Study On Dynamic And Control Methods Of Altra-precision Gas Magnetic Bearing Shafting

In this dissertation a new method is presented to improve the rotary accuracy of bearing. Gas bearings and magnetic bearings are popularly used because of their high rotary accuracy character. They play an important role in more and more fields, including military, aviation industry and daily industry. Even though they have many virtues, they have their respective disadvantages. Gas bearings have small mechanical friction, no leakage, but are difficult to manufacture and control; magnetic bearings have good controllability and high accuracy but sustentation is limited. Gas bearing and magnetic bearing are usually used separately, so when we exert their advantages we cannot get rid of their disadvantages.At present, either gas bearings or active magnetic bearings(AMB) are excellent in high speed rotary bearings and ultraprecise rotary bearings. However, the precision of ultraprecise manufacture put forward by cusp technology is more and more rigid. Recently, improved methods applied in the fields of engineer and science has been to improve the two kinds of bearings' manufacture precision and features, adopt new materials and investigate more advanced control algorithm. Although these methods are feasible, they are not ideal and the improved extent is limited. In practice, people realize that the two bearings can use their respective virtues to make up the other one' s shortages. Therefore, we have the idea of using them together.In this dissertation gas bearings are used as the main supporting elements, AMB as control and error compensation device, thus they can make up each other. This can not only exert gas bearings' high supporting capacity and AMB' s controllability, but also avoid their defects when they are used separately. This kind of combination can simplify control system and easily make the bearings work in the linear scope. We combine the two bearings, through modifying gas bearings' error and outsidedisturb to achieve ultraprecision.The history, development, present research status, characters and application of gas bearings and magnetic bearings are reviewed in this dissertation respectively and briefly. After analyzing the two kinds' working principles, we integrate their respective advantages to set up dynamics and control models of gas-magnetic bearing with single freedom of motion and five freedom of motions. According to gas-magnetic bearing' s requirement of the controller, we finish the design and implement of hardware of the digital controller of TMS320F2812 Processor. At the basis of analysis of classical control methods, we optimize the control algorithm and deduce the digital PID control method of gas-magnetic bearing. After the design of hardware we also finish the design of software and the debugging and simulation of the whole system.