Velocity-Free Attitude Controllers Subject to Actuator Magnitude and Rate Saturations

Abstract

We consider the “velocity-free” feedback control problem associated with attitude tracking for a rigid body subject to torque-magnitude and rate-saturation limits. Whereas no angular rate measurements are utilized within the feedback structure, the controller rigorously enforces actuator-magnitude and rate-saturation constraints. The associated stability proof is constructive and accomplished by the development of a novel Lyapunov function candidate. Although control smoothness is preserved at all times, it is important to note that the results of this paper that are derived with respect to magnitude saturation place no additional restrictions on the body inertias and make no other small-angle assumptions. The closed-loop performance of the new control solution derived here is evaluated extensively through numerical simulations in which we also include realistic levels of sensor noise in the feedback signals.