Design Of A Force Measuring System For Mav And Study On The Force Of Flapping Wing Prototype

The bionics flapping micro air vehicle(FMAV) has a good application prospect in the military and civil, because of its small size, good stealth performance, high propulsion efficiency, good mobility and other characteristics. It has been a hotspot in the research in recent years. The aerodynamic characteristics of flapping micro air vehicle determines not only the flight performance, but also the foundation of the flight control, so it has been the focus of people’s attention. In the research process of bionic flapping wing aerodynamic performance, the aerodynamic of low Reynolds number, unsteady effect is obvious, due to the small size of the flapping wing, low rate and fast flutter. So it is difficult for the traditional theory and methods to solve the problems, while the flapping wing prototype force measuring experiment is a method to obtain the aerodynamic performance. However, the weight of bionics flapping is light, and the lift and drag are relatively small, so the appropriate force measuring device is required to match the measuring force.Therefore, this article will develop a suitable small measuring range force system for flapping wing lift and thrust measurement, and study the aerodynamic characteristics of lift and thrust of flapping wing prototype.According to the characteristics of small changes and cycle dynamic change of flapping wing MAV aerodynamic, and taking into account that the resistance strain sensor is suitable for the characteristics of static and dynamic measurement, in this paper, the 3D small range of strain sensor is designed. After the research and analysis of the principle of the corresponding variable sensor, this paper designs a kind of "L" type of three-dimensional force sensor with low range. Through Ansys simulation, it is proved that the structure has a linear response to the applied force, good self-decoupling property, and is not sensitive to the disturbance of a certain range of spatial 3D torque. The "L" type of sensor is made by screw assembling processing. Though the theoretical analysis, the results shows that it has similar characteristics with integrated measurement sensor.In this paper, the static calibration of the combined sensor is carried out by means of experiments, and the input and output characteristics of the sensor are studied. The outcome indicates that the sensor has good linearity, good self-decoupling and the sensor has better resolution under zero load. The sensor gets higher precision by error analysis. The results of three dimensional force measurement show that the combined sensor is feasible.Flapping wing aerodynamic measurement belongs to dynamic measurement which is affected by the dynamic response, and multidimensional dynamic force coupling also affects the sensor’s accuracy. In this paper, the measurement of the single dimensional dynamic force is analyzed, and the method of the three-dimensional dynamic force decoupling is given. Finally, the modal analysis of the sensor is carried out with Ansys software. The results show that the sensor has high natural frequencies, which means good dynamic performance.This article makes an aerodynamic test on characteristics of flapping wing micro air vehicle prototype and gets the change of cycle aerodynamic force out-put by the three-dimensional force sensor. At the same time, the effects of fla pping frequency, air flow and other factors on the average lift and thrust is stu died, and the results are in accord with the related theories and experimental re-searches.In brief, the design of the force measuring platform of flapping wing air has reference value.