Study On The Principle And Signal Processing Method Of Sensing Angular Displacement With Self-Scale-Division And Non-Contact

Rotating machinery is a common mechanical structure form, such as transmitted chains of various processing machine tools, ship propellers, aiming and tracking apparatus of a weapon’s actuators, etc. The accurate measurement of angular displacement can help us to understand the operation states and performance, and to decide the kinetic characteristics for improving the accuracy of moving process control of rotating systems, and can also do us a favor to acquire fault information in machine diagnoses. Therefore, the exact measurement of angular displacement is vitally important and it has been widely applied to mechanical testing field. Considering the common deficiency that a precise circular division disk is needed for the angular displacement sensor at present, this paper has proposed a new approach for sensing angular displacement by use of spatial filtering technique(SFT). The principle and signal processing methods of sensing angular displacement were preliminarily studied, and an experiment system was established. The main works in this paper are as the followings:This paper presented the principle of sensing angular displacement in detail after illustrating the study of domestic and abroad on measurement of angular displacement. Two parallel photovoltaic arrays arranged with a certain interval are used to form a double-differential-spatial-filtering(DDFS) sensor, and high frequency impulse interposition method that used to obtain two center frequencies of output signals of the DDSF is analyzed. Then an angular measurement method based on instantaneous angular velocity and time-slice is elaborated, namely, the quasi-instantaneous angular velocity is obtained by use of the two central frequencies, and micro angular displacement in a time-slice is obtained by multiplying the quasi-instantaneous angular velocity and the time-slice into each equant time-slice, and the angular displacement of target object is obtained by adding the micro angular displacement in each time-slice together.This paper analyzed the signal and information processing method in angular displacement sensing with SFT. That is, the output signals of the DDSF were converted into two complementary rectangular signals via the wave conversion, and the breadth of the two rectangular signals were completely obtained via high frequency pulse interposition method, so the central frequencies of the quasi-sinusoidal signals of the DDSF were gained by use of the breadth.Signal preprocessing, data acquisition and processing subsystem, which includes the forth-order butterworthe low-pass filter circuit, the rectangular signal transformation circuit, the counting circuit based on high frequency pulse interposition method and the data acquisition and processing circuit based on ARM9, was designed and manufactured.Finally, the extraction of central frequencies of output signals of DDSF was realized through programming, as well as the calculation and display of angular displacement of measured body, and the corresponding angular displacement sensing system was established.The sensing method is without any circular indexing plate coaxially installed in the measured body and can be used to measure the angular displacement with self-scal-division and non-contact. At the same time, the method has promising prospect of application since it is insensitive to the radial fluctuation, axial shift, eccentricity and parallel movement and installation error of the measured object and can be widely applied to monitoring various rotary system.