Search

An output-feedback control system for uncertain linear systems with arbitrary delay in the output signal and input disturbances is developed. The state of the system and the disturbances are estimated by observers connected in cascade. Unlike previous works, parametric uncertainties are allowed. Their effects are analysed by using the Small-Gain Theorem. The rejection of the exogenous and matched input disturbances is also considered in the system. The proposed control strategy guarantees global stability of the closed-loop system. A numerical example and an application to underwater vehicle control illustrate the effectiveness of the proposed control strategy to compensate arbitrary delays, disturbances and bounded uncertainties. [ABSTRACT FROM AUTHOR]

Summary: An adaptive sliding‐mode unit vector control approach based on monitoring functions to deal with disturbances of unknown bounds is proposed. An uncertain multivariable linear system is considered with a quite general class of nonsmooth disturbances. Global stabilization/tracking is demonstrated using either state or output feedback. The proposed adaptation method makes the control gain less conservative, becoming large enough when the disturbance grows and becoming smaller when it decreases, leading to reduced chattering effects. In contrast to previous methods, the new switching scheme is able to guarantee a prespecified transient time, maximum overshoot, and steady‐state error for multivariable uncertain plants. The proposed technique is applied to the trajectory tracking control of a surface vessel subjected to ocean currents, wind, and waves. Simulations are presented to show the performance of the new adaptation scheme in this adverse scenario of possibly growing, temporarily large, or vanishing exogenous disturbances. [ABSTRACT FROM AUTHOR]