Actuator Fault Adaptive Compensation Control For Nonlinear Systems

Due to the long running of the system and components of aging,actuators may encounter failures inescapability in nature.Very often it is impossible to predict in advance which actuators may fail during system operation when the failures occur,what types and what values of the failures are,it may also be impractical to determine the failure parameters after a failure occurs.In this case,the actuator failure compensation control design will be more difficult and complex.On the other hand,Actuator failures have damaging effect on the performance of control systems,leading to undesired system behavior or even instability.Actuator failures may cause seriously accidents in the aerospace and other import areas.Therefore,design a set of effective compensation control scheme of actuator failure is very necessary of both theory and practical significance.In this note,with the frame work of existing literature and results,we study a more general model of actuator failures for a class of nonlinear systems with unknown actuator failures,control parameters and external disturbance.Inspired the relevant papers,a novel adaptive compensation control scheme is proposed with the help of the new parameterized model is established.It is proved that all closed loop signals are bounded and tracking error converges to a small residue set and we mainly discuss the following two aspects.(1)The questions of adaptive failure compensation for a class of nonlinear systems with known control directionAccording to the actuator failure model we proposed,a new adaptive compensation control scheme is proposed for a class of nonlinear systems with unknown actuator failures,through the establishment of a new parameterized model.All actuators are allowed to change among the normal operation case and different failure case infinitely many time.The scheme which we proposed ensured all the signals of the closed-loop system are proved to be bounded.Moreover,the proposed scheme is able to steer the tracking error into a small residue set.(2)The questions of adaptive failure compensation for a class of nonlinear systems with unknown control directionWe further consider the problem of the above mentioned problem.By introducing a Nussbaum function to overcome the obstacle caused by the unknown sign control gain b_m.Then a new adaptive compensation scheme is proposed.