Octobot: the octopus as robot
Robots are often used to assist humans in boring monotonous jobs, like assembly lines of automobiles. Many of them move rigidly because they are programmed to make precise movements, not to be disturbed by external factors. But robotology has recently entered a new stage. The new robots, also designated as ‘soft’ robots are still controlled by electronic circuitry, but there are two a big differences: their external parts or ‘limbs’ are made of soft material and they are designed to interact with their environment. Cecilia Laschi, professor in Biorobotics at the ‘Scuala Superiore de Sant’Anna in Pisa calls this compliance. Their movements are more fluent and exploratory like they are seeking factors in the environment to adapt to. Potential fields of application are surgery rooms, nursing homes and rescue operations. For example, a soft rescue robot could even change the contour and volume of its body to crawl through narrow spaces in search of survivors in the debris after an earthquake.
The rapid development of soft robots was made possible by the advent of new and improved techniques for making the protypes: 3D printers, laser cutting and advanced synthetic materials like silicone rubber. Often living animals are used as inspiration for their designs, in particular soft tissue animals of the sea without a skeleton like the jelly fish and octopus. The octopus for example doesn’t need a skeleton to keep its muscles and body together because of the lack of gravity of its watery environment. Not surprisingly, engineers like Cecilia Laschi and Robert Wood, professor in Microrobotics from Harvard University have used the octopus for their prototype models. Woods model, baptized Octobot, is made of silicon rubber with a network of small silicone tubes running through its eight arms. The tubes are filled with liquid hydrogen peroxide. When pneumatic pressure is applied to the fluid the tubes will bend (think of your garden hose when you open the faucet). This makes Octobots arms bend and move somewhat like real arms. This process is controlled by a microchip circuit in its interior; more precise: a microfluidic logic circuitry.* Laschi’s octopus models however use a smart metal alloy that ‘remembers’ its original shape and that when deformed returns to its pre-deformed shape when heated. The alloy is a very thin metal spiral moulded in soft synthetic material.
Of course, these prototypes are simple and cannot replace the real octopus with its 50 billion of nerve cells controlling its arm movements. This research is still in an exploratory and playful stage, but could perhaps on the longer term provide new insights into the way our muscles and their movements have evolved during the process of evolution. And it could lead to useful applications to assist people in their increasingly complex world.
An integrated design and fabrication strategy for entirely soft, autonomous robots. Michael Wehner et al. 25 August, 2016, vol 536, Nature 451.