Research On Steering Laws Of SGCMGs

The SINGLE-GIMBAL control moment gyro system is regarded as effective torque generator for attitude control both for large space stations and small agile satellites because of its large torque amplification capability and storing large angular momentum over long periods of time capability. During the last three decades, CMGs as applied to spacecraft attitude control and momentum management have been extensively studied. They have been successfully employed for a variety of space missions. However, there still exist various practical as well as theoretical issues in inherent in the use of CMGs including system- level tradeoffs, optimal arrangement of CMG arrays, singularity robust steering logic design, computational issues for real-time implementation and the existing of dynamic friction and disturbing torque. This paper aim to provide effective steering law which overcoming the singularity problem as well as providing high precision output torque.The main contents of this dissertation are summarized as follows:Firstly, it examines the singularity problem inherent to redundant single- gimbal control moment gyro. It is intended to provide a comprehensive mathematical treatment of the CMG singularity problem. The author compared the configurations of CMG including three orthogonal single- gimbal CMGs configuration, pyramid array of four single- gimbal CMGs configuration and pentagonal pyramid array of six single- gimbal CMGs configuration. Then the paper visualized the different configurations and analyzed the advantage and the disadvantage of these configurations. Further, the author chose the pyramid array of four single-gimbal CMGs configuration to test the performance of the steering laws in the later chapter.Secondly,this paper introduce the basic steering laws and their overflows, design the zero steering law and the SR steering law which based on the Penrose-Moore steering law. Then this paper design a steering law combined by these steering laws, which can avoide and escape the singularity.Then we designed a steering law considering dynamic friction, disturbing torque and the gimbal servo system in the practical system. The new steering combined the capability of singularity avoidance and high accuracy output torque, which consider the factors in the practical system.At last, this paper begin with designing an equipment to test the torque generated by CMGs. This equipment can verify the steering law we designed. The main frame of the equipment is based on dual-axis air-bearing spacecraft simulators which can provide an isolation environment to reduce disturb and improve the accuracy of the measurement. This paper introduced the software and the hardware of the measurement system.