For the problem of attitude control of a quad tilt rotor aircraft with unknown external disturbances, a class of control methods based on a new exponential fast nonsingular terminal sliding surface, a new fast reachin...For the problem of attitude control of a quad tilt rotor aircraft with unknown external disturbances, a class of control methods based on a new exponential fast nonsingular terminal sliding surface, a new fast reaching law, and a super twisting sliding mode disturbance observer is investigated. First, the new exponential nonsingular terminal sliding surface is designed by using the advantages of nonsingular terminal sliding mode finite time convergence and strong robustness. Second, to solve the problem of a long convergence time and the serious shaking of the traditional reaching law, a new fast reaching law model with characteristics of the second-order sliding mode is put forward. Third,considering the existence of complex disturbances, the super twisting sliding mode disturbance observer is used to estimate and compensate the composite disturbances online. Finally, compared with the traditional nonsingular fast sliding mode control, simulation results show that the proposed control scheme achieves a good control performance.展开更多
Aim To put forward a type of math model for optimizing fan′s twisting law.Methods This math model wu based on turbo-machinery Euler equations and calculus of variation, it was conducted for optimizing the aerodynamic...Aim To put forward a type of math model for optimizing fan′s twisting law.Methods This math model wu based on turbo-machinery Euler equations and calculus of variation, it was conducted for optimizing the aerodynamic parameters along the blade height of the fan, and the math method was produced for the optimization of fan's twisting law. Results The type 6102Q engine cooling fan was optimized by use of this model, and the calculation on data were contrasted with those of iso-reaction coefficiency flow type and free vortex flow type. Some probleme existing in long blade can be solved by use of above method. Conclusion The design parameters needn't be determined artificially, so calculating results are more rational to a high degree than that from other mehods.展开更多
基金supported by the National Natural Science Foundation of China(11202162)
文摘For the problem of attitude control of a quad tilt rotor aircraft with unknown external disturbances, a class of control methods based on a new exponential fast nonsingular terminal sliding surface, a new fast reaching law, and a super twisting sliding mode disturbance observer is investigated. First, the new exponential nonsingular terminal sliding surface is designed by using the advantages of nonsingular terminal sliding mode finite time convergence and strong robustness. Second, to solve the problem of a long convergence time and the serious shaking of the traditional reaching law, a new fast reaching law model with characteristics of the second-order sliding mode is put forward. Third,considering the existence of complex disturbances, the super twisting sliding mode disturbance observer is used to estimate and compensate the composite disturbances online. Finally, compared with the traditional nonsingular fast sliding mode control, simulation results show that the proposed control scheme achieves a good control performance.
文摘Aim To put forward a type of math model for optimizing fan′s twisting law.Methods This math model wu based on turbo-machinery Euler equations and calculus of variation, it was conducted for optimizing the aerodynamic parameters along the blade height of the fan, and the math method was produced for the optimization of fan's twisting law. Results The type 6102Q engine cooling fan was optimized by use of this model, and the calculation on data were contrasted with those of iso-reaction coefficiency flow type and free vortex flow type. Some probleme existing in long blade can be solved by use of above method. Conclusion The design parameters needn't be determined artificially, so calculating results are more rational to a high degree than that from other mehods.
