Mechanism and experiments of asymmetrical pitch system for MAV
In view of problem for miniaturizing Micro Air Vehicles (MAV), a novel asymmetrical pitch system faced to rotary wing MAV is introduced. The pitch mechanism and control characteristics are studied and analyzed. Because the deformation of elasticity link is key to generate the blade pitch, it is analyzed and calculated by elasticity finite element method. And the results illustrate the linear relationship between blade pitch angles and the output torque of the motor. Based on control system of asymmetrical pitch, mechanism experiments based on strain gauge are done, and the factors that affect the deformation of the elastic linkage is analyzed. Results indicate that mechanism of asymmetrical pitch is effective.
A novel asymmetrical pitch system for a rotor micro air vehicle
Concerning to problems of the traditional machine pitch system for miniaturizing Micro Air Vehicles (MAVs), A novel asymmetrical pitch method is put forward in this paper. This novel method makes use of the deformation of an elasticity link to generate the blade pitch meeting the requirement of the MAV flight mode control. This new pitch mechanism has been verified by means of two experiments. One experiment measures blade pitch angle by a non-contact measurement using the high speed camera and image processing and the other experiment measures deformation of the elasticity link which is key part in asymmetrical pitch system based on strain gauge and rotating electrical connector. From relationship between blade pitch angles and the output torque of the main motor and deformation curves of the elasticity link, the pitch mechanism that the deformation will periodically change once with the rotor blade rounding a lap is proved.
Robust solutions of inverse problems in electromagnetic non-destructive evaluation
Non-destructive testing (NDT) is the application of physical measurement technology based on energy interaction with the material and its nonconformities. The material's response is sensed by transducers and sensors which?in most cases?scan the component and document the results in inspection images. However, NDT measures a physically defined quantity or even an intrinsic property. The difference between non-destructive evaluation (NDE) and NDT is in the interpretation of the inspection data. NDE has to discuss the inspection results in terms of quality elements and characteristics which are relevant to describe the fitness of the material for use. In the case of macroscopic defects these are the kind of defect (cracklike, globular) and its size and orientation to the main stress directions; in the case of material property determination the parameters are mainly mechanical properties. Therefore, in NDE one has to solve inverse problems. The solution of inverse problems based on mathematical procedures such as integral equations is a strong developing discipline and most of the articles prepared for this special issue of the journal have the objective of discussing the latest state of the art in that field. However, practical NDE needs robust and quick solutions which are to be applied mainly online. Therefore, we present here inversion procedures based on multiple linear regression algorithms applied to inspection data. We describe the calibration procedure to fit the free parameters of the model functions and give examples of practical applications in industry.