Speed estimation and control strategy for micro-reaction wheel

The speed control accuracy of micro-reaction wheel was improved in order to meet the accuracy requirements for the attitude control of pico-nano satellites and CubeSat. The speed measuring and control system was designed with the switch-type Hall sensor, a speed estimation method was proposed to ameliorate the measurement accuracy, which was combined of time measuring by variable prescalerT-method and average sliding filter with speed switching hysteresis loop. The discrete PID algorithm of integral separation was utilized to prevent the control saturation. Results show that the maximum error of speed control is less than 1.5%, the average error of speed control is less than 0.4‰ and the error variance of speed controlis about 0.25. The reaction wheel provided three-axis stability for the satellite, as an important part of the world's first 12U CubeSat "Star of AoXiang", which was launched by “CZ-7” on June 25, 2016. The satellite had successfully worked until atmospheric re-entry after 99 days. The ground test and in-orbit service of the satellite show that the proposed method is feasible and effective, both the speed estimation method and the control algorithm can satisfy the mission requirement of satellite attitude control system.