Search

Summary: In this paper, the practical leader‐following consensus via the sampled‐data protocol is investigated for second‐order nonlinear multiagent systems with external disturbances, where the velocity information of all agents are assumed to be unmeasurable. The consensus problem of the multiagent system is first transformed to a stabilization problem of the constructed error system. Because of the unknown of the agents' velocities, an observer is then proposed for the constructed error system to estimate the velocity errors. By the backstepping approach, a new protocol is designed with only position measurements and sampled‐data information. Furthermore, the upper bound of the sampling period is given. It is proved that the practical leader‐following consensus can be achieved by the proposed sampled‐data protocol with a proper sampling period. The result is then extended to the multiagent systems with multiple leaders. Finally, two numerical examples are provided to illustrate the effectiveness of the designed protocols. [ABSTRACT FROM AUTHOR]

Summary: This paper investigates attitude maneuver control issues of a flexible spacecraft with pyramid‐type single gimbaled control moment gyroscopes (SGCMGs) as the actuator. The LuGre friction model is adopted to precisely describe the nonlinearity of the SGCMG gimbal friction. Aiming at restraining the adverse effects of the friction existed in SGCMG on the attitude control performance, a robust adaptive attitude controller is proposed, and projection‐based adaptive laws are presented to estimate the friction parametric uncertainties and the bound of friction nonlinearity. By treating the flexible mode coupling effect and external disturbances as lump disturbances, the inertia uncertainties and the bound of the lump disturbances are also estimated and compensated simultaneously to reduce their adverse effect on the system. With the Lyapunov technique, the states of flexible spacecraft control system are proved to be uniformly ultimately bounded. Numerical simulations demonstrate the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]