Disturbance observer-based control design for a class of nonlinear stochastic systems with periodically intermittent measurement

This paper treats the control problem of a class of nonlinear stochastic systems with unknown external disturbance and periodically intermittent measurement. It is assumed that the external disturbance is generated by an exogenous system with unknown initial condition, and the state information ia available only on some disconnected time intervals. A composite control method using the intermittent state information is proposed, which consists of an intermittent feedback control law and a disturbance observer. The stability property of the closed-loop error system is analyzed using a piecewise-time-dependent Lyapunov function approach. Then, a sufficient condition for the existence of the desired composite controllers is derived in terms of matrix inequalities. Finally, a numerical example is given to illustrate the effectiveness of the proposed result.