Beyond vision   /   Grounded in touch

Touch-R1

Reinforcing Touch Reasoning in MLLMs

Turning contact evidence into physical understanding—across tactile perception, comparison, and reasoning.

TouchReason-1M   /   TouchReason-Bench

Research team & affiliations
Yingxin Lai1,5,*Yafei Zhou2,5,*Fucai Zhu5Siyu Zhu3Weihao Yuan4,5,†

1 Xiamen University   2 Great Bay University   3 Fudan University   4 Nanjing University   5 Daimon Robotics

* Equal contribution. Author order is random.   † Corresponding author.

Daimon Robotics
THE GEOMETRY OF CONTACT FIG. 01
An illustrative wireframe surface deforms at a contact point.
From contact to understanding.
Explore the object atlas ↗
CONCEPT VISUALIZATION
NOT SENSOR MEASUREMENTS
PHYSICAL EVIDENCE. STRUCTURED REASONING.Discover the research
4optical tactile sensors
1M+synchronized tactile pairs
4,800held-out benchmark QA pairs
60.1TouchReason-Bench average
01 / The idea

Seeing is not
the whole story.

Touch-R1 brings R1-style reinforcement learning to tactile reasoning. We build TouchReason-1M, a multi-sensor dataset with synchronized tactile-force records and verified reasoning QA, and TouchReason-Bench, a benchmark for tactile perception, ordinal comparison, cross-sensor consistency, and visual-tactile conflict. Touch-R1 combines ordinal-aware accuracy, cross-sensor physical consistency, structured-format control, and input-side tactile grounding, enabling MLLMs to revise visual priors using contact evidence.

02 / ROBOT EVIDENCE

From contact to control.

Explore real-robot interaction, then compare model rollouts task by task.

REAL-WORLD / ADAPTER INSERTION

Real robots. Physical contact.

Fine-tuned Qwen, fine-tuned Phi 0.5, and Touch-R1. Real-robot insertion at 2× speed.

03 REAL-ROBOT TRIALS
TRIAL 032× SPEED

Qwen (Fine-tuned)

FailedAdapter insertion

2× speed · muted

00:00HD ↗
TRIAL 012× SPEED

Phi 0.5 (Fine-tuned)

SuccessfulAdapter insertion

2× speed · muted

00:00HD ↗
OURS2× SPEED

Touch-R1 (Ours)

SuccessfulAdapter insertion

2× speed · muted

00:00HD ↗

Failed trial first · Outcomes shown per recording · 2× playback · Muted · HD videos available.

IN SIMULATION / CASE EXPLORER

See the task. Compare the rollout.

Choose a case. Compare the same task across three methods.

10 CASES / 30 ROLLOUTS
CHOOSE A CASE1 LIBERO SPATIAL / 9 METAWORLD

LIBERO Spatial · Case 43 · Recorded 1×

Bowl to plate

pick up the black bowl between the plate and the ramekin and place it on the plate

01 / 10

Preview speed · shared by all methods

Original Qwen

BASELINE
Not completed220 steps

Ready · recorded timing

0:00Video ↗

GPT-6 Astra

BASELINE
Not completed220 steps

Ready · recorded timing

0:00Video ↗

Touch-R1 (Ours)

OURS
Successful69 steps

Ready · recorded timing

0:00Video ↗

Selected simulation cases · Outcomes per recording · Inference waits omitted · Clips hold their final frame.

Recording protocol & case metadata ↗

These 10 examples were selected for Touch-R1 completion and Original Qwen non-completion: one LIBERO Spatial case and nine MetaWorld cases. They are curated demonstrations, not an aggregate benchmark success-rate sample.

GPT-6 Astra follows the model name supplied with these recordings; the backend model identity has not been independently verified. It uses zero-shot direct control; Qwen and Touch-R1 use action training, with different training budgets.

Source timing is preserved in the files: LIBERO 1× and MetaWorld 0.5×. The default 1× preview plays that source timing; the optional 2× preview multiplies all three methods equally without editing the recordings. Model-inference waiting time is omitted. Outcomes and action-step counts follow the supplied case manifest; clip duration is not an inference-speed measurement.

Source case metadata ↗Media provenance ↗
03 / The method

Three-stage tactile-grounded training.

Learn contact dynamics, connect touch to language, then reinforce reasoning grounded in physical evidence.

Tactile Dynamics

Pretrain a touch encoder by predicting future tactile tokens from contact histories.

QA SFT

Align touch, vision, and language to a structured reasoning interface.

Tactile-adapted GRPO

Reward answers that are correct, consistent, parsable, and tactile-dependent.

