Real-World Robot Learning with Masked Visual Pre-training Ilija RadosavovicTete XiaoStephen James Pieter Abbeel Jitendra MalikyTrevor Darrelly

2025-04-29 0 0 3.06MB 13 页 10玖币
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Real-World Robot Learning with
Masked Visual Pre-training
Ilija RadosavovicTete XiaoStephen James Pieter Abbeel Jitendra MalikTrevor Darrell
University of California, Berkeley
Abstract: In this work, we explore self-supervised visual pre-training on images
from diverse, in-the-wild videos for real-world robotic tasks. Like prior work, our
visual representations are pre-trained via a masked autoencoder (MAE), frozen,
and then passed into a learnable control module. Unlike prior work, we show that
the pre-trained representations are effective across a range of real-world robotic
tasks and embodiments. We find that our encoder consistently outperforms CLIP
(up to 75%), supervised ImageNet pre-training (up to 81%), and training from
scratch (up to 81%). Finally, we train a 307M parameter vision transformer on a
massive collection of 4.5M images from the Internet and egocentric videos, and
demonstrate clearly the benefits of scaling visual pre-training for robot learning.
Keywords: Self-supervised Learning, Visual Representations, Robot Learning
1 Introduction
Learning representations with large neural networks is the powerhorse of modern deep learning.
This has enabled impressive results in computer vision [1,2], natural language processing [3,4,5],
and audio generation [6,7]. How can we transfer the success stories of representation learning to
robotics? We can approach this from two ends: shared representations on the perception side or
shared representations on the action side. Our focus in this paper is on shared visual representations.
Of course, the devil is in the details. Recent developments in the field of visual learning have made
this more feasible: (1) the use of diverse, real-world data from the Internet and egocentric videos,
(2) self-supervised objectives that do not overly rely on data augmentations or other forms of strong
human-designed priors, (3) scalable and high-capacity transformer models [8,9], and (4) training of
control policies on top of frozen visual representations. In our recent work [10], we have shown that
this recipe for self-supervised visual pre-training is effective for motor control in simulation.
In this paper, we show that this framework is effective for real-world robotic tasks as well (Figure 1).
We build on our prior work, but make significant advances in terms of data scale and diversity (7×
larger), model size (15×bigger), and real-world experiments (extensive real robot evaluations).
In particular, we train self-supervised visual representations on real-world images and videos from
the Internet [11,12,13] and egocentric video datasets [14,15]. We leverage the masked autoen-
coders [16] that learn visual representations by masked prediction. The hope is that, by learning to
predict the missing content in real-world images, the model will learn useful properties of the visual
world that will enable it to learn to perform real-world robotic tasks. Given the pre-trained vision
encoder, we freeze the encoder and learn control policies on top. The same visual representations are
used for all downstream robotic tasks and embodiments. We focus on efficient real-world learning
through behavior cloning with a handful of human-provided demonstrations per task (20 - 80).
*,Equal contribution. Code, pre-trained models, and videos available on our project page.
arXiv:2210.03109v1 [cs.RO] 6 Oct 2022
Real-World Robotic Tasks
Two robots (xArm, Allegro hand)
Eight tasks (scenes, objects)
In-the-Wild Data
Over 4.5 million images
Five diverse data sources
Masked Autoencoder
Encoder
Decoder
(b) Autoencoder(a) Masking
Figure 1: Real-world robot learning with masked visual pre-training. We learn visual represen-
tations from a massive collection of Internet and egocentric data. We pre-train representations with
masked image modeling, freeze the encoder, and learn control policies for robotic tasks on top.
We evaluate our approach in an extensive real-world study and report results from 981 real-world
experiments. We consider basic motor control tasks (reach, push, pick), as well as tasks with varia-
tions in scenes and objects (Figure 1, right). We find that our approach achieves considerably higher
performance than CLIP (up to 75%), supervised pre-training (up to 81%), and training from scratch
(up to 81%). Furthermore, we observe that our representations lead to large improvements in sample
complexity, reaching the strongest baseline performance with half the number of demonstrations.
In addition, we demonstrate the benefits of scaling visual pre-training for robotics by training a
307M parameter vision encoder [9] on a massive collection of 4.5M images from ImageNet [11],
Epic Kitchens [17], Something Something [12], 100 Days of Hands [13], and Ego4D [15] datasets.
Importantly, we observe that it is not sufficient to scale the model alone and that larger models
require bigger datasets. To the best of our knowledge, ours is the largest vision model deployed for
robotics, and demonstrates clearly the benefits of visual pre-training scale for robot learning.
2 Related Work
End-to-end control is concerned with learning to predict robot actions (e.g., joint velocities, end-
effector poses, etc) directly from observations [18,19,20], without the need to perform explicit 3D
pose estimation [21], grasp planning [22], and motion planning [23]. However, these end-to-end
