SCU-Hand: Soft Conical Universal Robotic Hand for Scooping Granular Media from Containers of Various Sizes

TL;DR

The paper tackles the challenge of automating powder scooping in small-scale laboratory settings where container sizes vary and traditional rigid end-effectors struggle to maintain complete contact. It introduces the SCU-Hand, a soft, conical, developable-sheet end-effector that morphs to fit container diameters without force sensing or reinforcement learning, and validates its performance through design, fabrication, and experiments. The key contributions include a single-sheet cone mechanism with reconfigurable size, demonstrated scooping improvements (≈20% higher than a commercial tool) and >95% scooping efficiency across container diameters from 67 to 110 mm and multiple granular media. The work has practical impact for low-cost, easily deployable lab automation, enabling more efficient material synthesis and characterization with minimal setup.

Abstract

Automating small-scale experiments in materials science presents challenges due to the heterogeneous nature of experimental setups. This study introduces the SCU-Hand (Soft Conical Universal Robot Hand), a novel end-effector designed to automate the task of scooping powdered samples from various container sizes using a robotic arm. The SCU-Hand employs a flexible, conical structure that adapts to different container geometries through deformation, maintaining consistent contact without complex force sensing or machine learning-based control methods. Its reconfigurable mechanism allows for size adjustment, enabling efficient scooping from diverse container types. By combining soft robotics principles with a sheet-morphing design, our end-effector achieves high flexibility while retaining the necessary stiffness for effective powder manipulation. We detail the design principles, fabrication process, and experimental validation of the SCU-Hand. Experimental validation showed that the scooping capacity is about 20% higher than that of a commercial tool, with a scooping performance of more than 95% for containers of sizes between 67 mm to 110 mm. This research contributes to laboratory automation by offering a cost-effective, easily implementable solution for automating tasks such as materials synthesis and characterization processes.

Figures (8)

• Figure 1: SCU-Hand: (a) A reconfigurable robotic hand that can fit containers of different sizes. (b) scooping by maintaining full contact with the container surface via flexibility. (c) and (d) scooping from small containers. *In these figures, a colored sheet was used for the end-effectors, which was different from the sheet used in the experiment.
• Figure 2: Different adaptive deformations caused by differences in end-effector size relative to the container size: (a) If the end-effector is smaller than the container, the contact area can be widened by contact with the container. (b) If the end-effector is larger than the container, insertion is possible, but the contact area becomes smaller. (c) Buckling of flat sheet structure with flexible material while sliding according to surface.
• Figure 3: (a)-(d) are developable surfaces and can be deformed from a single plate. (e) requires a large elongation in the material
• Figure 4: Size reconfiguration of a cone: initially slides one end of the circular sheet and morphs it into a conical surface by overlapping it, thereby reducing its diameter.
• Figure 5: (a) Force generated on the cone structure during the scooping operation, (b) Contact tolerance.