Velocity-free attitude tracking control of rigid spacecrafts under control constraints

This paper considers the output feedback, attitude tracking control of rigid spacecrafts subject to the absence of angular velocity measurements and control saturations. It is assumed that only attitude measurement, which is represented by Modified Rodrigues Parameter (MRP), is available for feedback. A stable filter driven by the attitude variable is adopted to reconstruct velocity-like signals. The proposed control scheme is shown to achieve global asymptotic attitude tracking through a rigorous Lyapunov analysis, with an adoption of. a particular non-quadratic Lyapunov function. Numerical simulations demonstrate the practical applicability of the proposed approach.