Data Generation For

Behavior Cloning

RLG Long Talk

March 8, 2024

Adam Wei

Agenda

  • Motivation: why data generation?
  • Experiments & (empirical) results
  • Future work

 

Single Maze

Multi-Maze

Motion Planning  Experiments

Planar Pushing

Sim2Real Transfer

Scaling Laws & Generalization

Motivation: Learning Perspective

Motivation: Learning Perspective

Tesla

1X

...if we can collect enough data, we can solve the task

- Shuran at CoRL

If we have enough data... is robotics (mostly) solved?

If we have enough data... is robotics (mostly) solved?

1. How can we get robot data at scale?

Big data

Big transfer

Small data

No transfer

Ego-Exo

 robot teleop

Open-X

simulation rollouts

Slide credit: Russ

If we have enough data... is robotics (mostly) solved?

2. Is scaling all we need?

We need to scale and generalize across:

  • objects, tasks, embodiments, environments, camera views, sensor modalities, etc

 

This is a big ask!

Proposal: Begin by exploring questions about scale directly in simulation

Motivation: Model-Based Perspective

Model-Based Challenges

  • Requires state estimation
  • Real-time & reactive planning

Behavior Cloning...

  • Visuomotor policy
  • "Amortizes" the compute

Agenda

Single Maze

Multi-Maze

Motion Planning  Experiments

Planar Pushing

Sim2Real Transfer

Scaling Laws & Generalization

Agenda

Single Maze

Multi-Maze

Motion Planning  Experiments

Planar Pushing

Sim2Real Transfer

Scaling Laws & Generalization

Single Maze: Problem Set Up

Goal: Train a policy to navigate a single maze

  • Sequence of robot actions
  • History of robot positions
  • Target position

Single Maze: Training

Dataset:

  • 50k GCS demonstrations

GCS settings

  • Min length and time objectives
  • Box velocity constraints
  • Bezier order 3

Single Maze: Results

Multi-Maze: Problem Set Up

Goal: Obtain a policy that can navigate arbitary mazes

  • Sequence of robot actions
  • History of images
  • History of robot positions 
  • Target position

Spoiler: Diffusion Policy cannot solve this task

Multi-Maze: Training

Dataset:

  • 250k unique mazes
  • 2 trajectories per maze
  • Trinary images

GCS Settings

  • Same as single maze case
  • Padded obstacles

Multi-Maze: Training

RGB

Trinary

64x64x3    [0, 255]

52x52x1    [0, 2]

Multi-Maze: [Selected] Results

Multi-Maze: Results

Multi-Maze: Takeaways

  • The distribution conditioned on mazes is complex and hard to learn (combinatorial)
    • Ex. Given a list of numbers, you wouldn't use a neural network to do sorting
  • Need a planner to solve mazes, not a policy
  • Generalization in images could just be hard?
    • Training on 6250 trajectories yields similar performance as full dataset

Multi-Maze: Related Work

  • Diffusing entire plans instead of policies
  • One model per maze

Might work for multi-maze?

Multi-Maze: Related Work

Thank you to Ahbinav

for sharing this work

Similar recipe to video prediction:

 1. Visually hallucinate a plan

 2. Back out actions from the hallucination

??

Agenda

Single Maze

Multi-Maze

Motion Planning  Experiments

Planar Pushing

Sim2Real Transfer

Scaling Laws & Generalization

Brief discussion

Motion Planner Comparisons

  • Compared different motion planners for diffusion training in the single maze setting

GCS

RRT

RRT (shortcut)

RRT*

Motion Planner: Takeaways

Data quality matters: diffusion is shockingly good at imitating the characteristics of the expert​

  • Optimality, smoothness, robustness, etc are important

Ex. RRT

  • The policy struggles to converge to the target (too random)
  • Diffusion doesn't smooth out the randomness

RRT

Agenda

Single Maze

Multi-Maze

Motion Planning  Experiments

Planar Pushing

Sim2Real Transfer

Scaling Laws & Generalization

Learning Perspective

  • Scale-up data collection
  • Learn a useful representation of physics in simulation; then transfer to real

Data Generation In Simulation

Model-based Perspective

  • [Mostly] addresses the 'state estimation' problem
  • Real-time and reactive planning (amortizes the compute)

Policy

Training

Data

Trajectory Generation

Data Generation In Simulation

Example: Push-T Task

Policy

Training

Data

Trajectory Generation

Data Generation In Simulation

Example: Push-T Task (with Kuka)

Implementation Details

Data quality matters!

