Reaction Wheels for Attitude Control of Chandrayaan-3

Reaction Wheel (RW) actuators are required for the precise attitude control and three-axis stabilization of a spacecraft. They play a vital role in the control of spacecraft orientation without disturbing the orbit, unlike thrusters. Considering the Chandrayaan-3 inertia and maneuver requirements, four Reaction Wheels each of 0.1 Nm torque capability and 10 Nms angular momentum capacity were chosen for the mission. Each Reaction Wheel is controlled by an FPGA-based Wheel Drive Electronics (WDE), which interfaces to the On-Board Computer (OBC) through MIL STD 1553B interface. The input torque command resolution is 0.03 gcm/bit. The performance of the Reaction Wheel Assembly (RWA), during the earth bound as well as lunar bound orbits, was excellent and consistent.