RoboBoom
GRASP Lab· February 20, 2026· 1:08:52

Spring 2026 GRASP on Robotics - David Held, Carnegie Mellon University

David Held, associate professor at Carnegie Mellon University and head of the RPAD Lab, presents research on precise, generalizable robot manipulation at a GRASP on Robotics seminar hosted by a Penn faculty member.

In this talk

  1. 2:09

    Why general-purpose policies need precision

    Held contrasts broad vision-language-action models, which can identify a requested target but may place an object inaccurately, with specialist systems that perform narrow tasks well. He argues that robots need both broad task understanding and the precision of specialized methods, and proposes a hierarchy that separates choosing a goal from executing motion.

  2. 8:45

    Hierarchical learning for articulated objects

    Held describes training on more than 40,000 simulated trajectories for opening doors, drawers, and other articulated objects. An end-to-end diffusion policy struggled with unseen objects, while a hierarchical imitation approach predicted key gripper poses and used a lower-level policy to produce motion. The resulting policy transferred from simulation to three robot embodiments in real settings.

  3. 24:50

    Extending the hierarchy across tasks

    The SMITH follow-up applies hierarchical policies to opening, closing, grasping, and pick-and-place, using 140,000 simulated demonstrations. Its high-level dense Gaussian mixture model represents multiple possible target poses, supporting multimodal tasks such as grasping in clutter. Held reports better performance than the compared generalist models and results close to task-specific specialists, while noting the system uses a short list of fixed language prompts.

  4. 39:39

    Point-cloud diffusion for precise placement

    For tasks ranging from mug hanging to industrial insertion, Held describes diffusing object point clouds toward a target placement and then using a planner or learned policy to execute the motion. The method separately predicts object shape and placement frame, and initializes the frame estimate with a dense Gaussian mixture model. In tests on three NIST insertion connectors, reported success ranged from 80% to 100% at roughly millimeter and one-degree precision; point-cloud diffusion also generalized better than SE(3) diffusion across diverse mugs.

  5. 54:26

    Open questions and future directions

    Held summarizes the shared structure: a high-level model predicts a goal or placement, and a low-level component handles motion. He identifies key-frame selection, combining tasks without negative transfer, and scaling to more tasks as unresolved challenges. He also points to tool use and learning with planning as future directions.

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