Least-squares identification of closed-loop systems

Wellstead, P. E.; Edmunds, J. M.

doi:10.1080/00207177508922023

Cited by 86 publications

(23 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1) and Emax fluctuations, in turn, causing CVP and ABP fluctuations (feed-forward pathway). To determine the targeted openloop systems as they operate in closed-loop, the identification is based on a parametric model so that causality can be enforced (31).…”

Section: Overview and Rationale Of Mathematical Analysismentioning

confidence: 99%

Stimulation of the cardiopulmonary baroreflex enhances ventricular contractility in awake dogs: a mathematical analysis study

Sala‐Mercado

Moslehpour

Hammond

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

-The cardiopulmonary baroreflex responds to an increase in central venous pressure (CVP) by decreasing total peripheral resistance and increasing heart rate (HR) in dogs. However, the direction of ventricular contractility change is not well understood. The aim was to elucidate the cardiopulmonary baroreflex control of ventricular contractility during normal physiological conditions via a mathematical analysis. Spontaneous beat-to-beat fluctuations in maximal ventricular elastance (E max), which is perhaps the best available index of ventricular contractility, CVP, arterial blood pressure (ABP), and HR were measured from awake dogs at rest before and after ␤-adrenergic receptor blockade. An autoregressive exogenous input model was employed to jointly identify the three causal transfer functions relating beat-to-beat fluctuations in CVP to E max (CVP ¡ Emax), which characterizes the cardiopulmonary baroreflex control of ventricular contractility, ABP to E max, which characterizes the arterial baroreflex control of ventricular contractility, and HR to E max, which characterizes the force-frequency relation. The CVP ¡ E max transfer function showed a static gain of 0.037 Ϯ 0.010 ml Ϫ1 (different from zero; P Ͻ 0.05) and an overall time constant of 3.2 Ϯ 1.2 s. Hence, E max would increase and reach steady state in ϳ16 s in response to a step increase in CVP, without any change to ABP or HR, due to the cardiopulmonary baroreflex. Following ␤-adrenergic receptor blockade, the CVP ¡ E max transfer function showed a static gain of 0.0007 Ϯ 0.0113 ml Ϫ1 (different from control; P Ͻ 0.10). Hence, E max would change little in steady state in response to a step increase in CVP. Stimulation of the cardiopulmonary baroreflex increases ventricular contractility through ␤-adrenergic receptor system mediation.beat-to-beat variability; cardiopulmonary baroreflex; maximal ventricular elastance; system identification; ventricular contractility THE BAROREFLEX SYSTEMS ARE primarily responsible for maintaining blood pressure in the short term (seconds to minutes) and also appear to contribute to longer-term blood pressure regulation (29,30). It is well known that the arterial baroreflex senses arterial blood pressure (ABP) via stretch receptors lying in the carotid sinus and aortic arch and buffers an increase in ABP by decreasing, for example, total peripheral resistance (TPR), heart rate (HR), and ventricular contractility. The sensory receptors of the cardiopulmonary baroreflex are more complex, residing mainly in the cardiac chambers but also in the pulmonary vessels (5). These receptors have been shown to be responsive to both central venous pressure (CVP) (7,25) and left atrial pressure (LAP) (10, 21), which often change in parallel. The cardiopulmonary baroreflex responds to a change in these pressures by inducing an opposite change in TPR (1,16,25). An increase in the preload pressures also leads to an increase in HR (i.e., Bainbridge effect) in dogs (3), but an opposite change may occur in humans (7).However, the cardiopulmon...

show abstract

Section: Overview and Rationale Of Mathematical Analysismentioning

confidence: 99%

Stimulation of the cardiopulmonary baroreflex enhances ventricular contractility in awake dogs: a mathematical analysis study

Sala‐Mercado

Moslehpour

Hammond

et al. 2014

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

“…The other process signals-APRM (x~> neutron flux), Dome pressure (x 2 ), Turbine pressu1·e (x 3 ) -are also needed for the whole system identification. to include whose time (13) the zero regression term, constants are fairly small.…”

Section: Ll Ar Model and Associate Matrixmentioning

confidence: 99%

Identification of Pressure Control System Dynamics in BWR Plant by Multivariate Autoregressive Modeling Technique

Kanemoto

Andoh

Yamamoto

et al. 1982

Journal of Nuclear Science and Technology

View full text Add to dashboard Cite

Dynamics of a BWR plant pressure control system were studied using stationary noise data for development of a plant diagnosis technique. A multivariate autoregressive (AR) modeling technique has been widely used for similar purposes. However, this cannot be applied to the pressure control system, since the system contains highly coherent signals and its partial transfer mechanism possesses a fast time constant. The present study solved these difficulties by introducing an associate matrix, which described a priori relationships between objective signals, into the conventional AR model.Using this modified AR model, internal (open loop) and closed loop transfer functions were identified. Their validity was confirmed by comparing with actual transient test data. These results show the effectiveness of noise data for evaluating not only partial component dynamics in the pressure control system but also whole system dynamics, such as a plant stability.

show abstract

“…Consequently closed-loop identification has attracted a great deal of reserchers' attention. Several closed-loop identification methods have been developed, and they can be classified into three main categories such as the direct methods (Ljung et al, 1974;Wellstead and Edmunds, 1975), the indirect methods (Hansen and Franklin, 1988;den Hof et al, 1995) and the joint input-output methods. In the indirect methods or the joint input-output methods, the external exciting test signals are used hence it is possible to reduce the closed-loop identification problem into several stable open loop identifications, where the external test signal is considered as the input signals of these open loops.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, when the test signal is unavailable, or the power of test signal allowed in the regular operation is too small to do significant contribution to system identification, it seems that the direct method is the unique choice to the closed-loop identification problem. The identifiability condition for the conventional direct method usually requires that the order of the controller should be higher than that of the plant (Wellstead and Edmunds, 1975). However, under the case where the feedback controller is designed by using a reduced-order nominal model, it is hardly possible to satisfy the identifiability condition.…”

Section: Introductionmentioning

confidence: 99%

Cyclic Spectral Based Approach to Closed-Loop Identification

Sun

Sano

2005

IFAC Proceedings Volumes

View full text Add to dashboard Cite

The direct closed-loop identification algorithm based on cyclic spectral is considered in frequency domain in this paper. It is illustrated that the input and output signals obtained through inter-sampling technique have cyclic spectral, and the cyclic spectral contain plant model information, then the plant model can be estimated just from the cyclic spectral of the plant input and output signals. It is clarified that the test signal is not necessary, and the new algorithm does not depend on the controller structure. The effectiveness of the proposed algorithm is also demonstrated through several numerical examples.

show abstract

Least-squares identification of closed-loop systems

Cited by 86 publications

References 5 publications

Stimulation of the cardiopulmonary baroreflex enhances ventricular contractility in awake dogs: a mathematical analysis study

Stimulation of the cardiopulmonary baroreflex enhances ventricular contractility in awake dogs: a mathematical analysis study

Identification of Pressure Control System Dynamics in BWR Plant by Multivariate Autoregressive Modeling Technique

Cyclic Spectral Based Approach to Closed-Loop Identification

Contact Info

Product

Resources

About