Selective Commitment for Language-Guided Object Retrieval under Partial Observability
Organizations: School of Electrical, Computing, and Software Engineering, University of Arizona, Tucson, AZ 85721, USA · Department of Electrical and Computer Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
Abstract
Language-guided object retrieval under partial observability requires deciding whether to gather more evidence, interact with the scene, grasp a candidate, or abstain. We present a closed-loop framework that coordinates these decisions for retrieving a target specified in relation to a reference container. The framework maintains a persistent joint belief over target identity, container relation, and presence through tracked-object, unobserved-target, and target-absent hypotheses. View-conditioned categorical VLM observations update this belief; conformal grasp eligibility and robot feasibility govern commitment, while finite-horizon belief-space planning selects information-gathering actions. Across five different scenarios, our proposed method succeeds in 19/25 simulation episodes versus 12/25 for the best-performing task-adapted baseline and is the only evaluated policy to achieve at least one success in each scenario. Ablations show that cross-view memory improves success under partial occlusion, while the full system does not consistently outperform simplified variants. Real-robot trials demonstrate closed-loop re-observation and autonomous recovery from injected grasp failures, while injected viewpoint failures end in false defer. Experimental results demonstrate the feasibility of coordinating evidence gathering and selective grasp commitment within a unified framework for retrieval under partial observability.
Figures & tables
| Scenario | Decision challenge |
|---|---|
| Visible/Open | Identify and retrieve the visible target without unnecessary sensing. |
| Partially Occluded | Acquire another view to resolve incomplete identity or visibility before commitment. |
| Covered Container | Remove the cover and re-observe before deciding to grasp or defer. |
| Ambiguous Inside/Outside | Resolve conflicting identity and container-relation evidence among similar candidates. |
| Target Absent | Preserve uncertainty when target evidence remains unresolved. Defer rather than commit to a distractor. |
| Method | Analyzed | Visible | Partial | Covered | Ambig. | Absent | Task success (Wilson 95% CI) |
|---|---|---|---|---|---|---|---|
| RoboEXP [ 4 ] | 25 | 2/5 | 0/5 | 5/5 | 0/5 | 0/5 | 28.0% [14.3, 47.6] |
| DovSG [ 5 ] | 24 | 2/5 | 0/5 | 0/5 | 0/4 | 5/5 | 29.2% [14.9, 49.2] |
| IntroPlan [ 13 ] | 25 | 5/5 | 0/5 | 0/5 | 2/5 | 5/5 | 48.0% [30.0, 66.5] |
| ActPerMoMa [ 3 ] | 24 | 0/5 | 0/5 | 0/5 | 1/4 | 5/5 | 25.0% [12.0, 44.9] |
| Ours | 25 | 5/5 | 3/5 | 3/5 | 3/5 | 5/5 | 76.0% [56.6, 88.5] |
| Method variant | Visible | Partial | Covered | Ambig. | Absent | Task success (Wilson 95% CI) |
|---|---|---|---|---|---|---|
| Ours (full) | 5/5 | 3/5 | 3/5 | 3/5 | 5/5 | 76.0% [56.6, 88.5] |
| Observations pooled across views | 5/5 | 2/5 | 3/5 | 3/5 | 5/5 | 72.0% [52.4, 85.7] |
| No cross-view memory | 4/5 | 0/5 | 5/5 | 4/5 | 5/5 | 72.0% [52.4, 85.7] |
| Factorized belief over identity and relation | 5/5 | 3/5 | 4/5 | 3/5 | 5/5 | 80.0% [60.9, 91.1] |
| Hypothesis-independent future observations | 5/5 | 4/5 | 4/5 | 3/5 | 5/5 | 84.0% [65.3, 93.6] |
| No terminal execution-risk term | 5/5 | 2/5 | 4/5 | 3/5 | 5/5 | 76.0% [56.6, 88.5] |
| Condition | Task success | Mean duration (s) | |
| Visible/Open | 5 | 5/5 | 134 |
| Viewpoint change (right) | 5 | 5/5 | 160 |
| Covered Container | 5 | 5/5 | 209 |
| Target Absent | 5 | 5/5 | 175 |
| Injected grasp-failure report | 5 | 5/5 | 180 |
| Injected viewpoint-failure report | 5 | 0/5 | 166 |