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Created by Nur Muhammad (Mahi) Shafiullah, Zichen Jeff Cui, Ariuntuya (Arty) Altanzaya, and Lerrel Pinto at New York University.

While behavior learning has made impressive progress in recent times, it lags behind computer vision and natural language processing due to its inability to leverage large, human generated datasets. Human behavior has a wide variance, multiple modes, and human demonstrations naturally don’t come with reward labels. These properties limit the applicability of current methods in Offline RL and Behavioral Cloning to learn from large, pre-collected datasets. In this work, we present Behavior Transformer (BeT), a new technique to model unlabeled demonstration data with multiple modes. BeT retrofits standard transformer architectures with action discretization coupled with a multi-task action correction inspired by offset prediction in object detection. This allows us to leverage the multi-modal modeling ability of modern transformers to predict multi-modal continuous actions. We experimentally evaluate BeT on a variety of robotic manipulation and self-driving behavior datasets. We show that BeT significantly improves over prior state-of-the-art work on solving demonstrated tasks while capturing the major modes present in the pre-collected datasets. Finally, through an extensive ablation study we further analyze the importance of every crucial component in BeT.

In this repository, you can find the code to reproduce Behavior Transformer (BeT). The following assumes our current working directory is the root folder of this project repository; tested on Ubuntu 20.04 LTS (amd64).

• Install the project environment:

  conda env create --file=conda_env.yml
  

• Activate the environment:

  conda activate behavior-transformer
  

• Clone the Relay Policy Learning repo:

  git clone https://github.com/google-research/relay-policy-learning
  

• Install MuJoCo 2.1.0: https://github.com/openai/mujoco-py#install-mujoco
• Install CARLA server 0.9.13: https://carla.readthedocs.io/en/0.9.13/start_quickstart/#a-debian-carla-installation
• To enable logging, log in with a wandb account:

  wandb login
  

  Alternatively, to disable logging altogether, set the environment variable WANDB_MODE:

  export WANDB_MODE=disabled
  

Datasets used for training will be available at this OSF link: https://osf.io/983qz/.

• Download and extract the datasets from the tar archive.
• Activate the conda environment with conda activate behavior-transformer.
• In the extracted folder, run python3 process_carla.py carla to preprocess the CARLA dataset into tensors.
• In ./config/env_vars/env_vars.yaml, set the dataset paths to the unzipped directories.
  • carla_multipath_town04_merge: CARLA environment
  • relay_kitchen: Franka kitchen environment
  • multimodal_push_fixed_target: Block push environment

The following assumes our current working directory is the root folder of this project repository.

To reproduce the experiment results, the overall steps are:

1. Activate the conda environment with

   conda activate behavior-transformer
   

2. Train with python3 train.py. A model snapshot will be saved to ./exp_local/...;
3. In the corresponding environment config, set the load_dir to the absolute path of the snapshot directory above;
4. Eval with python3 run_on_env.py.

See below for detailed steps for each environment.

• Train:

  python3 train.py --config-name=train_carla
  

  Snapshots will be saved to a new timestamped directory ./exp_local/{date}/{time}_carla_train
• In configs/env/carla_multipath_merge_town04_traj_rep.yaml, set load_dir to the absolute path of the directory above.
• Evaluation:

  python3 run_on_env.py --config-name=eval_carla
  

• Train:

  python3 train.py --config-name=train_kitchen
  

  Snapshots will be saved to a new timestamped directory ./exp_local/{date}/{time}_kitchen_train
• In configs/env/relay_kitchen_traj.yaml, set load_dir to the absolute path of the directory above.
• Evaluation:

  export PYTHONPATH=$PYTHONPATH:$(pwd)/relay-policy-learning/adept_envs
  python3 run_on_env.py --config-name=eval_kitchen
  

  (Evaluation requires including the relay policy learning repo in PYTHONPATH.)

• Train:

  python3 train.py --config-name=train_blockpush
  

  Snapshots will be saved to a new timestamped directory ./exp_local/{date}/{time}_blockpush_train
• In configs/env/block_pushing_multimodal_fixed_target.yaml, set load_dir to the absolute path of the directory above.
• Evaluation:

  ASSET_PATH=$(pwd) python3 run_on_env.py --config-name=eval_blockpush
  

  (Evaluation requires including this repository in ASSET_PATH.)

• Rendering can be disabled for the kitchen and block pushing environments: set enable_render: False in configs/eval_kitchen.yaml, configs/eval_blockpush.yaml.

  (This option does not affect CARLA, as it requires rendering for RGB camera observations.)

• CARLA (Unreal Engine 4) renders on GPU 0 by default. If multiple GPUs are available, running the evaluated model on other GPUs can speed up evaluation: e.g. set device: cuda:1 in configs/eval_carla.yaml.

We are indebted to the following codebases and tools for making our lives significantly easier.

• karpathy/MinGPT: MinGPT implementation and hyperparameters.
• facebookresearch/hydra: Configuration managements.
• psf/black: Linting.