Distributed and Performance Guaranteed Robust Control for Uncertain MIMO Nonlinear Systems With Controllability Relaxation

In this article, we investigate the distributed output tracking problem for networked uncertain nonlinear multi-inputs-multi-outputs (MIMO) strict-feedback systems with intermittent actuator faults under a directed protocol. By embedding some user-designed performance functions into a backstepping-like design procedure, a distributed robust control scheme is developed that exhibits several salient features: 1) relaxing the system controllability conditions by inserting some differentiable compensation terms into the controllers that enables a larger class of system models to be coped with; 2) dealing with mismatched uncertainties and accommodating actuation ineffectiveness automatically while achieving prescribed transient and steady-state tracking performance, i.e., the output tracking error converges into an arbitrarily predefined residual set exhibiting an arbitrarily preselected convergence rate; 3) lowering structural and computational complexity by avoiding the derivatives of virtual controllers and desired trajectory, eluding the usage of extra observers to estimate the states of the neighbors, and demanding little prior information on system nonlinearities or no approximator to compensate for them; 4) reducing the communication burden by requiring only the output information from the neighbors for control design. Furthermore, all the closed-loop signals are ensured to be semiglobally ultimately uniformly bounded. Finally, the benefits of this method are verified via numerical simulation.