Moto: Latent Motion Token as the Bridging Language for Robot
  Manipulation
Authors: name: Yi Chen, name: Yuying Ge, name: Yizhuo Li, name: Yixiao Ge, name: Mingyu Ding, name: Ying Shan, name: Xihui Liu

Recent developments in Large Language Models pre-trained on extensive corpora
have shown significant success in various natural language processing tasks
with minimal fine-tuning. This success offers new promise for robotics, which
has long been constrained by the high cost of action-labeled data. We ask:
given the abundant video data containing interaction-related knowledge
available as a rich "corpus", can a similar generative pre-training approach be
effectively applied to enhance robot learning? The key challenge is to identify
an effective representation for autoregressive pre-training that benefits robot
manipulation tasks. Inspired by the way humans learn new skills through
observing dynamic environments, we propose that effective robotic learning
should emphasize motion-related knowledge, which is closely tied to low-level
actions and is hardware-agnostic, facilitating the transfer of learned motions
to actual robot actions. To this end, we introduce Moto, which converts video
content into latent Motion Token sequences by a Latent Motion Tokenizer,
learning a bridging "language" of motion from videos in an unsupervised manner.
We pre-train Moto-GPT through motion token autoregression, enabling it to
capture diverse visual motion knowledge. After pre-training, Moto-GPT
demonstrates the promising ability to produce semantically interpretable motion
tokens, predict plausible motion trajectories, and assess trajectory
rationality through output likelihood. To transfer learned motion priors to
real robot actions, we implement a co-fine-tuning strategy that seamlessly
bridges latent motion token prediction and real robot control. Extensive
experiments show that the fine-tuned Moto-GPT exhibits superior robustness and
efficiency on robot manipulation benchmarks, underscoring its effectiveness in
transferring knowledge from video data to downstream visual manipulation tasks.