Spatio-Temporal Alignment with a Motion Prior

STAMP

Robot Motion Transitions with Human Motion Prior

1 Department of Artificial Intelligence, Korea University

2 ROBOTIS

3 Department of Statistics, Korea University

* Corresponding author: Sungjoon Choi

Connecting independently acquired humanoid motions with learned spatio-temporal alignment.

Korea UniversityROBOTIS

Video

Overview

Overview

STAMP connects independently acquired robot motions while preserving the content and order of the input clips. Given two motions, it determines their relative position, heading, and transition duration, then generates the motion connecting them.

The input motions are first retargeted to a human rig. A learned alignment model selects boundary conditions for a human motion prior to generate the transition. The completed sequence is retargeted to the robot and used to train a motion-tracking policy. Repeating this process composes motion primitives into longer sequences.

Method

Robot-to-Human-to-Robot framework

Connect robot motions through a shared human motion space.

STAMP pipeline showing robot-to-human retargeting, learned alignment, human motion inbetweening, and retargeting back to the robot
01

Transfer to human space

Retarget the two robot motions to a shared human rig.

02

Learn the alignment

Rank candidate positions, headings, and durations using the boundary motion contexts.

03

Generate the transition

Use a human motion prior to fill the gap under the selected boundary conditions.

04

Return to the robot

Retarget the completed sequence and train a motion-tracking policy.

Physical robot experiments

Running-to-punching transition

Running to punching, with a transition that allows continued forward movement.

InterpolationSTAMP

Interpolation and STAMP

Interpolation places the punching start at the running endpoint. STAMP places it farther forward, allowing the motion prior to generate a connecting step.

Physical execution on ROBOTIS K1.

Evaluation

Transition tracking results

18 motion pairs per robot, evaluated under a common tracking-policy protocol.

Unitree G1

80.69%

Transition tracking success

STAMP
80.69%
Interpolation
69.59%
MotionBricks
56.91%
Kimodo†
50.69%

ROBOTIS K1

87.52%

Transition tracking success

STAMP
87.52%
Interpolation
84.70%
Kimodo†
64.55%

Paper Tables II–III. 1,024 rollouts per motion pair; 18,432 rollouts per method and robot. Each policy is evaluated against its own reference, measuring trackability rather than similarity to a shared ground-truth transition. Kimodo† denotes the Kimodo-based inbetweening model.

Long-horizon Motion Composition

Connecting motion primitives into complete scenarios.

Diverse Motion Combinations

Composing the same motion primitives into different sequences.

Each complete motion sequence, including the generated transitions, is used as a reference to train a sequence-specific tracking policy with BeyondMimic.

Alignment model results

The learned model ranks candidate positions, headings, and transition durations. These videos show transitions generated under different candidate alignments in human motion space.

Lower rank indicates lower predicted transition cost. These are qualitative examples; the quantitative ranking ablation compares ranks 1 and 100.