Explicit reference governor on SO(3) for torque and pointing constraint management

This paper focuses on the constrained attitude control of a rigid body. We propose an Explicit Reference Governor (ERG) specifically designed to handle constraints on SO(3). Two types of constraints are considered: (i) input torque constraints, and (ii) geometric conic pointing constraints. The objective of this paper is to design a control law that is able to steer the attitude of a rigid body to the desired attitude reference while enforcing constraints at all times. To this end, the first step is to design a controller that makes the desired attitude asymptotically stable when constraints (i) and (ii) are neglected. Next, the proposed control scheme is augmented with a novel ERG scheme able to add constraint-handling capabilities to the overall architecture. All the proposed solutions are defined in terms of SO(3) and do not make use of any parameterization such as quaternions or Euler angles. Numerical simulations are carried out to show the effectiveness of the proposed control scheme.