Influence of Gripper Design on Human Demonstration Quality for Robot Learning
Authors: Gina L. Georgadarellis, Natalija Beslic, Seonhun Lee, Frank C. Sup, Meghan E. Huber
Organizations: Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, Amherst, MA 01003 USA · Elaine Marieb Center for Nursing and Engineering Innovation, University of Massachusetts Amherst, Amherst, MA 01003 USA · Center for Personalized Health Monitoring, Institute for Applied Life Sciences, University of Massachusetts Amherst, Amherst, MA 01003
Opening sterile medical packaging is routine for healthcare workers but remains challenging for robots. Learning from demonstration enables robots to acquire manipulation skills directly from humans, and handheld gripper tools such as the Universal Manipulation Interface (UMI) offer a pathway for efficient data collection. However, the effectiveness of these tools depends heavily on their usability. We evaluated UMI in demonstrating a bandage opening task, a common manipulation task in hospital settings, by testing three conditions: distributed load grippers, concentrated load grippers, and bare hands. Eight participants performed timed trials, with task performance assessed by success rate, completion time, and damage, alongside perceived workload using the NASA-TLX questionnaire. Concentrated load grippers improved performance relative to distributed load grippers but remained substantially slower and less effective than hands. These results underscore the importance of ergonomic and mechanical refinements in handheld grippers to reduce user burden and improve demonstration quality, especially for applications in healthcare robotics.
Figures & tables
Fig. 1: A: Gripper Conditions. Participants bimanually opened bandages with three different gripper conditions. B: Experimental Protocol. In each trial, participants opened a bandage and removed it from its wrapper.
Fig. 2: Redesigned finger mount of the UMI handheld gripper. The modification allows the fingers to make direct contact when fully closed, enabling effective grasping.
Fig. 3: Task Performance Results. Bar graphs of task performance metrics ( A: Bandages Opened, B: Bandages Damaged, and C: Time to Open Bandage) averaged across participants in each gripper condition (Hands, H ; Concentrated Load Grippers, C ; Distributed Load Grippers, D ). D: Time to Open Bandage over trials averaged across participants in each gripper condition. Error bars and shaded regions represent the 95% confidence intervals. *, **, ***, and **** indicate that the Bonferroni-corrected planned comparison between gripper conditions was statistically significant with padj<0.05,0.01,0.005 , and 0.001 , respectively.
Subscale Title
Description
ANOVA Results: Gripper Condition
Mental Demand
How mentally demanding was the task?
F(2,12)=22.33,p<0.001
Physical Demand
How physically demanding was the task?
F(2,12)=13.71,p<0.001
Temporal Demand
How hurried or rushed was the pace of task?
F(2,12)=2.35,p=0.14
Performance
How successful were you in accomplishing what you were asked to do?
F(2,12)=13.05,p<0.001
Effort
How hard did you have to work to accomplish your level of performance?
F(2,12)=21.01,p<0.001
Frustration
How insecure, discouraged, irritated, stressed, and/or annoyed were you?
F(2,12)=24.92,p<0.001
TABLE I: NASA-TLX Questions and ANOVA Results
Fig. 4: Perceived Workload Results. Bar graphs of task performance metrics ( A: NASA-TLX overall raw score and B: NASA-TLX subscale scores averaged across participants in each gripper condition (Hands, H ; Concentrated Load Grippers, C ; Distributed Load Grippers, D ). Error bars represent the 95% confidence intervals. *, **, ***, and **** indicate that the Bonferroni-corrected planned comparison between gripper conditions was statistically significant with padj<0.05,0.01,0.005 , and 0.001 , respectively.
Human demonstrations are a scalable data source for learning robot manipulation policies. However, common sources of human demonstration data, such as motion-capture trajectories and internet videos, capture mostly motion and appearance while missing the contact forces that are critical for force-sensitive manipulation. In this paper, we introduce ForceBand, a low-cost wrist-worn sEMG system that turns human muscle activity into force-enriched demonstrations. We first collect a 10-hour multimodal dataset containing egocentric video, sEMG, IMU, and fingertip force measurements across diverse actions and objects. Using this dataset, we pre-train an EMG2Force model that predicts per-finger forces from sEMG and IMU signals. After a short user-specific calibration, users can collect target-task demonstrations using only ForceBand and video; EMG2Force then labels these demonstrations with per-finger force traces, producing force-augmented demonstrations for robot policy learning. Experiments show that ForceBand recovers fine-grained fingertip interactions with over 50% lower force prediction error than vision-based baselines and achieves an 87% success rate on pick, squeeze, and place tasks that require object-specific force control across objects with diverse shapes, sizes, and weights. Project website: https://forceband-emg.github.io
Botao He, Zhi Wang, Linna Kuang +8
Amazon FAR · University of Maryland · Johns Hopkins University
High-quality demonstration data are essential for humanoid robot skill learning, especially for whole-body behaviors that require coordinated perception, locomotion, and manipulation. Existing data-collection methods largely rely on robot teleoperation, which is constrained by hardware accessibility, operator expertise, and limited efficiency. Inspired by the Universal Manipulation Interface (UMI), we propose HumanoidUMI, a portable and robot-free framework for humanoid whole-body data collection. HumanoidUMI uses lightweight VR devices and UMI-inspired grippers to collect sparse human keypoint trajectories, wrist-view observations, and gripper actions. These demonstrations train a high-level policy to predict future keypoints, which are retargeted to robot-native whole-body references and executed by a whole-body controller. Experiments in five real-world scenarios demonstrate the effectiveness of the proposed framework and validate the collected demonstrations for transferable humanoid whole-body skill learning.
Collecting dexterous manipulation demonstrations for each robot hand requires repeated task-specific data acquisition. We ask whether one shared corpus of natural human demonstrations can instead serve as a reusable data interface for different dexterous hands, without collecting task demonstrations on each target robot. We present Human2Dex, a wrist-centric human demonstration interface that separates shared human observation and motion semantics from embodiment-specific execution. It aligns observations through local hand-appearance adaptation and a shared 21-point hand representation with consistent structural semantics across human and robot observations. It constructs executable supervision by retargeting fused human hand motion to each target hand, and introduces the Grasp-Pocket Interaction Representation (GPIR) to express tracked objects relative to a hand-centered Functional Grasp Pocket. The corpus is converted into separate training sets for Linker O6 and Wuji, while action labels, normalization, training, and diffusion-policy checkpoints remain hand-specific. Across six real-world tasks, Human2Dex achieves 109/120 (90.8%) successes on Linker O6 and 97/120 (80.8%) on Wuji. Across both hands, Human-Raw achieves 63/240 (26.3%) successes, whereas the complete Human2Dex configuration achieves 206/240 (85.8%). These results support the use of wrist-centric human demonstrations as a reusable interface across calibrated dexterous hands while retaining embodiment-specific policy learning. The project website is publicly available at https://human2dex.pages.dev/.
Jiachen Zhang, Yuanyuan Li, Shaqi Luo
Beijing Academy of Artificial Intelligence, Beijing, China.