A Sensitivity Based Iterative Approach for Tuning Damper Parameters in Combination With the Controller to Increase Closed Loop Performance

2014 ◽  
Author(s):  
C. A. M. Verbaan ◽  
P. C. J. N. Rosielle ◽  
M. Steinbuch
Keyword(s):  
Closed Loop ◽  
Optimization Procedure ◽  
Iterative Approach ◽  
Main Difficulty ◽  
Frequency Range ◽  
Plant Model ◽  
Motion System ◽  
Controller Gain ◽  
Disturbance Suppression ◽  
Stiffness And Damping

In motion systems, high controller gains are beneficial in order to suppress disturbances acting on the system. Low-damped non-rigid body (NRB) resonances usually limit this controller gain. The result is a bound on the maximum achievable sensitivity, i.e. the suppression of low frequent position disturbances. Robust Mass Dampers (RMD’s) with a relatively high damping value have shown to be able to increase the NRB damping over a broad frequency range. The main difficulty is to determine the stiffness and damping parameters for these damper mechanisms in order to optimize the closed loop performance of the motion system. This paper proposes a modulus margin based iterative optimization procedure which includes a plant model with dampers added and a PID+ type controller. The results are optimal damper parameters — stiffness and damping — in combination with an as high as possible controller gain, which result in an improved disturbance suppression at frequencies below the bandwidth and a faster setpoint tracking.

Accommodation of Multi-Shaft Gas Turbine Switching Control Gain Tuning Problem to IGV Position

2021 ◽  
Author(s):  
Yujia Ma ◽  
Liu Jinfu ◽  
Linhai Zhu ◽  
Qi Li ◽  
Huanpeng Liu ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Optimization Procedure ◽  
Switching Control ◽  
Inlet Guide Vane ◽  
Multi Objective ◽  
Control Gain ◽  
Controller Gain ◽  
Compressor Inlet ◽  
Comprehensive Indicator

Abstract This article aims to discuss the influence of compressor Inlet Guide Vane (IGV) position on gas turbine switching control system gain tuning problem. The distinction between IGV and normally reckoned working conditions is differentiated, and an improved double-layer LPV model is proposed to estimate the protected parameters under various IGV positions. Controller gain tuning is conducted with single and multi-objective intellectual optimization algorithms. Simulation results reveal that normally used multi-objective optimization procedure is unnecessary and time-consuming. While with the comprehensive indicator introduced in this paper, the calculation burden can be greatly eased. This improvement is especially advantageous when tuning work is carried out under multiple IGV positions.

An LQ Controller With a Prescribed Pole Region—A Data-Based Design Approach

1997 ◽  
Vol 119 (2) ◽  
pp. 271-277 ◽  
Author(s):  
Jenq-Tzong H. Chan
Keyword(s):  
Closed Loop ◽  
Explicit Knowledge ◽  
Controller Design ◽  
Design Approach ◽  
Output Data ◽  
Plant Model ◽  
Modified Method ◽  
Input And Output ◽  
Z Domain

In this paper, we present a modified method of data-based LQ controller design which is distinct in two major aspects: (1) one may prescribe the z-domain region within which the closed-loop poles of the LQ design are to lie, and (2) controller design is completed using only plant input and output data, and does not require explicit knowledge of a parameterized plant model.

scholarly journals Stability of Optimal Closed-Loop Cleaning Scheduling and Control with Application to Heat Exchanger Networks under Fouling

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1623
Author(s):  
Federico Lozano Santamaria ◽  
Sandro Macchietto
Keyword(s):  
Heat Exchanger ◽  
Closed Loop ◽  
Operating Cost ◽  
Optimization Procedure ◽  
Loop Model ◽  
Loop Scheduling ◽  
Loop Optimization ◽  
Trade Offs ◽  
Heat Exchanger Networks ◽  
And Control

Heat exchanger networks subject to fouling are an important example of dynamic systems where performance deteriorates over time. To mitigate fouling and recover performance, cleanings of the exchangers are scheduled and control actions applied. Because of inaccuracy in the models, as well as uncertainty and variability in the operations, both schedule and controls often have to be revised to improve operations or just to ensure feasibility. A closed-loop nonlinear model predictive control (NMPC) approach had been previously developed to simultaneously optimize the cleaning schedule and the flow distribution for refinery preheat trains under fouling, considering their variability. However, the closed-loop scheduling stability of the scheme has not been analyzed. For practical closed-loop (online) scheduling applications, a balance is usually desired between reactivity (ensuring a rapid response to changes in conditions) and stability (avoiding too many large or frequent schedule changes). In this paper, metrics to quantify closed-loop scheduling stability (e.g., changes in task allocation or starting time) are developed and then included in the online optimization procedure. Three alternative formulations to directly include stability considerations in the closed-loop optimization are proposed and applied to two case studies, an illustrative one and an industrial one based on a refinery preheat train. Results demonstrate the applicability of the stability metrics developed and the ability of the closed-loop optimization to exploit trade-offs between stability and performance. For the heat exchanger networks under fouling considered, it is shown that the approach proposed can improve closed-loop schedule stability without significantly compromising the operating cost. The approach presented offers the blueprint for a more general application to closed-loop, model-based optimization of scheduling and control in other processes.

