In this paper,an intelligent control method applying on numerical virtual flight is proposed.The proposed algorithm is verified and evaluated by combining with the case of the basic finner projectile model and shows a...In this paper,an intelligent control method applying on numerical virtual flight is proposed.The proposed algorithm is verified and evaluated by combining with the case of the basic finner projectile model and shows a good application prospect.Firstly,a numerical virtual flight simulation model based on overlapping dynamic mesh technology is constructed.In order to verify the accuracy of the dynamic grid technology and the calculation of unsteady flow,a numerical simulation of the basic finner projectile without control is carried out.The simulation results are in good agreement with the experiment data which shows that the algorithm used in this paper can also be used in the design and evaluation of the intelligent controller in the numerical virtual flight simulation.Secondly,combined with the real-time control requirements of aerodynamic,attitude and displacement parameters of the projectile during the flight process,the numerical simulations of the basic finner projectile’s pitch channel are carried out under the traditional PID(Proportional-Integral-Derivative)control strategy and the intelligent PID control strategy respectively.The intelligent PID controller based on BP(Back Propagation)neural network can realize online learning and self-optimization of control parameters according to the acquired real-time flight parameters.Compared with the traditional PID controller,the concerned control variable overshoot,rise time,transition time and steady state error and other performance indicators have been greatly improved,and the higher the learning efficiency or the inertia coefficient,the faster the system,the larger the overshoot,and the smaller the stability error.The intelligent control method applying on numerical virtual flight is capable of solving the complicated unsteady motion and flow with the intelligent PID control strategy and has a strong promotion to engineering application.展开更多
Friction systems are a kind of typical non-linear dynamical systems in the actual engineering and often generate abundant dynamics phenomena.Because of non-smooth characteristics,it is difficult to handle these system...Friction systems are a kind of typical non-linear dynamical systems in the actual engineering and often generate abundant dynamics phenomena.Because of non-smooth characteristics,it is difficult to handle these systems by conventional analysis methods directly.At the same time,random perturbation often affects friction systems and makes these systems more complicated.In this context,we investigate the steady-state stochastic responses and stochastic P-bifurcation of friction systems under random excitations in this paper.And in order to retain the non-smooth of friction system,the generalized cell mapping(GCM)method is first used to the original stochastic friction systems without any approximate transformation.To verify the accuracy and validate the applicability of the suggested approach,we present two classical nonlinear friction systems,i.e.,Coulomb force model and Dahl force model as examples.Meanwhile,this method is in good agreement with the Monte Carlo simulation method and the computation time is greatly reduced.In addition,further discussion finds that the adjustable parameters can induce the stochastic P-bifurcation in the two examples,respectively.The stochastic P-bifurcation phenomena indicate that the stability of the friction system changes very sensitively with the parameters.Research of responses analysis and stochastic P-bifurcation has certain significances for the reliability and stability analysis of practical engineering.展开更多
文摘In this paper,an intelligent control method applying on numerical virtual flight is proposed.The proposed algorithm is verified and evaluated by combining with the case of the basic finner projectile model and shows a good application prospect.Firstly,a numerical virtual flight simulation model based on overlapping dynamic mesh technology is constructed.In order to verify the accuracy of the dynamic grid technology and the calculation of unsteady flow,a numerical simulation of the basic finner projectile without control is carried out.The simulation results are in good agreement with the experiment data which shows that the algorithm used in this paper can also be used in the design and evaluation of the intelligent controller in the numerical virtual flight simulation.Secondly,combined with the real-time control requirements of aerodynamic,attitude and displacement parameters of the projectile during the flight process,the numerical simulations of the basic finner projectile’s pitch channel are carried out under the traditional PID(Proportional-Integral-Derivative)control strategy and the intelligent PID control strategy respectively.The intelligent PID controller based on BP(Back Propagation)neural network can realize online learning and self-optimization of control parameters according to the acquired real-time flight parameters.Compared with the traditional PID controller,the concerned control variable overshoot,rise time,transition time and steady state error and other performance indicators have been greatly improved,and the higher the learning efficiency or the inertia coefficient,the faster the system,the larger the overshoot,and the smaller the stability error.The intelligent control method applying on numerical virtual flight is capable of solving the complicated unsteady motion and flow with the intelligent PID control strategy and has a strong promotion to engineering application.
基金the National Science Foundation of China through the Grants(11872306,11772256)the Central University Fundamental Research Fund(3102018zy043).
文摘Friction systems are a kind of typical non-linear dynamical systems in the actual engineering and often generate abundant dynamics phenomena.Because of non-smooth characteristics,it is difficult to handle these systems by conventional analysis methods directly.At the same time,random perturbation often affects friction systems and makes these systems more complicated.In this context,we investigate the steady-state stochastic responses and stochastic P-bifurcation of friction systems under random excitations in this paper.And in order to retain the non-smooth of friction system,the generalized cell mapping(GCM)method is first used to the original stochastic friction systems without any approximate transformation.To verify the accuracy and validate the applicability of the suggested approach,we present two classical nonlinear friction systems,i.e.,Coulomb force model and Dahl force model as examples.Meanwhile,this method is in good agreement with the Monte Carlo simulation method and the computation time is greatly reduced.In addition,further discussion finds that the adjustable parameters can induce the stochastic P-bifurcation in the two examples,respectively.The stochastic P-bifurcation phenomena indicate that the stability of the friction system changes very sensitively with the parameters.Research of responses analysis and stochastic P-bifurcation has certain significances for the reliability and stability analysis of practical engineering.
