Aiming at the problem that flight data recorder taken aircraft directly as testing signal resource in the process of development and debugging of the flight data recorder is very difficult, the flight data signal generator based on embedded system is designed, which purpose is to simulate the status signal of aircraft and each component of aircraft during flight, providing test signal source for flight data recorder. Interactive interface was designed on PC by LabVIEW, which was used for setting parameter values of each signal; STM32 microcontroller received the parameter value and controlled each generating module to generate electric signal. All generating modules link with the Bus network, and the network will be easy to increase or decrease generating module. Experiment results show that the flight data signal generating system can simultaneously generate 138 signals, including analog, digital, synchronous, frequency, ARINC429 bus signals etc, and can work stably.

The introduction of the direct digital frequency synthesis (DDS) technology in the field of communication is against the traditional ultrasonic machining power supply which does not have the multi-frequency tracking shortcomings to build a frequency conversion type ultrasonic power. Frequency conversion type ultrasonic power supply is based on DSP embedded system and adopts direct digital frequency synthesis (DDS) technology combined with a software phase locked frequency of composite frequency tracking scheme to realize automatic search transducer resonance frequency and frequency automatic tracking function which can response the different characteristics of the transducer dynamical; With the use of phase shift control power-principle to realize the output power regulating function when the frequency changes and reduce the switching power loss; It provides an important reference for the design of new frequency conversion type ultrasonic power.

To recognize whether there exist crack damages in the inner structure of aircraft engine based on the borescope images, a method is presented by estimating the coarse feature of edges extracted from borescope images. The method first decomposes an edge into the approximation and details using wavelet transform at all of the possible scales. For the coefficients of the wavelet transform, the logarithm entropy is presented to represent the respective strength of the approximation and details, and the ratio of the two logarithm entropies is defined as coarseness factor. The coarseness factor can be used to estimate the coarseness of an edge. The greater the coarseness factor is, the coarser the edge is. Experiment results show that using coarseness factor as recognition feature of borescope images, the crack damages of the inner structure of aircraft engine can be recognized successfully.

For the requirement of the department for aviation accident investigation, a computer information system of processing the broken tape of flight data recorder has been designed. The main principles of the system are that magnetic track images are first preprocessed using image processing techniques, furthermore, the position coordinates of tracks are obtained using image recognizing techniques, finally, the data corresponding to track coordinates are obtained by encoding the track coordinates using the serial-parallel scanning method that is specially designed. The accurate ratio of automatic encoding is 99.3%. The times of automatic encoding are reduced to proximate 5 seconds from about 4 hours of two operators for one frame track image. This system is significant for aviation accident investigations.

A measurement method based on digital MEMS’ acceleration sensor is proposed. The paper analyzes the working principle of capacitive acceleration sensor. According to the coordinate space transformation theory, a mathematical model of the measurement method was built, and the mathematical expressions of the angle displacement of aircraft rudder was deduced; A measurement system of aircraft tail wing inclined was established using MEMS’ acceleration ADXL345, and taken STM32 as controller. Setting different angles in 3D turntable and aiming at a typical inclination angles, the aircraft tail rotation angle experiment was simulated, and experiment achieved angle measurement arranging from-90°-90°. Experiment results demonstrate that when the inclination is close to the real inclination of aircraft tail wing, the maximum error is 0.277°, less than 0.3°, which meets the requirement of measurement. For aircraft currently being used, the measurement method can achieve the angle measurement of aircraft tail wing rotating effectively.