Quaternion-based Discrete-time Nonlinear Attitude Tracking Control of Spacecraft

Recent space programs require agile and large angle attitude maneuvers for applications in various fields such as observational astronomy. To achieve the agility for large angle attitude maneuvers, the controller design must be formulated as a nonlinear tracking control problem. Since a computer, which is a digital device, is employed as a spacecraft controller, the control method should have a discrete-time control or sampled-data control framework. This paper considers a discrete-time nonlinear attitude-tracking control problem of spacecraft. We first derived an Euler approximation system with respect to the tracking error. Then, we designed a quaternion-based discrete-time nonlinear attitude-tracking controller so that the tracking error of the Euler approximation system asymptotically convergences to zero. Finally, we verified the effectiveness of the proposed control method through numerical simulations.