Design Of The Real-time Measurement System For Absolute Optical Encoders

A measurement system for absolute optical encoders is designed based on the survey of the measurement requirements of absolute optical encoders in an enterprise.FPGA is employed as the main control chip for the measurement controller in this system.The system hardware is composed of the USB interface chip and other cooperative chips.The software is used for data processing to measure absolute optical encoders.This thesis first introduces the development of absolute optical encoders and their main working principles.Also,the shortcomings of the existing measurement systems are deeply discussed to implement the measurement in real applications.Second,the measurement controller is designed for measuring on the basis of deeply understanding some techniques of absolute optical encoders,which are communication protocol,USB communication protocol,USB driver,BISS communication protocol,FPGA chips.Next,with the study BISS communication protocol,the host IP core is designed in Quartus II,the FPGA development software.Then,the software framework is designed based on the IP core.Modules are designed for specific functions in software.Finally,the software of the measurement controller is designed.The software of the upper computer is implemented for the communication between the upper computer and the FPGA chip through USB interfaces.That is,the measurement controller is controlled by the upper computer to complete various instructions.Finally,a testing platform is built for absolute optical encoders.A large number of testing experiments are carried out by using the laser interferometer as the reference.Then,error compensation is implemented.The parameters of the software are adjusted and the modules are optimized in the experiments,which are useful for reducing the delay.The experiment results show that the measurement controller can realize the precision measurement of the absolute optical encoder with a relative low latency.