arXiv Machine Learning

FAITH: Feasibility-Aware Safety-Filtered RL for High-Dimensional Systems

FAITH is a model‑free reinforcement learning framework that separates safety from task performance by using a learned safety filter. The filter approximates the optimal state‑action safety value with a feedforward network, allowing the task policy to optimize return through filtered dynamics without a competing safety term. Experiments on a double integrator, Safety Gym, a 29‑DoF humanoid, and a real Unitree G1 show that FAITH achieves high returns while maintaining near‑perfect safety and handling infeasible starts gracefully.

arXiv Machine Learning
Sep 21

Provably Optimal Reinforcement Learning under Safety Filtering

The paper proves that using a permissive safety filter in reinforcement learning does not compromise asymptotic performance. By formalizing safety through a safety‑critical Markov decision process and a filtered MDP, the authors show that optimal policies in the filtered MDP achieve the same return as the best safe policy in the original setting. Experiments on Safety Gymnasium confirm zero violations during training and performance that matches or exceeds unfiltered baselines.

By Donggeon David Oh, Duy P. Nguyen, Haimin Hu, Jaime Fern\'andez Fisac
arXiv Machine Learning
Sep 3

Humanoid Safe Stop via Learned Stoppability Value

The paper introduces Safe-Stop, a task‑agnostic framework for humanoid robots that determines whether an emergency stop command can be safely executed from the current state. It couples a learned stop policy with two complementary stoppability estimators: a stop‑probability estimator trained on outcomes of a fixed stop policy, and a reach‑avoidance estimator trained via Hamilton‑Jacobi backup. By requiring agreement between both estimators before committing to a stop, Safe‑Stop can robustly decide to stop or hand off to a fall‑damping fallback without needing retraining for different upstream tasks.

By Junfeng Long, Pieter Abbeel, Koushil Sreenath, Roberto Horowitz, Guanya Shi, C. Karen Liu
arXiv AI
Sep 12

ActSafeGuard: Differentiable and Training-Aligned Constraint Enforcement for Flow-Matching Policies

arXiv:2609. 11697v1 Announce Type: cross Abstract: Vision-Language-Action (VLA) and World-Action Models (WAMs) have demonstrated strong capabilities in general-purpose robotic manipulation, yet their generated actions may violate hard physical constraints and therefore be unsafe or infeasible for deployment.

By Jianming Ma, Rongjun Jin, Xiaxi Si, Yang Zhang, Yiheng Li, Yue Gao
arXiv Machine Learning
Sep 24

LEAP-CBF: A Safety Filter for Uncertain Systems with Least-Effort Adversarial Potentials

The paper introduces LEAP-CBF, a safety filter that uses Least‑Effort Adversarial Potentials to quantify how much disturbance effort is needed to cause failure in nonlinear dynamical systems. LEAP serves as a control barrier function for the undisturbed system and can be combined with a robust safety filter that tolerates disturbances with bounded cumulative effort. The authors develop a deep reinforcement learning method to construct LEAPs and validate their effectiveness through simulations of multi‑agent systems and hardware experiments on a quadruped and quadrotors.

By Oswin So, Eric Yu, Chuchu Fan
arXiv AI
Sep 24

Turning Safety into Competence: Minimally Exploitable Robot Policies via Safety-Filtered Reinforcement Learning

The paper introduces Safety to Competence (S2C), a two‑stage reinforcement learning framework that first learns a safety filter and then trains a competitive task policy while embedding the filter. By separating safety synthesis from task learning, S2C reduces training complexity and prevents the policy from being exploited by adversarial attacks. Experiments on simulated touchdown games show that S2C achieves higher win rates, better Elo ratings, and lower exploitability than eight safe‑RL baselines, and hardware tests confirm its competence against a human opponent.

By Ruihan Wu, Rui Yang, Donggeon David Oh, Duy Nguyen, Haimin Hu
arXiv Machine Learning
Oct 8

Safe on Average, Unsafe in the Tail: When Is the Episodic-Cost Tail Controllable?

The paper investigates safe reinforcement learning by focusing on the episodic-cost tail rather than just the mean cost. It introduces the use of γαρα_{0.1} (the average cost of the worst 10% of episodes) to classify policies as tail-safe. The authors evaluate standard algorithms on Safety-Gymnasium tasks, identify tail-unsafe policies, and explore constraint families to control tail violations while maintaining return.

By Samuel Tetteh, Cody Fleming