טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentDavis Solomon
SubjectAutoresonance and Modal Filtering for Fast Sensing and
Actuation
DepartmentDepartment of Mechanical Engineering
Supervisor Professor Izhak Bucher
Full Thesis textFull thesis text - English Version


Abstract

Mechanical or electro-mechanical systems typically possess multiple vibration modes with corresponding natural frequencies. There are many applications which require one to excite such systems at one or more natural frequencies. For example, a near-filed acoustic levitator must be excited at a specific natural frequency to achieve significant levitation force. Or one may wish to excite and identify the rotation-dependent natural frequencies of a gyroscopic system. A problem with many of these systems however, is that the natural frequency may be unknown, or may be continuously drifting or changing. Therefore, a resonance tracking feedback loop may be required to achieve proper operation. The goal of this thesis is the analysis and development of the Autoresonance feedback loop for achieving constant excitation of the natural frequency of such a system. In this work, a new approach to the Autoresonance loop will be explored, by combining it with modal vibration techniques. Such an approach allows one to efficiently predict the behavior of the feedback loop, namely the frequency and amplitude of the limit cycle. Furthermore, when the Autoresonance loop is combined with a modal filter, this allows one to easily select and resonate single or multiple vibration modes automatically. It will be shown that such control over the vibration modes allows for the realization of an acoustic levitation motor, and in-situ identification of the frequency branches of a gyroscopic system. Additionally, a new analysis of the Autoresonance loop in the time domain will reveal that Autoresonance tracks any changes to the natural frequency extremely quickly. It will be shown that this behavior holds great promise in the field of high-speed, non-contact atomic force microscopy.