DAPPT: Domain-Aware Policies from Procedural Trajectories for Sim-to-Real Dexterous Tool Use

Beining Han  Β·  Jia Deng Princeton University

Abstract

Sim-to-real RL has achieved impressive results in dexterous manipulation but remains limited to tasks with accurate rigid-body simulation. However, these methods cannot be applied to skills that involve deformable and particles, with which the simulation speed will become too slow for large-scale RL learning. We present DAPPT, a sim-to-real framework for end-to-end dexterous tool-use manipulation skills, e.g., sand scooping, play-dough rod-rolling, without simulating non-rigid materials. Our method learns a domain-aware RL policy by tracking procedural trajectories parameterized by domain parameters, and distills it into an end-to-end domain-aware sensorimotor policy. Furthermore, explicit domain representation enables fast selection of domain parameters that can maximize downstream task performance. We evaluate DAPPT end-to-end on six dexterous manipulation tasks, including sand scooping, play-dough rod-rolling, sand scraping, mouse-wheel scrolling, dispenser pressing, and spray triggering. Our method achieves 1.5-3.8× in task metrics through the best domain parameter and transfers zero-shot to the real world.

MethodTrack procedural trajectories, not a fixed demonstration

We simulate only the rigid tool and train the robot to track procedural trajectories T(c;t) generated from domain parameters c (for scooping: insertion angle, depth, and speeds). The policy π(p;o;c) takes c as input, so one policy covers many behaviors.

After training, a quick search over c (domain identification) picks the setting that maximizes the real task metric, e.g. grams of sand scooped.

Domain-aware policy diagram: proprioception, point-cloud, and domain parameters feed a policy that tracks procedural trajectories T(c;t)

Experiments β€” Sim-to-Sim Transfer

Trained in rigid-body IsaacLab, evaluated in Genesis with MPM sand and dough. Genesis Avg: mean over sampled domain parameters. Genesis Best: the best one.

Genesis Best
01 Scooping
Genesis Best
02 Rod-Rolling
Genesis Best
03 Scraping
Genesis Best
04 Mouse-Wheel
Genesis Best
05 Dispenser
Genesis Best
06 Spray

Comparison with SimToolReal

SimToolReal (Kedia et al., 2026) tracks GPT-6-generated 6D pose references using ground-truth poses; ours is end-to-end from vision.

Scrape ↓Rod-Roll ↑Scoop ↑Mouse-Wheel ↑Dispenser ↑Spray ↑
Genesis Best (ours)17%2.85 cm13.9 g0.37 rad#2.26k#9.12k
SimToolReal95%0 cm9.2 g0.19 rad#0#0
Scrape: sand left (lower is better). Dispenser / Spray: emitted water particles.

Choosing the best domain parameter

Bar chart: percentage difference of Genesis Best over Genesis Avg, for tracking error and task metric, across all six tasks
Percentage difference of Genesis Best over Genesis Avg, for both the average per-step tracking error (pose / joint value) and the task metric. Lower tracking error does not imply a better task metric.

Why an explicit domain-aware policy is necessary

A policy trained only on the fixed Genesis Best trajectory loses roughly half or more of the task performance.

Mouse-WheelDispenserScoop
Domain-Aware (ours)0.37 rad#2.26k13.9 g
Fixed-Domain0.19 rad#0.96k0.32 g
Performance drop48.6%57.5%97.7%

Experiment - Real-worldZero-shot sim-to-real transfer

Zero-shot on XHand1 + Franka with one depth camera, using Genesis Best, 20 trials per task. Task metric is averaged over task-success trials.

01Scooping

Use the scoop to lift as much sand as possible from the container. Task metric: sand weight in the scoop.

20/20 motion success14/20 task success7.7 g avg. task metric (real)
Real Rollouts
#1
#2

02Rod-Rolling

Roll the rod over the play-dough. Task metric: distance the play-dough is rolled over.

16/20 motion success11/20 task success2.7 cm avg. task metric (real)
Real Rollouts
#1
#2

03Scraping

Scrape a pile of sand off the table with the scraper. Task metric: proportion of sand left unscraped (lower is better).

19/20 motion success19/20 task success29% sand remaining (real)
Real Rollouts
#1
#2

04Mouse-Wheel

Scroll a mouse's wheel as far as possible with a single swing of a finger β€” challenging due to the wheel's small size and noisy depth readings. Task metric: angle the wheel scrolls.

19/20 motion success19/20 task success0.33 rad avg. task metric (real)
Real Rollouts
#1
#2

05Dispenser

Press the dispenser head down. Task metric (sim): amount of water emitted.

18/20 motion success14/20 task success
Real Rollouts
#1
#2
Water emission is not used in real trials for safety.

06Spray

Grasp and lift the spray bottle, then press the trigger. Task metric (sim): amount of water emitted from the spray head.

16/20 motion success10/20 task success
Real Rollouts
#1
#2
Water emission is not used in real trials for safety.

Experiment - Qualitative Interpretation

Qualitative comparison of Genesis Best vs. other domain parameters on Scoop, Scrape, and Rod-Roll

Because domain parameters have direct physical meaning, their effect on behavior is interpretable in the real world too:

  • Scooping β€” using the mean of the sampling range for all 4 domain parameters yields 2.9 g of scooped sand across 10 trials; the Genesis Best parameter setting reaches 7.7 g.
  • Rod-Rolling β€” a smaller target rolling velocity produces firmer contact and deeper play-dough deformation; a faster velocity shortens the contact window and rolls shallower.
  • Scraping β€” the Genesis Best parameter targets a scraper height slightly above the table (leaving more sand behind), while a lower target height closes the gap and leaves a visibly cleaner table.