ESA GNC Conference Papers Repository

Several future space missions have very stringent pointing accuracy requirements. The disturbances generated by Reaction Wheels have a significant overall impact on the pointing accuracy of the S/C. Those disturbances are applied in all 3 directions in force and moment and are known as micro-vibrations. From the S/C side, usage of dampers and operating at lower speed ranges are some of the strategies applied to reduce the micro-disturbances. However, disturbances originating from torque irregularities from the Reaction Wheel are known to have a low frequency content which are difficult to be damped. With a Reaction Wheel internal speed and net torque controller, those disturbances can be internally minimized, resulting in a lower impact on pointing accuracy at S/C level and improving the performance of the entire system. Under ESA Core Technology Program (CTP), Bradford Engineering together with SYDERAL Polska and SYDERAL Swiss performed a preliminary assessment, trade-off and preliminary design of an internal speed control with updated Wheel Drive Electronics (WDE). The current design of the Reaction Wheel Assembly (RWA) would only require minor modifications.