Online identification of continuous-time systems with unknown time delay

Ren, Xuhui; Rad, A.B.; Chan, Patrick P. K.; Lo, W.L.

doi:10.1109/tac.2005.854640

Cited by 106 publications

(49 citation statements)

References 6 publications

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“…Up to now, various techniques have been proposed for the delay identification problem, such as identification by using variable structure observers Drakunov et al, by a modified least squares technique Ren et al (2005), by convolution approach Belkoura (2005), by using the fast identification technique proposed in Fliess and Sira-Ramirez (2004) to deal with online identification of continuous-time systems with structured entries Belkoura et al (2009) and so on.…”

Section: Introductionmentioning

confidence: 99%

Delay estimation algorithm for nonlinear time-delay systems with unknown inputs

Barbot

Zheng

Floquet

et al. 2012

IFAC Proceedings Volumes

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Abstract:The theory of non-commutative rings allows determining whether or not there exists an equation called algebraically essential in order to estimate the delay on a nonlinear system. In this paper, it firstly recalls some literature results on algebraically essential equation. Then it is shown that this equation is generally not enough to guarantee the delay estimation, thus the notion of persistent signal with respect to delay estimation is introduced. Furthermore, based on the definitions of algebraically essential equation and of persistent signal, a delay estimation algorithm is proposed. Some simulation results have been presented in order to highlight the robustness (with respect to measurement noise) of the proposed algorithm.

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Section: Introductionmentioning

confidence: 99%

Delay estimation algorithm for nonlinear time-delay systems with unknown inputs

Barbot

Zheng

Floquet

et al. 2012

IFAC Proceedings Volumes

View full text Add to dashboard Cite

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“…They have been widely used in signal processing, robotics, civil engineering. On the other hand, timedelay estimation of systems with unknown time delay is a challenging problem that has attracted continuous attention during the last four decades (Ren, 2005). Even though considerable efforts have been made on parameter estimation, there are still many open problems in time-delay identification due to difficulty in formulation (Richard, 2003;Belkoura et al, 2009;Khan, 2011;El-Fallah and El-Sallam, 2011;Khan and Khan, 2010).…”

Section: Introductionmentioning

confidence: 99%

Time-Delay Estimation using the Characteristic Roots of Delay Differential Equations

Yi¹

2012

American Journal of Applied Sciences

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Problem statement: For ordinary dynamic systems (i.e., non-delayed), various methods such as linear least-squares, gradient-weighted least-squares, Kalman filtering and other robust techniques have been widely used in signal processing, robotics, civil engineering. On the other hand, time-delay estimation of systems with unknown time-delay is still a challenging problem due to difficulty in formulation caused. Approach: The presented method makes use of the Lambert W function and analytical solutions of scalar first-order Delay Differential Equations (DDEs). The Lambert W function has been known to be useful in solving delay differential equations. From the solutions in terms of the Lambert W function, the dominant characteristic roots can be obtained and used to estimate time-delays. The function is already embedded in various software packages (e.g., MATLAB) and thus, the presented method can be readily used for time-delay systems. Results: The presented method and the provided examples show ease of formulation and accuracy of time-delay estimation. Conclusion: Estimation of time-delays can be conducted in an analytical way. The presented method will be extended to general systems of DDEs and application to physical systems.

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“…A serious problem in the model-based control of robotic systems is that the computational burden imposed on the robot computer is heavy, causing the real-time exploitation of the control algorithm to take high costs [18]. To date, some solutions have been proposed to solve this problem based on identification and estimation strategies [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. To solve this problem, we propose a model that can be supposed directly between actuators' outputs and the sensors measurements of distances from the sliding surfaces.…”

Section: Introductionmentioning

confidence: 99%

Real-time regulated sliding mode controller design of multiple manipulator space free-flying robot

Khaloozadeh

Homaeinejad

2010

J Mech Sci Technol

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The problem of controlling Space Free-flying Robots (SFFRs), which have many degrees of freedom caused by their mechanical manipulators, is challenging because of the strong nonlinearities and their heavy computational burden for the implementation of modelbased control algorithms. In this paper, a chattering avoidance sliding mode controller is developed for SFFR as highly nonlinear-coupled systems. To fulfill stability requirements, robustness properties, and chattering elimination, a regulating routine is proposed to determine the proper positive values for the coefficient of sliding condition. To solve the run-time problem, an explicit direct relationship between the SFFR's output of actuators (force/torque) and the measurement of distances from the corresponding sliding surfaces is also assumed. To reach perfect performance, the parameters are estimated recursively using the Kalman filter as a parameter estimator. The explicit dynamics of a 14-DOF SFFR is derived using SPACEMAPLE, and the recursive prediction error method (RPEM) is used to parameterize the SFFR model. To alleviate the chattering trend, a multi-input sliding mode control law is proposed and applied to the given SFFR based on the online estimated dynamics to control its orientation and position to catch a moving target. To evaluate the new proposed algorithm in a more complicated condition, only on-off actuators are assumed for controlling the base of SFFR because it is the case in real systems. The obtained results show that the proposed regulated sliding mode controller can significantly reduce the chattering trend. Consequently, energy consumption will be substantially decreased, and running the control algorithm will be within a reasonable time duration.

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Online identification of continuous-time systems with unknown time delay

Cited by 106 publications

References 6 publications

Delay estimation algorithm for nonlinear time-delay systems with unknown inputs

Delay estimation algorithm for nonlinear time-delay systems with unknown inputs

Time-Delay Estimation using the Characteristic Roots of Delay Differential Equations

Real-time regulated sliding mode controller design of multiple manipulator space free-flying robot

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