Research On Key Technology Of Laser Tracing Measurement

With the rapid development of modern industrial technology,the requirement of measuring accuracy,measuring range,real time and rapidity is more and more eigent.Laser tracing and measuring technology,as the kernel technology of fast precision measuring equipment,is playing an increasingly important role in the field of modern precision industry and engineering measurement.The purpose of "Research on Key Technology of Laser Tracing Measurement" is to study a laser tracing measurement technology on the basis of its mechanical structure.The research can realize precise tracing measurement for space target points,which provides a technical reserve for the innovation and independent research of laser tracing measuring instruments in our country.Firstly,principles of laser tracing measurement system are analyzed based on its mechanical structure.From the practical application,the mechanism of photoelectricity signal noise is analyzed in laser tracing measurement.And the fractional Fourier transform method is applied to filter the background noise of interference signal and tracing control signal,which lays a solid theoretical foundation for the establishment of the measurement control model and the development of the laser tracing measurement system.In this paper,a precise measurement method of relative displacement of space target points is presented.Based on the principle of laser interferometry and optical phase shift,a laser interference and tracing optical path system is constructed.The interference signal which can reflect the relative displacement of the spatial target point is obtained,and the offset of the spatial target point is obtained in real time.Combining the photoelectric receiving and signal processing circuit,the method can realize precision measurement of the relative displacement of space target points.In order to realize the precise tracking of space target points,a tracing control model with three closed loops of current,velocity and position is established.In this model,the current prediction algorithm based on the extended state observer is introduced into the design of the current loop,which avoids the influence of many internal and external factors for the traditional PI control.And it improves the dynamic characteristics and control accuracy of the current.The three-loop tracing control model effectively improves the dynamic and static characteristics of the system and improves the tracing speed and tracing accuracy of the system to the dynamic target.A laser tracing measurement system is proposed and developed.The laser interferometric ranging technology is applied to measure the relative displacement of space target points in real time and high precision.Meanwhile,with the PMAC motion control card as the main control unit,an electronic control system which integrates handwheel control,servo tracking control,signal processing and external analog power design is developed.The control system can realize the high-precision tracing of space target points.At last,the key technologies of the laser tracing measurement are simulated and verified by experiments.Works that have been done are outlined as belows:(1)The circuit of photoelectric receiving and signal processing is developed,which obtain the interference sinusoidal signal and square wave signal with 90 °phase difference.It proves the correctness and reliability of the circuit designed in this paper.(2)Based on motor model and vector control algorithm,the current loop predictive control algorithm is simulated and tested by MATLAB/Simulink software.(3)The measurement of laser tracing and spot offset is analyzed and verified by experiments.In the range of ±500 ?m,the average time for the offset laser spot to return to the center of the quadrant photodetector is 0.259 ms,and the maximum measurement error of the spot offset is 9 ?m.It verifies the effectiveness of the laser tracing measurement system developed in this paper.