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26 July 2004 Using a pole-placement switching technique to avoid resonance in systems forced by a swept sinewave disturbance
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Many forced systems are prone to undesirable levels of oscillation if lightly damped modes are present with their frequency range of operation. Rotary systems, for example, can experience these problems during the speed up or speed down stage of operation. Resonant motion can damage or effect the accuracy of operation of such systems and is, therefore, highly undesirable. Many closed-loop controllers avoid this by suppressing the mode itself such that at resonance the modal vibration amplitude is small (i.e. highly damped). The current work presents an alternative novel switching controller, which suppresses the system not by applying a high amount of damping but rather by moving the resonant mode such that it is never excited. From the basis of an accurate plant model, two pole-placement controllers are designed and implemented both in simulation and experiment on a cantilever smart structure. These controllers are shown to successfully change the natural frequency value, while retaining the same damping ratio value. A novel switching system is employed that calculates the optimal switching position by running a simulation of the desired systems in parallel to the controlled open-loop system. Moreover, the system minimises transients occurred by switching back and forth between controllers, thus increasing the efficiency of the system. By comparing the experimental results to a conventional high damping pole-placement controller that applies a similar amount of control effort, a lower overall level of amplitude suppression can be seen.
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Robin G. Scott, Andrew P. H. Weightman, and Martin C. Levesley "Using a pole-placement switching technique to avoid resonance in systems forced by a swept sinewave disturbance", Proc. SPIE 5390, Smart Structures and Materials 2004: Smart Structures and Integrated Systems, (26 July 2004);

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