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This paper presents a multirobot cooperative event based localization scheme with improved bandwidth usage in a heterogeneous group of mobile robots. The proposed method relies on an agent based framework that defines the communications between robots and on an event based Extended Kalman Filter that performs the cooperative sensor fusion from local, global and relative sources. The event is generated when the pose error covariance exceeds a predefined limit. By this, the robots update the pose using the relative information available only when necessary, using less bandwidth and computational resources when compared to the time based methods, allowing bandwidth allocation for other tasks while extending battery life. The method is tested using a simulation platform developed in the programming language JAVA with a group of differential mobile robots represented by an agent in a JADE framework. The pose estimation performance, error covariance and number of messages exchanged in the communication are measured and used to compare the traditional time based approach with the proposed event based algorithm. Also, the compromise between the accuracy of the localization method and the bandwidth usage is analyzed for different event limits. A final experimental test with two SUMMIT XL robots is shown to validate the simulation results. [ABSTRACT FROM AUTHOR]

To address the difficulty of controlling industrial processes with long time delay, a novel design of dead-time compensator (DTC) is introduced, which can be used to predict the undelayed output response of any process (no matter stable or unstable) such that the control design may be focused on the delay-free part of the process for performance optimization. Based on the undelayed output estimation, a two-degree-of-freedom (2DOF) control scheme is analytically developed for optimizing the set-point tracking and disturbance rejection, respectively. By proposing the desired transfer functions, the corresponding controllers are analytically derived based on commonly used low-order process models. A notable advantage is that there is a single adjustable parameter in the proposed DTC, as well as in each controller, which can be monotonically tuned to meet a good tradeoff between the prediction (or control) performance and its robustness. Illustrative examples from the literature and a practical application to a temperature control system of a jacketed reactor are used to demonstrate the effectiveness of the proposed predictor-based control scheme. [ABSTRACT FROM PUBLISHER]

This paper deals with the problem of stabilizing a class of input-delayed systems with (possibly) nonlinear uncertainties by using explicit delay compensation. It is well known that plain predictive schemes lack robustness with respect to uncertain model parameters. In this work, an uncertainty estimator is derived for input-delay systems and combined with a modified state predictor, which uses current available information of the estimated uncertainties. Furthermore, based on Lyapunov-Krasovskii functionals, a computable criterion to check robust stability of the closed-loop is developed and cast into a minimization problem constrained to an LMI. Additionally, for a given input delay, an iterative-LMI algorithm is proposed to design stabilizing tuning parameters. The main results are illustrated and validated using a numerical example with a second-order dynamic system. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The design of decoupling controllers for multivariable systems with time delays is a complex issue, even more for non‐square plants, and some approximations are usually required. In this study, based on the inverted decoupling structure, a model‐based designed centralised controller is decomposed into two controllers: one is in the direct path and the other is in a feedback loop. Owing to the non‐square nature of the process, the expression of the controller in the direct path might be very complicated, mainly for large‐size systems. The main contribution of this study is the introduction of a new diagonal pre‐compensator which to simplify the controller structure. The different possible configurations of the controller structure are analysed to satisfy the physical realisability of the compensators taking into account the possible existence of time delays and non‐minimum phase behaviour. The control goal is to achieve a decoupled dynamic behaviour characterised by the bandwidth of each loop. Comparisons with existing works through several simulation examples demonstrate the effectiveness and significant performance improvement of the proposed methodology. The need of additional manipulated variables is illustrated. [ABSTRACT FROM AUTHOR]

In this paper, a new robust control strategy based on a predictor and the uncertainty and disturbance estimator is developed for a class of uncertain nonlinear systems with input/output delays. The closed-loop system is analyzed and sufficient stability conditions are derived based on Lyapunov analysis. The proposed strategy is applied to the particular case of quadrotor systems and validated through extensive simulations to evaluate performance and robustness. The controller is also implemented in a quadrotor prototype and validated in flight tests. [ABSTRACT FROM PUBLISHER]