scholarly journals Control-Oriented High-Frequency Turbomachinery Modeling: Single-Stage Compression System 1D Model

1993 ◽  
Author(s):  
O. O. Badmus ◽  
S. Chowdhury ◽  
K. M. Eveker ◽  
C. N. Nett
Keyword(s):  
Experimental Data ◽  
High Frequency ◽  
Closed Loop ◽  
Open Loop ◽  
Rotating Stall ◽  
Single Stage ◽  
Model Parameters ◽  
Compression System ◽  
First Order ◽  
Direct Model

In this paper, a 1D unsteady compressible viscous flow model of a generic compression system previously developed by the authors is applied to a multi-stage axial compressor experimental rig configured for single–stage operation. The required model parameters and maps are identified from experimental data. The resulting model is an explicit system of 9 first order ODE’s. The model inputs are compressor speed, nozzle area, compressor discharge bleed area, plenum bleed area, inlet total pressure and entropy, and nozzle and bleed exit static pressures. The model and experimental data are compared with respect to both open–loop uncontrolled and closed–loop controlled behaviors. These comparisons focus on i) forced transients and ii) global nonlinear dynamics and bifurcations. In all cases the comparison between the model and experimental data is excellent. Of particular interest is the ability of the model, which does not include any hysteretic maps, to predict experimentally observed hysteresis with respect to the onset and cessation of surge. This predictive capability of the model manifests itself as the coexistence of a stable equilibrium (rotating stall) and a stable periodic solution (surge) in the model at a single fixed set of system input values. Also of interest is the fact that the controllers used for closed–loop comparisons were designed directly from the model with no a posteriori tuning of controller parameters. Thus, the excellent closed–loop comparisons between the model and experimental data provide strong evidence in support of the validity of the model for use in direct model based controller design. The excellent agreement between the model and experimental data summarized above is attributed in large part to the use of effective lengths within the model, as functions of axial Mach number and nondimensional compressor rotational speed, as prescribed by the modeling technique. The use of these effective lengths proved to be far superior to the use of physical lengths. The use of these effective lengths also provided substantial improvement over the use of physical lengths coupled with fixed first order empirical lags, as proposed by other authors for the modeling of observed compressor dynamic lag. The overall success of this model is believed to represent a positive first step toward a complete experimental validation of the approach to control–oriented high–frequency turbomachinery modeling being developed by the authors.

Control-Oriented High-Frequency Turbomachinery Modeling: Single-Stage Compression System One-Dimensional Model

1995 ◽  
Vol 117 (1) ◽  
pp. 47-61 ◽  
Author(s):  
O. O. Badmus ◽  
S. Chowdhury ◽  
K. M. Eveker ◽  
C. N. Nett
Keyword(s):  
Experimental Data ◽  
High Frequency ◽  
Closed Loop ◽  
Rotating Stall ◽  
Single Stage ◽  
Model Parameters ◽  
Compression System ◽  
One Dimensional ◽  
First Order ◽  
Direct Model

In this paper, a one-dimensional unsteady compressible viscous flow model of a generic compression system previously developed by the authors is applied to a multistage axial compressor experimental rig configured for single-stage operation. The required model parameters and maps are identified from experimental data. The resulting model is an explicit system of nine first-order ODEs. The model inputs are compressor speed, nozzle area, compressor discharge bleed area, plenum bleed area, inlet total pressure and entropy, and nozzle and bleed exit static pressures. The model and experimental data are compared with respect to both open-loop uncontrolled and closed-loop controlled behaviors. These comparisons focus on (i) forced transients and (ii) global nonlinear dynamics and bifurcations. In all cases the agreement between the model and experimental data is excellent. Of particular interest is the ability of the model, which does not include any hysteretic maps, to predict experimentally observed hysteresis with respect to the onset and cessation of surge. This predictive capability of the model manifests itself as the coexistence of a stable equilibrium (rotating stall) and a stable periodic solution (surge) in the model at a single fixed set of system input values. Also of interest is the fact that the controllers used for closed-loop comparisons were designed directly from the model with no a posteriori tuning of controller parameters. Thus, the excellent closed-loop comparisons between the model and experimental data provide strong evidence in support of the validity of the model for use in direct model based controller design. The excellent agreement between the model and experimental data summarized above is attributed in large part to the use of effective lengths within the model, as functions of axial Mach number and nondimensional compressor rotational speed, as prescribed by the modeling technique. The use of these effective lengths proved to be far superior to the use of physical lengths. The use of these effective lengths also provided substantial improvement over the use of physical lengths coupled with fixed first-order empirical lags, as proposed by other authors for the modeling of observed compressor dynamic lag. The overall success of this model is believed to represent a positive first step toward a complete experimental validation of the approach to control-oriented high-frequency turbomachinery modeling being developed by the authors.

