Processing And Applying Of The Heidenhain Encoders With High Precision

In the large inertia turntable control system of modern industry, the control of the motorservo control system is its important component. As a locating and speed measuring device, theencoder testsmotors’displacement (linear displacement or angular displacement) and speed,then sends feedback signals to the numerical control device, which is a constituent part of servosystem’s closed loop or half closed loop control, thus making workbench path accuratelyaccording to the instructions.The choice of the encoder and its signals’ processing directlyaffect the stability and reliability of the whole system’s working. Aiming at high-precisionphotoelectric encoders that produced by Germany Heidenhain company, this thesis,on the baseof Xilinx FPGA chip xc3s700AN and Texas Instrument(TI) DSP chip TMS320F28335, designeda general encoder signal measurement and processing system, which can measure and processthe incremental encoder signals, and absolute encoder signal with EnDat2.2two-way digitalinterface.First of all, in this paper, I’ve studied the encoder relevant background knowledge, and thecoding and measuring theory of photoelectric encoder. An incremental encoder makes directpulse output, does not have memory function when power supply drops. People can improvethe measuring accuracy of incremental encoder by means offrequency multiplication, pulsesubdivision and signal acquisition by multi-read heads, etc. TheHeidenhainincremental encoderwith two scale codes not only has high precision, can also speed up the reference point back tozero. With EnDat2.2two-way digital interface, Heidenhain absolute encoders work reliably, andcan send additional information such as parameters.Then, this thesis introducesthe hardware design,whose core structures arethe xc3s700ANchip and TMS320F28335chip,and the software design according to the hardware structure andchip functions module. The FPGA part completesthe direction-discriminating and pulsescounting processing of incremental encoders, communication with absolute encoder, and thedata written to the dual port RAM. The DSP part reads data from the FPGA chip,calculateslocation value, and passes the final data to the PC.After the experiments and analysis of the system obtained, this essay introduced theapplication of Heidenhain encoders and this system in our lab.Thegeneral signal measuring and processing system of Heidenhain encoders with highprecision based on FPGA and DSP, which designed in this thesis, has features as listed below:users can quickly grasp its convenient use and debugging; through experiments and detection,its proved to be working reliable as target; the system is modular and can be incorporated into embedded systems very well.At present, the system modules have been combined into the drive control boxes and putinto use.