English

Harnessing Bounded-Support Evolution Strategies for Policy Refinement

Machine Learning 2025-11-17 v2 Artificial Intelligence Robotics

Abstract

Improving competent robot policies with on-policy RL is often hampered by noisy, low-signal gradients. We revisit Evolution Strategies (ES) as a policy-gradient proxy and localize exploration with bounded, antithetic triangular perturbations, suitable for policy refinement. We propose Triangular-Distribution ES (TD-ES) which pairs bounded triangular noise with a centered-rank finite-difference estimator to deliver stable, parallelizable, gradient-free updates. In a two-stage pipeline - PPO pretraining followed by TD-ES refinement - this preserves early sample efficiency while enabling robust late-stage gains. Across a suite of robotic manipulation tasks, TD-ES raises success rates by 26.5% relative to PPO and greatly reduces variance, offering a simple, compute-light path to reliable refinement.

Keywords

Cite

@article{arxiv.2511.09923,
  title  = {Harnessing Bounded-Support Evolution Strategies for Policy Refinement},
  author = {Ethan Hirschowitz and Fabio Ramos},
  journal= {arXiv preprint arXiv:2511.09923},
  year   = {2025}
}

Comments

10 pages, 6 figures, to be published in Australasian Conference on Robotics and Automation (ACRA 2025)

R2 v1 2026-07-01T07:35:00.234Z