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Momentum Wheel and Its Subassembly
Momentum Wheel and Its Subassembly

Momentum Wheel and Its Subassembly



Momentum Wheel and Its Subassembly

    • The momentum wheel is a key component of the satellite attitude control system. The bearing subassembly is the core component of the momentum wheel. The momentum wheel and its subassembly are applied in all the satellites, of which the reaction-torque produced by the gyroscopic stability and the variation is used to stabilize or change the attitude of a satellite. The service life, precision and reliability of the momentum wheelspacecraft wheel and its subassembly have a great influence on the service life, precision of controlling and reliability of a satellite.

      The research and development of the momentum wheel and its subassembly and spacecraft wheel of satellite in ZYS started in 1988. Various types and series of the momentum wheels and subassemblies have been developed in succession. There are two kinds of momentum wheels: disc structure and spoke structure. The angular momentum is 0.5Nms~68Nms. The rotating speed is 500rpm~6,000rpm. The physical dimension is 60mm~350mm. The minimum power dissipation in stable state is 1W. The speed of the bearing subassembly is 50rpm~9,500rpm. The bearing subassembly has minimal-quantity lubrication system. By now, ZYS has developed controlling assembly for large aircraft with an angular momentum of 200Nms. ZYS has the ability to develop subassemblies with an angular momentum of 1000Nms.

      Through researches, with a rotating speed of 4,600rpm, the friction torque has been lowered from 180g.cm to 140g.cm, and the fluctuation has been lowered from 10% to 5% by ZYS. The precision has been raised from P4 to P2 (the highest level in the world). The service life has been increased from 2 years to 5 years. More than 100 bearing subassemblies of 4 types have already been applied in the satellite momentum wheels and spacecraft wheel of several models, which are all working normally. Some of the bearing subassemblies have passed the working life examinations.

      ZYS can also offer the reaction wheel, which occupies an important position in modern high-precision satellite attitude control. However, because the reaction wheel works at a low speed, the nonlinear characteristics of the friction torque when its speed crosses zero will have a greater impact on the attitude control accuracy and affect the satellite operating life. Based on the Dahl friction model, a mathematical model of the reaction wheel system driven by a DC motor is established, and on this basis, a compensation observer for improving the low-speed performance of the reaction wheel is designed and applied to the three-orthogonal structure attitude control system. The digital simulation shows that this method can effectively suppress the disturbance caused by the low-speed friction of the reaction wheel, thereby greatly improving the satellite attitude control accuracy and attitude stability.


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