Piezo-based flexural vibration suppression for an annular rotor via rotating-frame H2 control optimization

2021 ◽  
pp. 1045389X2110235
Author(s):  
Ziv Brand ◽  
Matthew OT Cole
Keyword(s):  
Optimal Control ◽  
Vibration Suppression ◽  
Flexural Vibration ◽  
Elastic Vibration ◽  
Rotating Frame ◽  
H2 Control ◽  
Forcing Function ◽  
Optimal Controllers ◽  
Thin Walled ◽  
Cylindrical Steel

Elastic vibration can arise in annular and thin-walled rotor structures, impacting on operating performance and the risk of failure. Feedback control to reduce flexural vibration can be realized using lightweight actuators and sensors embedded in the rotor structure. To design optimal controllers, rotating-frame models of both the structural dynamics and sources of excitation are required. This paper describes a solution to this problem for the case of an annular rotor equipped with piezo patch actuators and sensors. To account for space-fixed external excitation sources, a forcing function is considered involving specified spatial and frequency domain distributions. A model-based [Formula: see text] synthesis is used to compute optimal control solutions. These are tested experimentally on a thin-walled cylindrical steel rotor for cases with narrowband and broadband excitation sources, applied from the fixed frame. The results show that frequency-splitting within the rotating-frame dynamics plays a key role in predicting and controlling resonance. The effectiveness of the optimal control methodology in reducing circumferential vibration of the annular rotor is also confirmed.

scholarly journals Strain Sensing With Piezoelectric Zinc Oxide Thin Films for Vibration Suppression in Hard Disk Drives

2008 ◽  
Author(s):  
Sarah Felix ◽  
Stanley Kon ◽  
Jianbin Nie ◽  
Roberto Horowitz
Keyword(s):  
Vibration Suppression ◽  
Transfer Functions ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Strain Sensing ◽  
Linear Quadratic ◽  
H2 Control ◽  
Hard Drives ◽  
Optimization Methodology

This paper describes the integration of thin film ZnO strain sensors onto hard disk drive suspensions for improved vibration suppression for tracking control. Sensor location was designed using an efficient optimization methodology based on linear quadratic gaussian (LQG) control. Sensors were fabricated directly onto steel wafers that were subsequently made into instrumented suspensions. Prototype instrumented suspensions were installed into commercial hard drives and tested. For the first time, a sensing signal was successfully obtained while the suspension was flying on a disk as in normal drive operation. Preliminary models were identified from experimental transfer functions. Nominal H2 control simulations demonstrated improved vibration suppression as a result of both the better resolution and higher sensing rate provided by the sensors.

Buckling of Thin-Walled Long Steel Cylinders Subjected to Bending

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Sotiria Houliara ◽  
Spyros A. Karamanos
Keyword(s):  
Structural Response ◽  
Cylinder Wall ◽  
Imperfection Sensitivity ◽  
Bifurcation Instability ◽  
Buckling Mode ◽  
Cross Sectional ◽  
Moment Capacity ◽  
Thin Walled ◽  
Cylindrical Steel ◽  
Element Technique

The present paper investigates structural response and buckling of long unstiffened thin-walled cylindrical steel shells, subjected to bending moments, with particular emphasis on stability design. The cylinder response is characterized by cross-sectional ovalization, followed by buckling (bifurcation instability), which occurs on the compression side of the cylinder wall. Using a nonlinear finite element technique, the bifurcation moment is calculated, the post-buckling response is determined, and the imperfection sensitivity with respect to the governing buckling mode is examined. The results show that the buckling moment capacity is affected by cross-sectional ovalization. It is also shown that buckling of bent elastic long cylinders can be described quite accurately through a simple analytical model that considers the ovalized prebuckling configuration and results in very useful closed-form expressions. Using this analytical solution, the incorporation of the ovalization effects in the design of thin-walled cylinders under bending is thoroughly examined and discussed, considering the framework of the provisions of the new European Standard EN1993-1-6.

Cluster Analysis and Switching Algorithm of Multi-Objective Optimal Control Design

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Zhi-Chang Qin ◽  
Jian-Qiao Sun
Keyword(s):  
Optimal Control ◽  
Cluster Analysis ◽  
Control Algorithm ◽  
Control Design ◽  
Optimal Designs ◽  
Pareto Optimal ◽  
Pareto Optimal Solutions ◽  
Multi Objective ◽  
Switching Algorithm ◽  
Optimal Controllers

The multi-objective optimal control design usually generates hundreds or thousands of Pareto optimal solutions. How to assist a user to select an appropriate controller to implement is a postprocessing issue. In this paper, we develop a method of cluster analysis of the Pareto optimal designs to discover the similarity of the optimal controllers. After we identify the clusters of optimal controllers, we develop a switching strategy to select controls from different clusters to improve the performance. Numerical and experimental results show that the switching control algorithm is quite promising.

scholarly journals Comparison of Optimal Control Designs for a 5 MW Wind Turbine

2021 ◽  
Vol 11 (18) ◽  
pp. 8774
Author(s):  
Yiza-srikanth Reddy ◽  
Sung-ho Hur
Keyword(s):  
Optimal Control ◽  
Wind Turbine ◽  
Control Design ◽  
Drive Train ◽  
Linear Quadratic ◽  
Design Models ◽  
Wind Speeds ◽  
Operating Modes ◽  
Optimal Controllers ◽  
The Time Domain

Optimal controllers, namely Model Predictive Control (MPC), H∞ Control (H∞), and Linear Quadratic Gaussian control (LQG), are designed for a 5 MW horizontal-axis variable-speed wind turbine. The control design models required as part of the optimal control design are obtained by using a high fidelity aeroelastic model (i.e., DNV Bladed). The optimal controllers are eventually designed in three operating modes: below-rated, just below-rated, and above rated-wind speeds, based on linearized control design models. The linearized models are reduced by using a model reduction technique to facilitate the design of optimal controllers. The controllers are analyzed not only in the time domain but also in the frequency domain and on the torque/speed plane. Simulation results demonstrated that optimal controllers perform better than the standard proportional-integral-derivative (PID) controller, particularly for removing oscillation due to the drive-train mode without incorporating a drive-train damper.

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