Distributionally Safe Reinforcement Learning under Model Uncertainty: A Single-Level Approach by Differentiable Convex Programming (2310.02459v1)
Abstract: Safety assurance is uncompromisable for safety-critical environments with the presence of drastic model uncertainties (e.g., distributional shift), especially with humans in the loop. However, incorporating uncertainty in safe learning will naturally lead to a bi-level problem, where at the lower level the (worst-case) safety constraint is evaluated within the uncertainty ambiguity set. In this paper, we present a tractable distributionally safe reinforcement learning framework to enforce safety under a distributional shift measured by a Wasserstein metric. To improve the tractability, we first use duality theory to transform the lower-level optimization from infinite-dimensional probability space where distributional shift is measured, to a finite-dimensional parametric space. Moreover, by differentiable convex programming, the bi-level safe learning problem is further reduced to a single-level one with two sequential computationally efficient modules: a convex quadratic program to guarantee safety followed by a projected gradient ascent to simultaneously find the worst-case uncertainty. This end-to-end differentiable framework with safety constraints, to the best of our knowledge, is the first tractable single-level solution to address distributional safety. We test our approach on first and second-order systems with varying complexities and compare our results with the uncertainty-agnostic policies, where our approach demonstrates a significant improvement on safety guarantees.
- S. Li, Y. Wu, X. Cui, H. Dong, F. Fang, and S. Russell, “Robust multi-agent reinforcement learning via minimax deep deterministic policy gradient,” in Proceedings of the AAAI Conference on Artificial Intelligence, vol. 33, no. 01, 2019, pp. 4213–4220.
- K. Zhang, Z. Yang, and T. Basar, “Policy optimization provably converges to nash equilibria in zero-sum linear quadratic games,” Advances in Neural Information Processing Systems, vol. 32, 2019.
- C. Sun, D.-K. Kim, and J. P. How, “Romax: Certifiably robust deep multiagent reinforcement learning via convex relaxation,” arXiv preprint arXiv:2109.06795, 2021.
- B. Yang, L. Zheng, L. J. Ratliff, B. Boots, and J. R. Smith, “Stackelberg maddpg: Learning emergent behaviors via information asymmetry in competitive games,” 2022.
- Z. Zhou and H. Xu, “Decentralized adaptive optimal tracking control for massive autonomous vehicle systems with heterogeneous dynamics: A stackelberg game,” IEEE Transactions on Neural Networks and Learning Systems, vol. 32, no. 12, pp. 5654–5663, 2021.
- N. Lauffer, M. Ghasemi, A. Hashemi, Y. Savas, and U. Topcu, “No-regret learning in dynamic stackelberg games,” arXiv preprint arXiv:2202.04786, 2022.
- Y. Bai, C. Jin, H. Wang, and C. Xiong, “Sample-efficient learning of stackelberg equilibria in general-sum games,” Advances in Neural Information Processing Systems, vol. 34, 2021.
- W. Jin, S. Mou, and G. Pappas, “Safe pontryagin differentiable programming,” Advances in Neural Information Processing Systems, vol. 34, 2021.
- Y. Liu, J. Ding, and X. Liu, “Ipo: Interior-point policy optimization under constraints,” in Proceedings of the AAAI Conference on Artificial Intelligence, vol. 34, no. 04, 2020, pp. 4940–4947.
- J. Achiam, D. Held, A. Tamar, and P. Abbeel, “Constrained policy optimization,” in Proceedings of the 34th International Conference on Machine Learning-Volume 70. JMLR. org, 2017, pp. 22–31.
- P. Geibel and F. Wysotzki, “Risk-sensitive reinforcement learning applied to control under constraints,” Journal of Artificial Intelligence Research, vol. 24, pp. 81–108, 2005.
- Y. Chow, M. Ghavamzadeh, L. Janson, and M. Pavone, “Risk-constrained reinforcement learning with percentile risk criteria,” The Journal of Machine Learning Research, vol. 18, no. 1, pp. 6070–6120, 2017.
- Y. Chow, O. Nachum, E. Duenez-Guzman, and M. Ghavamzadeh, “A lyapunov-based approach to safe reinforcement learning,” in Advances in neural information processing systems, 2018, pp. 8092–8101.
- A. Stooke, J. Achiam, and P. Abbeel, “Responsive safety in reinforcement learning by pid lagrangian methods,” arXiv preprint arXiv:2007.03964, 2020.
- B. Amos and J. Z. Kolter, “Optnet: Differentiable optimization as a layer in neural networks,” arXiv preprint arXiv:1703.00443, 2017.
- H. Zhang, H. Chen, C. Xiao, B. Li, M. Liu, D. Boning, and C.-J. Hsieh, “Robust deep reinforcement learning against adversarial perturbations on state observations,” Advances in Neural Information Processing Systems, vol. 33, pp. 21 024–21 037, 2020.
