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Abstract We examine how a human–robot interaction (HRI) system may be designed when input–output data from previous experiments are available. Our objective is to learn an optimal impedance in the assistance design for a cooperative manipulation task with a new operator. Due to the variability between individuals, the design parameters that best suit one operator of the robot may not be the best parameters for another one. However, by incorporating historical data using a linear autoregressive (AR-1) Gaussian process, the search for a new operator’s optimal parameters can be accelerated. We lay out a framework for optimizing the human–robot cooperative manipulation that only requires input–output data. We characterize the learning performance using a notion called regret, establish how the AR-1 model improves the bound on the regret, and numerically illustrate this improvement in the context of a human–robot cooperative manipulation task. Furthermore, we show how our approach’s input–output nature provides robustness against modeling error through an additional numerical study. 

Security of cyber-physical systems (CPS) continues to pose new challenges due to the tight integration and operational complexity of the cyber and physical components. To address these challenges, this article presents a domain-aware, optimization-based approach to determine an effective defense strategy for CPS in an automated fashion—by emulating a strategic adversary in the loop that exploits system vulnerabilities, interconnection of the CPS, and the dynamics of the physical components. Our approach builds on an adversarial decision-making model based on a Markov Decision Process (MDP) that determines the optimal cyber (discrete) and physical (continuous) attack actions over a CPS attack graph. The defense planning problem is modeled as a non-zero-sum game between the adversary and defender. We use a model-free reinforcement learning method to solve the adversary’s problem as a function of the defense strategy. We then employ Bayesian optimization (BO) to find an approximatebest-responsefor the defender to harden the network against the resulting adversary policy. This process is iterated multiple times to improve the strategy for both players. We demonstrate the effectiveness of our approach on a ransomware-inspired graph with a smart building system as the physical process. Numerical studies show that our method converges to a Nash equilibrium for various defender-specific costs of network hardening.