Constrained Update Projection Approach to Safe Policy Optimization
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Abstract (arXiv)
Safe reinforcement learning (RL) studies problems where an intelligent agent has to not only maximize reward but also avoid exploring unsafe areas. In this study, we propose CUP, a novel policy optimization method based on Constrained Update Projection framework that enjoys rigorous safety guarantee. Central to our CUP development is the newly proposed surrogate functions along with the performance bound. Compared to previous safe RL methods, CUP enjoys the benefits of 1) CUP generalizes the surrogate functions to generalized advantage estimator (GAE), leading to strong empirical performance. 2) CUP unifies performance bounds, providing a better understanding and interpretability for some existing algorithms; 3) CUP provides a non-convex implementation via only first-order optimizers, which does not require any strong approximation on the convexity of the objectives. To validate our CUP method, we compared CUP against a comprehensive list of safe RL baselines on a wide range of tasks. Experiments show the effectiveness of CUP both in terms of reward and safety constraint satisfaction. We have opened the source code of CUP at this link https://github.com/zmsn-2077/ CUP-safe-rl.
Key facts. Cited by 55 papers in the map (data through 7 Oct 2026). Builds on 29 of its 64 references that are in the map. First posted on arXiv 15 Sep 2022.
Builds on
29 of 64 references.
References · 29
- 2017Proximal Policy Optimization Algorithmscited by 14,441
- 2015Trust Region Policy Optimizationcited by 2,503
- 2021Convex optimizationcited by 2,479
- 2015High-Dimensional Continuous Control Using Generalized Advantage Estimationcited by 1,916
- 2017Constrained Policy Optimizationcited by 928
- 2018Reward Constrained Policy Optimizationcited by 397
- 2016Benchmarking Deep Reinforcement Learning for Continuous Controlcited by 361
- 2018A Lyapunov-based Approach to Safe Reinforcement Learningcited by 278
- 2019End-to-End Safe Reinforcement Learning through Barrier Functions for Safety-Critical Continuous Control Taskscited by 256
- 2019Batch Policy Learning under Constraintscited by 242
- 2018Safe Exploration in Continuous Action Spacescited by 237
- 2020Projection-Based Constrained Policy Optimizationcited by 195
17 more
- 2021Reinforcement learning based recommender systems: A surveycited by 187
- 2019Constrained Reinforcement Learning Has Zero Duality Gapcited by 144
- 2019IPO: Interior-point Policy Optimization under Constraintscited by 119
- 2020Conservative Safety Critics for Explorationcited by 107
- 2018Variance Reduction for Policy Gradient with Action-Dependent Factorized Baselinescited by 65
- 2018Accelerated Primal-Dual Policy Optimization for Safe Reinforcement Learningcited by 61
- 2019Risk-Averse Trust Region Optimization for Reward-Volatility Reductioncited by 53
- 2021A Primal-Dual Approach to Constrained Markov Decision Processescited by 42
- 2020Constrained Markov Decision Processes via Backward Value Functionscited by 33
- 2020Robust Constrained-MDPs: Soft-Constrained Robust Policy Optimization under Model Uncertaintycited by 23
- 2019Temporal Logic Guided Safe Reinforcement Learning Using Control Barrier Functionscited by 20
- 2019Policy Optimization with Stochastic Mirror Descentcited by 17
- 2020Sample Complexity of Policy Gradient Finding Second-Order Stationary Pointscited by 16
- 2018Supervised Policy Update for Deep Reinforcement Learningcited by 11
- 2020Reinforcement Learning Control of Constrained Dynamic Systems with Uniformly Ultimate Boundedness Stability Guaranteecited by 7
- 2018A Unified Approach for Multi-step Temporal-Difference Learning with Eligibility Traces in Reinforcement Learningcited by 4
- 2020On Convergence of Gradient Expected Sarsa(λ)cited by 4
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Citing papers per year: 2022: 1; 2023: 8; 2024: 17; 2025: 10; 2026: 19.
55 papers.
