Modern fighters are designed to fly at high angle of attacks reaching 90 deg as part of their routine maneuvers.These maneuvers generate complex nonlinear and unsteady aerodynamic loading.In this study,different aerod...Modern fighters are designed to fly at high angle of attacks reaching 90 deg as part of their routine maneuvers.These maneuvers generate complex nonlinear and unsteady aerodynamic loading.In this study,different aerodynamic prediction tools are investigated to achieve a model which is highly accurate,less computational,and provides a stable prediction of associated unsteady aerodynamics that results from high angle of attack maneuvers.These prediction tools include Artificial Neural Networks(ANN)model,Adaptive Neuro Fuzzy Logic Inference System(ANFIS),Fourier model,and Polynomial Classifier Networks(PCN).Themain aim of the predictionmodel is to estimate the pitch moment and the normal force data obtained from forced tests of unsteady delta-winged aircrafts performing high angles of attack maneuvers.The investigation includes three delta wing models with 1,1.5,and 2 aspect ratios with four determined variables:change rate in angle of attack(0 to 90 deg),non-dimensional pitch rate(0 to.06),and angle of attack.Following a comprehensive analysis of the proposed identification methods,it was found that the newly proposed model of PCN showed the least error in modeling and prediction results.Based on prediction capabilities,it is seen that polynomial networks modeling outperformed ANFIS and ANN for the present nonlinear problem.展开更多
This paper proposes a method of using multi controllers to control supermaneuverable aircraft. A nonlinear dynamic inversion controller is used for supermaneuver. A gain scheduled controller is used for routine man...This paper proposes a method of using multi controllers to control supermaneuverable aircraft. A nonlinear dynamic inversion controller is used for supermaneuver. A gain scheduled controller is used for routine maneuver. A switch algorithm is designed to switch the controllers. The flight envelopes of the controllers are different but have a common area in which the controllers are switched from one to the other. In the common area, some special boundaries are selected to decide switch conditions. The controllers all use vector thrust for lower velocity maneuver control. Unlike the variation structure theory to use a single boundary, this paper uses two boundaries for switching between the two controllers. One boundary is used for switching from dynamic inversion to gain scheduling, while the other is used for switching from gain scheduling to dynamic inversion. This can effectively avoid the system vibration caused by switching repeatedly at a single boundary. The method is very easy for engineering. It can reduce the risk of design of the supermaneuverable aircraft.展开更多
文摘Modern fighters are designed to fly at high angle of attacks reaching 90 deg as part of their routine maneuvers.These maneuvers generate complex nonlinear and unsteady aerodynamic loading.In this study,different aerodynamic prediction tools are investigated to achieve a model which is highly accurate,less computational,and provides a stable prediction of associated unsteady aerodynamics that results from high angle of attack maneuvers.These prediction tools include Artificial Neural Networks(ANN)model,Adaptive Neuro Fuzzy Logic Inference System(ANFIS),Fourier model,and Polynomial Classifier Networks(PCN).Themain aim of the predictionmodel is to estimate the pitch moment and the normal force data obtained from forced tests of unsteady delta-winged aircrafts performing high angles of attack maneuvers.The investigation includes three delta wing models with 1,1.5,and 2 aspect ratios with four determined variables:change rate in angle of attack(0 to 90 deg),non-dimensional pitch rate(0 to.06),and angle of attack.Following a comprehensive analysis of the proposed identification methods,it was found that the newly proposed model of PCN showed the least error in modeling and prediction results.Based on prediction capabilities,it is seen that polynomial networks modeling outperformed ANFIS and ANN for the present nonlinear problem.
文摘This paper proposes a method of using multi controllers to control supermaneuverable aircraft. A nonlinear dynamic inversion controller is used for supermaneuver. A gain scheduled controller is used for routine maneuver. A switch algorithm is designed to switch the controllers. The flight envelopes of the controllers are different but have a common area in which the controllers are switched from one to the other. In the common area, some special boundaries are selected to decide switch conditions. The controllers all use vector thrust for lower velocity maneuver control. Unlike the variation structure theory to use a single boundary, this paper uses two boundaries for switching between the two controllers. One boundary is used for switching from dynamic inversion to gain scheduling, while the other is used for switching from gain scheduling to dynamic inversion. This can effectively avoid the system vibration caused by switching repeatedly at a single boundary. The method is very easy for engineering. It can reduce the risk of design of the supermaneuverable aircraft.
