Measurement Method And Implementation Of Velocity And Distance Of Landing Sensor

With the continuous exploration of space in various space power countries in recent years,human research on planetary exploration technology is also becoming more and more advanced.The countries have launched space exploration and completed the mission of detecting the moon and Mars.China also successfully launched the No.4 this year and realized the autonomous landing of the Lunar 4 detector on the back of the moon,achieved the soft landing of the first human moon.In order to further realize deep space exploration,China plans to conduct a land-based patrol inspection for Mars 400 million kilometers away in 2020,and obtain data with scientific research value.Drawing on the experience of the United States in implementing exploration missions and successfully landing on Mars in recent years in recent years,it can be seen that the key to the Mars exploration mission in China is undoubtedly the process of decelerating the landing of the parachute after the detector enters the Martian atmosphere.Therefore,whether the lander sensor can safely complete the precise fixed-point landing has become the top priority of the entire Mars exploration program.This thesis designs the landing radar signal processing system based on FPGA,realizes real-time processing of FMCW radar echo and obtains the speed and distance of the landing sensor relative to the complex Martian surface.Firstly,the design idea of landing sensor signal processor system based on FPGA+DSP is expounded.The process of measuring the internal speed measurement ranging signal of the land sensor FPGA and its implementation scheme are described.The implementation principle of the key steps in the process is detailed.Secondly,it focuses on the difficulties in the implementation of several key technologies in the speed measurement and ranging process of signal processing systems based on FPGA system design,mainly in the following aspects.Assign FPFA internal resources to complete system design;The digital down-conversion,noise estimation,and CFAR detection of the echo are implemented based on the FPGA,and the difference frequency of the frequency-modulated continuous wave echo signal is obtained by using the gravity center estimation method.Finally,in order to accurately evaluate the signal processing system and obtain its measurement performance.The difference frequency echo signals at each moment are simulated by the surface topographic relief information of Mars,the radar motion track information,the lander spatial position information and the attitude information,and the simulated results are modulated by the simulator and input to the FPGA signal processing system.After the solution,the distance and velocity information of the landing sensor relative to the surface of Mars is obtained.The speed measurement results after the FPGA processing are analyzed for error,and the factors affecting the accuracy of the system speed measurement are discussed and the accuracy of the speed measurement is evaluated.It is verified that the system can accurately obtain the distance and velocity information of the landing sensor relative to the surface of Mars within a certain error range.It verifies the correctness of the velocity measurement and the feasibility of the system design scheme.