Active visuo-tactile perception

AVT-FabricActive Visuo-Tactile Perception via Adaptive Evidence Selection for Efficient Robotic Fabric Comparison

Chang Gao1*, Zhuo Chen1*, Suhang Xia1, Jihong Zhu2, Jiankang Deng3 and Shan Luo1

1 King’s College London   2 University of York   3 Imperial College London

* Equal contribution · Correspondence: Zhuo Chen

Look first. Use touch when more evidence is needed.

AVT-Fabric compares fabrics from RGB images, selectively processes force-tagged tactile observations, and turns property comparisons into robotic fabric recommendations.

A robot uses RGB appearance and GelSight observations to select a soft, elastic fabric for a user.
From a user request to fabric selection: visual comparison, uncertainty-guided tactile evidence processing, and property-based ranking.
98.0%accuracy on 400 held-out comparisons
1.60 / 5observation stages processed on average
61.8%lower model-side latency than passive inference

Main benchmark: held-out questions about seen fabrics, using Qwen2-VL-7B. Physical observations are acquired before inference; latency excludes acquisition and robot motion.

Abstract

Robotic fabric comparison needs to actively combine visual appearance and tactile cues. Here, we present AVT-Fabric, an RGB-first framework that allocates tactile evidence according to the difficulty of each comparison. A dual-scale gate evaluates answer-token confidence and raw logit separation to determine whether another force-tagged GelSight observation is needed. Compact textual memory preserves the executed history, and majority voting consolidates the selected predictions.

On 400 held-out comparisons, AVT-Fabric achieves 98.0% accuracy with a compact 7B Multimodal Large Language Model (MLLM), surpassing the 94.0% reported by the 90B MLLM-Fabric baseline by 4.0 percentage points while processing only 1.60 of five available stages on average. It improves on matched passive inference by 9.25 percentage points and reduces model-side latency by 61.8%, while also improving on RGB-only accuracy. Experiments with four additional MLLM backbones assess the framework’s generalizability, accuracy, and efficiency. Deployed on a real robotic system, it achieves 78.1% pairwise ranking accuracy and correct fabric selection in seven of eight application scenarios.

Robot demonstration

See the sensing setup, fabric comparison, and robotic selection in action.

1080p · 2 min 44 sec · Download video (MP4, 18.4 MB)

Adaptive evidence selection

AVT-Fabric pipeline: RGB-first observation bank, multimodal comparison with textual memory, confidence and logit-margin stopping, and majority voting.
The model processes one image pair at each stage. A reliability gate decides whether to stop or process the next stored tactile pair.

01 · Compare

Begin with RGB images and a query about elasticity, thickness, texture, or softness.

02 · Select evidence

Continue through force-ordered tactile pairs when confidence or logit separation is insufficient. Textual memory carries earlier predictions forward.

03 · Consolidate

Vote over the executed predictions, resolving ties with the latest prediction, then rank fabrics for the request.

Accuracy and inference efficiency

Matched Qwen2-VL-7B evaluation on 400 held-out comparisons.

Inference policyAccuracyMean stagesTime / pair
RGB only95.50%1.006.38 s
Passive voting88.75%5.0023.46 s
AVT-Fabric98.00%1.608.95 s

Time measures model-side inference, excluding physical data acquisition. See the paper for multi-seed results, additional backbones, and fine-grained and unseen-fabric evaluations.

Real-robot fabric selection

A Franka Emika Panda integrates an RGB camera, GelSight Mini, and force–torque sensing. Acquired observations support pairwise comparison and garment selection across eight application scenarios, with 78.1% mean pairwise ranking accuracy and 7 of 8 correct final selections.

Robot sensing hardware and RGB and force-tagged GelSight observation sequences for dataset and demonstration fabrics.
Robot sensing hardware and force-tagged observation sequences. The observation bank is acquired before inference and can be reused across property queries.

Citation

@misc{gao2026avtfabric,
  title = {AVT-Fabric: Active Visuo-Tactile Perception via
           Adaptive Evidence Selection for Efficient
           Robotic Fabric Comparison},
  author = {Gao, Chang and Chen, Zhuo and Xia, Suhang and
            Zhu, Jihong and Deng, Jiankang and Luo, Shan},
  year = {2026},
  note = {Manuscript}
}