Rotorcraft Smoothing via Linear Time Periodic Methods

<p>Helicopter flight relying on rotary motion of a complex mechanical system is predisposed to vibration. While the helicopter has many sources of vibrations the main rotor system generates by far the largest magnitude vibrations and can render the vehicle inoperable if left unaddressed. Thus proper maintenance to reduce vibrations is essential to the safe operation of any helicopter. This maintenance however is costly and time consuming. Improving the maintenance procedure for balancing the main rotor system has been an area of active interest since the inception of the helicopter. However the state of the art in rotor balancing still requires several iterations of rotor adjustments each necessitating a separate test flight and then time consuming maintenance to reduce the vibrational level to an acceptable amount. This research provides the basis for an improved rotor vibrational reduction methodology that significantly reduces the number of adjustment iterations required to reduce main rotor vibrations. To address these issues it was the intent of this research to develop an on-line linear time periodic rotor vibration controller. The Cramer-Rao bound was developed for a linear time periodic system in order to identify the quality of identified system parameters that are used in system models for controller development.</p><p>This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work was reproduced from the original artifact and remains as true to the original work as possible. Therefore you will see the original copyright references library stamps (as most of these works have been housed in our most important libraries around the world) and other notations in the work.</p><p>This work is in the public domain in the United States of America and possibly other nations. Within the United States you may freely copy and distribute this work as no entity (individual or corporate) has a copyright on the body of the work.</p><p>As a reproduction of a historical artifact this work may contain missing or blurred pages poor pictures errant marks etc. Scholars believe and we concur that this work is important enough to be preserved reproduced and made generally available to the public. We appreciate your support of the preservation process and thank you for being an important part of keeping this knowledge alive and relevant.</p>