Adaptive practical consensus control for a second-order nonlinear MAS with unknown parameters

In this paper, we investigate the leaderless consensus problem for MAS consisting of second-order nonlinear subsystems with a class of unknown parameters. The communication topology among subsystems is directed and fixed. An adaptive control approach based on backstepping technique is proposed. The estimations of the unknown parameters of the neighbors' systems are no longer required in constructing the local adaptive controller. Moreover, the additional local estimates to compensate for the uncertainties involved in its neighbors as well as extra transmissions of online parameter estimates required among linked subsystems can be avoided. It is proven that the boundedness of all closed-loop signals and the practical consensus for all the subsystems are ensured. Simulation results show the effectiveness of the proposed control scheme.