Engineers have come up with a groundbreaking way of combining hard and soft materials in a robot.

Most robots are rigid, metallic devices, a fact that sometimes restricts their complexity, but soft robots are of increasing interest. They are adaptable and resilient, but engineers struggle to make them autonomous because most robotics components are rigid, writes Luigi Lugmayr for i4u.

3D-Printed Soft Robot Hops Around Using Jet Power

Autonomous, soft robot marks real progress in the field

Soft robots are slow and difficult to make, but now engineers at Harvard have developed a robot which combines the characteristics of a rigid robot with those of a soft one. The device is one of the first 3D-printed soft robots which is capable of moving autonomously.

The design was profiled in the journal Science, and offers a great example of the combination of rigid and soft materials in one robot. In order to overcome the issues associated with both kinds of robots, the engineers combined the best of both worlds.

Its body is soft in places before transitioning to harder materials where sensitive components are located. This helps to reduce stress in areas where rigid electronic components join the body, and make the robot more durable.

Components protected by transition from soft to hard materials

The body was 3D-printed in one single job, from various materials, in order to further increase strength, and eliminates joints and cracks where dirt can accumulate.

“The vision for the field of soft robotics is to create robots that are entirely soft, “said senior author Robert J. Wood, Charles River Professor of Engineering and Applied Sciences at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). “But for practical reasons, our soft robots typically have some rigid components — things like batteries and control electronics. This robot is a demonstration of a method to integrate the rigid components with the body of the soft robot through a gradient of material properties, eliminating an abrupt hard-to-soft transition that is often a failure point.”

The robot can control which direction it bounces in, and also deforms in a predictable way on landing, allowing valuable components to be protected. It looks a little like a lampshade-jellyfish cross, and uses a jet propulsion system to move around.

Engineers state that the robot can jump up to six times its own height, while being able to control the direction in which it moves. This capability is down to a trio of deformable legs which inflate to varying degrees in order to adjust the launch direction.

Robotics mimicking nature

The force of impact is soaked up by the rubbery shell, which is made from different materials to prevent the force being transferred directly to the components. In order to do so the 3D printer blends materials “that were mixed at different ratios to form a 9-layer spectrum from completely rigid to completely soft,” explained engineer Nicholas Bartlett.

Nature is full of examples of the benefits of combining hard and soft materials, including the transition from a soft, deformable body to a hard beak in an octopus.

The use of soft materials in robots would allow them to be used in harsh environments, or as part of disaster rescue teams, where their durability would make them more useful than fragile, rigid robots.

Advances in 3D-printing technology are allowing scientists to manufacture robots made from an increasingly wide range of materials, and driving progress in the field.