Ordinal-aware accuracy
Cross-sensor consistency
Structured format
Tactile grounding
J_Touch-R1(theta) = J_GRPO(theta; R) + gamma G_tg(theta),    R = 0.6 R_acc + 0.3 R_cs + 0.1 R_fmt
Touch-R1 final framework: tactile dynamics pretraining, QA supervised fine-tuning, and tactile-adapted GRPO
Three-stage Touch-R1 training: tactile dynamics pretraining, QA supervised fine-tuning, and tactile-adapted GRPO. Open original figure (PDF) ↗
04 / TouchReason-1M

Multi-sensor data for tactile reasoning.

TouchReason-1M couples tactile frames, deformation fields, shear, depth, force, metadata, ordinal labels, and reasoning QA.

THE ACQUISITION DEVICE

Built around physical contact.

A handheld acquisition setup combines an optical tactile sensor, a six-axis force/torque sensor, and an integrated IMU. A RealSense D405 provides the external view.

  • Optical touch
  • 6-axis F/T
  • IMU
  • RealSense D405
View original device figure ↗
Acquisition device showing the optical tactile sensor, six-axis force/torque sensor, integrated IMU, handle, and RealSense D405 camera
The acquisition device and its labeled sensing components. Click to inspect the original figure.
CONTACT / Two motions. Seen and felt.

2 acquisition sequences · RGB + optical tactile

01

Normal press

Increasing normal contact reveals deformation over time.

RGB view
Tactile view
00:00RGB ↗Touch ↗
02

Upward shear

Tangential motion reveals a changing contact response.

RGB view
Tactile view
00:00RGB ↗Touch ↗

Source recordings of a soft plastic cup-lid protrusion under normal press and upward shear. Each pair shows the same contact from two views. Explore five more contact samples ↗

THE CONTACT COLLECTION / FIVE PAIRED RECORDINGS

One contact.
Two perspectives.

Explore the external RGB view alongside the optical tactile response. Choose a sample below, then play both views together.

Sample 01

RGB / OPTICAL TACTILE
RGB view
Tactile view
00:00RGB ↗Touch ↗
SELECT A CONTACT SAMPLE01 / 05

Source acquisition footage. Each sample pairs the external scene with its optical tactile recording, showing the contact and sensor response together.

THE OBJECT ATLAS / 80 COLLECTION SAMPLES

A world you can touch.

Everyday objects. Real surfaces.
A closer look at the diversity behind TouchReason-1M.

Selected photographs from the acquisition collection.80 SAMPLES / 1,000+ OBJECTS IN THE DATASET
1,000+ objectsEveryday objects spanning nine material categories.
14,700 sequencesValid tactile contact sequences collected under a unified interaction protocol.
1.323M pairsSynchronized tactile data pairs with deformation, shear, depth, and contact-force signals.
4 sensorsDM-Tac X · GelSight Mini · Xense · Tac3D.
Overview of TouchReason-1M
TouchReason-1M: multi-sensor contact acquisition and reasoning data construction.
Representative tactile contact features
Representative tactile signals: raw deformation, displacement, shear, and depth.
05 / The evidence

Stronger tactile reasoning across benchmark families.

Touch-R1-7B outperforms frontier MLLMs, general VLMs, and tactile-specialist baselines on TouchReason-Bench.

Qualitative Touch-R1 reasoning examples
Qualitative reasoning examples: interpreting contact evidence and revising physical-property judgments. Watch the model comparisons ↓

TouchReason-Bench

Tactile perception, comparison, and consistency.

60.1AVG / 100
Qwen2.5-VL-7B
28.0
GPT-4o
35.4
Octopi-13B
41.7
SToLa
47.5
Touch-R1-7B
60.1

Average scores on a 0–100 scale. Higher is better.

ModelOMAE ↓L2-EMCSCAvg
Gemini-2.5-Pro0.6713.841.837.6
SToLa0.4522.151.947.5
Touch-R1-7B0.2439.571.360.1

OMAE: ordinal error (lower is better). CSC: cross-sensor consistency.

06 / A closer look

What makes tactile reasoning work?

Model-scale comparisons and controlled ablations isolate the contributions of training data and reward design.

07 / Build on this work

BibTeX

touch-r1.bib
@misc{lai2026touchr1reinforcingtouchreasoning,
  title         = {{Touch-R1}: Reinforcing Touch Reasoning in {MLLMs}},
  author        = {Yingxin Lai and Yafei Zhou and Fucai Zhu and Siyu Zhu and Weihao Yuan},
  year          = {2026},
  eprint        = {2605.27154},
  archivePrefix = {arXiv},
  primaryClass  = {cs.CV},
  url           = {https://arxiv.org/abs/2605.27154}
}

TOUCHREASON-1M / THE OBJECT ATLAS

The physical world, up close.

Selected acquisition views from TouchReason-1M. Choose a sample to inspect the photograph.

01–16 / 80
Expanded research figure