Control And Design Of High Precisionactive Magnetic Suspending North Finding System

The magnetic suspension north finder is a kind of autonomous azimuth indicator, which adopts the inertial theory, and it can find north q uickly and accurately under all weather conditions. It has a variety of applications in national defense and civil fields. However, to a large extent, the directional accuracy of the magnetic suspension north finder system depends on the precision of gyro. According to the fact that the single degree of freedom gyrocompass has advantages of simple structure, quick response, but it is difficult to eliminate the bracing and friction or the suspension torque, a high precision magnetic suspension north finder is studied and developed in this dissertation. The single degree of freedom gyroscope is suspended using active magnetic bearing which fundamentally change the friction characteristics. Then north finder has a good condition for finding meridian. Single degree of freedom gyroscope north finder with active magnetic suspension is developed firstly in China and international relevant studies have not been seen yet.Meanwhile, due to the strong nonlinear and the distributed-parameter characteristic of the active magnetic suspension system, it is difficult to builded the system model exactly. In this dissertation, a multi-objective optimization and multiple constrain controller design method is studied with Parameter Dependent Lyapunov stability theory and Linear Matrix Inequality method. The main results consist of the following parts:Firstly, the magnetic north-finding program is investigated and a single degree of freedom gyro program is determined that north-finding accuracy and rapidity is easily achieved with high-precision magnetic suspension. Mechanical structure of the north finder is designed, and a detailed analysis of the complexity of flexible suspension is investigated.Then, magnetic suspension system is introduced with a detailed analysis of the magnetic suspending north finder. The structural design of the radial magnetic bearings and axial magnetic bearing is studied. Mathematical model, including a single degree of freedom model and five degrees of freedom model is established.Sequentially, the control technique of the magnetic suspension is the key technique in the magnetic suspending north finder. Good suspension characteristics are the basis to ensuring the accuracy of the seeking north. So some kinds of indices are required such as higher precision, better disturbance attenuation performance, and lower power consumption and so on. In this paper, multi-objective optimization theory is occupied; multi-objective controllers are designed with constraints of performance indexes. Parameter dependent Lyapunov stability theory and linear matrix inequality method are approached in the study of the multi-objective controller optimization. A robust optimal guaranteed cost output feedback controller is designed with constraints of model uncertainty, and four degrees of freedom magnetic bearing H∞ output feedback controller is designed with constraints of disturbance attenuation performance. Further more, a multi-objective robust dynamic compensator is approached by considerating multiple constraints such as robust stability, disturbance attenuation, and minimization power consumption. Finally, the corresponding simulation of the magnetic suspension controller is proposed.Finally, magnetic north finder control system prototype is designed and developed. The control system hardware includes the displacement sensor and its conversion circuit, DSP controller, power amplifier, and man-machine interface circuit. A five degree of freedom magnetic suspension experiment and analysis is given. Experiment data show that the controller system meet the requirements of magnetic suspension north finder. Control algorithms can achieve stability in suspending the framework of a single degree of freedom gyroscope.