Plans and The Structure of Target Acquisition Behavior

1981 ◽  
Vol 25 (1) ◽  
pp. 571-575
Author(s):  
R. A. Miller ◽  
R. J. Jagacinski ◽  
R. B. Nalavade ◽  
W. W. Johnson
Keyword(s):  
Closed Loop ◽  
Position Control ◽  
Open Loop ◽  
General Strategy ◽  
Velocity Control ◽  
Additional Time ◽  
First Order ◽  
Oscilloscope Screen ◽  
Activity Sequence ◽  
Event Based

Subjects manipulated a position control stick with one hand and a velocity control stick with the other hand in order to capture a moving target displayed on an oscilloscope screen. The two control sticks were additively coupled. In order to understand the coordination of the two control sticks, event-based first-order markov “activity sequence generators” were constructed for individual subjects. These discrete probabilistic structures are closely related to each subject's overall plan or general strategy for the capture task. Striking individual differences and strategic errors in performance were revealed. When combined with additional time-conditioned (open-loop) and error-conditioned (closed-loop) details, the activity sequence generators provide a basis for a hierarchic description of this perceptual-motor skill.

scholarly journals Closed-loop updating of wind turbine models using blade pitch excitation

2021 ◽  
Author(s):  
Bo Marcel Schwarz-Wolf ◽  
Martin Dalgaard Ulriksen ◽  
Dawid Augustyn ◽  
Martin Skovmand Jensen ◽  
Ronnie Refstrup Pedersen
Keyword(s):  
Wind Turbine ◽  
Output Feedback ◽  
Closed Loop ◽  
Model Updating ◽  
Element Model ◽  
Open Loop ◽  
Model Parameters ◽  
Linear Transformations ◽  
Application Study ◽  
Ill Posed

Structural monitoring of wind turbines often involves the use of a numerical model, which must be regularly updated to yield an adequate representation of the governing dynamics. The model updating can be cast as an inverse problem, in which selected model parameters are estimated by minimizing the discrepancy between experimental target poles and model-predicted ones. An issue that may prevail in this setting is that the problem will be ill-posed, because the number of model parameters to be updated exceeds the number of target poles. The noted issue can be remedied by a virtual implementation of output feedback, which allows for computation of multiple closed-loop (CL) eigenstructures through non-linear transformations of the open-loop transfer matrix. The present paper offers an application study, in which virtual output feedback is used for updating numerical wind turbine models based on CL system poles. In particular, we explore the feasibility of employing the excitation stemming from the blade pitch control system as the input in the open-loop input-output realization required in the virtual output feedback. The methodological concept is outlined, and subsequently the applicability of the procedure is tested numerically in the context of simulations with a finite element model of a parked wind turbine. The preliminary findings suggest that procedures for customizing the pitch excitation to yield sufficient system excitation are required for the CL model updating to be feasible.

Analysis and Control of Multi-Mode Axial Flow Compression System Models1

1999 ◽  
Vol 122 (3) ◽  
pp. 393-401 ◽  
Author(s):  
MingQing Xiao ◽  
Tamer Bas¸ar
Keyword(s):  
Closed Loop ◽  
Controller Design ◽  
Axial Flow ◽  
Pressure Rise ◽  
Open Loop ◽  
Rotating Stall ◽  
Flow Compression ◽  
The Right ◽  
And Control ◽  
Multi Mode

The paper studies the behavior of multi-mode systems of the Moore-Greitzer model. Its main result is the existence of a parameterized nonlinear state feedback controller which stabilizes the system to the right of the peak of the compressor characteristic. In this process, a rotating stall envelope surface is discovered, and it is shown that the controller design achieves the tasks of preventing the closed-loop system from entering either rotating stall or surge, and making the closed-loop pressure rise coefficient be able to approach its maximum. Numerical simulations of the open-loop and closed-loop models are presented to illustrate the analysis and the results. [S0022-0434(00)00803-0]

scholarly journals A dual-loop tracking control approach to precise nanopositioning

2018 ◽  
Vol 25 (3) ◽  
pp. 666-674 ◽  
Author(s):  
Mohammed Altaher ◽  
Douglas Russell ◽  
Sumeet S. Aphale
Keyword(s):  
Closed Loop ◽  
Reference Signal ◽  
Open Loop ◽  
Performance Criteria ◽  
Control Technique ◽  
Loop Control ◽  
Control Approach ◽  
First Order ◽  
Integral Controller ◽  
Double Integrator

