Sliding-mode formation control for cooperative nonholonomic robots with uncertainties

For the decentralized formation problem of multiple robots, this paper presents a kind of robust sliding mode controller based on nonlinear disturbance observer. According to the leader-follower-based formation mechanism, the dynamic model with external disturbances and system uncertainties is established. To perform a formation control and to guarantee system robustness, a novel formation algorithm combining sliding model control and nonlinear disturbance observer is presented. Sliding mode control (SMC) is a special nonlinear control strategy, which has invariance against the matched uncertainties, but the chattering produced by SMC limits its application to the practical system. By using nonlinear disturbance observer technology, the uncertainties cover both matched and mismatch uncertainties can be compensated. In addition, the SMC control law can be designed successfully so that chattering can be effectively alleviated. In the sense of Lyapunov, a sufficient condition is drawn to guarantee that the formation system can be asymptotically stabilized. Simulation results confirm the effectiveness of the proposed control scheme.