Recent vision-based action models have demonstrated strong capabilities in complex manipulation, but they rarely leverage explicit object physical properties to adapt their policies. We introduce ViTacPhys, a visual-tactile framework and data acquisition system that estimates object mass and friction-coefficient classes, together with continuous stiffness, from human manipulation demonstrations. Trained on data from 60 rigid and deformable objects, ViTacPhys combines temporal visual-tactile modeling, cross-attention multimodal fusion, and a semantic prior derived from a vision-language model. On seen objects, it achieves 97.2% mass classification accuracy, 98.8% friction-coefficient classification accuracy, and a stiffness mean absolute percentage error (MAPE) of 5.51%. On held-out objects from known categories, it achieves 87.5% mass accuracy, 97.5% friction-coefficient accuracy, and a stiffness MAPE of 9.08%. We transfer ViTacPhys from the human domain to the robot domain using limited robot teleoperation data, robot-style video augmentation, and human demonstrations with matched actions, and deploy it as an online module for adaptive grasping. The resulting physical-property-conditioned policy achieves total grasping success rates of 95.0% on in-distribution objects and 83.4% on out-of-distribution objects. For out-of-distribution objects successfully grasped by both methods, its force profiles are more consistent with human teleoperation than those produced by ACT. These results demonstrate the feasibility of explicitly estimating and conditioning on object physical properties for real-world adaptive grasping.
Figures & tables
Fig. 1: ViTacPhys predicts object mass class, stiffness, and friction-coefficient class from visual–tactile observations and conditions a downstream adaptive grasping policy on these estimates. The examples compare grasping outcomes for visually similar objects with different physical properties against ACT and ViTacFormer [ 1 , 2 ] .
Fig. 2: Panel (a) shows the human visual–tactile data collection setup, which synchronizes wrist-view video, fingertip pressure maps, and motion-capture measurements. Panel (b) shows the everyday objects in the dataset, ranging from rigid mugs to soft rubber toys. Panel (c) shows the corresponding sensor locations on the wearable device and robot platform.
Fig. 3: Object-level label distributions in the ViTacPhys dataset. Mass and friction coefficient are discretized into three ordered classes, whereas stiffness is a continuous regression target shown on a log10 scale. The displayed dataset-level class boundaries are fitted once using all annotated objects and fixed across evaluation splits.
Fig. 4: Overview of ViTacPhys. (A) The predictor combines temporal visual–tactile observations, flow features, and a VLM-derived semantic prior computed from pre-contact RGB frames. (B) Human-to-robot transfer uses robot teleoperation, matched-action human demonstrations, and visually augmented human demonstrations. (C) During deployment, the VLM prior is computed before contact. After contact, the system immediately begins rolling prediction from a 30-frame visual–tactile queue; unavailable initial entries repeat the earliest post-contact observation before 15 frames and 14 adjacent flow fields are sampled. Cumulative temporal voting stabilizes the predicted classes and stiffness bin before they are passed to the downstream policy.
Mass
Stiffness
Friction Coeff.
Setting
Acc. ↑
Macro-F1 ↑
MAE ↓
RMSE ↓
MAPE ↓
Pearson r↑
Within 10% ↑
Within 20% ↑
Acc. ↑
Macro-F1 ↑
In distribution
0.972 ± 0.008
0.970
0.248 ± 0.032
0.386
5.51 ± 0.45
0.980
84.22
96.56
0.988 ± 0.005
0.984
Held-out-object
0.875 ± 0.019
0.866
0.435 ± 0.127
0.577
9.08 ± 2.31
0.947
61.56
89.64
0.975 ± 0.003
0.971
One-shot
0.492 ± 0.072
0.480
0.837 ± 0.045
1.457
16.84 ± 0.95
0.680
49.47
75.19
0.569 ± 0.089
0.527
TABLE II: Physical-property prediction results averaged over three independent training runs. The main evaluation metrics are highlighted with a gray background.
Mass
Stiffness
Friction Coeff.