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- 2023Safety-Gymnasium: A Unified Safe Reinforcement Learning Benchmarkcited by 135
- 2023OmniSafe: An Infrastructure for Accelerating Safe Reinforcement Learning Researchcited by 76
- 2023SafeDreamer: Safe Reinforcement Learning with World Modelscited by 50
- 2024Balance Reward and Safety Optimization for Safe Reinforcement Learning: A Perspective of Gradient Manipulationcited by 21
- 2022Evaluating Model-free Reinforcement Learning toward Safety-critical Taskscited by 18
- 2025Mitigating Reward Over-Optimization in RLHF via Behavior-Supported Regularizationcited by 14
- 2024Off-Policy Primal-Dual Safe Reinforcement Learningcited by 13
- 2024Verification-Guided Shielding for Deep Reinforcement Learningcited by 13
- 2024Embedding Safety into RL: A New Take on Trust Region Methodscited by 9
- 2024Enhancing Efficiency of Safe Reinforcement Learning via Sample Manipulationcited by 8
- 2025SPiDR: A Simple Approach for Zero-Shot Safety in Sim-to-Real Transfercited by 8
- 2023Imitate the Good and Avoid the Bad: An Incremental Approach to Safe Reinforcement Learningcited by 7
38 more
- 2023Risk Sensitive Dead-end Identification in Safety-Critical Offline Reinforcement Learningcited by 6
- 2023Reduced Policy Optimization for Continuous Control with Hard Constraintscited by 5
- 2024Safety through feedback in Constrained RLcited by 5
- 2024Exterior Penalty Policy Optimization with Penalty Metric Network under Constraintscited by 5
- 2023Feasible Policy Iteration for Safe Reinforcement Learningcited by 4
- 2026How Does the Lagrangian Guide Safe Reinforcement Learning through Diffusion Models?cited by 4
- 2024Flipping-based Policy for Chance-Constrained Markov Decision Processescited by 3
- 2026Extreme Value Policy Optimization for Safe Reinforcement Learningcited by 3
- 2024FlagVNE: A Flexible and Generalizable Reinforcement Learning Framework for Network Resource Allocationcited by 2
- 2024Safe Reinforcement Learning using Finite-Horizon Gradient-based Estimationcited by 2
- 2025Adaptive Shielding for Safe Reinforcement Learning under Hidden-Parameter Dynamics Shiftscited by 2
- 2025Safe In-Context Reinforcement Learningcited by 2
- 2026Off-Policy Safe Reinforcement Learning with Constrained Optimistic Explorationcited by 2
- 2024Diffusion Models for Offline Multi-agent Reinforcement Learning with Safety Constraintscited by 1
- 2024Constrained Reinforcement Learning for Safe Heat Pump Controlcited by 1
- 2025Proactive Constrained Policy Optimization with Preemptive Penaltycited by 1
- 2026Controlling Underestimation Bias in Constrained Reinforcement Learning for Safe Explorationcited by 1
- 2026Safety Generalization Under Distribution Shift in Safe Reinforcement Learning: A Diabetes Testbedcited by 1
- 2026SteinGate: Tail-Sensitive Safe Reinforcement Learning via Stein Discrepancycited by 1
- 2026Vision--Language Signals in Constrained RL: Safety Gains Without Anticipationcited by 1
- 2023A General Perspective on Objectives of Reinforcement Learningcited by 0
- 2024GenSafe: A Generalizable Safety Enhancer for Safe Reinforcement Learning Algorithms Based on Reduced Order Markov Decision Process Modelcited by 0
- 2024mathrmE2CFD: Towards Effective and Efficient Cost Function Design for Safe Reinforcement Learning via Large Language Modelcited by 0
- 2024Autoregressive Policy Optimization for Constrained Allocation Taskscited by 0
- 2024Reinfier and Reintrainer: Verification and Interpretation-Driven Safe Deep Reinforcement Learning Frameworkscited by 0
- 2024From Text to Trajectory: Exploring Complex Constraint Representation and Decomposition in Safe Reinforcement Learningcited by 0
- 2025TraCeS: Learning Per-Timestep Constraint-Violation Credit from Sparse Trajectory-Level Labelscited by 0
- 2025A universal policy wrapper with guaranteescited by 0
- 2025Incentivizing Safer Actions in Policy Optimization for Constrained Reinforcement Learningcited by 0
- 2025KFCPO: Kronecker-Factored Approximated Constrained Policy Optimizationcited by 0
- 2025SB-TRPO: Towards Safe Reinforcement Learning with Hard Constraintscited by 0
- 2026Enhance the Safety in Reinforcement Learning by ADRC Lagrangian Methodscited by 0
