An Approach For Micro-lift Launch Vehicle Robust Attitude Control Based On Predictive Functional Control

With the demand of launching micro-satellites and developing operationally responsive space ability,low-cost,rapid-launch,micro-lift launch vehicle will lead an important trend in developing launch vehicles.Micro-lift launch vehicle adopts different actuators when it is in different height and is subject to fierce and various external disturbances,which lead to strong coupling and nonlinear flight dynamics with fast time-varying parameters.Taking micro-lift launch vehicle as the research object,this dissertation focuses on the attitude control system design and presents an approach for robust attitude control system design based on the predictive functional control(PFC).The main contents and results of this research are as follows:The control performance of PFC heavily depends on the accuracy of the predictive model.In order to tackle this problem,a novel robust predictive functional control based on equivalent input disturbance(EID)and generalized extended state observer(GESO)is presented(EID-GESO-based PFC).By means of the technique of EID,various disturbances and noises,as well as model parameter perturbations resulted from truncated nonlinear items and uncertainties can regarded as a lumped disturbance that acts via the control channel.The lumped disturbance can be timely estimated by GESO and eliminated in the negative feedback loop.And then the predictive model meets the model matching condition,which guarantees the precise tracking performance and strong robustness against disturbance and uncertainties of PFC.Meanwhile,closed-loop stability of the composite control is also provided with consideration of the dynamics of GESO.The presented approach is aimed at minimum informative demand for disturbances and the plant,affordable computational burden.And this method can be applied for non-integral chain fast-dynamics system subject to mismatched uncertainties without requiring availability of all the states and coordinate transformation.An application of the presented method to control system design of the micro-lift launch vehicle engineering example that adopts aerodynamic control surfaces as actuators is conducted.The numerical simulation results illustrate that micro-lift launch vehicle precisely and stably tracks the reference input command under the designed controller.Furthermore,a control performance comparison with some prominent methods in the presence of significant uncertainties demonstrates the effectiveness and robustness of the proposed design.Based on the EID-GESO-based PFC,another approach is presented in this dissertation,namely a multiple-input-multiple-output state dependent coefficient predictive functional control based on the generalized extended state observer(GESO-based SDC-MPFC).Inheriting the excellent control performance and strong robustness from the EID-GESO-based PFC,the novel method is applicable for multiple-input-multiple-output system.By means of the technique of quasi-Linear Parameter Varying(q-LPV),the pre-condition for EID-GESO-based PFC will be more easily meted in the practical application.At the same time,there is no need for decoupling and Jacobian linearization,which simplify the design process and saves the design time for introducing the technique of q-LPV.Furthermore,the presented approach makes it possible to work for the complete trajectory of the system state by a single design.This method is applied to design a three-channel coupling attitude controller for the upper-stage of micro-lift launch vehicle for angle of attitude tracking control.The feasibility of the method is illustrated by the satisfactory performance through the numerical simulation.In order to further demonstrate the superior of the presented method,a comparison with some pre-existing designs undergoing disturbances and measurement noise is exhibited.Under the significant uncertainties and disturbances,the phase plane controller,LQR-PWPF controller and PFC-PWPF controller fails in precisely tracking the reference input command but requiring frequency on/off control command,while the result of the proposed controller show excellent performance with high accuracy,fast response.The effect of the considerable uncertainty and disturbance is successfully estimated and rejected,where the effectiveness and the robustness of the proposed method is demonstrated and validated.This dissertation systematically investigates the micro-lift launch vehicle robust attitude control system design.The result of research could offer theoretical support and engineering application for flight attitude control system design,and also possesses great reference value and research significance for predictive functional control methodology research and robust attitude control system design.