Authors: Seongjin Bien, Carlo Kneissl, Tobias Jülg, Frank Fundel, Thomas Ressler-Antal, Florian Walter, Björn Ommer, Gitta Kutyniok, Wolfram Burgard
Organizations: Department of Computer Science & Artificial Intelligence, University of Technology Nuremberg, Germany · Ludwig Maximilian University of Munich · TUM School of Computation, Information and Technology, Technical University of Munich, Germany
Tactile sensation is essential for contact-rich manipulation tasks. It provides direct feedback on object geometry, surface properties, and interaction forces, enhancing perception and enabling fine-grained control. An inherent limitation of tactile sensors is that readings are available only when an object is touched. This precludes their use during planning and the initial execution phase of a task. Predicting tactile information from visual information can bridge this gap. A common approach is to learn a direct mapping from camera images to the output of vision-based tactile sensors. However, the resulting model will depend strongly on the specific setup and on how well the camera can capture the area where an object is touched. In this work, we introduce FlowTouch, a novel model for view-invariant visuo-tactile prediction. Our key idea is to use an object's local 3D mesh to encode rich information for predicting tactile patterns while abstracting away from scene-dependent details. FlowTouch integrates scene reconstruction and Flow Matching-based models for image generation. Our results show that FlowTouch is able to bridge the sim-to-real gap and generalize to new sensor instances. We further show that the resulting tactile images can be used for downstream grasp stability prediction. Our code, datasets and videos are available at https://flowtouch.github.io/
Figures & tables
Fig. 1: FlowTouch at a glance: The robot first looks at the object and creates a mesh with scene mesh generation foundation models. Given the particular touch point on the mesh and the static background image of the tactile sensor, FlowTouch then predicts the resulting tactile image.
Fig. 2: The FlowTouch architecture: The blue area shows the image-to-PCN sampling pipeline, while the green area shows the generative model’s structure. Snowflakes indicate components with frozen weights.
Fig. 3: Left: A selection of primitive geometries used for generating the simulation data. Right: Taxim GelSight images rendered from a single contact point (corner of a cube), with local translations and rotations.
Name
Sensor
Training # (# obj.)
Validation # (# obj.)
OFR-G
GelSight
887 (36)
135 (6)
SIM-G
GelSight
200K (135)
113K (60)
YCB-D
DIGIT
2578 (7)
1084 (3)
SIM-D
DIGIT
200K (135)
—
SELF-D
DIGIT
—
547 (13)
GS-G
GelSight
13372 (6*)
3379 (6*)
TABLE I: List of datasets used for evaluation. * indicates within-object split.
Variant
PSNR ( ↑ )
SSIM ( ↑ )
LPIPS ( ↓ )
Base
24.28
0.52
0.40
BG-Enc
25.52
0.57
0.34
BG-Scene-Enc
24.91
0.54
0.38
BG-Stack
25.53
0.59
0.35
TABLE II: Ablation study on network design choices evaluated on the GelSight OFR dataset. All metrics are reported on the held-out validation set.
Training Method
YCB-D
OFR-G
SELF-D (unseen)
PSNR ( ↑ )
SSIM ( ↑ )
LPIPS ( ↓ )
PSNR ( ↑ )
SSIM ( ↑ )
LPIPS ( ↓ )
PSNR ( ↑ )
SSIM ( ↑ )
LPIPS ( ↓ )
Naive Finetuning
20.23
0.612
0.284
24.58
0.553
0.410
16.05
0.355
0.415
Data Augmentation
−0.56
−0.015
+0.013
−0.43
−0.031
+0.009
−0.37
−0.030
+0.004
Sparsh Perceptual Loss
−0.20
−0.006
+0.005
+0.17
−0.001
−0.006
+0.06
−0.000
−0.002
Optimizer Reset
−0.03
−0.001
+0.000
+0.28
−0.005
−0.004
+0.07
+0.001
−0.001
Domain Conditioning
+2.18
+0.058
−0.055
+0.90
+0.029
−0.045
+0.78
+0.032
−0.021
TABLE III: Quantitative comparison of different sim-to-real training techniques across the pretraining SIM-G, finetuning OFR-G, and unseen SELF-D datasets. Values for experimental methods are shown as absolute differences relative to the Naive Finetuning baseline and are calculated on the validation dataset.
Fig. 4: Tactile predictions of the model ablations listed in Tab. III . Samples are taken from the validation dataset.
Fig. 5: Left: Objects used for data collection. Center: Robot setup. Right: Collected grasp poses aligned to generated mesh, with unique color for each finger pair.
Fig. 6: Meshes used for the ObjectFolder Benchmark grasp stability test.
Name
Pre-training ds.
Fine-tuning ds.
Accuracy (%)
GT
—
—
85.83
A
Full GS-G
—
86.06
B
SIM-{D,G}
Full GS-G
85.17
C
Mixed-DG
10% of GS-G
83.74
D
SIM-{D,G}
OFR-G, YCB-D
81.35
D, no Sparsh
SIM-{D,G}
OFR-G, YCB-D
78.59
TABLE IV: Training dataset ablations for grasp stability task. Values are averaged over 100 trainings.
Fig. 7: Tactile predictions from the grasp stability task on the dataset ablations listed in Tab. IV . Samples are taken from the validation dataset. SELF-D has not been seen during training.