Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 13 of 13 for “"positive position feedback"”.
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An experimental investigation into active damage control systems using positive position feedback for AVC
This work discusses the use of Positive Position Feedback (PPF) for Active Vibration Control as part of an Active Damage Control System (ADCS). Vibration control increases the fatigue life of a structure and decreases the in-plane stresses that can cause delamination in a composite. PPF is a …
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Dynamics and Control of Smart Structures for Space Applications
… vibration control, and a piezoelectric nanopositioner for control of instrumentation. Shape memory alloys are used to control the surface flatness of a prototype membrane structure. As these actuators exhibit a hysteretic nonlinearity, they need their own controller to operate as required. …
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Dynamics and Control of a Pressurized Optical Membranes
… control of the membrane is implemented using a positive position feedback approach. The theory is also extended to positive velocity and positive acceleration feedback. Three experiments are carried out to validate the models previously mentioned. Successful implementation of a control …
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Optimal Vibration Suppression Using On-line Pole/Zero Identification
… transfer function to design the optimum Positive Position Feedback (PPF) control law. The PPF control law uses second-order filters to add closed-loop damping to resonant structural modes. An on-line PPF design algorithm was developed based on the theoretical model of the collocated …
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Adaptive Collocated Feedback for Noise Absorption in Acoustic Enclosures
This thesis focuses on adaptive feedback control for low frequency acoustic energy absorption in acoustic enclosures. The specific application chosen for this work is the reduction of high interior sound pressure levels (SPL) experienced during launch within launch vehicle payload fairings. Two …
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Performance of Nonlinear Mechanical, Resonant-Shunted Piezoelectric, and Electronic Vibration Absorbers for Multi-Degree-of-Freedom Structures
… electronic vibration absorber (also denoted a positive position feedback controller). A single, consistent, physically similar model capable of examining the response of all three devices is developed. The performance of vibration absorbers attached to single-degree-of-freedom structures is …
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Structural Identification and Buffet Alleviation of Twin-Tailed Fighter Aircraft
… a nonlinear control law based on cubic velocity feedback to suppress the response of the model to a principal parametric excitation. The performance of the control law is studied by comparing the open- and closed-loop responses of the system. Furthermore, we conduct experiments to verify the …
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Vibration Suppression Using Smart Materials in the Presence of Temperature Changes
… controller. The active controller utilizes three positive position feedback (PPF) filters implemented through a digital signal processor board. This research develops two different adaptation methods to perform vibration suppression in the presence of thermally induced frequency changes of the …
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Decentralized control of sound radiation from periodically stiffened panels
… control strategies such as direct velocity feedback and positive position feedback. Increasing the structural damping can supplement the performance of the model-based control strategy and reduce the destabilizing interaction between neighboring control units. Instead of using low-authority …
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Active, Regenerative Control of Civil Structures
… linear control system design, which is based on positive position feedback concepts, is developed. The dependency of the required energy capacity on hybrid realizations of the control law are discussed, and hybrid designs are found which minimize this quantity for specific disturbance …
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A Comprehensive Experimental Evaluation of Actively Controlled Piezoceramics with Positive Posistion Feedback for Structural Damping
… of actively controlled piezoceramics with positive position feedback (PPF) for reducing structural vibrations. A comparison is made between active control with PPF and a parallel resistor-inductor (RLC) shunt technique. The primary objectives of this study are to: 1. Explore the feasibility …
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Modal and Impedance Modeling of a Conical Bore for Control Applications
… presented in this thesis focuses on the use of feedback control for lowering acoustic levels within launch vehicle payload fairings. Due to the predominance of conical geometries within payload fairings, our work focused on the analytical modeling of conical shrouds using modal and impedance …
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Macro-Fiber Composites for Sensing, Actuation and Power Generation
… satellite component. The control system used a positive position feedback (PPF) controller and two pairs of sensors and actuators in order to provide global vibration suppression of an inflated torus. The experiments found that the MFC and control system was very effective at attenuating the …