55 research outputs found
Synchronization of Uncertain Heterogeneous Agents: An Adaptive Virtual Model Reference Approach
No full textSynchronization of Multi-Agent Systems (MASs) has the potential to benefit many technologicalareas such as formation control for unmanned vehicles, cooperative adaptivecruise control, and spacecraft attitude control. Information plays a crucial role in MASs:in centralized approaches, a central node utilizes global information to achieve synchronization,while in distributed approach agents only utilize local information, i.e. neighbors’information. A big concern in MASs is the presence of parametric uncertainties(unknown dynamics), which might require adaptive control gains instead of fixed controlgains.This work thus provides a novel adaptive distributed control for MASs of heterogeneousagents with unknown dynamics based on model reference adaptive control (MRAC).We study both the synchronization of linear systems and the synchronization of Euler-Lagrange (EL) systems. The implementation of this scheme is based on distributedmatching condition assumptions. We study such matching conditions both for the statefeedbackcase and output-feedback case. Since all matching gains are unknown in viewof the unknown dynamics, the gains are adapted online via Lyapunov-based estimation.The asymptotic convergence of the synchronization error is analytically provenby introducing an appropriately defined Lyapunov function, and numerical examplesshow the effectiveness of the approach. The practical advantage of the proposed distributedMRAC is the possibility of handling unknown dynamics by simply exchangingthe states/output, and inputs with neighbors, without any extra auxiliary variables (distributedobserver) nor sliding mode. Because of the mutual dependence of control inputs,well-posedness problems will arise in the presence of cyclic communication, if the inputsare generated without a prescribed priority. In this work, we study such well-posednessproblems via parameter projection methods.Electrical Engineering | Embedded System
Model+Learning-based Optimal Control: An Inverted Pendulum Study
No full textThis work extends and compares some recent model+learning-based methodologies for optimal control with input saturation. We focus on two methodologies: a model-based actor-critic (MBAC) strategy, and a nonlinear policy iteration strategy. To evaluate the performance of the algorithms, these strategies are applied to the swinging up an inverted pendulum. Numerical simulations show that the neural network approximation in the MBAC strategy can be poor, and the algorithm may converge far from the optimum. In the MBAC approach neither stabilization nor monotonic convergence can be guaranteed, and it is observed that the best value function is not always corresponding to the last one. On the other side the nonlinear policy iteration approach guarantees that every new control policy is stabilizing and generally leads to a monotonically decreasing cost.Accepted Author ManuscriptTeam Bart De Schutte
Adaptive state-feedback synchronization with distributed input: the cyclic case
No full textInternational audienceany distributed observer variables), the problem of synchronizing an acyclic network of linear uncertain agents has been formulated recently as a distributed model reference adaptive control (MRAC) where each agent tries to converge to the model defined by its neighbors. In this work we show how to parametrize the distributed MRAC in cyclic and undirected graphs
Adaptive Synchronization for Heterogeneous Multi-Agent Systems with Switching Topologies
No full textThis work provides a multi-agent extension of output-feedback model reference adaptive control (MRAC), designed to synchronize a network of heterogeneous uncertain agents. The implementation of this scheme is based on multi-agent matching conditions. The practical advantage of the proposed MRAC is the possibility of handling the case of the unknown dynamics of the agents only by using the output and the control input of its neighbors. In addition, it is reasonable to consider the case when the communication topology is time-varying. In this work, the time-varying communication leads to a switching control structure that depends on the number of the predecessor of the agents. By using the switching control structure to handle the time-varying topologies, we show that synchronization can be achieved. The multi-agent adaptive switching controller is first analyzed, and numerical simulations based on formation control of simplifier quadcopter dynamics are provided
Leader–Follower Synchronization of Uncertain Euler–Lagrange Dynamics with Input Constraints
No full textThis paper addresses the problem of leader–follower synchronization of uncertain Euler–Lagrange systems under input constraints. The problem is solved in a distributed model reference adaptive control framework that includes positive μ-modification to address input constraints. The proposed design has the distinguishing features of updating the gains to synchronize the uncertain systems and of providing stable adaptation in the presence of input saturation. By using a matching condition assumption, a distributed inverse dynamics architecture is adopted to guarantee convergence to common dynamics. The design is studied analytically, and its performance is validated in simulation using spacecraft dynamics
Analisis Struktur Dan Nilai Moral Dalam Seri Cerita Rakyat Riau Karya Maria Rosa Anggraini, S.s.
No full textRakyak story is one of the fictional literary works in which there are elements that build the story and contain values that can be applied in human life. The lack of interest of teenagers today to read a folk tale due to the times, they chose to play gadgets and games. Though there are so many lessons and values in life that can be obtained in folklore. After reading the book collection of the Riau Folklore Series by Maria Rosa Anggraini, S.S. The author discovers the existence of structures and moral values in these literary works. Literary works in this contain the structure of the story that is in the form of themes, flow, background, figure, character and mandate, as well as moral values related to responsibility, conscience and obligation. This is what makes the writer interested in researching the collection of Riau Folklore Series by Maria Rosa Anggraini, S.S. Problems in this study 1) What is the structure contained in the collection of Riau Folklore Series compiled by Maria Rosa Anggraini, S.S.? 2.) What is the moral value contained in the collection of the Riau Folk Story Series compiled by Maria Rosa Anggraini, S.S. the scope of the study of literature, especially literary criticism that examines structure and moral values. The theory used to analyze the problem of this study is Priyatni (2012). Nurgiantoro (2013) and supporting theories such as Suroto (1990). Hamidy (2012). The method used in this research is descriptive method with a qualitative approach. The techniques used in this study are documentation techniques and hermeneutical techniques. The data analysis technique is the presentation technique referred to by Hamidy, uu (2003). The results of this study suggest the elements of inter-national and moral values contained in the Riau Folklore Series by Maria Rosa Anggraini, S.S. Interinsic elements include 1) theme, 2) plot, 3) background, 4) character and character, 5) mandate. Whereas moral values include 1) moral values related to responsibility, 2) moral values related to conscience, 3) moral values related to obligations
شاعری بطورعملِ تاریخ
No full textThis article titled “Poetry as an Act of History” is an Urdu translation of María Rosa Menocal’s essay, along with the translator’s notes. The author studies how the influence of the Andalusian culture and the forgotten past of three great civilizations associated with it sill echoes in literary works, especially poetry. The article begins with Andalusian references in Cervantes’ Don Quixote and moves on to trace these in poems of Mahmoud Darwish and Lorca’s translations of Andalusian poetry. The author argues that historicity is revealed more in literature than in history itself
Author Correction: Mortality outcomes with hydroxychloroquine and chloroquine in COVID-19 from an international collaborative meta-analysis of randomized trials.
No full textThe original version of this Article contained an error in the spelling of the author Muhammad Shahzad, which was incorrectly given as Muhammad Shehzad. This has now been corrected in both the PDF and HTML versions of the Article
Platooning merging maneuvers in the presence of parametric uncertainty
No full textInternational audienceRecently, adaptive platooning strategies to cope with uncertain vehicle parameters have been proposed. However, in line with most platooning literature, only acyclic graphs have been considered. This work addresses the merging maneuver in the presence uncertain vehicle parameters: during this maneuver, a cyclic communication graph is instantiated, which must be handled in a suitable way. Ideas used to handle this situation and corresponding results are illustrated using a platoon of three vehicles implementing a merging maneuver
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