- 2026A Safety-Constrained Reinforcement Learning Framework for Reliable Wireless Autonomycited by 0
- 2026Constraint-Enhanced Reinforcement Learning Based on Dynamic Decoupled Spherical Radial Squashingcited by 0
- 2026Kernel-Based Safe Exploration in Deep Reinforcement Learningcited by 0
- 2026Latent Q-Barrier Shielding for Safe In-Context Reinforcement Learningcited by 0
- 2026COP-Q: Safety-First Reinforcement Learning for Robot Control via Cholesky-Ordered Projectioncited by 0
- 2026Seeing Before Colliding: Anticipatory Safe RL with Frozen Vision-Language Modelscited by 0
50 most cited of 55 All 55 (JSON)
- 2026VERA: Verifiable Feasibility Representations with Counterfactual Credit for Constrained Multi-Agent Control30 Sep 2026
- 2026Vision--Language Signals in Constrained RL: Safety Gains Without Anticipation28 Sep 2026
- 2026Safe Score Matching: Diffusion Policies with Hamilton-Jacobi Reachability for Online Safe Reinforcement Learning27 Sep 2026
- 2026Boundary-Seeking Policy Gradient for Safe Reinforcement Learning10 Aug 2026
- 2026SteinGate: Tail-Sensitive Safe Reinforcement Learning via Stein Discrepancy14 Jul 2026
- 2026Imagine to Ensure Safety in Hierarchical Reinforcement Learning21 Jun 2026
- 2026CSPO: Constraint-Sensitive Policy Optimization for Safe Reinforcement Learning12 Jun 2026
- 2026Seeing Before Colliding: Anticipatory Safe RL with Frozen Vision-Language Models9 Jun 2026
- 2026COP-Q: Safety-First Reinforcement Learning for Robot Control via Cholesky-Ordered Projection3 Jun 2026
- 2026Latent Q-Barrier Shielding for Safe In-Context Reinforcement Learning24 May 2026
- 2026Kernel-Based Safe Exploration in Deep Reinforcement Learning21 May 2026
- 2026Constraint-Enhanced Reinforcement Learning Based on Dynamic Decoupled Spherical Radial Squashing5 May 2026
38 more
- 2026Off-Policy Safe Reinforcement Learning with Constrained Optimistic Exploration25 Mar 2026
- 2026How Does the Lagrangian Guide Safe Reinforcement Learning through Diffusion Models?2 Feb 2026
- 2026Safety Generalization Under Distribution Shift in Safe Reinforcement Learning: A Diabetes Testbed28 Jan 2026
- 2026Enhance the Safety in Reinforcement Learning by ADRC Lagrangian Methods26 Jan 2026
- 2026Extreme Value Policy Optimization for Safe Reinforcement Learning17 Jan 2026
- 2026Controlling Underestimation Bias in Constrained Reinforcement Learning for Safe Exploration17 Jan 2026
- 2026A Safety-Constrained Reinforcement Learning Framework for Reliable Wireless Autonomy12 Jan 2026
- 2025SB-TRPO: Towards Safe Reinforcement Learning with Hard Constraints29 Dec 2025
- 2025KFCPO: Kronecker-Factored Approximated Constrained Policy Optimization2 Nov 2025
- 2025Safe In-Context Reinforcement Learning29 Sep 2025
- 2025SPiDR: A Simple Approach for Zero-Shot Safety in Sim-to-Real Transfer23 Sep 2025
- 2025Incentivizing Safer Actions in Policy Optimization for Constrained Reinforcement Learning11 Sep 2025
- 2025Proactive Constrained Policy Optimization with Preemptive Penalty3 Aug 2025
- 2025Adaptive Shielding for Safe Reinforcement Learning under Hidden-Parameter Dynamics Shifts20 May 2025
- 2025A universal policy wrapper with guarantees18 May 2025
- 2025TraCeS: Learning Per-Timestep Constraint-Violation Credit from Sparse Trajectory-Level Labels17 Apr 2025
- 2025Mitigating Reward Over-Optimization in RLHF via Behavior-Supported Regularization23 Mar 2025
- 2024Safe Reinforcement Learning using Finite-Horizon Gradient-based Estimation15 Dec 2024
- 2024From Text to Trajectory: Exploring Complex Constraint Representation and Decomposition in Safe Reinforcement Learning12 Dec 2024
- 2024Embedding Safety into RL: A New Take on Trust Region Methods5 Nov 2024
- 2024Reinfier and Reintrainer: Verification and Interpretation-Driven Safe Deep Reinforcement Learning Frameworks19 Oct 2024
- 2024Flipping-based Policy for Chance-Constrained Markov Decision Processes9 Oct 2024
- 2024Constrained Reinforcement Learning for Safe Heat Pump Control29 Sep 2024
- 2024Autoregressive Policy Optimization for Constrained Allocation Tasks27 Sep 2024
- 2024Exterior Penalty Policy Optimization with Penalty Metric Network under Constraints22 Jul 2024
