Analysis of Optimal Reaction Wheel Configurations for Integrated Three Axes Control for On-Orbit Servicing Nano-satellites

摘要

Satellites are designed to reach space and serve their mission objective for designed mission life. However, certain fully operational satellites are often decommissioned due to depletion of onboard fuel. In addition, other satellites fail in orbit due to unforeseen faults which can cause system failure representing the loss in the billions of dollars. On-orbit servicing (OOS) satellites approach the faulty satellites and execute the repairs, replacements or refuelling to regain operations of the faulty satellite. The main purpose of the paper is to understand the possibilities to demonstrate the OOS capabilities with reduced cost nano-satellites. Miniaturization of actuators viz. Magnetic Torquer Rods (MTR), reaction wheels and control moment gyros provide scope for agility and miniaturised thrusters provide orbit modification capability in servicing satellites. This study provides the feasibility analysis on using the commercially of the shelf (COTS) reaction wheels and MTRs for the attitude and angular rate control of OOS nano-satellites. The analysis of torque distribution under the circumstances of reaction wheel failure and autonomously decide the contingency action under actuator failure for a given trajectory is also essential. The continuous and smooth control of satellite upon failure of one or more wheels has been studied with simulations providing the attitude control possibilities using magnetic torquer rods under wheel failure. The paper provides the simulation results in terms of attitude accuracy achieved in a failure mode where only one wheel is operational.