A group of engineers from Massachusetts Institute of Technology (MIT) have created a robotic system capable of extending its appendages to navigate its environment – much like a plant – and lift objects.

The robot can extend chain-like appendages which can ‘grow’ into different lengths and shapes. These appendages are flexible enough to twist and turn through any route, but they are also rigid enough to support heavy loads (of almost half a kilogram) and manipulate objects. This makes the robots ideal for tasks such as assembling parts in tight, otherwise inaccessible spaces.

Once a task is complete, the robot can retract the appendage and return to its original shape, ready to adapt to the next task.

The robot was inspired by the growth of plants to adapt to their surroundings, transporting liquid nutrients upwards through the plant to create a solid stem gradually. The MIT team’s robot “exhibits the same kind of functionality, at a certain abstract level” as a growing plant; it consists of a gearbox (‘growing point’) which feeds out a chain of 3D-printed blocks which interlock with their neighbours to form a rigid appendage and pulls the loosened chain back in after a task is completed.

Massachusetts Institute of Technology Image credit: Massachusetts Institute of Technology

By locking some units together and leaving others unlocked, the robot can ‘grow’ in certain directions, such as to arrange itself in a curved path around an obstacle.

The researchers hope that arming the robot with tools like cameras, grippers and sensors could allow it to perform maintenance work in spaces which are difficult to access by other means, such as tightening screws deep within an aircraft’s propulsion system.

“Think about changing the oil in your car. After you open the engine roof, you have to be flexible enough to make sharp turns, left and right, to get to the oil filter and then you have to be strong enough to twist the oil filter cap to remove it,” said Professor Harry Asada, a mechanical engineering expert at MIT who has worked to address the “last one-foot problem” - the final task that must be completed by a robot, typically challenging and requiring a distinct set of skills.

Tongxi Yan, who led the project, added: “Now we have a robot that can potentially accomplish such tasks. It can adapt to its environment.”

Many research groups are engaged in efforts to create robots to perform these “last one-foot” tasks, often using soft robotics such as a soft robot composed of thin actuators and ‘artificial muscle’ which can change shape in response to its surroundings and crawl with a caterpillar-like motion.

Asada said that his team’s new plant-inspired robot is unlike soft extendable robots in that it is sturdy enough to support tools like cameras, rendering it capable of carrying out a wider range of tasks at its destination.

“Our solution is not actually soft, but a clever use of rigid materials,” Asada commented.