Burak Sarsılmaz

Research

Selected publications are classified according to the selected research topics.

A. Cooperative Output Regulation of Multi-agent Systems

In cooperative control of multi-agent systems, one of the fundamental problems is to design a distributed control law such that the output of every agent asymptotically tracks (rejects) a class of reference (disturbance) signals while preserving the closed-loop stability. The term ‘cooperative output regulation’ was coined in the 2010s to refer to this problem. It has been mainly treated by two approaches, namely feedforward and p-copy internal model. This problem offers a unifying framework that considers heterogeneity in multi-agent systems, paves the way for a capability of tracking and rejecting a large class of signals, and contains typical cooperative control problems such as leader-following and formation as subcases.

Our p-copy internal model-based contributions are reported in the archival publications below. The symbol * is followed by their main contributions.

[COR1] A Distributed Control Approach for Heterogeneous Linear Multiagent Systems

S. B. Sarsılmaz and T. Yucelen

International Journal of Control, vol. 94, no. 5, p. 1402-1414, 2021

DOI: 10.1080/00207179.2019.1651455

[COR2] Cooperative Output Regulation of Heterogeneous Multiagent Systems: A Global Distributed Control Synthesis Approach

A. T. Koru, S. B. Sarsılmaz, T. Yucelen, and E. N. Johnson

IEEE Transactions on Automatic Control, vol. 66, no. 9, pp. 4289–4296, 2021

DOI: 10.1109/TAC.2020.3032496

[COR3] Regional Eigenvalue Assignment in Cooperative Linear Output Regulation

A. T. Koru, S. B. Sarsılmaz, T. Yucelen, J. A. Muse, F. L. Lewis, and B. Açıkmeşe

IEEE Transactions on Automatic Control, vol. 68, no. 7, pp. 4265–4272, 2023

DOI: 10.1109/TAC.2022.3207419

* For networks of nonidentical linear systems over directed graphs, [COR1] presents the solvability of the cooperative output regulation problem with three p-copy internal model-based distributed control laws. Both the global and agent-wise local conditions are provided. The global ones, including the overall closed-loop stability, are the key to any p-copy internal model-based distributed control laws. By the agent-wise local conditions, the problem boils down to stabilizing augmented exosystem-free dynamics for each agent with a disturbance attenuation level determined by a spectral property of the graph. This enables an independent control design for each agent and, hence, a level of scalability. However, [COR1] does not incorporate transient response requirements, for instance, minimal decay rate and damping ratio, into the design. To gain the capability of improving the overall performance, a structured Lyapunov inequality, a convex formulation of the overall closed-loop stability, is constructed in [COR2] for the distributed dynamic state feedback control law by considering the networks of systems as a whole. The existence of a solution to this linear matrix inequality is ensured if there exist control parameters satisfying the aforementioned agent-wise local conditions for every agent. Though the proposed linear matrix inequality yields performance guarantees, it lacks scalability. [COR3], on the other hand, provides a scalable p-copy internal model-based distributed dynamic state feedback control synthesis technique with performance guarantees. Specifically, it is shown that a specific robust D-stability condition for every agent implies the D-stability of the overall closed-loop system.

[COR4] A Distributed Adaptive Control Approach to Cooperative Output Regulation of a Class of Heterogeneous Uncertain Multi-agent Systems

S. B. Sarsılmaz, A. T. Koru, T, Yucelen, and B. Açıkmeşe

A book chapter in Control of Autonomous Aerial Vehicles: Advances in Autopilot Design for Civilian UAVs, A. L’Afflitto, G. Inalhan, and H.-S. Shin, Eds. Springer, 2024

DOI: 10.1007/978-3-031-39767-7_11

[COR5] Application of a Distributed Adaptive Control Approach to a Heterogeneous Multiagent Mechanical Platform

E. Yildirim, S. B. Sarsılmaz, and T. Yucelen

AIAA SciTech Forum, CA, 2019

DOI: 10.2514/6.2019-1427

* Although internal model-based distributed control is robust against small-scale parameter uncertainties, it is not robust concerning large-scale ones. Therefore, in the presence of linearly parameterized matched system uncertainties, the distributed controllers in [COR1]-[COR3] cannot directly solve the cooperative output regulation. To this end, [COR4] proposes a distributed dynamic state feedback control law involving a distributed reference model characterizing the desired closed-loop response, a parameter adaptation rule handling the uncertainties, and a decoupling virtual tracking error. The proposed distributed control law, especially the decoupling virtual tracking error, breaks the original problem into two problems: i) cooperative linear output regulation with an internal model-based distributed control, where the results of [COR1]-[COR3] are utilized to construct a distributed reference model; ii) model reference adaptive control for each agent. [COR5] demonstrates the performance of the distributed control law with an experimental study on a heterogeneous multi-agent system composed of two cart-inverted pendulums and a cart.