Trends in the Stability Properties of CLSS Controllers: A Root-Locus Analysis

Huey, John; Singhose, William

doi:10.1109/tcst.2009.2031681

Cited by 27 publications

(10 citation statements)

References 42 publications

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“…Moreover, the time-delay term in the CLSS results in non-minimum phase system which, according to [21], limits the performance of the control system by limiting the maximum achievable bandwidth. The third disadvantage of the CLSS was pointed out by Huey and Singhose [19] that the CLSS requires accurate plant model in order to avoid unexpected instability.…”

Section: P S Is S C S P S Y S R S D S D S P S Is S C S P S Is S C S Pmentioning

confidence: 99%

“…Since the exponential function is transcendental, it is difficult to analyze the stability property or to design a controller for the system. For example, Huey and Singhose [19] showed that, with CLSS, there are infinitely many root locus branches. Only in simple cases, a finite number of root locus branches closest to the real axis can be used in stability analysis.…”

Section: Introductionmentioning

confidence: 99%

“…Only in simple cases, a finite number of root locus branches closest to the real axis can be used in stability analysis. From the root locus stability analysis, Huey and Singhose [19] pointed out that CLSS requires quite an accurate plant model to avoid unexpected instability. Huey and Singhose [20] showed that CLSS cannot suppress the vibration induced by the plant-input disturbance or by non-zero initial conditions.…”

Section: Introductionmentioning

confidence: 99%

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Improving Closed-Loop Signal Shaping of Flexible Systems with Smith Predictor and Quantitative Feedback

Chatlatanagulchai

Poedaeng

Pongpanich

2016

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Abstract. Input shaping is a technique used to move flexible systems from point to point rapidly by suppressing the residual vibration at the destination. The vibration suppression is obtained from the principle of destruction of impulse responses. The input shaper, when placed before the flexible system inside the control loop, proves to deliver several benefits. However, this so-called closed-loop signal shaping has one major disadvantage that it adds time delays to the closed-loop system. Being a transcendental function, the time delays cause difficulty in analysis and design of the feedback controller. In most cases, the time delays also limit the maximum achievable bandwidth. In this paper, for the very first time, Smith predictors were applied to the closed-loop signal shaping to remove the time delay from the loop. It was shown in simulation result that the detrimental effect of the time delays was completely removed in the case of perfect plant model. The quantitative feedback control was used in the study to quantify the amount of achievable bandwidth and to suppress vibrations from the plant-input disturbance.

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Section: P S Is S C S P S Y S R S D S D S P S Is S C S P S Is S C S Pmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improving Closed-Loop Signal Shaping of Flexible Systems with Smith Predictor and Quantitative Feedback

Chatlatanagulchai

Poedaeng

Pongpanich

2016

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“…Recently, the input shaper is placed inside the feedback loop, so-called closed-loop signal shaping (CLSS) [2], to gain benefits such as eliminating the vibration induced by plantoutput disturbance, ease in stabilizing the non-collocated systems, ease in handling hard nonlinearities (backlash, deadzone, saturation), and improving performance of manual control. Recently, the CLSS has been applied to actual systems including bridge crane with distributed mass [3], 3D crane with PID controller [4], and helicopter [5].…”

Section: Introductionmentioning

confidence: 99%

Closed-Loop Signal Shaping With Inner-Loop Model Matching

Chatlatanagulchai

Yaovaja

Poedaeng

2017

Volume 4B: Dynamics, Vibration, and Control

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Input shaper is a pre-filter, designed to suppress residual vibration of flexible systems. The input shaper can be placed inside the feedback loop, in front of the flexible plant, to avoid exciting the plant vibratory modes. The performance of this so-called closed-loop signal shaping is limited due to the time delay brought about by the input shaper. The input shaper has more time delay when the plant mode parameters are uncertain. In this paper, an inner-loop controller based on the quantitative feedback theory is designed to match the uncertain flexible plant to a reference model. As a result, the input shaper needs not be robust, and the time delay is reduced. Other benefits include shorter input shaper length, increasing controller bandwidth, applicable to time-varying plant, and reducing cost of feedback. Simulation and experiment have confirmed the effectiveness of the newly proposed technique.

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“…Subsequently, in Hung (2003), a direct augmentation of the standard feedback loop with pre-tuned input command shaper was proposed. Closed loop stability issues related to this setup are further discussed by Huey and Singhose (2010) using root locus diagrams, and by Staehlin and Singh (2003). It can be concluded however that the signal shaper being placed in the loop between the controller and the system is rather ineffective in the given objective of suppressing the vibrations caused by disturbance variables.…”

mentioning

confidence: 99%

Spectral design of output feedback controllers for systems pre-compensated by input shapers∗∗The presented research has been supported by the Czech Science Foundation under the project No. 13–06962S, by the Programme of Interuniversity Attraction Poles of the Belgian Federal Science Policy Office(IAP P6–DYSCO), by OPTEC, the Optimization in Engineering Center of the KU Leuven, and the project G.0712.11N and G.0717.11N of the Research Foundation –Flanders (FWO).

2015

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The primary objective is to investigate the applicability of spectral methods for designing feedback controllers for a closed loop system with an input shaper with time delays. The shaper is included in the feedback loop in order to pre-compensate low-damped oscillatory modes of a flexible subsystem. However, after inserting a shaper into the feedback loop, the closed loop dynamics becomes infinite dimensional. A robust controller design then requires guaranteeing that all the infinitely many poles of the closed loop system will safely be located in the left half of the complex plane. Besides, the closed loop dynamics need to be sufficiently fast in order to take over and keep filtering properties of the input shaper. For the spectral design of the controller, the recently developed spectral abscissa minimization approach for interconnected time delay systems is applied. The presented methods are tested on a case study simulation example, which is a multi-degree of freedom mechanical system.

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Trends in the Stability Properties of CLSS Controllers: A Root-Locus Analysis

Cited by 27 publications

References 42 publications

Improving Closed-Loop Signal Shaping of Flexible Systems with Smith Predictor and Quantitative Feedback

Improving Closed-Loop Signal Shaping of Flexible Systems with Smith Predictor and Quantitative Feedback

Closed-Loop Signal Shaping With Inner-Loop Model Matching

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