Closed Loop Resonator Based Compact UWB Antenna with Single Notched Band Varying between WLAN and X-band for UWB Applications

Frequenz ◽  
2020 ◽  
Vol 74 (5-6) ◽  
pp. 201-209
Author(s):  
Mohammad Ahmad Salamin ◽  
Sudipta Das ◽  
Asmaa Zugari
Keyword(s):  
Closed Loop ◽  
Ground Plane ◽  
Frequency Range ◽  
Uwb Antenna ◽  
Notched Band ◽  
X Band ◽  
Compact Size ◽  
Simulation Results ◽  
Uwb Applications ◽  
Good Agreement

AbstractIn this paper, a novel compact UWB antenna with variable notched band characteristics for UWB applications is presented. The designed antenna primarily consists of an adjusted elliptical shaped metallic patch and a partial ground plane. The proposed antenna has a compact size of only 17 × 17 mm2. The suggested antenna covers the frequency range from 3.1 GHz to 12 GHz. A single notched band has been achieved at 7.4 GHz with the aid of integrating a novel closed loop resonator at the back plane of the antenna. This notched band can be utilized to alleviate the interference impact with the downlink X-band applications. Besides, a square slot was cut in the loop in order to obtain a variable notched band. With the absence and the existence of this slot, the notched band can be varied to mitigate interference of the upper WLAN band (5.72–5.82 GHz) and X-band (7.25–7.75 GHz) with UWB applications. A good agreement between measurement and simulation results was achieved, which affirms the appropriateness of this antenna for UWB applications.

The virtual AirDyn: a simulation technique for evaluating the aerodynamic impact of ship superstructures on helicopter operations

2013 ◽  
Vol 117 (1198) ◽  
pp. 1233-1248 ◽  
Author(s):  
C. H. Kääriä ◽  
J. S. Forrest ◽  
I. Owen
Keyword(s):  
Closed Loop ◽  
Simulation Technique ◽  
Cad Model ◽  
Frequency Range ◽  
Dynamics Model ◽  
Fixed Position ◽  
Control Activity ◽  
Unsteady Forces ◽  
The Mean ◽  
Flight Dynamics Model

AbstractThis paper describes a simulation technique that has been developed to quantify the unsteady forces and moments that are imposed onto a maritime helicopter by a ship’s airwake during a deck landing. An unsteady CFD-generated airwake, created using a CAD model of the ship, is integrated with a flight dynamics model of a helicopter. By holding the helicopter at a fixed position in the airwake it is possible to quantify the unsteady forces and moments imposed on the aircraft. The technique is therefore a software-based airwake dynamometer, and has been called the virtual AirDyn. As well as determining the mean loads, from consideration of the unsteady loads in the closed-loop pilot response frequency range of 0·2-2Hz it is also possible to quantify the magnitude of the unsteady disturbance in each axis. The loads are also indicators of the control activity the pilot would have to exert to maintain aircraft position and attitude. By placing the virtual AirDyn at different positions around the landing deck in different wind conditions, it is able to quantify the effect of the airwake on the mean and unsteady loads. The quantified loads can be explained by examining the CFD-generated flow field, and the geometric features on the ship’s superstructure that gave rise to them can be identified. The virtual AirDyn is therefore a tool that can be used to evaluate and inform ship design for maritime helicopter operations.

Robust control for hypersonic vehicles with parametric and unstructured uncertainties

2017 ◽  
Vol 232 (13) ◽  
pp. 2369-2380 ◽  
Author(s):  
Hao Liu ◽  
Deyuan Liu ◽  
Jianxiang Xi ◽  
Yao Yu
Keyword(s):  
Robust Control ◽  
Closed Loop ◽  
Hypersonic Vehicles ◽  
Frequency Range ◽  
Parameter Uncertainties ◽  
Loop Control ◽  
Control Approach ◽  
Closed Loop Control System ◽  
Loop Control System ◽  
Multiple Uncertainties

A robust flight controller is proposed for the longitudinal model of generic hypersonic vehicles, whose dynamics involves nonlinearities, parameter uncertainties, and unstructured uncertainties. The proposed longitudinal controller is developed based on the standard [Formula: see text] theory and the robust compensating approach. The robust compensating approach is introduced to reduce the influences of multiple uncertainties and nonlinearities on the closed-loop control system. Compared to the [Formula: see text] control theory, these influences in the whole frequency range can be restrained. Theoretical analysis and numerical simulation results are presented to illustrate the tracking performance properties of the designed robust control approach.

Recursive Plant Model Identification in Closed Loop

2011 ◽  
pp. 293-327
Author(s):  
Ioan Doré Landau ◽  
Rogelio Lozano ◽  
Mohammed M’Saad ◽  
Alireza Karimi
Keyword(s):  
Closed Loop ◽  
Model Identification ◽  
Plant Model
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