Positive Position Feedback Vibration Control of a Composite I-Beam With Fuzzy Gain Tuning

Author(s):  
H. Gu ◽  
G. Song

Positive position feedback (PPF) control is widely used in active vibration control of flexible structures. To ensure the vibration is quickly suppressed, a large PPF scalar gain is often applied in a PPF controller. However, PPF control with a large scalar gain causes initial overshoot, which is undesirable in many situations. In this paper, a fuzzy gain tuner is proposed to tune the gain in the positive position feedback control to reduce the initial overshoot while still maintaining a quick vibration suppression. The fuzzy system is trained by the desired input-output data sets by batch least squares algorithm so that the trained fuzzy system can behave like the training data. A 3.35 meter long I-beam with piezoceramic patch sensors and actuators is used as the experimental object. The experiments include the standard PPF control, standard PPF control with traditional fuzzy gain tuning, and PPF control with batch least squares fuzzy gain tuning. Experimental results clearly demonstrate that PPF control with batch least squares fuzzy gain tuner behaves much better than the other two in terms of successfully reducing the initial overshoot and quickly suppressing vibration.


2020 ◽  
Vol 26 (21-22) ◽  
pp. 2026-2036
Author(s):  
Xiangdong Liu ◽  
Haikuo Liu ◽  
Changkun Du ◽  
Pingli Lu ◽  
Dongping Jin ◽  
...  

The objective of this work was to suppress the vibration of flexible structures by using a distributed cooperative control scheme with decentralized sensors and actuators. For the application of the distributed cooperative control strategy, we first propose the multiple autonomous substructure models for flexible structures. Each autonomous substructure is equipped with its own sensor, actuator, and controller, and they all have computation and communication capabilities. The primary focus of this investigation was to illustrate the use of a distributed cooperative protocol to enable vibration control. Based on the proposed models, we design two novel active vibration control strategies, both of which are implemented in a distributed manner under a communication network. The distributed controllers can effectively suppress the vibration of flexible structures, and a certain degree of interaction cooperation will improve the performance of the vibration suppression. The stability of flexible systems is analyzed by the Lyapunov theory. Finally, numerical examples of a cantilever beam structure demonstrate the effectiveness of the proposed methods.



Author(s):  
Ehsan Omidi ◽  
S. Nima Mahmoodi

One of the predominant difficulties in the theory of distributed structure control systems comes from the fact that these resonant structures have a large number of active modes in the working band-width. Among the different methods for vibration control, Positive Position Feedback (PPF) is of interest, which uses piezoelectric actuation to overcome the vibration as a collocated controller. Modified Positive Position Feedback (MPPF) is later presented by adding a first-order damping compensator to the conventional second-order compensator, to have a better performance for steady-state and transient disturbances. In this paper, Multivariable Modified Positive Position Feedback (MMPPF) is presented to suppress the unwanted resonant vibrations in the structure. This approach benefits the advantages of MPPF, while it controls larger number vibration modes. An optimization method is introduced, consisting of a cost function that is minimized in the area of the stability of the system. LQR problem is also used to optimize the controller performance by optimized gain selection. It is shown that the LQR-optimized MMPPF controller provides vibration suppression in more efficiently manner.



Author(s):  
Brij N. Agrawal ◽  
Hyochoong Bang

Abstract The application of piezoelectric actuators and sensors in the vibration suppression of flexible structures is demonstrated experimentally. Navy Type II piezoceramic wafers were bonded at the base of a flexible arm to increase damping of its first structural mode at at 0.138 Hz. A Positive Position Feedback (PPF) analog compensator was used for active vibration control. The damping of the first mode was increased from 0.3% to 1.5 % by using the active control.



Author(s):  
S. Nima Mahmoodi ◽  
Mehdi Ahmadian

A novel active vibration control technique based on positive position feedback method is developed. This method, which is a modified version of positive position feedback, employs a first-order compensator that provides damping control and a second-order compensator for vibration suppression. In contrast, conventional positive position feedback uses a single second-order compensator. The technique is useful for strain-based sensors and can be applied to piezoelectrically controlled systems. After introducing the concept of modified positive position feedback, this paper investigates the stability of the new method for locating gain limits. Stability conditions are global and independent of the dynamical characteristics of the open-loop system. Using root locus plots, proper compensator frequency is identified and damping of the closed-loop system is studied. The performance of the modified positive position feedback for both steady-state and transient dynamic control is studied. The experimental and numerical results show that the proposed method is significantly more effective in controlling steady-state response and slightly advantageous for transient dynamics control, as compared with conventional positive position feedback.





Author(s):  
Giovanni Ferrari ◽  
Margherita Capriotti ◽  
Marco Amabili ◽  
Rinaldo Garziera

The active vibration control of a rectangular sandwich plate by Positive Position Feedback is experimentally investigated. The thin walled structure, consisting of carbon-epoxy outer skins and a Nomex paper honeycomb core, has completely free boundary conditions. A detailed linear and nonlinear characterization of the vibrations of the plate was previously performed by our research group [1, 2]. Four couples of unidirectional Macro Fiber Composite (MFC) piezoelectric patches are used as strain sensors and actuators. The positioning of the patches is led by a finite element modal analysis, in the perspective of a modal control strategy aimed at the lowest four natural frequencies of the structure. Numerical and experimental verifications estimate the resulting influence of the control hardware on the modal characteristics of the plate. Experimental values are also extracted for the control authority of the piezoelectric patches in the chosen configuration. Single Input – Single Output (SISO) and MultiSISO Positive Position Feedback algorithms are tested and the transfer function parameters of the controller are tuned according to the previously known values of modal damping. A totally experimental procedure to determine the participation matrices, necessary for the Multiple-Input and Multiple-Output configuration, is developed. The resulting algorithm proves successful in selectively reducing the vibration amplitude of the first four vibration modes in the case of a broadband disturbance. PPF is therefore used profitably on laminated composite plates in conjunction with strain transducers, for the control of the low frequency range up to 100 Hz. The relevant tuning procedure moreover, proves straightforward, despite the relatively high number of transducers. The rigid body motions which arise in case of free boundary conditions do not affect the operation of the active control.



Author(s):  
Hassan Ali Kadhem ◽  
Ahmed Abdul Hussein

Active vibration control is presented as an effective technique used for vibration suppression and for attenuating bad effects of disturbances on structure. In this work Proportional-Integral-Derivative control were employed to study suppression of active vibration wing affected by wind airflow. Two different composite wings with different manufacturing materials had been made with specific size to be suitable for using in wind tunnel. Piezoelectric (PZT (transducers are used as sensors and actuators in vibration control systems. The velocity was 25 m/s and three different attack angles (0, 10, 20 degrees) had been taken to show their effect on the wings vibrations suppression. The results shows that the suppression of the wing amplitude is reduced when the attack angle increases for both woven and random composite wing matt and this happened due to the vortex which became more violent at the increase of attack angle and also due to the area that face the wind which will increase when the attack angle increase and this will reduces the suppression. The maximum control amplitude of woven Glass-fiber matt was 1.75cm and the damping was about 38 % at zero attack angle while it was 2cm and the damping was about 26 % at 20 degree attack angle for random Glass-fiber composite matt



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