SCU-Hand with Integrated Single-Sheet Valve: A Funnel-Shaped Robotic Hand for Milligram-Scale Powder Handling
Tomoya Takahashi, Yusaku Nakajima, Cristian Camilo Beltran-Hernandez, Yuki Kuroda, Kazutoshi Tanaka, Masashi Hamaya, Kanta Ono, Yoshitaka Ushiku
AI summary
Problem
Fully automating milligram-scale powder handling remains a bottleneck in laboratory automation due to complex powder flow dynamics, diverse container geometries, and the need for precise weighing without frequent tool switching.
Approach
The authors developed the SCU-Hand-SV, a soft conical end-effector with a controllable valve at its apex, integrated with an electronic balance and controlled via a model-based feedback system that uses online parameter identification to adapt to varying powder flow.
Key results
- Development of SCU-Hand-SV with integrated single-sheet valve
- Validation of hopper-based powder flow prediction model
- ±2 mg accuracy achieved in 80% of trials across 20 mg to 3 g range
- Model-based control with online identification outperforms direct PID control
Why it matters
Enables efficient, flexible, and precise milligram-to-gram powder weighing for continuous, human-free laboratory automation in materials science.
Abstract
Laboratory Automation (LA) has the potential to accelerate solid-state materials discovery by enabling con- tinuous robotic operation without human intervention. While robotic systems have been developed for tasks such as powder grinding and X-ray diffraction (XRD) analysis, fully automating powder handling at the milligram scale remains a significant challenge due to the complex flow dynamics of powders and the diversity of laboratory tasks. To address this challenge, this study proposes the SCU-Hand-SV (Soft Conical Universal Robotic Hand with Single-sheet Valve), which preserves the soft- ness and conical sheet designs in prior work while incorporating a controllable valve at the cone apex to enable precise, incre- mental dispensing of milligram-scale powder quantities. The SCU-Hand-SV is integrated with an external balance through a feedback control system based on a model of powder flow and online parameter identification. Experimental evaluations with glass beads, monosodium glutamate, and titanium dioxide demonstrated that 80% of the trials achieved an error within ±2 mg, and the maximum error observed was approximately 20 mg across a target range of 20 mg to 3 g. In addition, by incorporating flow prediction models commonly used for hoppers and performing online parameter identification, the system is able to adapt to variations in powder dynamics. Compared to direct PID control, the proposed model-based control significantly improved both accuracy and convergence speed. These results highlight the potential of the proposed system to enable efficient and flexible powder weighing, with scalability toward larger quantities and applicability to a broad range of laboratory automation tasks.