Nanopositioners are mechanical devices that can accurately move with a resolution in the nanometer scale. Due to their mechanical construction and the piezoelectric actuators popularly employed in nanopositioners, these devices have severe performance limitations due to resonance, hysteresis and creep. A number of techniques to control nanopositioners, both in open-loop and closed-loop, have been reported in the literature. Closed-loop techniques clearly outperform open-loop techniques due to several desirable characteristics, such as robustness, high-bandwidth, absence of the need for tuning and high stability, along with others. The most popular closed-loop control technique reported is one where a damping controller is first employed in an inner loop to damp the mechanical resonance of the nanopositioner, thereby increasing achievable bandwidth. Consequently, a tracking controller, typically an Integral controller or a proportional–integral controller, is implemented in the outer loop to enforce tracking of the reference signal, thereby reducing the positioning errors due to hysteresis and creep dynamics of the employed actuator. The most popular trajectory a nanopositioner is forced to track is a raster scan, which is generated by making one axis of the nanopositioner follow a triangular trajectory and the other follow a slow ramp or staircase. It is quite clear that a triangle wave (a finite velocity, zero acceleration signal) cannot be perfectly tracked by a first-order integrator and a double integrator is necessary to deliver error-free tracking. However, due to the phase profile of the damped closed-loop system, implementing a double integrator is difficult. This paper proposes a method by which to implement two integrators focused on the tracking performance. Criteria for gain selection, stability analysis, error analysis, simulations, and experimental results are provided. These demonstrate a reduction in positioning error by 50%, when compared to the traditional damping plus first-order integral tracking approach.

Self-Sensing Active Magnetic Dampers for Vibration Control

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Angelo Bonfitto ◽  
Xavier De Lépine ◽  
Mario Silvagni ◽  
Andrea Tonoli
Keyword(s):  
Vibration Control ◽  
Closed Loop ◽  
Flexible Structures ◽  
Open Loop ◽  
System Response ◽  
Model Parameters ◽  
Loop Model ◽  
Single Degree Of Freedom ◽  
Luenberger Observer ◽  
Model Response

The aim of this paper is to investigate the potential of a self-sensing strategy in the case of an electromagnetic damper for the vibration control of flexible structures and rotors. The study has been performed in the case of a single degree of freedom mechanical oscillator actuated by a couple of electromagnets. The self-sensing system is based on a Luenberger observer. Two sets of parameters have been used: nominal ones (based on simplifications on the actuator model) and identified ones. In the latter case, the parameters of the electromechanical model used in the observer are identified starting from the open-loop system response. The observed states are used to close a state-feedback loop with the objective of increasing the damping of the system. The results show that the damping performance are good in both cases, although much better in the second one. Furthermore, the good correlation between the closed-loop model response and the experimental results validates the modeling, the identification procedure, the control design, and its implementation. The paper concludes on a sensitivity analysis, in which the influence of the model parameters on the closed-loop response is shown.

Aircraft Engine Committee Best 1993 Paper Award: Control-Oriented High-Frequency Turbomachinery Modeling: General One-Dimensional Model Development

1995 ◽  
Vol 117 (3) ◽  
pp. 320-335 ◽  
Author(s):  
O. O. Badmus ◽  
K. M. Eveker ◽  
C. N. Nett
Keyword(s):  
High Frequency ◽  
Linear Models ◽  
Nonlinear Models ◽  
Model Development ◽  
Rotating Stall ◽  
Combustion Heat ◽  
Compression System ◽  
One Dimensional ◽  
System Models ◽  
Turbojet Engine

In this paper, an approach for control-oriented high-frequency turbomachinery modeling previously developed by the authors is applied to develop one-dimensional unsteady compressible viscous flow models for a generic turbojet engine and a generic compression system. We begin by developing models for various components commonly found in turbomachinery systems. These components include: ducting without combustion, blading, ducting with combustion, heat soak, blading with heat soak, inlet, nozzle, abrupt area change with incurred total pressure losses, flow splitting, bleed, mixing, and the spool. Once the component models have been developed, they are combined to form system models for a generic turbojet engine and a generic compression system. These models are developed so that they can be easily modified and used with appropriate maps to form a model for a specific rig. It is shown that these system models are explicit (i.e., can be solved with any standard ODE solver without iteration) due to the approach used in their development. Furthermore, since the nonlinear models are explicit, explicit analytical linear models can be derived from the nonlinear models. The procedure for developing these analytical linear models is discussed. An interesting feature of the models developed here is the use of effective lengths within the models, as functions of axial Mach number and nondimensional rotational speed, for rotating components. These effective lengths account for the helical path of the flow as it moves through a rotating component. Use of these effective lengths in the unsteady conservation equations introduces a nonlinear dynamic lag consistent with experimentally observed compressor lag and replaces less accurate linear first-order empirical lags proposed to account for this phenomenon. Models of the type developed here are expected to prove useful in the design and simulation of (integrated) surge control and rotating stall avoidance schemes.

