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Distributed Velocity-Free Attitude Coordination Control with Torque Constraint

Considering attitude-only measurements, physical limitations of actuator and state-independent observer time, a distributed velocity-free attitude coordination control problem for multiple formation spacecraft with torque saturation is studied in this work. Initially, aiming at speeding up the convergence rate and realizing the maximum value of the convergence time without requiring prior knowledge of the initial system state values, a fixed-time observer is constructed to estimate the desired time-varying states in fixed time. Then, a filter system is developed for the spacecraft with attitude-only measurements. With the application of the fixed-time observers and the filter systems, a distributed velocity-free attitude coordination controller with torque constraint is designed to grantee that the leader with desired state trajectory can be tracked coordinately by the formation spacecraft. Finally, the performance of the proposed controller is demonstrated by simulation results.