Xiaojin Zhu

An Orthogonal Curvature Fiber Bragg Grating Sensor Array for Shape Reconstruction

An orthogonal curvature fiber Bragg grating (FBG) sensor array is introduced, and it can detect the deformation and vibration of flexible structures such as rod, keel, etc. The sensor array composed of 20 sensors which were averagely distributed on four optical fibers was mounted on the body of cylindrical shape memory alloy(SMA) substrate with staggered orthogonal arrangement. By the method of calibration, the relation coefficient between curvature and wavelength shift was obtained and the curvature of sensor was calculated accordingly, then, the space shape was reconstructed with the help of the space curve fitting method based on curvature information of discrete points. In this paper, the operation principle, the design, packaging, calibration of FBG sensor array and the method of experiment were expounded in detail. The experiment result shows that the reconstructed spatial shape is lively, thus indicates that the relevant method and technology are feasible and practicable.

Analysis and implementation of MIMO FULMS algorithm for active vibration control

This correspondence focuses on the analysis and implementation of multi-input multi-output (MIMO) filtered-u least mean square (FULMS) algorithm for active vibration suppression of a cantilever smart beam with surface bonded lead zirconate titanate patches. By analysing a single-input single-output FULMS algorithm, the MIMO FULMS controller structure is given. Then an active vibration control experimental platform is established, with optimal placement of the actuators and sensors based on the maximal modal force rule. Simulation contrast analysis of FULMS algorithm and the most famous filtered-x least mean square (FXLMS) algorithm is performed while the reference signal is extracted from the exciter as well as directly from the controlled structure. Simulation results show that if the feedback information reflects the reference signal collected by the reference transducers, the FXLMS controller could hardly suppress the vibration while the FULMS controller is still effective. Then the actual control experiment is performed, and the result confirms the simulation results. The designed MIMO FULMS vibration controller has a good control performance, suppressing the vibration significantly with rapid convergence.

Robust H ∞ control in active vibration control of piezoelectric smart structure

This paper mainly analyzes the method of the robust H∞ control and does some experimental researches aiming at the piezoelectric smart flexible structure, under the background of the active vibration control of the aircraft structure. The analysis of the robust control method and the control process are given in this paper. On the basis of these, the structure and the technical parameter of the experiment are described. The structure model of the MIMO system is obtained by the frequency domain identification. According to the frequency domain uncertain and the disturbance, a robust Hinfin controller is designed considering the mixed sensitivity control problem. In order to verify the effectiveness and the feasibility of the control algorithm, a simulation is carried out after identifying the control channel. The result of the simulation shows that the control method and the controller design in this paper is useful.

An improved filter-u least mean square vibration control algorithm for aircraft framework

Active vibration control of aerospace vehicle structures is very a hot spot and in which filter-u least mean square (FULMS) algorithm is one of the key methods. But for practical reasons and technical limitations, vibration reference signal extraction is always a difficult problem for FULMS algorithm. To solve the vibration reference signal extraction problem, an improved FULMS vibration control algorithm is proposed in this paper. Reference signal is constructed based on the controller structure and the data in the algorithm process, using a vibration response residual signal extracted directly from the vibration structure. To test the proposed algorithm, an aircraft frame model is built and an experimental platform is constructed. The simulation and experimental results show that the proposed algorithm is more practical with a good vibration suppression performance.

Fitting and reconstruction of three-dimensional curve based on orthogonal curvature

Taking the active monitoring survey for the configuration of higher performance crafts as the research background and the flexible rod based on the Fiber Bragg Grating Sensor Array as a model for the experiment, a fitting and reconstruction method for three dimensional space curve based on the orthogonal curvature is researched and analyzed in this paper. After giving a sketch of the curvature detection principle of the orthogonal distributed Fiber Bragg Grating as well as analyzing and constructing of the moving coordinate system for the space curve from the view of differential geometry, fitting and reconstruction method for three-dimensional curve is analyzed with detailed algorithm processes and implementation steps, meanwhile, approaches making discrete curvature continuous is presented and analyzed in this paper. With Visual C++ and OpenGL, a visual simulation platform for analyzing and verifying the method and processes of the algorithm is developed. In addition, effects comparison of the graphical reconstruction for the shape of space curves made up by different curvature simulation data is presented on the basis of three types of method making discrete curvature continuous. Simulation results not only verify the efficiency of the reconstruction method and the experimental processes, but also obtain the related beneficial results about discrete curvature continuous methods.

Shape Apperception and Reconstruction of Fiber Grating Intelligent Flexible Structure Based on Orthogonal Curvatures

with emphasis on the process of design and development method for the intelligent flexible structure distributed with orthogonal Fiber Bragg Grating sensor array, a fitting and reconstruction method based on orthogonal curvatures for three-dimensional curve and a method to make discrete curvatures continuous are analyzed with detailed algorithm processes and implementation steps in this paper. On the basis of the experimental calibration analysis with FBG model structures, a real-time apperception and reconstruction platform of intelligent flexible structures for analyzing and verifying the methodology and processes of the algorithm is developed with the technology of Visual C++ and OpenGL. The academic methodology and implementation technique are analyzed experimentally in the visualization platform. It reflects more accurately the real-time changes of intelligent flexible structures by employing an intelligent structure based on FBG as an experiment model. Experimental results prove the feasibility of the model design and the effectiveness of the three-dimensional reconstruction algorithm.

3D Reconstruction and Visualization for Wing Structure of High-Aspect-Ratio Aircraft

The simulation model referred to the paper is wing structure based on high-aspect-ratio near-space aircraft, the multipoint discrete curvature information of wing structure can be detected based on space-division multiplex technique and wavelength division multiplex technique of FBG sense network; In order to apperceive the vibration shape of wing accurately, the interpolation arithmetic of curvature is analyzed; The space- curved-face 3D-reconstruction method and algorithm process are analyzed and researched with the coalesce of moving coordinate system, curvature vector and osculating plane; Combining computers graphics processing technology to develop simulation testing environment, 3D-reconstruction and visualization of vibration shape of simulation wing structure based on high- aspect-ratio near-space aircraft are realized. Simulation results show that the adopted 3D-reconstruction method based on discrete curvature for wing structure and visualization technology can reflect low modal real-time vibration shape of the space-curved-face structure of simulation wing more accurately.