Constrained rigid body attitude stabilization: an anti-windup approach

This paper considers the rigid body attitude stabilization problem with actuator saturation. This problem has been considered in the literature before, but most approaches achieve stability at the expense of strict constraints on the control gains, thereby limiting small-signal performance. The approach proposed here removes the constraints on the gains of the nominal controller and instead deals with the control constraints through an anti-windup mechanism, effectively allowing for more freedom in small signal behavior whilst preserving stability in the large. Although the rigid body stabilization problem is inherently nonlinear, the spirit of the results developed here resemble constrained-control results for linear systems containing imaginary axis poles, despite some subtle differences which need careful consideration.