approaches tend to be too sample inefficient for real-world training. Some works have tried to find
a balance between these explicitly pipelined approaches and end-to-end approaches [24,25,26].
Supervised pre-training for robotics learns one or more pretext tasks through strong supervision
and then transfers the representations to downstream robotic tasks. Lin et al. [27] shows that rep-
resentations learned from semantic tasks such as detection and segmentation correlate with affor-
dance maps for object manipulation. Shridhar et al. [28] use language-supervised CLIP model [29]
for learning language-conditioned imitation policy. In concurrent work, Nair et al. [30] explore
pre-training visual representations using time contrastive learning and language descriptions from
human annotators. These methods all require expert labels or cross-domain supervision.
Self-supervised learning in robotics has been explored as a means of improving sample efficiency.
Examples include: learning a dynamic model from interaction with environments [31]; learning
visual representation from interaction with environments [32]; learning vision-based policies on
self-collected trajectories [33,34]; learning visual autoencoders on trajectories [35]; learning spa-
tiotemporal representations through videos [36,37]; learning visual correspondence [38]; utilizing
non-parametric nearest-neighbor retrieval [39]; and conducting visual self-supervised learning on
pre-collected demonstrations [40]. These methods require in-domain data collection, and thus may
be difficult to extend beyond the training environment and task. In contrast, our approach uses a
large-scale and diverse collection of real-world images and videos, making it more generalizable.
2
𝜋!"#$ 𝜋%&"!
𝜋%'"()* 𝜋%'+",
𝜋'*-#.
Pre-trained Vision Encoder
𝜋/"0$
Figure 2: One encoder for all robots and tasks. We train control policies per task, on top of the
frozen encoder. The same vision encoder is used for all downstream robotic tasks and embodiments.
3 Real-World Robot Learning with Masked Visual Pre-training
3.1 Masked Visual Pre-training
Data collection. We first compile a large-scale dataset for learning visual representations. We
primarily use Ego4D [15], a massive scale, egocentric dataset from nine countries recorded via
portable devices, covering over 3,670 hours of daily-life activities. We combine the Ego4D data with
the ImageNet [11], as well as the Hand-object Interaction (HoI) data used in [10], which comprises
of the egocentric Epic Kitchens [17] dataset, the YouTube 100 Days of Hands dataset [13], and the
crowd-sourced Something-Something dataset [12]. Our training data totals 4.5 million images, 6.5x
of the HoI data. We find that a sufficiently large and diverse pre-training dataset to perform the mask
image modeling self-supervisory task is critical to scale up the vision backbone for real robot tasks.
Self-supervised objective. At the core of our self-supervised representation learning approach is
masked image modeling via the masked autoencoders (MAE) [16]. MAE masks out random patches
in an image and reconstructs the missing content with a vision transformer (ViT) [9]. A high masking
ratio, e.g., 75%, and asymmetrical heavy-encoder light-decoder design, are important for learning
good visual representations efficiently. Simple and free from dataset or task-specific augmenta-
tions [41], MAE is the state-of-the-art self-supervised framework in computer vision [42,43,44,45],
and has been demonstrated to work well for motor control tasks in simulation as well [10].
Architecture. We use the ViT models as our vision encoders. While the MAE-trained ViT models
yield improving performance in vision tasks as model sizes grow [9,16,46], previous work [10]
does not show improvement from switching a ViT-Small model to the ViT-Base counterpart of 4x
as many parameters. In this work, we scale the model up to the ViT-Large and deploy it on the
real robot. The model contains 307M parameters and runs at 64 gigaflops at input size 224×224,
approximately 15x as many as the commonly adopted ResNet-50 [47], the largest vision model
deployed for robotics. As we will show in the experiments, scaling model sizes while training on
sufficiently large data leads to consistent performance improvement on downstream robotic tasks.
3.2 Real-World Robot Learning
We learn to perform real-robot tasks through behavior cloning (BC). We collect demonstrations
containing trajectories of RGB images from a wrist-mounted camera and the robot’s joint state at
each time step. For most of the tasks, we use the motion-tracked HTC Vive VR system to control the
end-effector. For some tasks that are difficult to demonstrate via the motion controller, e.g., closing
fridge door, we use kinesthetic teaching. Given the recorded demonstrations, we train a control
policy that takes in the input image features and proprioceptive states (joint positions) at time step
tand predicts the action at time step t+ 1. We perform joint position control; we do not use any
end-effector information (e.g., the 6-DoF pose). We build on our MVP pipeline [10] and freeze
the image encoder throughout the policy learning, which prevents large pre-trained encoders from
overfitting to a specific setting or task, and greatly reduces GPU memory footprint and training time.
3
摘要:

Real-WorldRobotLearningwithMaskedVisualPre-trainingIlijaRadosavovicTeteXiaoStephenJamesPieterAbbeelJitendraMalikyTrevorDarrellyUniversityofCalifornia,BerkeleyAbstract:Inthiswork,weexploreself-supervisedvisualpre-trainingonimagesfromdiverse,in-the-wildvideosforreal-worldrobotictasks.Likepriorwork,o...

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