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Implicit Safe Set Algorithm for Provably Safe Reinforcement Learning


Основні поняття
The proposed Implicit Safe Set Algorithm (ISSA) synthesizes a safety index and a safe control law without requiring an explicit analytical model of the system dynamics, enabling provably safe reinforcement learning.
Анотація
The paper presents the Implicit Safe Set Algorithm (ISSA) for provably safe reinforcement learning. The key contributions are: ISSA synthesizes a safety index and a safe control law without requiring an explicit analytical model of the system dynamics. This is achieved by leveraging a black-box dynamics function (e.g., a digital twin simulator) and two key techniques: A safety index design rule for continuous-time and discrete-time systems that ensures the set of safe controls is non-empty. A sample-efficient black-box optimization algorithm called Adaptive Momentum Boundary Approximation (AdamBA) to efficiently find safe controls on the boundary of the safe control set. ISSA provides theoretical guarantees of forward invariance and finite-time convergence to a safe subset of the safe set for both continuous-time and discrete-time systems. ISSA is validated on the Safety Gym benchmark, where it achieves zero safety violations and 95% ± 9% cumulative reward compared to state-of-the-art safe reinforcement learning methods. The paper first formulates the problem of safeguard synthesis for reinforcement learning agents. It then introduces the ISSA algorithm, including the safety index design rule and the AdamBA optimization algorithm. Theoretical results on the forward invariance and finite-time convergence properties of ISSA are provided. Finally, the experimental validation on Safety Gym demonstrates the effectiveness of the proposed approach.
Статистика
The paper reports that the proposed ISSA method achieves zero safety violations and 95% ± 9% cumulative reward compared to state-of-the-art safe reinforcement learning methods on the Safety Gym benchmark.
Цитати
"The key insight we have is that the safe control law can be synthesized without the knowledge of white-box analytical dynamics model, as long as we have a black-box dynamics function, i.e., a function that maps the current state and control to the next state." "We show that under certain assumptions, the proposed safety index design rule together with the proposed black-box optimization algorithm can guarantee forward invariance and finite time convergence to the safe set."

Ключові висновки, отримані з

by Weiye Zhao,T... о arxiv.org 05-07-2024

https://arxiv.org/pdf/2405.02754.pdf
Implicit Safe Set Algorithm for Provably Safe Reinforcement Learning

Глибші Запити

How can the proposed ISSA algorithm be extended to handle stochastic dynamics and uncertainties in the system model

To extend the Implicit Safe Set Algorithm (ISSA) to handle stochastic dynamics and uncertainties in the system model, we can incorporate robust safe control techniques. One approach is to utilize robust control methods such as robust model predictive control (MPC) or robust adaptive control. These techniques can account for uncertainties in the system dynamics by formulating the control problem as a robust optimization problem. By considering a set of possible system models within a certain uncertainty bound, the controller can be designed to ensure safety and stability under all possible scenarios. Additionally, techniques like probabilistic safety guarantees can be integrated into the safety index design rule to account for stochastic dynamics. By incorporating probabilistic constraints or risk-aware optimization, the safety index can be designed to provide guarantees under uncertain and stochastic conditions.

How can the safety index design rule and the AdamBA optimization be generalized to handle higher-dimensional state and action spaces beyond the 2D collision avoidance problem

To generalize the safety index design rule and the AdamBA optimization for higher-dimensional state and action spaces beyond the 2D collision avoidance problem, we can extend the formulation to accommodate multi-dimensional state and action spaces. For the safety index design rule, the key parameters and constraints can be adapted to higher-dimensional spaces by considering the interactions and dependencies among the variables. The safety index can be designed to capture the complex relationships between the states and actions in a higher-dimensional space, ensuring that the set of safe controls remains non-empty. Similarly, for the AdamBA optimization, the algorithm can be modified to handle higher-dimensional spaces by adjusting the sampling intervals and grid search techniques accordingly. By partitioning the multi-dimensional space into smaller regions and applying adaptive sampling strategies, AdamBA can efficiently search for boundary points in higher-dimensional spaces. Additionally, techniques like dimensionality reduction or advanced optimization algorithms can be employed to enhance the scalability and effectiveness of the optimization process in higher-dimensional spaces.

What are the potential applications of the ISSA algorithm beyond reinforcement learning, such as in traditional control systems or other robotic domains

The Implicit Safe Set Algorithm (ISSA) has potential applications beyond reinforcement learning in various domains, including traditional control systems and other robotic applications. In traditional control systems, ISSA can be utilized to enhance the safety and robustness of control algorithms in industrial processes, autonomous vehicles, aerospace systems, and more. By integrating ISSA into traditional control frameworks, systems can be safeguarded against unexpected disturbances, uncertainties, and failures, ensuring reliable and safe operation. In robotic domains, ISSA can be applied to a wide range of robotic systems, including manipulators, drones, autonomous mobile robots, and collaborative robots. By incorporating ISSA into the control architecture of robots, safety-critical tasks such as obstacle avoidance, path planning, and human-robot interaction can be executed with provable safety guarantees. ISSA can enable robots to operate in dynamic and uncertain environments while maintaining safety and efficiency.
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