- 2024mathrmE2CFD: Towards Effective and Efficient Cost Function Design for Safe Reinforcement Learning via Large Language Model8 Jul 2024
- 2024Diffusion Models for Offline Multi-agent Reinforcement Learning with Safety Constraints30 Jun 2024
- 2024Safety through feedback in Constrained RL28 Jun 2024
- 2024Verification-Guided Shielding for Deep Reinforcement Learning10 Jun 2024
- 2024GenSafe: A Generalizable Safety Enhancer for Safe Reinforcement Learning Algorithms Based on Reduced Order Markov Decision Process Model6 Jun 2024
- 2024Enhancing Efficiency of Safe Reinforcement Learning via Sample Manipulation31 May 2024
- 2024Balance Reward and Safety Optimization for Safe Reinforcement Learning: A Perspective of Gradient Manipulation2 May 2024
- 2024FlagVNE: A Flexible and Generalizable Reinforcement Learning Framework for Network Resource Allocation19 Apr 2024
- 2024Off-Policy Primal-Dual Safe Reinforcement Learning26 Jan 2024
- 2023Imitate the Good and Avoid the Bad: An Incremental Approach to Safe Reinforcement Learning16 Dec 2023
- 2023Safety-Gymnasium: A Unified Safe Reinforcement Learning Benchmark19 Oct 2023
- 2023Reduced Policy Optimization for Continuous Control with Hard Constraints14 Oct 2023
- 2023SafeDreamer: Safe Reinforcement Learning with World Models14 Jul 2023
50 newest of 55 All 55 (JSON)
- 2026How Does the Lagrangian Guide Safe Reinforcement Learning through Diffusion Models?cited by 4
- 2024Diffusion Models for Offline Multi-agent Reinforcement Learning with Safety Constraintscited by 1
- 2026Safe Score Matching: Diffusion Policies with Hamilton-Jacobi Reachability for Online Safe Reinforcement Learningcited by 0
- 2026Safe Score Matching: Diffusion Policies with Hamilton-Jacobi Reachability for Online Safe Reinforcement Learning27 Sep 2026
- 2026How Does the Lagrangian Guide Safe Reinforcement Learning through Diffusion Models?2 Feb 2026
- 2024Diffusion Models for Offline Multi-agent Reinforcement Learning with Safety Constraints30 Jun 2024
- 2023Safety-Gymnasium: A Unified Safe Reinforcement Learning Benchmarkcited by 135
- 2023OmniSafe: An Infrastructure for Accelerating Safe Reinforcement Learning Researchcited by 76
- 2024Balance Reward and Safety Optimization for Safe Reinforcement Learning: A Perspective of Gradient Manipulationcited by 21
- 2022Evaluating Model-free Reinforcement Learning toward Safety-critical Taskscited by 18
- 2024Off-Policy Primal-Dual Safe Reinforcement Learningcited by 13
- 2024Verification-Guided Shielding for Deep Reinforcement Learningcited by 13
- 2024Embedding Safety into RL: A New Take on Trust Region Methodscited by 9
- 2024Enhancing Efficiency of Safe Reinforcement Learning via Sample Manipulationcited by 8
- 2025SPiDR: A Simple Approach for Zero-Shot Safety in Sim-to-Real Transfercited by 8
- 2023Imitate the Good and Avoid the Bad: An Incremental Approach to Safe Reinforcement Learningcited by 7
- 2023Reduced Policy Optimization for Continuous Control with Hard Constraintscited by 5
- 2024Safety through feedback in Constrained RLcited by 5
12 most cited of 47 All 47 (JSON)
- 2026VERA: Verifiable Feasibility Representations with Counterfactual Credit for Constrained Multi-Agent Control30 Sep 2026
- 2026Vision--Language Signals in Constrained RL: Safety Gains Without Anticipation28 Sep 2026
- 2026Boundary-Seeking Policy Gradient for Safe Reinforcement Learning10 Aug 2026
- 2026SteinGate: Tail-Sensitive Safe Reinforcement Learning via Stein Discrepancy14 Jul 2026
- 2026CSPO: Constraint-Sensitive Policy Optimization for Safe Reinforcement Learning12 Jun 2026
- 2026COP-Q: Safety-First Reinforcement Learning for Robot Control via Cholesky-Ordered Projection3 Jun 2026
- 2026Latent Q-Barrier Shielding for Safe In-Context Reinforcement Learning24 May 2026
- 2026Kernel-Based Safe Exploration in Deep Reinforcement Learning21 May 2026
- 2026Constraint-Enhanced Reinforcement Learning Based on Dynamic Decoupled Spherical Radial Squashing5 May 2026
- 2026Off-Policy Safe Reinforcement Learning with Constrained Optimistic Exploration25 Mar 2026
- 2026Safety Generalization Under Distribution Shift in Safe Reinforcement Learning: A Diabetes Testbed28 Jan 2026
- 2026Enhance the Safety in Reinforcement Learning by ADRC Lagrangian Methods26 Jan 2026
12 newest of 47 All 47 (JSON)