Research On Signal Process And Calibration Algorithm In Online Dynamic Balancing Measurement

In order to realize the high speed, high efficiency, high precision machining, the most suitable spindle shape of CNC is directly putting stator and rotor into the interior of spindle unit, which forms an integrated structure of that motor rotor is the spindle and the shell of sprindle unit is motor base. The spindle unit is segregates from drive system and integral structure, called motor spindle. In the technology field of motor spindle, it is vital to speed up researching online dynamic balance technology for the development of high-speed and high-precision CNC. The online dynamic balance technology is a complicated problem which includes multidiscipline knowledge, the key of the online dynamic balance technology is designing reasonable and efficient signal processing algorithm, extracting dynamic unbalance signal and calibrating the amount of imbalance. The subject, funded by National Science and Technology Major Project, applying computer control technology and DSP, researches unbalance dynamic response analysis, test method, test signal processing and calibration for test signal of online dynamic balance. The main work is followed.1. the imbalance dynamic response analysis of the motor spindleThe paper, according to the kinetic equation of motor spindle, constructs finite element solid model and completes the modal analysis, reveals the kinetic characteristics in free modal of motor spindle. Through theoretical solution of kinetic model and simulation analysis of finite element model(FEM), the paper calculates the transfer characteristic of motor spindle in the function of the amount of unbalance, analyses kinetic response characteristics caused by imbalance and the changing rule of vibration response because of different amount of unbalance. The conclusion of theoretical solution and digital simulation simultaneously show that when rotate speed and damp are constant, dynamic response of unbalance is simple harmonic vibration, which is equal to the frequency of rotate speed and the amplitude is proportional to the imbalance amount.2. the component anaryzing and trend term processing of the vibration signal of motor spindleThe paper, according to the theory of online dynamic balance testing, comparatively analyses the theory and characteristics of several sensors, discusses the gain and process method of reference signal and vibration signal in great detail. Because of zero drift, acceleration signal integral in time-domain will generate trend term. So the paper puts forward a time domain integral algorithm of acceleration signal to eliminate the trend term and proves its effectiveness through simulation, which lays necessary foundation for the subsequent characteristics extraction of dynamic unbalance signal.3. the extraction and process of the dynamic unbalance signalThe vibration signal of motor spindle is low SNR and with strong interference, the paper designs and verifies two methods for extracting the amplitude and phase of unbalance signal. Pay attention to the low precision of conventional cross-correlation extraction of phase, which is caused by quantization error and nearly frequency interference, the paper puts forward a kind of improved signal extraction method based on cross-correlation. The method modifies and simplifies the algorithm of cross-correlation operation. The experiment verifies that this method obviously improves the extraction precision of amplitude and phase of vibration signal.The research shows that adaptive redundant second generation wavelet can effectively restrain frequency aliasing. On that basis, the paper comes up with a new algorithm of vibration signal de-noising, which combins adaptive redundant second generation wavelet with double variable improved threshold function. The simulation verifies the improvement of signal de-nosing effect resulted by bringing into double variable improved threshold function.4. the calibration algorithm of online dynamic balance testing system based on improved influence coefficient method.On the basis of the analysis of dynamic balance testing calibration model in ideal situation, the paper analyses the influence on calibration because of the main error of measurement. Starting with the three kind of error characteristics, the paper introduces simple linear regression theory and puts forward an influence coefficient calibration model with error correction function, and designs a amount of unbalance calibration algorithm which is rapid convergence and meets real-time requirement of online dynamic balance. Using the same calibration data, the system is separately demarcated by conventional influence coefficient method and the evolutionary influence coefficient method based on simple linear regression theory. The results show the validity and superiority.5. online dynamic balance testing prototype systemBased on the above research, the paper improves gradually software and hardware of system and builds a prototype system which satisfy the function and characteristics requirements of the online dynamic balance of motor spindle.