Biologists have calculated the allometric growth patterns of birds in terms of morphological and motion parameters,expressing the five parameters of wingspan,wing area,cruising speed,flapping frequency,and flight powe...Biologists have calculated the allometric growth patterns of birds in terms of morphological and motion parameters,expressing the five parameters of wingspan,wing area,cruising speed,flapping frequency,and flight power as power functions of weight.Aviation designers utilize this formula to derive the initial values of the morphological and motion parameters of Flapping Wing Air Vehicles(FWAV),a process we refer to as the traditional scaling method.Traditional avian scaling laws establish power-exponential relationships between body weight and key flight parameters,guiding bionic aircraft design.However,limitations persist in their direct application to FWAVs.This study proposes an enhanced scaling law methodology addressing four critical aspects:(1)Introducing a weight correction coefficient to map avian flight functionality specifically to FWAVs design requirements,isolating flight-related mass from total avian mass associated with broader biological activities.(2)Rectifying the frequency formula by incorporating wing length-frequency statistics and integrating flapping amplitude via the Strouhal number definition,comprehensively representing motion parameters through periodic average angular velocity.(3)Refitting scaling law parameters using morphological data from specific bionic objects(e.g.,pigeons,eagles)to reduce parameter scatter inherent in traditional laws derived from birds spanning grams to kilograms with divergent morphologies.(4)Validating the method through the design and testing of a pigeon-inspired FWAV prototype.Experimental results demonstrate that parameters estimated via the improved method align closely with the optimized aircraft’s performance,achieving an endurance of 185 min on a single charge.This approach significantly reduces intermediate optimization needs,enhances design rationality,and provides a novel pathway for efficient FWAV development.展开更多
According to detonation theory and hydrodynamic principle, a physical model has been set up in this paper. Based on the model a methodology for calculating dynamic initial shock parameters such as shock pressure pm sh...According to detonation theory and hydrodynamic principle, a physical model has been set up in this paper. Based on the model a methodology for calculating dynamic initial shock parameters such as shock pressure pm shock wave velosity Dm etc. of coupling charge on borehole wall has ben developed. The shock parameters have been calculated when high explosives works on granite, limestone and marble respectively. The magnitude of every parameter on borehole wall has been obtained from ignited dot to the end of borehole along axial direction. Some important conclusions are also gained.展开更多
A control algorithm for a 3-RPS parallel platform driven by pneumatic cylinders is discussed. All cylinders are controlled by proportional directional valves while the kinematic and dynamic properties of the system ar...A control algorithm for a 3-RPS parallel platform driven by pneumatic cylinders is discussed. All cylinders are controlled by proportional directional valves while the kinematic and dynamic properties of the system are modeled. The method of adaptive robust control is applied to the controller using a back-stepping approach and online parameter estimation. To compensate for the uncertainty and the influence caused by estimations, a fast dynamic compensator is integrated in the controller design. To prevent any influence caused by the load applied to the moving platform changing in a practical working situation, the identification of parameters is taken as the initialization of unknown parameters in the controller, which can improve the adaptability of the algorithm. Using these methods, the response rate of the parameter estimation and control performance were improved significantly.The adverse effects of load and restriction forces were eliminated by the initialization and online estimation.Experiments under different situations illustrated the effectiveness of the adaptive robust controller with parameter initialization, approaching average tracking errors of less than 1%.展开更多
The status of disturbances of both initial values and parameters in the models is further investigated,the exact explicit estimates on the disturbance energy and disturbance potential enstrophy are given;and while the...The status of disturbances of both initial values and parameters in the models is further investigated,the exact explicit estimates on the disturbance energy and disturbance potential enstrophy are given;and while the initial disturbance fields rely only on the initial disturbance potential enstrophy,initial disturbance velocity circulation along the boundary,disturbance parameters,and the nonlinear stability criteria paralleling to Arnold’s second theorem are obtained,and the main results of Mu are generalized.展开更多
基金supported by the National Natural Science Foundation of China under Grant 52175277 and 12272318the Fundamental Research Funds for the Central UniversitiesND Basic Research Funds under Grant G2022WD.
摘要Biologists have calculated the allometric growth patterns of birds in terms of morphological and motion parameters,expressing the five parameters of wingspan,wing area,cruising speed,flapping frequency,and flight power as power functions of weight.Aviation designers utilize this formula to derive the initial values of the morphological and motion parameters of Flapping Wing Air Vehicles(FWAV),a process we refer to as the traditional scaling method.Traditional avian scaling laws establish power-exponential relationships between body weight and key flight parameters,guiding bionic aircraft design.However,limitations persist in their direct application to FWAVs.This study proposes an enhanced scaling law methodology addressing four critical aspects:(1)Introducing a weight correction coefficient to map avian flight functionality specifically to FWAVs design requirements,isolating flight-related mass from total avian mass associated with broader biological activities.(2)Rectifying the frequency formula by incorporating wing length-frequency statistics and integrating flapping amplitude via the Strouhal number definition,comprehensively representing motion parameters through periodic average angular velocity.(3)Refitting scaling law parameters using morphological data from specific bionic objects(e.g.,pigeons,eagles)to reduce parameter scatter inherent in traditional laws derived from birds spanning grams to kilograms with divergent morphologies.(4)Validating the method through the design and testing of a pigeon-inspired FWAV prototype.Experimental results demonstrate that parameters estimated via the improved method align closely with the optimized aircraft’s performance,achieving an endurance of 185 min on a single charge.This approach significantly reduces intermediate optimization needs,enhances design rationality,and provides a novel pathway for efficient FWAV development.
摘要According to detonation theory and hydrodynamic principle, a physical model has been set up in this paper. Based on the model a methodology for calculating dynamic initial shock parameters such as shock pressure pm shock wave velosity Dm etc. of coupling charge on borehole wall has ben developed. The shock parameters have been calculated when high explosives works on granite, limestone and marble respectively. The magnitude of every parameter on borehole wall has been obtained from ignited dot to the end of borehole along axial direction. Some important conclusions are also gained.
基金Project supported by the National Natural Science Foundation of China(No.51375430)
摘要A control algorithm for a 3-RPS parallel platform driven by pneumatic cylinders is discussed. All cylinders are controlled by proportional directional valves while the kinematic and dynamic properties of the system are modeled. The method of adaptive robust control is applied to the controller using a back-stepping approach and online parameter estimation. To compensate for the uncertainty and the influence caused by estimations, a fast dynamic compensator is integrated in the controller design. To prevent any influence caused by the load applied to the moving platform changing in a practical working situation, the identification of parameters is taken as the initialization of unknown parameters in the controller, which can improve the adaptability of the algorithm. Using these methods, the response rate of the parameter estimation and control performance were improved significantly.The adverse effects of load and restriction forces were eliminated by the initialization and online estimation.Experiments under different situations illustrated the effectiveness of the adaptive robust controller with parameter initialization, approaching average tracking errors of less than 1%.
摘要The status of disturbances of both initial values and parameters in the models is further investigated,the exact explicit estimates on the disturbance energy and disturbance potential enstrophy are given;and while the initial disturbance fields rely only on the initial disturbance potential enstrophy,initial disturbance velocity circulation along the boundary,disturbance parameters,and the nonlinear stability criteria paralleling to Arnold’s second theorem are obtained,and the main results of Mu are generalized.