Fault-tolerant Control Of Launch Vehicle With Considering Engine Thrust Loss

According to launch situation of vehicle launches,the engine fault is the main fault in the flight of launch vehicle,and the thrust loss is its main performance.When the engine thrust has failures,rocket’s fuel is not consumed by the predetermined mode,which will cause the rocket kinetic parameters big deviations;Meanwhile,this also causes a change in rocket control torques,thus affecting the stability of the attitude control system of the rocket.This paper carries out the study fault-tolerant control problem of rocket engine thrust loss response to these problems,the following key elements:(1)The three-channel attitude dynamic coupling rocket model consideration of elastic vibration is described;then basic attitude control methods: designs of the PD controller and correction network are described.Based on these,the main effects of thrust loss on dynamic characteristics of a launch vehicle are analyzed: it will lead the dynamic model’s parameters to have large deviations and control torques to change.These are to lay the foundation for the take-over of fault-tolerant control.(2)Considering large deviations of the model parameters resulting from loss of thrust,the augmenting adaptive control(AAC)method is used to carry out the fault-tolerant control study.When the rocket thrust loss occurs,since the fuel consumption of failure to a predetermined pattern,causing the rocket quality characteristic changes,and resulting in a large deviation of rigid and elastic coefficients occurs.In this regard,firstly,the AAC study is carried out on the large deviation of rigid body parameters,the mechanism of AAC adaptive adjustment is analyzed,and the influence law and selection method of each design parameter on the control effect in AAC are given.Then,the large deviations of elastic frequencies and vibrations are further studied.Finally,the simulation results show the AAC has a good ability to apply large deviations of model parameters that rocket thrust loss causes.(3)For the problem of control torques change resulted in thrust loss,respectively control torque reconstruction and AAC with the torque reconstruction are used to carry out the faulttolerant control study.Engine thrust loss can lead to generating disturbance torques because of thrust force imbalance,and also leads to a change in control torques.In this regard,binding AAC and control torque reconstruction,the fault-tolerant control method of control torque reconstruction and AAC combined is proposed,and a study on it is taken.Simulation results show that the proposed fault-tolerant control method can well improve system response under the thrust loss,but oscillation problems caused by high gain should be paid attention to.