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Ali Azarbahram

Publications and source records attributed to Ali Azarbahram.

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Distributed Koopman Operator Learning for Perception and Safe Navigation

This paper presents a unified and scalable framework for predictive and safe autonomous navigation in dynamic transportation environments by integrating model predictive control (MPC) with distributed Koopman operator learning. High-dimensional sensory data are employed to model and forecast the motion of surrounding dynamic obstacles. A consensus-based distributed Koopman learning algorithm enables multiple computational agents or sensing units to collaboratively estimate the Koopman operator without centralized data aggregation, thereby supporting large-scale and communication-efficient learning across a networked system. The learned operator predicts future spatial densities of obstacles, which are subsequently represented through Gaussian mixture models. Their confidence ellipses are approximated by convex polytopes and embedded as linear constraints in the MPC formulation to guarantee safe and collision-free navigation. The proposed approach not only ensures obstacle avoidance but also scales efficiently with the number of sensing or computational nodes, aligning with cooperative perception principles in autonomous navigation applications. Theoretical convergence guarantees and predictive constraint formulations are established, and extensive simulations demonstrate reliable, safe, and computationally efficient navigation performance in complex environments.

eess.SY

Distributed Switching Model Predictive Control Meets Koopman Operator for Dynamic Obstacle Avoidance

This paper introduces a Koopman-enhanced distributed switched model predictive control (SMPC) framework for safe and scalable navigation of quadrotor unmanned aerial vehicles (UAVs) in dynamic environments with moving obstacles. The proposed method integrates switched motion modes and data-driven prediction to enable real-time, collision-free coordination. A localized Koopman operator approximates nonlinear obstacle dynamics as linear models based on online measurements, enabling accurate trajectory forecasting. These predictions are embedded into a distributed SMPC structure, where each UAV makes autonomous decisions using local and cluster-based information. This computationally efficient architecture is particularly promising for applications in surface transportation, including coordinated vehicle flows, shared infrastructure with pedestrians or cyclists, and urban UAV traffic. Simulation results demonstrate reliable formation control and real-time obstacle avoidance, highlighting the frameworks broad relevance for intelligent and cooperative mobility systems.

eess.SY

Koopman-Based Dynamic Environment Prediction for Safe UAV Navigation

This paper presents a Koopman-based model predictive control (MPC) framework for safe UAV navigation in dynamic environments using real-time LiDAR data. By leveraging the Koopman operator to linearly approximate the dynamics of surrounding objets, we enable efficient and accurate prediction of the position of moving obstacles. Embedding this into an MPC formulation ensures robust, collision-free trajectory planning suitable for real-time execution. The method is validated through simulation and ROS2-Gazebo implementation, demonstrating reliable performance under sensor noise, actuation delays, and environmental uncertainty.

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Distributed Koopman Operator Learning from Sequential Observations

This paper presents a distributed Koopman operator learning framework for modeling unknown nonlinear dynamics using sequential observations from multiple agents. Each agent estimates a local Koopman approximation based on lifted data and collaborates over a communication graph to reach exponential consensus on a consistent distributed approximation. The approach supports distributed computation under asynchronous and resource-constrained sensing. Its performance is demonstrated through simulation results, validating convergence and predictive accuracy under sensing-constrained scenarios and limited communication.

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Tracking Consensus of Networked Random Nonlinear Multi-agent Systems with Intermittent Communications

The paper proposes an intermittent communication mechanism for the tracking consensus of high-order nonlinear multi-agent systems (MASs) surrounded by random disturbances. Each collaborating agent is described by a class of high-order nonlinear uncertain strict-feedback dynamics which is disturbed by a wide stationary process representing the external noise. The resiliency level of this networked control system (NCS) to the failures of physical devices or unreliability of communication channels is analyzed by introducing a linear auxiliary trajectory of the system. More precisely, the unreliability of communication channels sometimes makes an agent incapable of sensing the local information or receiving it from neighboring nodes. Therefore, an intermittent communication scheme is proposed among the follower agents as a consequence of employing the linear auxiliary dynamics. The closed-loop networked system signals are proved to be noise-to-state practically stable in probability (NSpS-P). It has been justified that each agent follows the trajectory of the corresponding local auxiliary virtual system practically in probability. The simulation experiments finally quantify the effectiveness of our proposed approach in terms of providing a resilient performance against unreliability of communication channels and reaching the tracking consensus.

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Secure Dynamic Event-triggered Consensus Under Asynchronous Denial of Service

This article proposes a secure implementation for consensus using a dynamic event-triggered (DET) communication scheme in high-order nonlinear multi-agent systems (MAS) under asynchronous (distributed) denial of service (DoS) attacks. By introducing a linear auxiliary trajectory of the system, the DET data transmission scheme among the neighboring agents is employed to reduce the communication for each agent. The asynchronous DoS attacks can block each communication channel among the cooperative agents independently in an unknown pattern. To guarantee state consensus of auxiliary MAS under DoS, a linear matrix inequality (LMI) based optimization approach is proposed which simultaneously designs all the unknown DET communication parameters as well as the state feedback control gain. In addition to asynchronous DoS attacks over the graph topology, the destructive effects of independent DoS attacks over the communication links between actual and auxiliary states are compensated as an additional layer of resiliency for the system. The output of each agent ultimately tracks the auxiliary state of the system and this results in the output consensus.

eess.SY

H_inf Consensus of nonlinear complex multi-agent systems using dynamic output feedback controller: An LMI approach

This paper investigates a new method for consensus in a group of nonlinear complex multi-agent systems using fixed-order non-fragile dynamic output feedback controller, via an LMI approach. The proposed scheme is decentralized in the sense that each agent relies on the relative output information among the adjacent agents. The consensus based controllers are designed to minimize the effects of nonlinear terms of the agents as well as external disturbances. Converting consensus problem to stabilization of an equivalent augmented system using proper transformations, Lyapunov stability theorem is applied to obtain unknown controller parameters in order to guarantee consensus and simultaneously acquire considered control objectives. Finally, to demonstrate the effectiveness of the proposed algorithm and compare with similar earlier researches, a numerical example on a multi-agent system consisting of single link flexible manipulators is carried out.

math.OC

A New Delay Dependent Robust Fixed-Order Decentralized Output Feedback LFC Design for Interconnected Multi-Area Power Systems

This paper presents a novel load frequency control (LFC) design using integral-based decentralize fixed-order perturbed dynamic output tracking scheme in a delay dependent nonlinear interconnected multi-area power system via LMI approach. The tracking controller is designed such that the effects of the parameter variations of the plant and dynamic output controller as well as load disturbances are minimized. The inputs and outputs of each controller are local, and these independent controllers are designed such that the robust stability of the overall closed-loop system is guaranteed. Simulation results for both two- and three-area power systems are provided to verify the effectiveness of the proposed design scheme. The simulation results show that the decentralized controlled system behaves well even when there are large parameter perturbations and unpredictable disturbances on the power system.

math.OC