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First of all, a new multi-axis wrist force sensor with double bending beams was designed to meet the requirements of the intelligent manipulator. The new structure was easy to process and install. The impact of deformation, error and asymmetry caused by machining and aging treatment was avoided, and the performance of sensor was improved. Secondly, mechanical model of the sensor was established, and the force analyses from different directions were made. Thirdly, after strain gauges were pasted and the bridge was designed, loading tests to single beam and whole sensor were carried out, theoretical calculation and finite element analysis were completed, and the relative error was analyzed. Finally, the causes of relative error in different loading test were studied, and a solution of sensor calibration was put forward.

The characteristics of cockpit voices (sounds) recorded by Cockpit Voice Recorder (CVR) are key evidences in investigating accident causes for wrecked airplane. In order to analyzing and diagnosing wrecked airplane causes through cockpit voices in CVR, some researchers are made as followings in this paper: Firstly, some typical background sounds of cockpit voices, such as wind shear audio, near-earth audio warning, take-off form of audio warning, fire alarm and so on, are obtained and classified through listening and distinguishing by adobe audition audio software in laboratory. Then, the characteristics of these background sounds are extracted by signal analyses methods such as Fourier Transform (FT), Wavelet Transform (WT), and so on. Through these methods, the special characteristics are depurated, such as frequency value, spectral density, and frequency line numbers. Thirdly, as the key part of the paper, conditional rules and fault trees principles focuses on and applied in order to distinguish and diagnose these special characteristics for approximate or different background sounds of cockpit voices. And some available results are obtained finally. Through all these above researches, new analyzing and diagnosing approaches are put forward, which are suitable for accurate grasping the cause of flight accident and analyses and diagnose flight accident. All the researches and conclusions have a certain reference for analysis and diagnosis of flight accidents, and protect flight security.