Spatial Vibration Control of Thin Beams Using Multimode Modified Positive Position Feedback

2014 ◽  
Author(s):  
Ehsan Omidi ◽  
S. Nima Mahmoodi
Keyword(s):  
Vibration Suppression ◽  
Experimental Results ◽  
Controlled System ◽  
Norm Minimization ◽  
Positive Position Feedback ◽  
Resonant Modes ◽  
Vibration Attenuation ◽  
Position Feedback ◽  
High Level ◽  
Thin Beams

Spatial multimode resonant vibration suppression using Modified Positive Position Feedback (MPPF) approach is presented in this paper. Spatial implementation of the MPPF controller considers vibration attenuation in the whole structure, rather than on a limited number of local control points. This approach utilizes spatial norm minimization of H2 and H∞, which considers vibration amplitude of all points on the structure in a model-based design. The designed controller is then evaluated using a clamped-clamped (c-c) and a cantilever beam as the test platforms. According to the numerical simulations and experimental results, spatial MPPF controller using both norm minimization techniques provides a high level of vibration suppression all over the structure, and for all active resonant modes. The MPPF-H∞ controlled system has a smoother response in the frequency domain, which is more preferable when the closed-loop system experiences a frequency sweep disturbance. At exact resonant frequency however, experimental results confirm a better suppression performance using the spatial MPPF-H2 method on different points of both beam structures.

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

2002 ◽  
Author(s):  
H. Gu ◽  
G. Song
Keyword(s):  
Vibration Control ◽  
Least Squares ◽  
Fuzzy System ◽  
Vibration Suppression ◽  
Active Vibration Control ◽  
Flexible Structures ◽  
Training Data ◽  
Sensors And Actuators ◽  
Positive Position Feedback ◽  
Position Feedback

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.

Active Vibration Control of Resonant Systems via Multivariable Modified Positive Position Feedback

2013 ◽  
Author(s):  
Ehsan Omidi ◽  
S. Nima Mahmoodi
Keyword(s):  
Vibration Control ◽  
Vibration Suppression ◽  
Active Vibration Control ◽  
Optimization Method ◽  
Resonant Structures ◽  
Distributed Structure ◽  
Positive Position Feedback ◽  
Lqr Problem ◽  
Position Feedback ◽  
Resonant Systems

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.

Multiple Mode Spatial Vibration Reduction in Flexible Beams Using H2- and H∞-Modified Positive Position Feedback

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Ehsan Omidi ◽  
S. Nima Mahmoodi
Keyword(s):  
Cantilever Beam ◽  
Vibration Amplitude ◽  
Vibration Suppression ◽  
Controller Design ◽  
Flexible Structures ◽  
Laser Vibrometer ◽  
Beam Vibration ◽  
Spatial Vibration ◽  
Positive Position Feedback ◽  
Position Feedback

This paper develops H2 modified positive position feedback (H2-MPPF) and H∞-MPPF controllers for spatial vibration suppression of flexible structures in multimode condition. Resonant vibrations in a clamped–clamped (c–c) and a cantilever beam are aimed to be spatially suppressed using minimum number of piezoelectric patches. These two types of beams are selected since they are more frequently used in macro- and microscale structures. The shape functions of the beams are extracted using the assumed-modes approach. Then, they are implemented in the controller design via spatial H2 and H∞ norms. The controllers are then evaluated experimentally. Vibrations of multiple points on the beams are concurrently measured using a laser vibrometer. According to the results of the c–c beam, vibration amplitude is reduced to less than half for the entire beam using both H2- and H∞-MPPF controllers. For the cantilever beam, vibration amplitude is suppressed to a higher level using the H2-MPPF controller compared to the H∞-MPPF method. Results show that the designed controllers can effectively use one piezoelectric actuator to efficiently perform spatial vibration control on the entire length of the beams with different boundary conditions.

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