- K. Zhang, T. Sun, Y. Tao, S. Genc, S. Mallya, and T. Basar, “Robust multi-agent reinforcement learning with model uncertainty,” Advances in Neural Information Processing Systems, vol. 33, pp. 10 571–10 583, 2020.
- L. Brunke, M. Greeff, A. W. Hall, c. Yuan, S. Zhou, J. Panerati, and A. P. Schoellig, “Safe learning in robotics: From learning-based control to safe reinforcement learning,” Annual Review of Control, Robotics, and Autonomous Systems, vol. 5, 2021.
- B. Singh, R. Kumar, and V. P. Singh, “Reinforcement learning in robotic applications: a comprehensive survey,” Artificial Intelligence Review, pp. 1–46, 2021.
- J. Garcıa and F. Fernández, “A comprehensive survey on safe reinforcement learning,” Journal of Machine Learning Research, vol. 16, no. 1, pp. 1437–1480, 2015.
- J. Moos, K. Hansel, H. Abdulsamad, S. Stark, D. Clever, and J. Peters, “Robust reinforcement learning: A review of foundations and recent advances,” Machine Learning and Knowledge Extraction, vol. 4, no. 1, pp. 276–315, 2022.
- H. Eghbal-zadeh, F. Henkel, and G. Widmer, “Learning to infer unseen contexts in causal contextual reinforcement learning,” in Self-Supervision for Reinforcement Learning Workshop-ICLR 2021, 2021.
- K. Rakelly, A. Zhou, C. Finn, S. Levine, and D. Quillen, “Efficient off-policy meta-reinforcement learning via probabilistic context variables,” in International conference on machine learning. PMLR, 2019, pp. 5331–5340.
- J. Choi, F. Castañeda, C. J. Tomlin, and K. Sreenath, “Reinforcement learning for safety-critical control under model uncertainty, using control lyapunov functions and control barrier functions,” arXiv preprint arXiv:2004.07584, 2020.
- L. Zheng, Y. Shi, L. J. Ratliff, and B. Zhang, “Safe reinforcement learning of control-affine systems with vertex networks,” in Learning for Dynamics and Control. PMLR, 2021, pp. 336–347.
- R. Cheng, G. Orosz, R. M. Murray, and J. W. Burdick, “End-to-end safe reinforcement learning through barrier functions for safety-critical continuous control tasks,” in Proceedings of the AAAI Conference on Artificial Intelligence, vol. 33, 2019, pp. 3387–3395.
- A. D. Ames, X. Xu, J. W. Grizzle, and P. Tabuada, “Control barrier function based quadratic programs for safety critical systems,” IEEE Transactions on Automatic Control, vol. 62, no. 8, pp. 3861–3876, 2016.
- F. Berkenkamp, M. Turchetta, A. Schoellig, and A. Krause, “Safe model-based reinforcement learning with stability guarantees,” in Advances in neural information processing systems, 2017, pp. 908–918.
- C. Sun, D.-K. Kim, and J. P. How, “Fisar: Forward invariant safe reinforcement learning with a deep neural network-based optimizer,” in 2021 IEEE International Conference on Robotics and Automation (ICRA). IEEE, 2021, pp. 10 617–10 624.
- G. Shi, K. Azizzadenesheli, M. O’Connell, S.-J. Chung, and Y. Yue, “Meta-adaptive nonlinear control: Theory and algorithms,” Advances in Neural Information Processing Systems, vol. 34, pp. 10 013–10 025, 2021.
- M. O’Connell, G. Shi, X. Shi, K. Azizzadenesheli, A. Anandkumar, Y. Yue, and S.-J. Chung, “Neural-fly enables rapid learning for agile flight in strong winds,” Science Robotics, vol. 7, no. 66, p. eabm6597, 2022.
- B. P. Van Parys, D. Kuhn, P. J. Goulart, and M. Morari, “Distributionally robust control of constrained stochastic systems,” IEEE Transactions on Automatic Control, vol. 61, no. 2, pp. 430–442, 2015.
- I. Yang, “Wasserstein distributionally robust stochastic control: A data-driven approach,” IEEE Transactions on Automatic Control, vol. 66, no. 8, pp. 3863–3870, 2020.
- A. Hakobyan and I. Yang, “Wasserstein distributionally robust motion control for collision avoidance using conditional value-at-risk,” IEEE Transactions on Robotics, vol. 38, no. 2, pp. 939–957, 2021.
- A. Bahari Kordabad, R. Wisniewski, and S. Gros, “Safe reinforcement learning using wasserstein distributionally robust mpc and chance constraint,” 2022.
- J. Coulson, J. Lygeros, and F. Dörfler, “Distributionally robust chance constrained data-enabled predictive control,” IEEE Transactions on Automatic Control, vol. 67, no. 7, pp. 3289–3304, 2021.
