Development Of Long Distance Laser Ranging System Based On Dynamic Multi Threshold Error Correction Algorithm

Most civil pulsed laser ranging products didn't take into account precision impact derived from various complex measuring environments,so it is difficult to give consideration to the precision of both large and small targets.Laser based ranging technology is a commonly used method for distance measurement.For long-distance measurement requirements,it is difficult for the products and technologies on the market to balance the measurement distance and measurement accuracy except for some foreign products which are technically blocked and expensive.According to the above technical difficulties,this paper is concentrating on the lase based ranging technology,and designs laser based ranging hardware and software platform which achieves the precision of decimeter level with one kilometer range.The proposed laser based ranging system uses 905 nm wavelength semiconductor laser,avalanche photodiode(APD),and a picosecond resolution time measurement chip TDC-GPX2.Moreover,an automatic gain control(AGC)and an auto-correlation detection circuit are introduced for echo signal processing to improve ranging range and echo signal to noise ratio.At the aspect of software,UC-OSII embedded real-time operating system is adopted to realize time of flight measurement,data filtering processing,automatic gain control and dynamic multi-threshold error correction,therefore,multi-task processing modes applied to complete total ranging functions.Furthermore,a dynamic multi-threshold error correction algorithm is proposed to correct the time discrimination error of pulse front edge,and then the performance of dynamic multi-threshold error correction algorithm is verified by theoretical calculation and comparisons to the traditional double-threshold error correction algorithm.It is proved that the dynamic multi-threshold error correction algorithm can obtain ideal correction effect,so as to improve long-distance ranging accuracy.Finally,the system platform is built and the overall performance of the system is tested comprehensively.The results verified that the proposed system could achieve ranging resolution of0.15 cm,measuring distance of 1,000 meters the measuring precision of decimeter level,which meets the requirements in terms of ranging capability and measuring precision.