Three-Flywheel Assembly for Reduction of Attitude Jitter in Satellites

Multiple Flywheels Ensure Spacecraft Remain Functional if One or Two Flywheels Fail

This three-flywheel assembly reduces attitude jitter caused by momentum actuators in satellites, improving its on-orbit pointing stability. Spacecraft with momentum actuators suffer form attitude jitter and high frequency oscillations due to imbalance in the rotors of momentum actuators. These problems can interfere with a satellite’s orientation, imaging, and scientific experimentation, sometimes causing the whole spacecraft to become nonfunctional. Existing jitter control using active isolation techniques help to address some of the effects of jitter but are only effective in a localized area and cannot prevent wear and tear on the entire space system. Further, these systems are expensive and require a sophisticated control system. The three-flywheel assembly developed by researchers at the University of Florida provides continuous jitter control for higher performance and longer use. The three-flywheel assembly replaces the single-flywheel system and hence provides continuous on-orbit balancing capability. Existing systems with one flywheel may suffer from increased jitter over time due to imbalance growth, sometimes rendering the satellite inoperative. The use of multiple flywheels addresses this issue and the further adds layers of protection to the overall system, allowing for continued use of the satellite if one or even both of the other flywheels fail. The system also provides a cost advantage over existing active isolation techniques.

Application

A three-flywheel assembly reduces jitter and increases satellites’ performance

Advantages

• Significantly reduces jitter and provides a long-term jitter management solution, saving enormous costs on satellite replacement
• Minimizes static and dynamic imbalances, enhancing spacecraft performance
• Provides redundancy in the form of a multiple-flywheel system, maintaining functionality in the event that one or both of the other flywheels fail

Technology

University of Florida researchers have developed a three-flywheel assembly that reduces jitter in small satellites. The system includes two similarly balanced flywheels to counter the effect of residual imbalance from the first one. It cancels out jitter at the source to minimize static and dynamic imbalances while adapting to minor changes in the individual rotor imbalances that occur over time. The redundancy of multiple flywheels increases reliability and reduces the amplitude of jitter by manipulating phase difference using controlled balancing techniques.