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ATLA

Alternating Training with Learned Adversaries

OnlineLearner-centricBase · PPOClaims · observation shift

A policy trained against an observation adversary that is itself an RL agent.

Features

Feature Value
Group Robust Online Algorithms
Setting Online
Family Learner-centric
Base algorithm PPO
Claimed robustness Observation shift
Shifted-env rollout No
Adversarial network Yes
Learned model No
Training budget About 5M environment steps (2441 iterations of 2048 steps)
Original paper Zhang et al. Robust Reinforcement Learning on State Observations with Learned Optimal Adversary. ICLR, 2021.

Mechanism

ATLA trains a policy against an optimal observation adversary in the state-adversarial MDP. The adversary is itself an RL agent that outputs a bounded perturbation of the observation, is rewarded by the protagonist's negative return, and is updated in alternation with the protagonist.

Run the method

python baselines/train.py \
    -c robustrllib/configs/experiment/atla_hopper.yaml --seed 0
python baselines/evaluate.py --run runs/atla_hopper/seed0
File Path
Implementation baselines/atla
Algorithm card robustrllib/configs/algorithm/atla.yaml
Experiment file robustrllib/configs/experiment/atla_hopper.yaml

Training is on the nominal task. The configuration files are explained in Train an algorithm, and the evaluation of the frozen checkpoint in Evaluation Protocol.

Robust performance

Normalized score of the frozen checkpoint. Q1 to Q4 are the severity quartiles of each shift factor's scales, ordered by displacement from the nominal setting, and All covers every shifted condition. The last row averages the tasks.

Task Nominal Q1 Q2 Q3 Q4 All
CarRacing 58.7 54.8 54.5 46.8 40.7 48.7
FetchReach 85.3 85.3 86.0 77.1 67.9 79.1
HalfCheetah 45.3 42.6 33.9 26.2 20.2 30.7
Hopper 67.5 61.1 46.2 38.3 24.2 42.5
PointMaze 94.1 95.9 87.7 94.5 63.3 85.4
Walker2d 83.5 55.6 34.8 25.7 19.2 33.8
Average 72.4 65.9 57.2 51.4 39.3 53.4

References

  • Zhang et al. Robust Reinforcement Learning on State Observations with Learned Optimal Adversary. ICLR, 2021.
  • Zhang et al. Robust Deep Reinforcement Learning against Adversarial Perturbations on State Observations. NeurIPS, 2020.