Hypersonic Vehicle Attitude Control Based On Direct Parametric Approach

The hypersonic vehicle has the characteristics of high nonlinearity,strong coupling,fast time-varying and severe uncertainty.The design of the attitude control system is extremely complex and difficult.Therefore,the research of hypersonic vehicle attitude control method has become a challenging and meaningful topics.In recent years,a growing number of scholars committed to solve the hypersonic vehicle attitude control problems.In order to overcome the problem that is difficult to measure the angle of attack and sideslip angle,the dynamical model in a matrix second-order nonlinear form with respect to the three Euler angles is established for the attitude system of a rigid vehicle.And direct parametric approach is applied to solve the problem of hypersonic vehicle attitude control.With the proposed controller parametrization,vehicle attitude systems,though highly nonlinear,can be turned into a constant linear system with desire eigenstructures.The main contents are as follows.Firstly,the attitude nonlinear model of hypersonic vehicle based on Euler angle is established in this paper.The dynamic model of hypersonic vehicle and its related theories are introduced.The dynamical model in a matrix second-order nonlinear form with respect to the three Euler angles is firstly established for the attitude system of a rigid vehicle.In order to utilize the direct parametric method,the hypersonic vehicle attitude model is transformed into the fully-actuated second-order nonlinear equation.Secondly,the direct parametric approach and the model reference output tracking method are utilized to design the attitude tracking controller,and the tracking of the hypersonic vehicle attitude is realized.A model reference output tracking controller design method based on fully-actuated second-order nonlinear system is introduced and deduced.Then,a direct parametric state feedback controller is designed by the direct parametric method for the hypersonic vehicle attitude nonlinear model.And the feedforward compensator is designed by the model reference output tracking method,and the two are combined to obtain the attitude tracking controller.Then,this paper uses famous winged-cone hypersonic cruise vehicle data model to realize six-degree-of-freedom nonlinear simulation of hypersonic vehicle control system.By analyzing the simulation results of the hypersonic vehicle's feedback controller and attitude tracking controller,the effectiveness of the controller is verified.Finally,the attitude tracking problem of hypersonic vehicle is studied under external unknown disturbance.According to the above,the error system of the second-order attitude control model is obtained.And the direct parameter controller based on the disturbance observer is designed for the error system,which successfully observes unknown disturbances and realizes the tracking control of hypersonic vehicles.Comparing the attitude curve and the disturbance observation curve before and after adopting the disturbance observer,the validity of the nonlinear disturbance observer and the controller is proved.