The Research And Design Of FMT System Based On Absolute Displacement Sensor

After years hard work, time grating[1-3] displacement sensor has got some major breakthroughs .it is a new kind of displacement sensor with a new principle.Due to avoiding precise mechanical reticles, it reduces processing difficulty and cost, at the same time ,it can resist oil stain and bug dust strongly and be highly intelligent. So it has high commercial value. This paper focuses on the application of time grating instand of grating or other tradional sensors in the transmission field instand of grating or other tradional sensors which can promote time grating from laboratory to market .In the transmission field, due to the transmission effect determined by transmission chain , so in order to get high presicion transmission, only researching the manufacturing error of single gear is not enough and high precision measurement of transmission error of whole transmission chain is necessary .Transmission error measurement system based on absolute time grating displacement sensor is designed combining time grating property with original FMT[4-8] .it has less link error , high precision , compact conformation and low cost .The main contents and innovation are as follows:1. FMT system theory is created based on absolute displacement sensor.Equal time sampling data can be transformed into equal space sampling data with TST[9-10] (Time Space Transformation) theory and data fitting[11]. transmission effect can be got by getting the error curve and analyzing frequency spectrμm with corresponding high-speed ,low-speed terminal sampling data.2. In the previous FMT system based on grating , signal frequency demultiplication and high frequency pulses interpolation are carried out by CPLD , and then transmission error can be got by counting high frequency pulses with external counter 8254.For time grating signal is different from grating signal , processing methods are different. Three frequency demultipliers , six 32-bits counters , two read-write modules and two FIFO modules can be designed into CPLD.in this experiment,high-speed ,low-speed terminal angle displacement measurement can be measured by counting high frequence pulses and then MCU read the data and send them into host computer to process with data packet . The advantage of this design make the electrical circuit more compact and more stable.3. A TE measurement system is designed by calling matlab program packet with VC++ language. It mainly inclodes data collection , real time analysis and frequency spectrμm three parts.4.Three experiments have been designed : simulation experiment , driving chain experiment of single transmission ratio , driving chain experiment of multi- transmission ratio .