A new robotic hand design—GelPalm—developed in MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL), uses advanced sensors for a highly sensitive touch, helping the extremity handle objects with more detailed and delicate precision.
GelPalm has a gel-based, flexible sensor embedded in the palm, drawing inspiration from the soft, deformable nature of human hands. The sensor uses a special color illumination tech that uses red, green, and blue LEDs to light an object, and a camera to capture reflections. This mixture generates detailed 3D surface models for precise robotic interactions.
The team of researchers also developed some robotic phalanges—ROMEO (RObotic Modular Endoskeleton Optical)—with flexible materials and similar sensing technology as the palm. The fingers have “passive compliance,” where a robot can adjust to forces naturally, without needing motors or extra control. This in turn helps with the larger objective: increasing the surface area in contact with objects so they can be fully enveloped. Manufactured as single, monolithic structures via 3D printing, the finger designs are a cost-effective production.
Beyond improved dexterity, GelPalm offers safer interaction with objects, something that’s especially handy for potential applications like human-robot collaboration, prosthetics, or robotic hands with human-like sensing for biomedical uses.
Many previous robotic designs have typically focused on enhancing finger dexterity. MIT graduate Sandra Q. Liu, PhD, is the lead designer of GelPalm. Her approach shifts the focus to create a more human-like, versatile end effector that interacts more naturally with objects and performs a broader range of tasks.
“We draw inspiration from human hands, which have rigid bones surrounded by soft, compliant tissue,” said Liu, who developed the system as a CSAIL affiliate and PhD student in mechanical engineering. “By combining rigid structures with deformable, compliant materials, we can better achieve that same adaptive talent as our skillful hands. A major advantage is that we don’t need extra motors or mechanisms to actuate the palm’s deformation—the inherent compliance allows it to automatically conform around objects, just like our human palms do so dexterously.”
The researchers put the palm design to the test. Liu compared the tactile sensing performance of two different illumination systems—blue LEDs versus white LEDs—integrated into the ROMEO fingers. “Both yielded similar high-quality 3D tactile reconstructions when pressing objects into the gel surfaces,” she said.
But the critical experiment, according to Liu, was to examine how well the different palm configurations could envelop and stably grasp objects. The team got hands-on, slathering plastic shapes in paint and pressing them against four palm types: rigid, structurally compliant, gel compliant, and their dual compliant design. “Visually, and by analyzing the painted surface area contacts, it was clear having both structural and material compliance in the palm provided significantly more grip than the others,” Liu said. “It’s an elegant way to maximize the palm’s role in achieving stable grasps.”
One notable limitation is the challenge of integrating sufficient sensory technology within the palm without making it bulky or overly complex. The use of camera-based tactile sensors introduces issues with size and flexibility, the team said, as the current tech doesn’t easily allow for extensive coverage without trade-offs in design and functionality. Addressing this could mean developing more flexible materials for mirrors, and enhancing sensor integration to maintain functionality, without compromising practical usability, Liu said.
Editor’s note: This story was adapted from materials provided by Massachusetts Institute of Technology.