(at least in the low data regime)

Text

Maybe policies become less sensitive to data quality in the big data regime?

Pushing on the vertices

Pushing on the sides (more robust)

Agenda

Single Maze

Multi-Maze

Motion Planning  Experiments

Planar Pushing

Sim2Real Transfer

Scaling Laws & Generalization

Sim2Real

Sim2Real

Physics gap

  • Simulated physics doesn't need to be perfect; just good enough

Visual gap

  • Proposals: domain randomization, photo-realistic rendering (Blender, CycleGan, etc)

Sim2Real

Sim2Real: Real-World Data

  • Simulated data can do the heavy lifting, but we can benefit greatly from a small amount of real-world data
  • Goal: How can we most effectively leverage a small amount of real-world data?

Big data

Big transfer

Small data

No transfer

Ego-Exo

 robot teleop

Simulation

Open-X

Sim2Real

Sim2Real: Finetuning

  • Few shot fine-tuning / transfer learning
  • Need to train twice

Simulated Policy

Simulated Data

Trajectory Generation

Real Policy

Real-world  Data

Sim2Real

Sim2Real: Heterogeneous Datasets

Real-world data

Policy

Training

Data

Trajectory Generation

Sim2Real

Classifier-Free Guidance

  • Method to conditionally sample from classes

No guidance

With guidance

Sim2Real

Classifier-Free Guidance

  • Method to conditionally sample from classes

unconditional score

Cats

Dogs

  • Unconditional distribution can be complex

Sim2Real

Classifier-Free Guidance

  • Method to conditionally sample from classes

unconditional score

conditional score

Cats

Dogs

  • Conditional distributions are simpler

Sim2Real

Sim2Real: Classifier-Free Guidance

Real-world data collection

Policy

(trained via CFG)

Simulated Data + Labels

Trajectory Generation

(I would also be interested in a more rigorous exploration)

Real-world data + Labels

Sim2Real

Sim2Real: Classifier-Free Guidance

Sim Data

Real Data

Goal: learn the distributions for both the sim and real data

  • Hope that the sim and real distributions are similar enough that the sim data can help the model learn something useful about the real data
  • Simultaneously, learn the real distribution to deploy on hardware

Sim2Real

Sim2Real: Classifier-Free Guidance

Sim Data

Real Data

Goal: learn the distributions for both the sim and real data

 

Caveat: Might not give huge improvements... The policy could already implicitly distinguish between sim and real by the input images?

Agenda

Single Maze

Multi-Maze

Motion Planning  Experiments

Planar Pushing

Sim2Real Transfer

Scaling Laws & Generalization

Scaling Laws

Roughly speaking: For LLMs...

2x data => 2x model size

D = data, N = parameters, C =compute

Scaling Laws

Super useful for practitioners; however...

  • Power laws are only valid in the large-data regime
  • Power laws require tons of compute to identify (better suited for industry)

Instead, explore scaling and generalization at a smaller scale in simulation:

  • objects, tasks, embodiments, environments, camera views, sensor modalities, etc

Generalization Across Objects

Collect a planar-pushing dataset with N objects

Questions: If the policy has learned to push n objects...

  • how many of the N objects can it generalize to?
  • how much data is required to push the (n+1)th object

Generalization Across Tasks

  • Does learning one task make it easier to learn the others?
  • Does learning multiple tasks improve performance of individual tasks?
  • Can language guidance improve data efficiency?

Push-T

Insertion [IBC]

Sorting [IBC]

Thank you!

Copy of Spring 2024 Long Talk

By Bernhard Paus Græsdal

Source: weiadam

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