Research On High Precision Encoder Signal Acquisition And Processing System Based On FPGA

With the continuous development of numerical control technology in the direction of high speed and high precision,numerical control machine tools put forward higher and higher requirements on the resolution,accuracy and volume of the position detection system of the photoelectric encoder.It has become more and more difficult for optical subdivision to increase its resolution by increasing the scribing density of the encoder in terms of achieving high resolution and high precision.Therefore,Electronic subdivision has become the main development direction of the encoder signal processing system because of its high precision,easy to realize the characteristics of measurement and data processing automation,etc.In this paper,through the principle of electronic subdivision and embedded hardware system in-depth study,set up a FPGA-based high-precision encoder signal processing system to achieve the reduction of peripheral circuits and without increasing the physical encoder of the premise Improve encoder resolution and subdivision accuracy.First of all,this paper studies the background knowledge of encoder and the subdivision technology and measurement theory of incremental encoder.Incremental encoder can be directly output phase difference of 90 ° sine cosine pulse signal,there is no power-down memory function.The resolution and accuracy of incremental encoders can be increased by frequency multiplication and pulse subdivision.Then,this paper introduces the hardware design of Spartan-6 series XC6SLX25 T chip as the core,simplifies the peripheral circuit except the core chip to the only A/D sampling and low-pass signal processing circuit,and completes software design according to the hardware structure and the functional module of the chip.FPGA module to complete incremental encoder digital signal reception,waveform conversion,coarse frequency multiplication of four times,subdivision precision and the final position calculation.Get high-precision location information,the precise location of the information provided to the subsequent motion control card for speed,acceleration calculation or directly to the motor control.Finally,the experimental and data analysis of the system is done in this paper.After analysis,this article designed FPGA-based high-precision encoder signal acquisition and processing system has the following characteristics: easy to use and debug,the system is modular,can be well integrated into the embedded system;achieving the required resolution,Based on the mechanical subdivision of the encoder,the design can subdivide the signal by 120 times and increase the resolution of the incremental encoder to 6’’.Through theoretical analysis,this design can achieve higher accuracy.