Modal Analysis and Active Vibration Control of a Cable-Net Reflector

2016 ◽  
Vol 829 ◽  
pp. 137-143 ◽  
Author(s):  
Yong Sheng Wu ◽  
Wei Zhong Zhang ◽  
Xiu Yun Meng

A cable-net reflector is fist introduced and then the state space representation is derived based on the finite element model. Modal analysis is carried out for the purpose of vibration control in modal space. The first several natural frequencies and vibration modes are obtained to analyze the vibration characteristics. The optimal control theory based on LQR with full state feedback is used for the control problem. Numerical simulations of the impulse disturbance response and the frequency response are implemented. Also, the contrast between the uncontrolled and controlled cases is illustrated. The theoretical results confirm the effectiveness of the proposed active control strategy for the vibration suppress of the cable-net reflector.

Author(s):  
Ehsan Omidi ◽  
Nima Mahmoodi

Vibration control in smart structures is discussed in this paper using an approach based on connecting collocated control elements to one another via a network with certain topology. Consensus method is implemented to force disagreements between the control agents of the structure to zero, where each control agent consists of a multi-mode Positive Position Feedback (PPF) second-order compensator. Multi-agent state-space representation of actuator/sensor elements is used, accompanied with an optimal state-estimator. The consensus law is embedded in the dynamics of the PPF control elements. Required conditions for stability of the closed-loop multi-agent system are then extracted. Performance of the controller is numerically investigated, and synchronization of controller agents is examined. Significant advantage of the decentralized consensus-based vibration controller over centralized forms is in robustness to failure of components or an entire agent, and obtained synchronized performance of the whole control system.


2014 ◽  
Vol 598 ◽  
pp. 529-533
Author(s):  
Erdi Gülbahçe ◽  
Mehmet Çelik ◽  
Mustafa Tinkir

The main purpose of this study is to prepare mathematical model for active vibration control of a structure. This paper presents the numerical and experimental modal analysis of aluminum cantilever beam in order to investigate the dynamic characteristics of the structure. The results will be used for active vibration control of structure’s experimental setup. Experimental natural frequencies are obtained and compared to verify the proposed numerical model by using modal analysis results. MATLAB System Identification Toolbox and ANSYS harmonic response function are used together to estimate beam’s equations of motion which include its amplitude, frequency and phase angle values. Moreover, the mathematical model of beam is simulated in MATLAB/Simulink software to determine the dynamic behavior of the proposed system. Furthermore, another prediction model approach with multiple input and single output is used to find the realistic behavior of beam via an adaptive neural-network-based fuzzy logic inference system, in addition, impulse responses of the proposed models are compared and the control block diagram for active vibration control is implemented. As a first iteration, PID type controller is designed to suppress vibrations against the disturbance input. The results of modal analysis, the prediction models, controlled and uncontrolled system responses are presented in graphics and tables for obtaining a sample numerical active vibration control.


2009 ◽  
Vol 419-420 ◽  
pp. 173-176
Author(s):  
Wei Yuan Wang ◽  
Kai Xue ◽  
Dong Yan Shi

The purpose of this paper is to investigate the optimal placement of piezoelectric actuator for active vibration control of smart structure. The structures can be described in the modal space based on the independent modal space control method and dynamic equations derived from finite element model. The modal damping ratios are derived from modal equations and an optimal target is given by maximizing the modal damping ratios. Accumulation method is adopted to the optimization calculation. Simulations are carried out for active vibration control of a conical shell with distributed piezoelectric actuators. Control effects proved the validity of the optimal method above by compared with the non-optimal results. The optimal method in this paper gives a useful guide for quantity optimization of actuators to piezoelectric structures.


2013 ◽  
Vol 196 ◽  
pp. 62-73 ◽  
Author(s):  
Piotr Kohut

In the paper an application of vision methods and algorithms in various domains that contribute to mechatronics is presented. Regarding mechatronics devices and machines as robots, a vision system employed for a testing station simulating an industrial assembly line is discussed. Some numerical aspects concerning image pre-processing, analysis and geometrical transformations commonly used in robotics were introduced. To accomplish an effective investigation, the developed methodology and algorithms were implemented and verified on an experimental setup composed of two industrial robots and automation devices cooperating with two various vision systems. In the case of underwater robots for tank inspection, image pre-processing and analysis algorithms for the robot's position estimation, an image scale calculation and wall crack detection were investigated. An active vibration control system is treated as a mechatronic device which contains mechanical parts, electronics and software. In this example, a visual servoing architecture based on image features for controlling an active vibration control system was examined. For an effective investigation and synthesis of visual servoing algorithms, a MATLAB/Simulink/dSPACE hardware–software environment was employed. A vision system was used to analyze vibration amplitude of the vibro-isolation mass of the active suspension system and to provide a feedback control signal. The connection of 3D vision techniques with modal analysis was shown. Within the confines of the project a methodology for amplitude of vibration measurement and a software tool for modal analysis realization based on visual data were developed. The 3D measurements and structure of the construction were obtained by application and development of passive 3-D vision techniques. From this area, ‘structure from motion’ techniques were developed. In the experimental research, a mechatronic test stand was designed and manufactured enabling automatic two-axis control of a camera. A frame structure was built, in which a guiding-rail system was mounted enabling straight-line motion of a camera. Additionally, a system realizing rotational motion of a camera was built in. To control the experiment stand, software was created enabling the combination of the hardware-software part of the stand with the software part of a vision system. A tool was developed for the purpose of modal analysis and estimation of the quantities characterizing dynamic properties of the structure based on vision signals. As a conclusion, the presented, implemented and tested vision methods in various hardware-software programming platforms are discussed


2020 ◽  
Vol 14 (3) ◽  
pp. 166-174
Author(s):  
Mostefa Salah ◽  
Farouk B. Boukhoulda ◽  
Mohamed Nouari ◽  
Kouider Bendine

Abstract Due to their impressive capacity of sensing and actuating, piezoelectric materials have been widely merged in different industrial fields, especially aeronautic and aerospace area. However, in the aeronautic industry, the structures are operating under critical environmental loads such as high and very low temperature, which made the investigation of the effect of thermal forces on the piezoelectric structures indispensable to reach the high functionality and performance. The present paper focuses on the effect of thermal loads on the active vibration control (AVC) of structures like beams. For this purpose, a finite element model of composite beam with fully covered piezoelectric sensor and actuator based on the well-known high order shear deformation theory is proposed by taking into account the electrical potential field and a linear temperature field. Hamilton’s principle is used to formulate the electro-thermo-mechanical governing equations. The negative velocity feedback controller is implemented to provide the necessary gain for the actuator. Different analyses are effectuated to present the effect of the temperature ranging from -70°C to 70°C on the active vibration control of the composite beam.


Author(s):  
Punan Tang ◽  
A. B. Palazzolo ◽  
Gerald Brown ◽  
Eliseo DiRusso ◽  
Albert Kascak

A reliable electromechanical simulation model is essential for designing rotor systems supported by magnetic bearings. Accurate predictions of forced response, critical speeds and stability are required to assure machinery health and reliability. This paper presents a general methodology which couples a finite element based model of the rotor with state space models of the sensors, control system and actuators. A least squares based algorithm is presented for obtaining the state space representation of the digital (DSP) controller, actuator, and power amplifiers from their measured frequency response functions. This general simulation method is illustrated by application to a cryogenic magnetic bearing test rig at NASA Lewis.


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