Experiment
Acc. ↑
F1 ↑
MAE ↓
RMSE ↓
MAPE ↓
Pearson r↑
W10 ↑
W20 ↑
Acc. ↑
F1 ↑
w/o tactile content, w text
0.660
0.648
0.756
1.152
16.70
0.769
46.39
80.69
0.915
0.905
w/o visual content, w text
0.660
0.640
0.668
0.853
13.12
0.887
45.97
79.79
0.844
0.862
w/o visual flow, w text
0.757
0.751
0.457
0.579
9.44
0.942
59.70
88.39
0.905
0.886
w/o tactile flow, w text
0.736
0.727
0.412
0.563
8.54
0.950
70.87
89.52
0.888
0.870
w/o both flow, w text
0.661
0.662
0.858
1.366
18.91
0.633
56.94
73.47
0.898
0.857
TABLE III: Input-modality ablation. Bold and underlined entries indicate the best and second-best results. “w/o” denotes without, while “w” denotes with.
Mass
Stiffness
Friction Coeff.
Experiment
Acc. ↑
F1 ↑
MAE ↓
RMSE ↓
MAPE ↓
Pearson r↑
W10 ↑
W20 ↑
Acc. ↑
F1 ↑
Manual loss weights
0.778
0.799
0.540
0.714
11.01
0.922
59.51
83.06
0.935
0.938
DWA loss weights
0.762
0.772
0.576
0.764
12.38
0.880
54.72
84.44
0.947
0.950
Cross entropy
0.635
0.657
0.534
0.730
10.07
0.945
59.38
85.14
0.979
0.978
Ours
0.875
0.866
0.435
0.577
9.08
0.947
61.56
89.64
0.975
0.971
TABLE IV: Ablation of multi-task loss weighting strategies and loss functions.
Fig. 5: Robot teleoperation setup for downstream grasping. A Manus glove controls the dexterous hand to collect demonstrations in which the robot grasps and lifts objects with property-dependent forces.
Split
Init.
Training Data
Mass
Stiffness
Friction Coeff.
Tele.
Aug.
H
Acc. ↑
Macro-F1 ↑
MAE ↓
MAPE ↓
Acc. ↑
Macro-F1 ↑
ID
Train from scratch
✓
0.998
0.996
0.217
5.10
1.000
1.000
✓
✓
✓
0.960
0.966
0.315
6.78
0.965
0.973
Fine-tuned
✓
0.907
0.912
0.201
4.66
0.949
0.960
✓
✓
0.926
0.927
0.164
3.66
0.986
0.989
✓
✓
0.922
0.908
0.171
3.97
0.950
0.962
TABLE V: Human-to-robot transfer. Bold and underlined entries denote the best and second-best results.
Fig. 6: Adaptive grasping outcomes on ID and OOD objects. “GT Properties” conditions our policy on ground-truth properties, whereas “ViTacPhys Pred.” uses predicted properties. Clean success is the primary metric. Total success is the sum of clean and over-force outcomes and is reported as lift-and-hold success.
Comparison
Split
Method
Evaluated-object ratio
Abs. Err. ↓
Pearson r↑
Pairwise ↑
ACT vs. Ours
ID
ACT [ 1 ]
37/40 (92.5%)
0.040
0.889
0.852
Ours
0.035
0.862
0.843
OOD
ACT [ 1 ]
8/12 (66.7%)
0.076
0.438
0.639
Ours
0.061
0.852
0.806
ViTacFormer vs. Ours
ID
ViTacFormer [ 2 ]
17/40 (42.5%)
0.077
0.503
0.733
Ours
0.044
0.851
0.844
TABLE VI: Normalized grasping force comparison.
Fig. 7: Grasping force comparison between our method and baselines, grouped by the ground-truth mass, stiffness, and friction coefficient bins used as physical-property inputs to the downstream policy. “L”, “M”, and “H” denote low, medium, and high, respectively. For a given method, “X” indicates that all objects in the corresponding bin failed to be grasped by that method, while an empty bin indicates that no evaluated object in the corresponding split/subset belongs to that bin.