King's College London

A new mechanism based on the flexagon, a ‘wonder structure’ long thought to hold the keys to greater space exploration and renewable energy harvesting, is promising to reinvent the future of shape shifting robotics.

Undertaking the world’s first study of the geometry of the shape, the team led by Professor Jian Dai, Emeritus Professor of Mechanisms and Robotics at King’s College London, designed a structure that would allow robots and other mechanical devices to continually change shape – a world first.

By allowing robots to take different forms, from mammalian quadruped to fish, the researchers hope to harness millions of years of evolution to help these robots complete tasks – embedding what they refer to as ‘structural intelligence’ into the future of design.

The work builds on Origaker, an award-winning robot designed by Professor Dai and King’s Dr Emmanouil Spyrakos-Papastavridis, which used similar, origami-inspired, metamorphic mechanisms capable of reconfiguring its shape on the fly to traverse several different terrains.

Professor Dai said, ‘In our field algorithmic intelligence is not enough. No matter how smart a robot’s software brain is, it will be no good over rocky terrain if it is shaped like a sphere. But a robot with four legs and a high ground clearance might, even if its slower across a paved road – so why not allow them to change between the two?

‘By allowing robots to change shape to suit their task, whether that’s by expanding, shrinking, changing from having four legs to none and back again, we can seize upon the shapes nature has created for us to solve our problems in an ever-changing world. This adaptability is vital for creating truly useful robots and the core of our idea of “structural intelligence” in the form of metamorphosis.’

Origami has influenced engineers for many years, with Professor Dai having invented the artform to design economical and efficient perfume packaging for the company Unilever in the 1990s, with a Japanese satellite even deploying a folded solar panel in 1995. However, while paper is very forgiving when folded many times, materials such as ceramics and metal are not, leading to difficulty when scaling-up usable origami-inspired designs.

Through a comprehensive study of the mathematics of the flexagon based on his invented concept of “metamorphic mechanisms and robots”, an origami-inspired shape created using a Möbius strip (a flexible surface with only one continuous side and one continuous edge), the team have designed a structure which overcomes this problem – a dual-chiral flexagon linkage.

Linking several flexagons together in a ring, Professor Dai alongside researchers at the Southern University of Science and Technology – King's College London Joint Medical School and Zhejiang University in China, used the shape’s ability to continually invert itself to build a structure capable of constant changes in its shape.

These linkages are then attached to a series of panels and guided by advanced algorithms to continually change shape without the block of ‘mechanical interference’, when a structure cannot change because it has been folded too many times.

If implemented in a robot, this would be the first time a complete and continuous structure change has been achieved.

Professor Dai continued, ‘When origami was studied in the past, it lacked a strong mathematical foundation, and the foundational and mechanical study of the shapes. By taking this interdisciplinary approach with screw algebra and geometric kinematics, we can create a system without the traditional blockers of origami-inspired design – meaning we can now create complex systems capable of structure inversion, achieving structural intelligence.

‘Whether this is solar panels which change shape to capture the sun even when its dark, or a piece of furniture that can change itself from a soft sofa to a marble countertop, this technological step change will allow us to create truly useful and adaptable robots.’

As the approach is not linked to a single domain, the team hope that this work will be used across several frontier fields of engineering, including modular and soft robotics.