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Summary: This paper explores regulation theory for the design of robust precision attitude tracking of an uncertain rigid spacecraft with external disturbances. Focusing on the attitude system in terms of unit quaternions with an unknown inertia matrix and unmodeled input disturbances, we first introduce specific nonlinear logic such that the resultant error‐quaternion system has an input‐to‐state stability property. Then, we establish an attitude deviation system with an output feedback normal form that has a strict vector relative degree of unity. This enables us to achieve robust output regulation based on an internal model. In particular, we can construct a high‐gain stabilizer for the relevant augmented system. As a major consequence, our study achieves not only precision attitude tracking with exponential convergence but also the input‐to‐state stability disturbance attenuation for the closed‐loop system. Finally, we show extensive simulation and experimental results to illustrate the approach. [ABSTRACT FROM AUTHOR]

This paper focuses on robust nonlinear coordination of heterogeneous uncertain second-order multi-agent systems subject to directed communication topologies. We develop a nonlinear internal model principle based approach for the problem in a framework of cooperative global robust output regulation, independent of the a priori of the leader dynamics information except its order. As a major consequence, this study assures, by means of establishing a strict-Lyapunov function for the closed-loop system, not only a specified exponential convergence rate but also tolerable bounds of unmodeled disturbances. Hence, the former guarantees an appealing performance and the latter an important robustness property. [ABSTRACT FROM AUTHOR]

This paper presents a distributed event-based high gain feedback design for the cooperative global practical output regulation problem of nonlinear multi-agent systems with unit relative degree subject to the general nonlinear leader system. We first convert global practical output regulation problem into global practical stabilization problem, then prove the input-to-state stability of the closed-loop system by regarding the sampling error and the steady-state of the actuator together as the external input. Based on the high gain feedback technique, the input-to-state gain function can be made sufficiently small, and hence the tracking error can converge to an arbitrary predefined small residual set around the origin. A distinguishing feature of our result is that, our controller is static and purely digital, thus, giving rise to quite a simple structure. [ABSTRACT FROM AUTHOR]