Robotics

PartialBiGrasp Guesses the Hidden Side of the Object Before Two Arms Close

Shar Hendrix 4 min read

Most two-arm grasp planners want the whole object as a point cloud. PartialBiGrasp, posted to arXiv on August 19 by Ayush Kaura, Vignesh Vembar, Md Faizal Karim, Keshab Patra, and K. Madhava Krishna, starts from the messier thing you actually get: a partial view.

Large, heavy, or awkward objects often only have a few legal grasp patches, set by thickness, edges, and whether the gripper jaws fit. A full scan contains that geometry. A single depth camera usually does not. The hidden back side of a chair or a toolbox is exactly where a naive grasp wants to close.

Diagram showing a partial RGB-D view missing hidden geometry and producing bad dual-arm grasps
Teaser: partial views hide thickness and edges, so naive contacts fail. Source: arXiv:2608.19188.

Occupancy instead of a completed mesh

The method learns local geometry with convolutional occupancy networks, then reasons about graspability, collision-free contact, and thickness from that implicit field. It samples force-closure-compliant grasp pairs and runs a sampling-based refinement step to mop up the ambiguity left by missing geometry.

The authors evaluate with analytical force-closure scores, large-scale simulation, and real-robot runs on noisy partial clouds of novel objects. The paper does not put a single headline success percentage in the abstract, so I am not inventing one.

Real dual-arm lab setup with two white robot arms over a table of large objects
Real-robot setup used for the partial-view evaluations. Source: arXiv:2608.19188.

The object set in the paper’s real-world figure is the kind of stuff that actually needs two hands: a blue plastic chair, a toolbox, a monitor, pans, a bucket, a water bottle. That is the point. A single Franka can pick a mug. Two arms on a chair is the dual-arm problem.

Overhead photo of a chair, toolbox, monitor, pans, bucket, and other large objects on a table
Real-world object set used in the evaluations. Source: arXiv:2608.19188.

A Human’s Take

I like a paper that admits the camera cannot see the back of the chair. Completing a pretty mesh in simulation is a different sport from putting two grippers on a toolbox you only saw from one side. I want the real-robot table of wins and drops in a follow-up, with the same objects, lights left ugly.

Sources