الفهرس 
• INTRODUCTION AND AIM OF THE WORKOnly 14 pages are availabe for public view
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Abstract
The Actively-controlled Constrained Layer Damping treatment ACLD for flexible anns has been presented In this thesis. The proposed ACLD consists of a conventional Passive Constrained Layer Damping augmented with effective control means to control the strain of the constrained layer, in response to the vibration of the ann. The three-layer composite ACLD when bonded to the vibrating surface acts as a SMART constrained layer damping treatment with built-in sensing and actuation capabilities. Proportional and derivative contfollers are used separately to control the rigid and flexible body motion of the ann.
A finite element model is developed based on the Euler-Bernoulli beam theory to study the dynamic characteristics and control of the flexible ann. The model accounted for the behavior of the distributed piezoelectric sensor and actuator. The developed beam element has two nodes with four degrees of freedom per node to describe the longitudinal and the transverse displacements. The combined mass, stiffness and gyroscopic matrices obtained are utilized to compute the natural frequency of the ann. The Runge-Kutta fourth order method is utilized to simulate the response of the system under different control inputs using the state space representation of the system.
The effect of adding a tip mass to the ann on the vibration damping capability of the controller and on the dynamic response of the tip position ill general is studied theoretically as an indication of the robustness of the controller to parameter variations. It is found that the ACLD controller is robust to the parameter variation due to the loading conditions.
The theoretical predictions of the finite element model were compared with the experimental measurements of the ACLD for the arm at a proportional gain of 425 and at different command step angular positions. Good agreement is realized between the simulated tip position response and the experimental step response of the arm.
The effectiveness of the ACLD treatment in damping the vibration of the flexible arm is theoretically and experimentally demonstrated at different excitation conditions. Good attenuation characteristics are obtained with a simple analog amplifier. Without complex digital signal processmg. The results obtained emphasize the merits of the SMART Actively-controlled Constrained Layer Damping and suggest its suitability for nwnerous other applications. Further improvements of the characteristics of the ACLD treatment can be obtained by augmenting the control law with a derivative component in order to enhance its capabilities at high frequencies.
The use of a rigid body PD-controller to damp-out the vibration of the flexible ann shows that, it is better to have fast motions but smaller maneuvering angles for the arm to maintain lower amplitude of vibration. The experimental results obtained with the ACLD controller show that, wider maneuvering angles can be achieved, therefore the use of both controllers altogether is strongly recommended to obtain faster motions and wider maneuvering angles.
The development of analytical tools and modeling teclmiques which provide more accurate and complete representation of the system should be emphasized in future research. In particular, it is necessary to implement various finite element techniques and experimental procedures to extend the work to thick arms with shear effects. For example, the finite element model which is based on the Euler-Bernoulli beam theory in this thesis needs to be replaced by the Timoshenko’s deformation theory to better describe the deformation of the thick arms.
The motor dynamics of the arm should be included in the mathematical model in the future to better describe the dynamics of the model.
Multi-layers laminated composite arms should be considered to demonstrate the feasibility and merits of the ACLD concept. Also, the selection of the optimal control gains, robust control strategies and shaping of the piezoelectric sensor/actuator pairs should be studied to accommodate the tIDcertainties of the of the ACLD parameters and reject the effects of the noise and external disturbances in future design research.
The application of the ACLD controller to multi-link flexible manipulators should be considered, which requires the development of a mathematical model to describe the dynamics of the system and experimental verification of the model.