Rutgers engineers design a small, squishy robotic vehicle

Rutgers University engineers have challenged the traditional, rigid design of robotic vehicles by using unique materials to create soft components.

A soft, four-wheeled robotic vehicle powered by a unique soft engine developed by Rutgers University engineers. Photo courtesy of Xiangyu Gong

The small, squishy vehicle comes complete with soft wheels and axle assembly that allows the vehicle to traverse over tough terrain and run underwater.

The most important innovation is a soft motor that provides torque without bending or extending its housing, said Aaron D. Mazzeo, assistant professor in the Department of Mechanical and Aerospace Engineering, who coauthored the study.

The addition of these components in soft robotics enables vast improvement in the manipulation and mobility of devices, explains Mazzeo.

“If you build a robot or vehicle with hard components, you have to have many sophisticated joints so the whole body can handle complex or rocky terrain,” adds Xiangyu Gong, who earned a master’s degree in mechanical engineering at Rutgers in 2015 and is now a doctoral student at Rensselaer Polytechnic Institute in Troy, New York. “For us, the whole design is very simple, but it works very well because the whole body is soft and can negotiate complex terrain.”

To create the vehicle, the Rutgers engineers used silicone rubber that is nearly 1 million times softer than aluminum, Mazzeo said. Its softness is somewhere between a silicone spatula and a relaxed human calf muscle. The motors were created through 3D printed molds and soft lithography.

The soft vehicle includes many unique features and future versions of the robot will be able to expand beyond what anyone thought was capable.

One of the key innovations is the development of motor rotation without bending.

“It’s actually remarkably simple, but providing torque without bending is something we believe will be advantageous for soft robots going forward,” Mazzeo said.

Other features include a unique wheel and axle configuration that is not found in nature. The soft wheels may allow for passive suspensions in wheeled vehicles. The wheels use a process called peristalsis—the process humans use to push food to the stomach through the esophagus.

The vehicle offers a consolidated wheel and motor with an integrated “transmission”. The motor itself is soft and metal-free, which makes it more suitable for harsh environments with electromagnetic fields.

All of these components give the robotic vehicle unique capabilities, like the ability to handle and absorb significant impacts. The vehicle was tested and survived a fall eight times its height. The team also boasts that the soft vehicle has the ability to brake motors and hold them in a fixed position without the need for extra power.

The team is extremely hopeful when it comes to future applications. The creators suggest that this might be a versatile vehicle suitable for search and rescue missions, deep space and planet exploration and manipulating objects during magnetic resonance imaging (MRI).

“We think these robots also would be useful for working around children or animals, and you could envision them being helpful in hospitals,” Mazzeo said. “There are opportunities also for toys and for creating educational science or engineering kits.”

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