot) arms will have a combination of strong 'muscles' and sensitive 'nerves' created from smart polymeric materials, according to the research team led by the smart materials experts professor Stefan Seelecke and Gianluca Rizzello.

“Our technology is based on smart polymer systems and enables us to create novel soft robotic tools that are lighter, more manoeuvrable and more flexible than the rigid components in use today,” said Seelecke in a 22 June statement. 

The material used for the soft robot arms is 'dielectric elastomer', a special composite polymer known which can be compressed and stretched to regain its original shape. 

“We print electrodes onto both sides of the elastomer material. When we apply a voltage, the two electrodes attract each other, compressing the polymer and causing it to expand out sideways,” explained Rizzello, junior professor for adaptive polymer-based systems. 

The elastomer can thus be made to contract and relax, just like muscle tissue. 

According to Rizzello, the research team exploits this property when designing actuators. 

By precisely varying the electric field, the engineers can make the elastomer execute high-frequency vibrations or continuously variable flexing motions or even remain still in a particular desired intermediate position.

The researchers then combine a large number of these ‘small muscles' to create a flexible robot arm that produces motions that mimic those of an octopus arm. 

According to the research team, the tentacles are free to move in ‘almost any direction’, unlike the heavy, rigid robotic limbs currently in use.

Furthermore, they will be “far lighter” than the robot arms in use today, as they will not be driven by motors or by hydraulic or pneumatic systems and can be powered by the application of an electric current. 

The researchers are using artificial intelligence to control the polymer-based components, making the robotic arm ‘significantly more complex’ than its counterparts today.

“Every distortion of the elastomer, every change in its geometry causes a change in the material's capacitance, which enables the team to assign a precise electrical capacitance value to any specific deformation of the elastomer,” Rizzello explained. 

By measuring the capacitance, he added, the team knows exactly what shape the elastomer has adopted and can then extract sensor data.

The data can then be used to precisely model and programme the motion of the elastomer arm. 

Rizzello's research work is particularly focused on developing intelligent algorithms that can train the tentacles to move and respond in the required manner. 

The team hopes to have the tentacle prototype fully developed in about a year's time.

According to the university of Saarland, the technology will be scalable and can be used to create miniature tentacles for medical instruments or to make large robot arms for industrial applications.