This paper addresses the problem of navigation control of a general class of 2nd order uncertain nonlinear multi-agent systems in a bounded workspace, which is a subset of R 3 , with static obstacles. In particular, we propose a decentralized control protocol such that each agent reaches a predefined position at the workspace, while using local information based on a limited sensing radius. The proposed scheme guarantees that the initially connected agents remain always connected. In addition, by introducing certain distance constraints, we guarantee inter-agent collision avoidance as well as collision avoidance with the obstacles and the boundary of the workspace. The proposed controllers employ a class of Decentralized Nonlinear Model Predictive Controllers (DNMPC) under the presence of disturbances and uncertainties. Finally, simulation results verify the validity of the proposed framework.Proof. The proof can be found in Appendix A.
Problem Formulation
System ModelConsider a set V of N rigid bodies, V = {1, 2, . . . , N }, N ≥ 2, operating in a workspace W ⊆ R 3 . A coordinate frame {F i }, i ∈ V is attached to the center of mass of each body. The workspace is assumed to be modeled as a bounded sphere B (p W , r W ) expressed in an inertial frame {F o }. We consider that over time t each agent i ∈ V occupies the space of a sphere B (p i (t), r i ), where p i : R ≥0 → R 3 is the position of the agent's center of mass, and r i < r W is the radius of the agent's rigid body. We denote by q i (t) : R ≥0 → T 3 , the Euler angles representing the agents' orientation with respect to the inertial frame {F o }, with q i [φ i , θ i , ψ i ] . By defining: x i (t) [p i (t) , q i (t) ] , x i (t) : R ≥0 → M, v i (t) [ṗ i (t) , ω i (t) ] , v i (t) : R ≥0 → R 6 , we model the motion