A Passively Bendable, Compliant Tactile Palm with RObotic Modular Endoskeleton Optical (ROMEO) Fingers

TL;DR

This work introduces a passively compliant soft palm with high-resolution GelSight-inspired tactile sensing and ROMEO fingers featuring a soft-rigid endoskeleton. A low-cost flexible illumination system using painted LED filaments enables camera-based tactile sensing integrated into both fingers and palm, while a dual-compliance palm combines structural cantilevers and gel material to maximize contact area. Experiments show comparable high-resolution tactile reconstruction under different illumination schemes and demonstrate a measurable gain in contact area when both palm compliances are active, with a preliminary object classification task supporting the palm's contribution. The approach offers a scalable platform for exploring soft-rigid tactile hand designs and lays groundwork for more capable manipulation in cluttered or occluded environments.

Abstract

Many robotic hands currently rely on extremely dexterous robotic fingers and a thumb joint to envelop themselves around an object. Few hands focus on the palm even though human hands greatly benefit from their central fold and soft surface. As such, we develop a novel structurally compliant soft palm, which enables more surface area contact for the objects that are pressed into it. Moreover, this design, along with the development of a new low-cost, flexible illumination system, is able to incorporate a high-resolution tactile sensing system inspired by the GelSight sensors. Concurrently, we design RObotic Modular Endoskeleton Optical (ROMEO) fingers, which are underactuated two-segment soft fingers that are able to house the new illumination system, and we integrate them into these various palm configurations. The resulting robotic hand is slightly bigger than a baseball and represents one of the first soft robotic hands with actuated fingers and a passively compliant palm, all of which have high-resolution tactile sensing. This design also potentially helps researchers discover and explore more soft-rigid tactile robotic hand designs with greater capabilities in the future. The supplementary video can be found here: https://youtu.be/RKfIFiewqsg

Figures (8)

• Figure 1: A novel dual compliant palm with three novel ROMEO fingers in a 120$^{\circ}$ configuration grasping an orange. Both the palm and the fingers have GelSight-inspired tactile sensing through usage of the newly designed flexible illumination system. To the right of the image are the resulting difference images of the bumpy orange skin sensed by the palm and the orange stem sensed by the ROMEO finger tip.
• Figure 2: Rendered CAD files of the ROMEO finger (a) and the compliant palm (b, c), showing the various labeled parts.
• Figure 3: The manufacturing process of both the finger and the palm, which involve 3D printing the endoskeleton, prepping the flexible LED filaments, painting and pouring the silicone, and finally demolding the parts. Not pictured is the step where the aluminum paint mixture is airbrushed onto the mold before silicone is poured.
• Figure 4: The expected points of contact of a circle and rhombus object into the different types of palms, ranging from no compliance to both structural and material compliance. We expect having both types of compliance to give us maximum surface area contact.
• Figure 5: Our ROMEO fingers and three different passively double compliant palm configurations. From left to right, we have an anthropomorphic, a 120$^{\circ}$, and a "Y" configuration gripper.