Intrinsic UDE control of mechanical systems on SO(3)

The uncertainty and disturbance estimation (UDE) structure provides flexible and intuitive controller design for command following and disturbance rejection in uncertain linear and nonlinear systems. In this paper, an intrinsic UDE controller is demonstrated for fully-actuated mechanical systems on SO(3), the group of rigid-body rotations in three-dimensional Euclidean space. The controller is derived in a geometric framework, thereby avoiding issues arising from any particular set of coordinates. Simulations and experiments using a quadrotor test bed show that the controller can stabilize a desired equilibrium attitude in the presence of disturbances and parameter error.