The control of vibration in rotordynamic systems is an important problem in engineering. These unwanted oscillations can lead to premature failure or poor performance of the system. Traditionally active vibration control of rotordynamic systems is accomplished by adding actuators (electromagnets or active magnetic bearings) that apply a radial force to the shaft of the rotor. These actuators are used in feedback control systems that are designed to ameliorate the effects of the unwanted vibration. This project develops an approach to the control of vibration in rotordynamic systems that does not rely on external actuators. Here we consider rotordynamic systems that are driven by electromagnetic motors. By modifying the commutation and control of these motors they can be made to produce a torque and a radial force. This radial force can then be controlled to suppress the vibrations in the system. To evaluate the torque/force generating capability of motors this project has set three broad objectives; (1) To develop and experimentally validate models, suitable for use in control system design, that accurately predict the behavior of motors that are used as torque and radial force generators. (2) To demonstrate the practical feasibility of using motors as torque/force generators in actual rotordynamic systems. Specifically, a ywheel energy storage (FES) device and a a hard disk drive (HDD) system. (3) To integrate these new techniques into the undergraduate curriculum and provide research opportunities for women and underrepresented minority students. Intellectual Merits: The use of axial and radial ux permanent magnet motors to generate radial forces for vibration suppression is believed to be a novel approach. In addition, the actuator modeling and control techniques developed in this project can be applied to other AC/DC motor designs. Practical FES devices that use magnetic bearings require precise regulation of the air gap between the rotor and the stator. The controllers must provide stable operation over a range of speeds while rejecting the harmful effects of disk imbalance and base excitation. This project will design and implement a multiple model controller for a FES device that uses an axial ux motor for torque and radial force production. Broader Impacts: By eliminating the need for external force actuators this research will lead to FES devices with higher energy densities. This would make FES systems a practi-cal alternative to electrochemical energy storage systems. When used in conjunction with renewable energy sources these improved FES devices can help reduce national dependence on fossil fuels. This research can also provide a low-cost means for suppressing vibration in HDD sys-tems, thus improving the data storage capabilities of these devices. It is estimated that the United States digitally stored more than 400 billion documents in 1997, with 72 billion new documents being added each year. Thus, it is important to conduct research that will lead to increased reliability of HDD devices. The education initiatives of the proposed project will focus on bringing modern techno-logical developments in bearing design and motor control into the undergraduate classroom. Also, in collaboration with the UW/NSF LSAMP program the the project will focus on outreach activities by providing opportunities for underrepresented minorities and women to work in an engineering setting.
