MIT develops robotic hands with a sensitive palm
MIT researchers have developed a tactile palm that should be able to improve the dexterity of robotic hands.
MIT scientist Sandra Q. Liu holds the tactile robot gripper in her hands.
(Image: Michael Grimmett / MIT CSAIL)
Scientists at the Computer Science and Artificial Intelligence Laboratory (CSAIL) of the Massachusetts Institute of Technology (MIT) have developed a robotic hand whose palm is equipped with a novel, flexible, gel-based optical sensor. In combination with fingers with similar technology, the gripper achieves improved dexterity.
The MIT researchers led by Sandra Q. Liu, a graduate of MIT and designer of the sensor called GelPalm, based their work on biological models, in this case the human hand.
"We are inspired by human hands, which have rigid bones surrounded by soft, pliable tissue." She adds: "By combining rigid structures with malleable, compliant materials, we can achieve the same adaptability as our dexterous hands. A big advantage is that we don't need any additional motors or mechanisms to control the deformation of the palm - the inherent pliability allows it to automatically adapt to objects, just like our human palms do."
GelPalm combines a special color illumination technique that uses red, green and blue LEDs to illuminate an object, the researchers write in the scientific paper "A Passively Bendable, Compliant Tactile Palm with RObotic Modular Endoskeleton Optical (ROMEO) Fingers", which is published on Arxiv in preprint. The reflections are then analyzed by a camera and converted into a detailed 3D surface model that enables precise robot interactions.
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The MIT researchers provided GelPalm with corresponding fingers made of a flexible material with passive compliance and a sensor technology that works in a similar way to that used in the palm of the hand. The fingers were produced using a 3D printing process. The scientists call the system Robotic Modular Endoskeleton Optical (ROMEO). It improves the dexterity of the fingers and, in combination with GelPalm, of the entire hand.
Better gripping
The MIT scientists tested the gripper for robots in various experiments. They investigated how well different palm constructions were able to enclose individual objects and thus provide a stable grip. The researchers painted differently shaped objects with paint and applied the four palm types rigid, structurally compliant, gel compliant and their dual compliant design to them. This enabled them to determine which types were most suitable.
"Visually and by analyzing the painted surface contacts, it was clear that the structural-material compliant palm offered significantly more grip than the others," says Liu. "It's an elegant way to maximize the role of the palm in achieving stable grips."
However, there is one negative aspect of their system: it is difficult to integrate the sensor technology into the palm without making the hands too clunky or overly complex. The use of camera technology also means that the hands are less flexible. More work needs to be done on this. The scientific team assumes that more advanced robotic hands will be developed in the coming years, combining soft and rigid components with tactile properties. The team estimates that this development will be completed in the next ten to fifteen years.
(olb)