Closed-loop input shaping for flexible structures using time-delay control

Author(s):  
V. Kapila ◽  
A. Tzes ◽  
Qiguo Yan
1999 ◽  
Vol 122 (3) ◽  
pp. 454-460 ◽  
Author(s):  
Vikram Kapila ◽  
Anthony Tzes ◽  
Qiguo Yan

Input shaping techniques reduce the residual vibration in flexible structures by convolving the command input with a sequence of impulses. The exact cancellation of the residual structural vibration via input shaping is dependent on the amplitudes and instances of impulse application. A majority of the current input shaping schemes are inherently open-loop where impulse application at inaccurate instances can lead to system performance degradation. In this paper, we develop a closed-loop control design framework for input shaped systems. This framework is based on the realization that the dynamics of input shaped systems give rise to time delays in the input. Thus, we exploit the feedback control theory of time delay systems for the closed-loop control of input shaped flexible structures. A Riccati equation-based and a linear matrix inequality-based frameworks are developed for the stabilization of systems with uncertain, multiple input delays. Next, the aforementioned framework is applied to two input shaped flexible structure systems. This framework guarantees closed-loop system stability and performance when the impulse train is applied at inaccurate instances. Two illustrative numerical examples demonstrate the efficacy of the proposed closed-loop input shaping controller. [S0022-0434(00)00103-9]


1992 ◽  
Vol 114 (4) ◽  
pp. 544-555 ◽  
Author(s):  
K. Youcef-Toumi ◽  
S. Reddy

Time Delay Control has recently been suggested as an alternative scheme for control of systems with unknown dynamics and unpredictable disturbances. The proposed control algorithm does not require an explicit plant model nor does it depend on the estimation of specific plant parameters. Rather, it uses information in the recent past to directly estimate the unknown dynamics at any given instant, through time delay. In earlier papers, analysis and implementation of Time Delay Controller for nonlinear systems were discussed. This paper analyzes the continuous Time Delay Controller for a class of linear systems and presents necessary and sufficient conditions for control system stability. A necessary condition for stability is derived using the properties of linear time-delayed systems. This condition involves only a few of the system and controller parameters and facilitates design of the Time Delay Controller. It is proved that this necessary condition is also sufficient if the delay time is chosen to be infinitesimally small. The convergence of closed loop system error to zero for certain classes of inputs and disturbances when the system is stable is also established. It is also shown that certain approximations in the control algorithm and certain additional unmodeled dynamics render the closed loop system under continuous Time Delay Control to be not exponentially stable due to the controller poles on the imaginary axis at infinitely high frequencies. However, in digital implementation, all the signals are prefiltered by anti-aliasing filters prior to sampling. Hence, the highest frequency component is automatically limited and the issue of exponential instability is not encountered. A discussion is presented comparing Time Delay Control with Repetitive Control. It is indicated that the Time Delay Controller can perform the functions of a repetitive controller with the delay time replaced by the period of the reference input while the repetitive controller can perform the functions of Time Delay Controller for sufficiently small “period” for a certain class of linear systems. Furthermore, examples are included to illustrate the results.


2020 ◽  
Vol 53 (2) ◽  
pp. 16971-16976
Author(s):  
T.A. Alexeeva ◽  
W.A. Barnett ◽  
N.V. Kuznetsov ◽  
T.N. Mokaev

Author(s):  
Hossein Nejatbakhsh Esfahani ◽  
Rafal Szlapczynski

AbstractThis paper proposes a hybrid robust-adaptive learning-based control scheme based on Approximate Dynamic Programming (ADP) for the tracking control of autonomous ship maneuvering. We adopt a Time-Delay Control (TDC) approach, which is known as a simple, practical, model free and roughly robust strategy, combined with an Actor-Critic Approximate Dynamic Programming (ACADP) algorithm as an adaptive part in the proposed hybrid control algorithm. Based on this integration, Actor-Critic Time-Delay Control (AC-TDC) is proposed. It offers a high-performance robust-adaptive control approach for path following of autonomous ships under deterministic and stochastic disturbances induced by the winds, waves, and ocean currents. Computer simulations have been conducted under two different conditions in terms of the deterministic and stochastic disturbances and all simulation results indicate an acceptable performance in tracking of paths for the proposed control algorithm in comparison with the conventional TDC approach.


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