arg-VU: Affordance Reasoning with Physics-Aware 3D Geometry for Visual Understanding in Robotic Surgery

Affordance reasoning provides a principled link between perception and action, yet remains underexplored in surgical robotics, where tissues are highly deformable, compliant, and dynamically coupled with tool motion. We present arg-VU, a physics-aware affordance reasoning framework that integrates temporally consistent geometry tracking with constraint-induced mechanical modeling for surgical visual understanding. Surgical scenes are reconstructed using 3D Gaussian Splatting (3DGS) and converted into a temporally tracked surface representation. Extended Position-Based Dynamics (XPBD) embeds local deformation constraints and produces representative geometry points (RGPs) whose constraint sensitivities define anisotropic stiffness metrics capturing the local constraint-manifold geometry. Robotic tool poses in SE(3) are incorporated to compute rigidly induced displacements at RGPs, from which we derive two complementary measures: a physics-aware compliance energy that evaluates mechanical feasibility with respect to local deformation constraints, and a positional agreement score that captures motion alignment (as kinematic motion baseline). Experiments on surgical video datasets show that arg-VU yields more stable, physically consistent, and interpretable affordance predictions than kinematic baselines. These results demonstrate that physics-aware geometric representations enable reliable affordance reasoning for deformable surgical environments and support embodied robotic interaction.

Diffusion-SAFE: Shared Autonomy Framework with Diffusion for Safe Human-to-Robot Driving Handover

Safe handover in shared autonomy for vehicle control is well-established in modern vehicles. However, avoiding accidents often requires action several seconds in advance. This necessitates understanding human driver behavior and an expert control strategy for seamless intervention when a collision or unsafe state is predicted. We propose Diffusion-SAFE, a closed-loop shared autonomy framework leveraging diffusion models to: (1) predict human driving behavior for detection of potential risks, (2) generate safe expert trajectories, and (3) enable smooth handovers by blending human and expert policies over a short time horizon. Unlike prior works which use engineered score functions to rate driving performance, our approach enables both performance evaluation and optimal action sequence generation from demonstrations. By adjusting the forward and reverse processes of the diffusion-based copilot, our method ensures a gradual transition of control authority, by mimicking the drivers' behavior before intervention, which mitigates abrupt takeovers, leading to smooth transitions. We evaluated Diffusion-SAFE in both simulation (CarRacing-v0) and real-world (ROS-based race car), measuring human-driving similarity, safety, and computational efficiency. Results demonstrate a 98.5\% successful handover rate, highlighting the framework's effectiveness in progressively correcting human actions and continuously sampling optimal robot actions.

Probabilistic Task Parameterization of Tool-Tissue Interaction via Sparse Landmarks Tracking in Robotic Surgery

Accurate modeling of tool-tissue interactions in robotic surgery requires precise tracking of deformable tissues and integration of surgical domain knowledge. Traditional methods rely on labor-intensive annotations or rigid assumptions, limiting flexibility. We propose a framework combining sparse keypoint tracking and probabilistic modeling that propagates expert-annotated landmarks across endoscopic frames, even with large tissue deformations. Clustered tissue keypoints enable dynamic local transformation construction via PCA, and tool poses, tracked similarly, are expressed relative to these frames. Embedding these into a Task-Parameterized Gaussian Mixture Model (TP-GMM) integrates data-driven observations with labeled clinical expertise, effectively predicting relative tool-tissue poses and enhancing visual understanding of robotic surgical motions directly from video data.