Next generation robotic grippers should be soft and inspired by the hybrid nature of the versatile hands, tails, and arms of animals. Wageningen University & Research (WUR) is studying these biological grippers and uses this knowledge to build bioinspired robo-grippers for agricultural purposes. A multidisciplinary team of WUR researchers has published a paper about this subject in Science Robotics.
The grip of an elephant trunk is suitable to grasp a tree, but also to lift a single rice grain. ‘Animals know how to deal with all kinds of objects’, says researcher Julian Langowski. ‘Whether an object is small, big, light, heavy, smooth, rough, wet or dry’. Existing agrorobotic grippers experience difficulties to meet the various tasks and the variable conditions in an agricultural environment.
That is why WUR-researchers want to use nature’s toolbox of versatile grip to work towards bioinspired robo-grippers. Langowski: ‘Take the arm of an octopus or the sticky feet of tree frogs for example. We want to know what tricks these animals use. And then transfer these tricks out of biology into robotic systems’.
In the paper ‘In the soft grip of nature’ researchers identified three distinct gripping mechanisms: mechanical interlocking (the way how a snake wraps around a branch), friction (when you grip a glass of water) and adhesion (the mechanism with which a gecko sticks to a flat surface). Animals successfully combine some or even all of these mechanisms, while most recent prototypes of bioinspired robo-grippers use only one. Robotic grippers of the future need to combine these mechanisms in a hybrid manner.
Next to versatility, other challenges in agrobotic gripper design may be solved using a bioinspired approach as well. The ability of animals such as geckos and tree frogs to self-clean their appendages for example, may inspire the design of grippers that are unaffected by contamination.
In contrast to conventional robots, soft robots are made from compliant materials, which enables these machines to gently interact with delicate objects. Agrorobotics is a promising field of application for bioinspired soft robots, but also medical robots or search-and-rescue systems could be inspired by the many remarkable soft systems found in nature.