Energy saving in batch distillation for separation of ternary zeotropic mixture integrated with vapor recompression scheme: dynamics and control

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Gandu Radhika ◽  
Akash Kumar Burolia ◽  
Pandiyan Kuppusamy Raghu Raja ◽  
Seshagiri Rao Ambati ◽  
Dipesh S. Patle ◽  
...  
Keyword(s):  
Closed Loop ◽  
Energy Savings ◽  
Open Loop ◽  
Single Stage ◽  
Large Temperature ◽  
Thermodynamic Efficiency ◽  
Batch Distillation ◽  
Proportional Integral ◽  
Zeotropic Mixture ◽  
Vapor Recompression

Abstract In this work, tight composition control and in parallel the operation is integrated with vapor recompression scheme (VRC) is proposed to achieve energy savings and maximum product at a specified high purity for the separation of ternary zeotropic mixture in batch distillation. Firstly, the model representing a ternary system of hexanol/octanol/decanol has been simulated to analyze the open-loop and close-loop dynamics of the process. Secondly, the open-loop and closed-loop operations are integrated with single stage VRC scheme to achieve energy savings. Single stage VRC is operated at very high compression ratio (CR) due to the large temperature difference of the top and bottom streams in batch distillation column. To further improve the thermodynamic efficiency of single stage VRC, double stage compression without intercoolers between the stages of VRC is proposed. Two control schemes have been implemented for constant composition, namely proportional integral (PI) controller and nonlinear gain scheduling proportional integral (GSPI) with and without VRC in closed-loop. The results shows that double stage VRC with GSPI algorithm provides better performance than conventional in terms of energy, product amount and Integral Square Error (ISE).

scholarly journals Hamilton’s rule, gradual evolution, and the optimal (feedback) control of phenotypically plastic traits

2020 ◽  
Author(s):  
Piret Avila ◽  
Tadeas Priklopil ◽  
Laurent Lehmann
Keyword(s):  
Closed Loop ◽  
Expression Profiles ◽  
Open Loop ◽  
Order Conditions ◽  
Optimal Feedback Control ◽  
State Variables ◽  
First Order ◽  
Hamilton’S Rule ◽  
Gradual Evolution ◽  
Hamilton's Rule

AbstractMost traits expressed by organisms, such as gene expression profiles, developmental trajectories, behavioural sequences and reaction norms are function-valued traits (colloquially “phenotypically plastic traits”), since they vary across an individual’s age and in response to various internal and/or external factors (state variables). Furthermore, most organisms live in populations subject to limited genetic mixing and are thus likely to interact with their relatives. We here formalise selection on genetically determined function-valued traits of individuals interacting in a group-structured population, by deriving the marginal version of Hamilton’s rule for function-valued traits. This rule simultaneously gives a condition for the invasion of an initially rare mutant function-valued trait and its ultimate fixation in the population (invasion thus implies substitution). Hamilton’s rule thus underlies the gradual evolution of function-valued traits and gives rise to necessary first-order conditions for their uninvadability (evolutionary stability). We develop a novel analysis using optimal control theory and differential game theory, to simultaneously characterise and compare the first-order conditions of (i) open-loop traits - functions of time (or age) only, and (ii) closed-loop (state-feedback) traits - functions of both time and state variables. We show that closed-loop traits can be represented as the simpler open-loop traits when individuals do no interact or when they interact with clonal relatives. Our analysis delineates the role of state-dependence and interdependence between individuals for trait evolution, which has implications to both life-history theory and social evolution.

Remarks on the Modelling of Active Structures With Colocated Piezoelectric Actuators and Sensors

1995 ◽  
Author(s):  
N. Loix ◽  
A. Preumont
Keyword(s):  
High Frequency ◽  
Closed Loop ◽  
Transfer Functions ◽  
Open Loop ◽  
Loop System ◽  
Closed Loop System ◽  
Local Effects ◽  
Open Loop System ◽  
Active Structures ◽  
Modelling Techniques

Abstract This paper aims to attract the attention of the designers of active structures on the importance of evaluating properly the feedthrough component of the open-loop transfer functions. It is shown that overlooking the feedthrough component can change significantly the location of the zeros of the open-loop system and, as a result, alter drastically the performance of the closed-loop system. The feedthrough term may result from the quasi-static contribution of the high frequency modes or from local effects that are neglected by over-simplified modelling techniques (e.g. plate or beam instead of shell). The problem is illustrated with a cantilever beam provided with strain actuators.

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