On-line Frequency Estimation and Adaptive Vibration Control of Composite Structures with Delaminations

Designing a controller for multi-body systems including flexible and rigid bodies has always been one of the major engineering challenges. Equations of motion of these systems comprise extremely nonlinear and coupled terms. Vibrations of flexible bodies affect sensors of rigid bodies and might make the system unstable. Introducing a new control strategy for designing control systems which do not require the rigid–flexible coupling model and can dwindle vibrations without sensors or actuators on flexible bodies is the purpose of this paper. In this study, a spacecraft comprising a rigid body and a flexible panel is used as the case study, and its equations of motion are extracted using Lagrange equations in terms of quasi-coordinates. For oscillations on a rigid body to be eliminated, a frequency estimation algorithm and an adaptive filtering are used. A controller is designed based on the rigid model of the system, and then robust stability conditions for the rigid–flexible system are obtained. The conditions are also developed for the spacecraft with more than one active frequency. Finally, the robust adaptive vibration control system is simulated in the presence of resonance. Simulations’ results indicate the advantage of the control method even when several active frequencies simultaneously resonate the dynamics system.

Download Full-text

Robust adaptive vibration control for a string with time-varying output constraint

International Journal of Robust and Nonlinear Control ◽

10.1002/rnc.4300 ◽

2018 ◽

Vol 28 (17) ◽

pp. 5213-5231 ◽

Cited By ~ 1

Author(s):

Wei He ◽

Zhe Jing ◽

Xiuyu He ◽

Jin-Kun Liu ◽

Changyin Sun

Keyword(s):

Vibration Control ◽

Time Varying ◽

Robust Adaptive ◽

Adaptive Vibration Control ◽

Output Constraint

Download Full-text

A Vision-Based Gap Detection Method during the Placement of Large-Scale Composite Structures

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.186.11 ◽

2011 ◽

Vol 186 ◽

pp. 11-15

Author(s):

Li Cao ◽

Wen Chen ◽

Jun Xiao

Keyword(s):

Image Processing ◽

Video Processing ◽

Composite Structures ◽

Large Scale ◽

Low Cost ◽

High Quality ◽

Detection Technology ◽

Gap Measurement ◽

Automatic Placement ◽

On Line

Video processing technology is regarded as a low-cost detection technology in complex environment. Because the placement layer is thin and the surface is complex that causes high detection error and high cost in laser measurement. Two problems must be solved before using it in large-scale composite structures automatic placement. One is to obtain the high-quality and stable image, and the other is to improve efficiency of image processing. In this paper, a method obtaining the high quality placement gap images was studied. It made use of the optical characteristics of composite material’s surface texture. And some parameters were determined by experiments. To reduce the calculation cost of image processing, a placement gap measurement method based on line scanning was also proposed here. The method was effective in our detection experiments on an actual workpiece.

Download Full-text