The Full-waveform Laser Ranging Algorithm Based On Autocorrelation Interpolation And Realization On FPGA

Laser was widely used because of its good performance characteristics in all walks of life,laser ranging technology gradually replaced the traditional measuring method in the process of perfecting.At present,3D laser scanner based on the laser ranging technology has been used in the digital city,space system,mobile measurement and other fields,promoting the rapid development of national economy.It was generally believed that the accuracy was one of the important indicators to measure laser scanner performance.In recent years,the full-waveform laser ranging finder was favored by researchers because of its high accuracy.Its principle was to use the AD to code the echo signal,and then get its interval of time,eventually calculating the measured distance.In addition,the full-waveform ranging technology could also record intensity,be cable to more times echo amplitude analysis.However,in the process of actual measurement,especially in long distance measurement,laser pulse energy was a large amount of consumption,causing that the echo pulse was likely to be distorted in noise,which resulted in the received echo signal unidentified and brought huge difficulties to it.In this paper,the main research was aimed at solving the problems above.First of all,this paper analyzed the full-waveform laser ranging principle,and gave signal processing module design;Then,according to the situation laser echo signal becomes weak in long distance measurement,a full-waveform laser ranging algorithm was proposed based on autocorrelation interpolation.Following that,this paper completed the simulations based on MATLAB.Finally,with the FPGA as the hardware core,this paper implemented the algorithm and made experimental verification.The proposed algorithm firstly used the autocorrelation method to reduce the noise,and made pulse of seed and echo laser be superimposed as one signal.After the autocorrelation operation was carried out on it,the obtained three peaks waveform SNR was improved significantly.And then,this paper used cubic spline interpolation method to make curve fitting,which selected 0.01ns as interpolation interval time and the fitted waveform became very smooth.Following,using peaks value detection to determine the time interval and calculated the results.The simulations On MATLAB showed that theoretical precision up to 5mm@100 m based on the sampling rate 1.25 GHz.And it applied to the situation echo pulse was weak.Finally,with the FPGA as the device core,this paper completes the algorithm Verilog hardware language implementation and experimental verification.The proposed algorithm was successfully applied in the 3D laser scanner made by Wuhan Hi-target,which was consistent with the results of simulations on MATLAB.The proposed algorithm was of high accuracy and had better anti-interference ability.