Active control of structures with adaptive modified positive position feedback

2011 ◽  
Author(s):  
S. Nima Mahmoodi ◽  
Mehdi Ahmadian
Keyword(s):  
Active Control ◽  
Positive Position Feedback ◽  
Position Feedback

A Comparative Study of Actively Controlled and Shunted Piezoelectric Materials for Structural Damping

2007 ◽  
Author(s):  
Mehdi Ahmadian
Keyword(s):  
Active Control ◽  
Piezoelectric Materials ◽  
Structural Vibration ◽  
Structural Damping ◽  
Test Plate ◽  
Plate Vibrations ◽  
Positive Position Feedback ◽  
Position Feedback ◽  
Control Authority ◽  
Circuit Technique

A comparison between actively-controlled piezoelectric (PZT) material with positive position feedback (PPF) and a parallel resistor-inductor shunt circuit technique is provided. This study focuses on the performance of each technique at reducing structural vibration on a test plate for both narrowband and broadband frequency reductions. The comparison between the shunted and active PZT damping techniques used in this study shows that active control with positive position feedback was more effective at controlling vibrations of a test plate. The active PZT method was able to add damping to each of the modes targeted in the frequency range of interest. In addition, active control with positive position feedback was able to achieve this level of control authority with a single PZT patch located in the center of the test plate. Conversely, shunted PZTs used three PZT actuators to reduce the test plate vibrations. The results show that actively-controlled PZTs can provide much more damping per square area of PZT than shunted PZTs, by as much as four times more.

Independent Modal Space Control With Positive Position Feedback

1992 ◽  
Vol 114 (1) ◽  
pp. 96-103 ◽  
Author(s):  
A. Baz ◽  
S. Poh ◽  
J. Fedor
Keyword(s):  
Control System ◽  
Active Control ◽  
Complex Structure ◽  
Flexible Structures ◽  
Optimal Time ◽  
Time Sharing ◽  
Positive Position Feedback ◽  
Position Feedback ◽  
Active Control System ◽  
Modal Space

This study presents an Independent Modal Space Control (IMSC) algorithm whose modal control forces are generated based on a Positive Position Feedback (PPF) strategy. This is in contrast to conventional modal controllers that rely in their opeation on negative feedback of the modal position and velocity. The proposed algorithm combines the attractive attributes of both the IMSC and the PPF. It maintains the simplicity of the IMSC as it designs the controller of a complex structure at the uncoupled modal level. At the same time, it utilizes only the modal position signal to provide a damping action to undamped modes. The paper presents the theory behind this algorithm when using first order filters to achieve the PPF effect. The optimal time constants of the filters are determined. The performance of the algorithm is enhanced by augmenting it with a “time sharing” strategy to share a small number of actuators between larger number of modes. The effectiveness of the algorithm in damping out the vibration of flexible structures is validated experimentally. A simple cantilevered beam is used as an example of a flexible structure whose multi-modes of vibration are controlled by a single actuator. A piezo-electric actuator is utilized, in this regard, as a part of a computer-controlled active control system. The performance of the active control system is determined in the time and the frequency domains. The results are compared with those obtained when using the IMSC, PPF with second order filters, the Psuedo-Inverse (PI) and a Modified Independent Modal Space Control (MIMSC). The experimental results suggest the potential of the proposed method as a viable means for controlling the vibration of large flexible structures.

Sign in / Sign up

Export Citation Format

Share Document