| 1. |
- Chen, Fei, et al.
(författare)
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Cooperative control of heterogeneous multi-agent systems under spatiotemporal constraints
- 2024
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Ingår i: Annual Reviews in Control. - : Elsevier BV. - 1367-5788 .- 1872-9088. ; 57
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Forskningsöversikt (refereegranskat)abstract
- A current trend in research on multi -agent control systems is to consider high-level task specifications that go beyond traditional control objectives and take into account the heterogeneity of each agent in the system, i.e., the different capabilities of the agents in terms of actuation, sensing, communication and computation. This article provides an overview of our work on the problem of control of heterogeneous multi -agent systems under both spatial and temporal constraints as well as our perspective on the challenges and open problems associated with the consideration of such spatiotemporal constraints. Initially, we review a set of control strategies introduced by the authors addressing the satisfaction of cooperative tasks such as formation control as well as individual objectives such as reference tracking. The satisfaction of those objectives is ensured using prescribed performance control. Building upon these approaches we then review recent results on control under high-level spatiotemporal objectives expressed in Signal Temporal Logic, a formal language that allows to express complex spatial tasks that must be satisfied within pre -defined deadlines. Theoretical results considering multi -agent systems with various capabilities under spatiotemporal constraints are presented.
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| 2. |
- Ishii, Hideaki, et al.
(författare)
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An overview on multi-agent consensus under adversarial attacks
- 2022
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Ingår i: Annual Reviews in Control. - : Elsevier BV. - 1367-5788 .- 1872-9088. ; 53, s. 252-272
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Forskningsöversikt (refereegranskat)abstract
- This paper presents an overview on the recent advances in the research of security of cyber-physical systems. We place particular emphases on consensus problems for multi-agent systems in hostile environments and their analyses on the resiliency against two types of attacks. First, we discuss a class of data injection attacks by focusing on the approach based on mean subsequence reduced (MSR) algorithms and their variants. Agents equipped with such algorithms will ignore their neighbors taking extreme state values. Characterizations on the properties necessary for network topologies and moreover a number of extensions with enhanced resiliency will be established. As the second class of attacks, the effects of denial-of-service (DoS) attacks will be examined in the context of multi-agent consensus. By employing a DoS model based on the energy constraints of the attacker, we will observe that robustness against such attacks may depend on system properties such as dynamics of the individual agents and network structures. Applications of the algorithms will be further discussed for clock synchronization in wireless sensor networks and control of a group of mobile robots.
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| 3. |
- Kim, Junsoo, et al.
(författare)
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Comparison of encrypted control approaches and tutorial on dynamic systems using Learning With Errors-based homomorphic encryption
- 2022
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Ingår i: Annual Reviews in Control. - : Elsevier BV. - 1367-5788 .- 1872-9088. ; 54, s. 200-218
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Forskningsöversikt (refereegranskat)abstract
- Encrypted control has been introduced to protect controller data by encryption at the stage of computation and communication, by performing the computation directly on encrypted data. In this article, we first review and categorize recent relevant studies on encrypted control. Approaches based on homomorphic encryption, multi-party computation, and secret sharing are introduced, compared, and then discussed with respect to computational complexity, communication load, enabled operations, security, and research directions. We proceed to discuss a current challenge in the application of homomorphic encryption to dynamic systems, where arithmetic operations other than integer addition and multiplication are limited. We also introduce a Learning With Errors based homomorphic cryptosystem called "Gentry-Sahai-Waters"scheme and discuss its benefits that allow for recursive multiplication of encrypted dynamic systems, without use of computationally expensive bootstrapping techniques.
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| 4. |
- Martin, Tim, et al.
(författare)
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Guarantees for data-driven control of nonlinear systems using semidefinite programming : A survey
- 2023
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Ingår i: Annual Reviews in Control. - : Elsevier. - 1367-5788 .- 1872-9088. ; 56
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Forskningsöversikt (refereegranskat)abstract
- This survey presents recent research on determining control-theoretic properties and designing controllers with rigorous guarantees using semidefinite programming and for nonlinear systems for which no mathematical models but measured trajectories are available. Data-driven control techniques have been developed to circumvent a time-consuming modelling by first principles and because of the increasing availability of data. Recently, this research field has gained increased attention by the application of Willems' fundamental lemma, which provides a fertile ground for the development of data-driven control schemes with guarantees for linear time-invariant systems. While the fundamental lemma can be generalized to further system classes, there does not exist a comparable data-based system representation for nonlinear systems. At the same time, nonlinear systems constitute the majority of practical systems. Moreover, they include additional challenges such as data-based surrogate models that prevent system analysis and controller design by convex optimization. Therefore, a variety of data-driven control approaches has been developed with different required prior insights into the system to ensure a guaranteed inference. In this survey, we will discuss developments in the context of data-driven control for nonlinear systems. In particular, we will focus on methods based on system representations providing guarantees from finite data, while the analysis and the controller design boil down to convex optimization problems given as semidefinite programming. Thus, these approaches achieve reasonable advances compared to the state-of-the-art system analysis and controller design by models from system identification. Specifically, the paper covers system representations based on extensions of Willems' fundamental lemma, set membership, kernel techniques, the Koopman operator, and feedback linearization.
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| 5. |
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| 6. |
- Verginis, Christos K., et al.
(författare)
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Control of cooperative manipulator-endowed systems under high-level tasks and uncertain dynamics
- 2022
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Ingår i: Annual Reviews in Control. - : Elsevier BV. - 1367-5788 .- 1872-9088. ; 54, s. 219-240
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Forskningsöversikt (refereegranskat)abstract
- This paper considers the problem of distributed motion-and task-planning of multi-agent and multi-agent -object systems under temporal-logic-based tasks and uncertain dynamics. We focus on manipulator-endowed robotic agents that can interact with their surroundings. We present first continuous control algorithms for multi-agent navigation and cooperative object manipulation that exhibit the following properties. First, they are distributed in the sense that each agent calculates its own control signal from local interaction with the other agents and the environment. Second, they guarantee safety properties in terms of inter-agent collision avoidance and obstacle avoidance. Third, they adapt on-the-fly to dynamic uncertainties and are robust to exogenous disturbances. The aforementioned algorithms allow the abstraction of the underlying system to a finite-state representation. Inspired by formal-verification techniques, we use such a representation to derive plans for the agents that satisfy the given temporal-logic tasks. Various simulation results and hardware experiments verify the efficiency of the proposed algorithms.
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