Once upon a time, robots were imagined as human-like machines with a distinct body complete with head, arms, hands, feet, and legs. More recently, designers have explored the benefits of emulating other creatures and their capabilities, with robots that can fly like birds, run like cheetahs, swim like a squids or, in this case, slither like snakes. Researchers at MIT's Computer Science and Artificial Intelligence Lab (CSAIL) have come up with a single 3D printed, soft-shelled tentacle that is designed to navigate through all manner of pipes, channels, and burrows.
The snake is proving to be a very versatile model when it comes to robotic biomimicry. Applications ranging from inspecting nuclear power plants to assembling aircraft and even exploring Mars have been identified for snake-like robots, but unlike these and many other robot designs, MIT's silicone rubber robot doesn’t have fixed-joints and the lack of mobility and flexibility they bring. Instead, this soft-shelled automaton is constructed with a group of hollow, individually inflatable channels ranged down either side of it that, when filled with air, change shape and bend that part of the arm in the required direction. Inflating or deflating these air pockets at various places on the arm means that it can be deformed into almost any curve or arc; a feat impossible with solid, fixed-joint machines.
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Being made of silicone rubber also helps in creating a body that doesn't get snagged easily, either. Traditional hard-bodied droids are often covered in a plethora of hard projections, edges and protrusions. MIT's soft snake, on the other hand, has a deformable, slippery carcass that is ideal for getting around in tight places and is not as affected by minor bumps and knocks. Though these advantages also have their own inherent challenges.
"Many so-called ‘soft’ robots have still had ‘hard’ elements, like high-pressure actuators and aluminum parts that hold everything together," said doctoral candidate Andrew Marchese, head of the design team. "Designing away all the hard components forces us to think about the more difficult questions. Is it possible to do useful manipulation with a robot that’s as soft as chewing gum?"
Part of the lab of CSAIL Director Daniela Rus (a lab responsible for such things as "bakable" robots and Origami-inspired automata), the team also developed a suite of complex algorithms to ascertain the body contortions the robot would require to achieve a variety of different motions when wending its way around its environment.
"To move a robot to a particular point in space, you have to determine the specific set of curved arcs needed to get there, which is a tricky task in itself," said Marchese. "Now imagine moving it through a compact space like a pipe, and having a whole array of points that need to be reached over time. That goal makes the underlying programming much more complicated."
The researchers also have to find new ways to connect other elements required to assist with robotic perambulation, such as actuators and drive motors, along with sensors made of hard electronic components. Given the potential of soft robotics and the evolution of this particular type of motion, overcoming these and other limitations is an obvious line of research for future iterations.
The MIT CSAIL researchers will present their work at the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2014) this month.
The short video below shows the MIT CSAIL tentacle robot in action.