The Study On Grating Subdivision Technology Based On DSP2812

Grating technology is widely used. In addition to used in large precision CNC machine tools, measuring instruments area, it also used in the portable precision measuring instruments also gradually popularized by recent years. Traction Power State Key Laboratory of Southwest Jiaotong University developed five-bar mechanism wear precision rofilometer is also used the Grating measurement to measuring the angle. Grating subdivision is an important way to realization precision measurement, in order to tracking the technology development, improve the measurement accuracy of five-bar mechanism wear precision rofilometer, this paper did research on grating subdivision technology as following:First, analysis the principle of grating measurement, studied on the characteristic of classics subdivision method and new subdivision method, according to the current development of modern digital signal processor (DSP), combined with the actual grating, selects a the amplitude phase subdivision method combining hardware and software. Designed the overall program, selecting and functional designing the main subdivision system function modules.Secondly, designing the hardware circuit of subdivision:DC component in the output signal filtered by differential amplifier circuit, then one road sine wave converted to square wave when passed over zero-crossing comparison circuit; the other road filtered the high-frequency noise by a low-pass filter circuit, the two road signals through separate addition and proportion arithmetic circuit with different parameters of for amplitude regulation for amplitude regulation to meet their the requirements of signa input subsequently; The orthogonal coding module of DSP2812chip was used to identify the direction and count, its AD conversion module detects the grating signal voltage waveform, serial communication module is used to send subdivision counting results.Once again, the preparation of the DSP software:initialized and set the QEP, AD module and serial port, designed the program of digital filtering on the number of samples is filtered, zero compensation program module to eliminate temperature drift designed amplitude phase subdivision table, writing the look-up table procedures, realized displacement of nonholonomic pulse subdivision count, designed the program of serial port sending to realized the correct data transmission.