- P. Coppens and P. Patrinos, “Data-driven distributionally robust mpc for constrained stochastic systems,” IEEE Control Systems Letters, vol. 6, pp. 1274–1279, 2021.
- A. Z. Ren and A. Majumdar, “Distributionally robust policy learning via adversarial environment generation,” IEEE Robotics and Automation Letters, vol. 7, no. 2, pp. 1379–1386, 2022.
- D. Morrison, P. Corke, and J. Leitner, “Egad! an evolved grasping analysis dataset for diversity and reproducibility in robotic manipulation,” IEEE Robotics and Automation Letters, vol. 5, no. 3, pp. 4368–4375, 2020.
- D. Wang, D. Tseng, P. Li, Y. Jiang, M. Guo, M. Danielczuk, J. Mahler, J. Ichnowski, and K. Goldberg, “Adversarial grasp objects,” in 2019 IEEE 15th International Conference on Automation Science and Engineering (CASE). IEEE, 2019, pp. 241–248.
- M. Xu, P. Huang, Y. Niu, V. Kumar, J. Qiu, C. Fang, K.-H. Lee, X. Qi, H. Lam, B. Li, et al., “Group distributionally robust reinforcement learning with hierarchical latent variables,” arXiv preprint arXiv:2210.12262, 2022.
- N. Kallus, X. Mao, K. Wang, and Z. Zhou, “Doubly robust distributionally robust off-policy evaluation and learning,” in International Conference on Machine Learning. PMLR, 2022, pp. 10 598–10 632.
- L. Shi and Y. Chi, “Distributionally robust model-based offline reinforcement learning with near-optimal sample complexity,” arXiv preprint arXiv:2208.05767, 2022.
- A. Sinha, H. Namkoong, and J. Duchi, “Certifiable distributional robustness with principled adversarial training,” arXiv preprint arXiv:1710.10571, vol. 2, 2017.
- J. Blanchet and K. Murthy, “Quantifying distributional model risk via optimal transport,” Mathematics of Operations Research, vol. 44, no. 2, pp. 565–600, 2019.
- H. Rahimian and S. Mehrotra, “Distributionally robust optimization: A review,” arXiv preprint arXiv:1908.05659, 2019.
- W. Xiao and C. Belta, “High-order control barrier functions,” IEEE Transactions on Automatic Control, vol. 67, no. 7, pp. 3655–3662, 2021.
- A. Agrawal, B. Amos, S. Barratt, S. Boyd, S. Diamond, and J. Z. Kolter, “Differentiable convex optimization layers,” Advances in neural information processing systems, vol. 32, 2019.
- A. Agrawal, S. Barratt, S. Boyd, E. Busseti, and W. M. Moursi, “Differentiating through a cone program,” arXiv preprint arXiv:1904.09043, 2019.
- A. E. Chriat and C. Sun, “On the optimality, stability, and feasibility of control barrier functions: An adaptive learning-based approach,” arXiv preprint arXiv:2305.03608, 2023.
- E. Daş, S. X. Wei, and J. W. Burdick, “Robust control barrier functions with uncertainty estimation,” arXiv preprint arXiv:2304.08538, 2023.
- A. E. Chriat and C. Sun, “Wasserstein distributionally robust control barrier function using conditional value-at-risk with differentiable convex programming,” Accepted to AIAA SciTech 2024, 2024.
- C. R. Givens and R. M. Shortt, “A class of wasserstein metrics for probability distributions.” Michigan Mathematical Journal, vol. 31, no. 2, pp. 231–240, 1984.
- J. M. Joyce, “Kullback-leibler divergence,” in International encyclopedia of statistical science. Springer, 2011, pp. 720–722.
- R. T. Rockafellar, S. Uryasev, et al., “Optimization of conditional value-at-risk,” Journal of risk, vol. 2, pp. 21–42, 2000.
- Y. Wang, G. Zhang, and J. Ba, “On solving minimax optimization locally: A follow-the-ridge approach,” arXiv preprint arXiv:1910.07512, 2019.
- K. K. Thekumparampil, P. Jain, P. Netrapalli, and S. Oh, “Efficient algorithms for smooth minimax optimization,” Advances in Neural Information Processing Systems, vol. 32, 2019.
- Z. Wang, X. Wang, L. Shen, Q. Suo, K. Song, D. Yu, Y. Shen, and M. Gao, “Meta-learning without data via wasserstein distributionally-robust model fusion,” in Uncertainty in Artificial Intelligence. PMLR, 2022, pp. 2045–2055.
- T. P. Lillicrap, J. J. Hunt, A. Pritzel, N. Heess, T. Erez, Y. Tassa, D. Silver, and D. Wierstra, “Continuous control with deep reinforcement learning,” arXiv preprint arXiv:1509.02971, 2015.