Research On Decoupling Algorithm Of 3D Scanning Probe And Development Of Precision Detection Circuit

Three-dimensional scanning probe is the key component in large precision measuring instrument,whose detection accuracy directly affects the accuracy of large precision measuring instrument.At present,most of the three-dimensional scanning probes adopt parallelogram flexible guiding mechanism,which may have cosine errors in principle,such as parallel reed,flexure hinge and flexible rod group.In the three-dimensional scanning probe,the errors in each direction will be coupled with each other,which will adversely affect the overall detection accuracy of the three-dimensional scanning probe.Therefore,by studying the topology of the three-dimensional scanning probe with series structure,establishing the coupling error compensation model of the three-dimensional scanning probe,designing the high precision detection circuit of the three-dimensional scanning probe.This study can realize the coupling error compensation in the lower computer..Besides,It can also provide technical reference for improving the detection accuracy of three-dimensional scanning probe.In this paper,the basic structure and measurement principle of three-dimensional scanning probe has been analyzed,and the basic structure of parallelogram flexible guiding mechanism has been summarized.The topology of three-dimensional scanning probe of series structure has been studied,and the mathematical model of corresponding coupling error of three-dimensional scanning probe of series structure has been established,which can provide a theoretical basis for realizing coupling error compensation.Secondly,according to the requirement of detection precision of three-dimensional scanning probe,the data acquisition circuit which focuses on ADA2200 demodulation circuit has been designed.It mainly includes ADG794CMOS switch circuit,ADA2200 demodulation circuit,AD7192 ADC conversion circuit,main control chip core circuit,power supply circuit and so on.The PCB board design,circuit welding and debugging has been completed,the RS232 communication mode has been adopted to communicate with the upper computer,and then the coupling error compensation has been realized in the lower computer software.Finally,the preliminary test shows that the three-dimensional scanning probe data acquisition system which has been already designed can realize the normal acquisition of LVDT displacement data.the standard deviation of the measured results is 0.0124μm,and the non-linearity is 0.414%by he least square fitting.