Decentralized adaptive output-feedback controller design for stochastic nonlinear interconnected systems

In this paper, the controller design for a class of stochastic interconnected systems with both parametric uncertainties and unknown nonlinear interactions is presented. The diffusion terms considered are dependent on the outputs of local subsystems and allowed to be unbounded. First, by employing decentralized state observers, totally decentralized adaptive tracking controllers with suitable parameter adaptive laws are designed to ensure the boundedness in probability of all the signals in the closed-loop system. It is shown that the tracking errors converge to small residual sets around the origin. Then, for systems with relaxed diffusion vector fields, a decentralized adaptive stabilizing scheme is proposed to ensure the boundedness in probability of all signals in the closed-loop system.