The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform

Piotr Tatjewski - One of the best experts on this subject based on the ideXlab platform.

  • disturbance modeling and state estimation for offset free predictive control with state space Process models
    International Journal of Applied Mathematics and Computer Science, 2014
    Co-Authors: Piotr Tatjewski
    Abstract:

    AbstractDisturbance modeling and design of state estimators for offset-free Model Predictive Control MPC with linear state-space Process models is considered in the paper for deterministic constant-type external and internal disturbances modeling errors. The application and importance of constant state disturbance prediction in the state-space MPC controller design is presented. In the case with a measured state, this leads to the control structure without disturbance state observers. In the case with an unmeasured state, a new, simpler MPC controller-observer structure is proposed, with observation of a pure Process state only. The structure is not only simpler, but also with less restrictive applicability conditions than the conventional approach with extended Process-and-disturbances state estimation. Theoretical analysis of the proposed structure is provided. The design approach is also applied to the case with an augmented state-space model in complete velocity form. The results are illustrated on a 2×2 example Process Problem.

  • disturbance modeling and state estimation for predictive control with different state space Process models
    IFAC Proceedings Volumes, 2011
    Co-Authors: Piotr Tatjewski
    Abstract:

    Abstract The paper is concerned with disturbance modeling and observer design for Model Predictive Control (MPC) with different formulations of state-space Process models. Systematic discussion is given, presenting the ways the deterministic disturbances most important in Process control applications should be treated in the MPC algorithm, to obtain disturbance attenuation and offset-free control. The closely related Problem of observer design and understanding is explained. It is shown that a simple approach with a Process state observer only, in the presence of deterministic disturbances, can work better than the conventional approach of extended Process-disturbance state estimation. The observer design is also considered for the case of extended velocity form state-space modeling including integrators. A simplified approach with reduced order observer is given. The results are illustrated on a 2×2 example Process Problem.

George J. Pappas - One of the best experts on this subject based on the ideXlab platform.

  • Optimal power management in wireless control systems
    2013 American Control Conference, 2013
    Co-Authors: Konstantinos Gatsis, Alejandro Ribeiro, George J. Pappas
    Abstract:

    This paper considers the control of a linear plant when a sensor transmits plant state information over a wireless fading channel to a controller physically separated from the sensor. The power allocated to these transmissions determines the probability of successful reception and is adapted to channel and plant state in order to conserve the sensor's energy resources. Our goal is to design plant control and power management policies to minimize an infinite horizon cost combining power consumption with the conventional linear quadratic regulator control cost. A method to separate the designs of plant inputs and transmitting powers is provided. The resulting optimal controller is the standard LQR control law while the optimal communication policy follows from a Markov decision Process Problem accounting for power at the sensor and state estimation error at the controller. The features of the optimal power management for general forward error correcting are examined qualitatively. In the particular case of transmissions protected with capacity achieving codes, conventional event-triggered policies are recovered, where the decision is whether to transmit or not. Further a suboptimal communication policy is computed using approximate dynamic programming and its behavior is validated in simulations and contrasted to other simple transmission policies.

Zhixing Yang - One of the best experts on this subject based on the ideXlab platform.

  • Efficient vertical handover scheme for heterogeneous VLC-RF systems
    IEEE OSA Journal of Optical Communications and Networking, 2015
    Co-Authors: Fang Wang, Zhaocheng Wang, Chen Qian, Zhixing Yang
    Abstract:

    Visible light communication (VLC) is a promising complementary technology to its radio frequency (RF) counterpart. Heterogeneous VLC-WiFi systems offer a solution for future indoor communications that combines VLC to support high data rate transmission and RF to support reliable connectivity. In such heterogeneous systems, vertical handover (VHO) is critical for improving the system performance. This paper investigates an efficient VHO scheme. We formulate it as a Markov decision Process Problem and adopt a dynamic approach to obtain a tradeoff between the switching cost and the delay requirement. The proposed scheme determines whether to perform VHO given the queue length and the condition of the optical wireless channel (available or unavailable). The simulation results demonstrate that the proposed scheme is able to save about 50% of the signaling cost of the VHO Process without an obvious loss in system performance. Moreover, the proposed scheme is adaptable to different scenarios.

V. Krishnamurthy - One of the best experts on this subject based on the ideXlab platform.

  • Opportunistic file transfer over a fading channel: A POMDP search theory formulation with optimal threshold policies
    IEEE Transactions on Wireless Communications, 2006
    Co-Authors: L.a. Johnston, V. Krishnamurthy
    Abstract:

    We present a computationally efficient algorithm that minimizes the transmission energy and latency associated with transmitting a file across a Gilbert Elliott fading channel. We formulate the optimal tradeoff between transmission energy and latency as a partially observed Markov decision Process Problem (POMDP). The channel state is not directly observed and hence transmission decisions must be based on ACK/NAK information provided over a feedback channel. The key idea is to reformulate the resulting POMDP as a Markovian search Problem, with optimal transmission control policies that are threshold in nature. Threshold policies are computationally inexpensive to implement. Our analysis shows that for different parameter values of the Gilbert Elliott fading channel, the optimal transmission policy, while threshold in structure, exhibits vastly different behaviour - from persistent retransmission to back-off and wait. Numerical examples demonstrate the performance improvements that can be obtained using the optimal threshold policies as compared to existing heuristic algorithms.

H. Sira-ramírez - One of the best experts on this subject based on the ideXlab platform.

  • A flatness based Active Disturbance Rejection Controller for the four tank benchmark Problem
    2015 American Control Conference (ACC), 2015
    Co-Authors: Congzhi Huang, H. Sira-ramírez
    Abstract:

    A flatness based decentralized Active Disturbance Rejection Control (ADRC) approach is here proposed as a means to deal with the fully nonlinear, exogenously perturbed, version, of the four-tank benchmark Process Problem under non-minimum phase behavior for the traditionally chosen system outputs. The liquid level control task, related to the two lower tanks, is transformed into a corresponding, indirect, multi-input multi-flat-output decoupling control Problem for the flat outputs. Decentralized robust active disturbance rejection controllers are proposed for the flat outputs, thus circumventing the well known non-minimum phase Problems. The effectiveness of the proposed approach is validated via extensive realistic simulation results, wherein unknown chaotic inputs are proposed as exogenous disturbances.