Abstract
The magnetically suspended control moment gyros (MSCMGs) are complex system with multivariable, nonlinear, and strongly gyroscopic coupling. Therefore, its reliability is a key factor to determine whether it can be widely used in spacecraft. Fault-tolerant magnetic bearing systems have been proposed so that the system can operate normally in spite of some faults in the system. However, the conventional magnetic bearing and fault-tolerant control strategies are not suitable for the MSCMGs because of the moving-gimbal effects and requirement of the maximum load capacity after failure. A novel fault-tolerant magnetic bearing system which has low power loss and good robust performances to reject the moving-gimbal effects is presented in this paper. Moreover, its maximum load capacity is unchanged before and after failure. In addition, the compensation filters are designed to improve the bandwidth of the amplifiers so that the nutation stability of the high-speed rotor cannot be affected by the increasing of the coil currents. The experimental results show the effectiveness and superiority of the proposed fault-tolerant system.
Highlights
Control moment gyros are capable of producing significant torques and handling large quantities of momentum over long periods of time
A control moment gyro with magnetic bearings that comprises of a rapidly spinning rotor mounted on a gimbal is called a Single-Gimbal Magnetically Suspended control moment gyro (SGMSCMG)
The forces and currents at the adjacent channels are decoupled at the magnetic center when the coil/amplifier fails. This is a distinct advantage of the four-pole permanent magnet-biased radial magnetic bearing (PMRMB) which differs from the traditional eightpole PMRMB
Summary
Control moment gyros are capable of producing significant torques and handling large quantities of momentum over long periods of time. Calculating the current distribution matrix is typically performed at the magnetic center so that the modeling of the bearing force can be simplified. This method is mainly applied to the target whose rotor is always suspended in the Mathematical Problems in Engineering. The bearing force which has been decoupled and linearized by the current distribution matrix will present strongly coupling and nonlinear characteristic again when the rotor is away from the magnetic center. For the fault-tolerant control of the SGMSCMG, the application of the current distribution matrix will be hindered.
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