Research On Hybrid Waveform And Target Detection Algorithm Of Millimeter Wave Radar

With the continuous improvement of people's living standards,higher requirements are put forward for the intelligent level of automobiles.The advanced driver assistance system appeared.After years of development,the advanced driver assistance system has formed a complex information collection system composed of multiple sensors,and millimeter wave radar is an important part of the system.Because the millimeter wave radar has the advantages of small size,low cost,and less impact from rain and snow,it has received extensive attention from major automobile manufacturers and scientific researchers.At present,mainstream millimeter wave radars in the automotive field are divided into two frequency bands,24 GHz and 77 GHz.The 24 GHz band radar has a lower frequency and a longer wavelength,and the detectable distance is longer.However,the bandwidth of this frequency band is only less than 250 MHz,and a single waveform cannot achieve better detection performance of high-speed and long-distance targets,which limits the use of millimeter-wave radars in this frequency band to a certain extent.Therefore,this thesis studies the mixed waveform design of the 24 GHz millimeter-wave radar,which improves the detection capability of the 24 GHz millimeter-wave radar for high-speed and long-distance targets.The 77 GHz millimeter wave radar has high frequency,short wavelength and large bandwidth.Sawtooth frequency modulation continuous wave has better target detection performance in this frequency band.However,when the target speed is greater than the maximum unambiguity speed of the radar system,there is a speed ambiguity problem.Therefore,this paper studies the millimeter wave radar speed defuzzification algorithm in the 77 GHz frequency band to improve the radar's ability to detect high-speed targets.First of all,this thesis introduces the research background and significance of millimeter-wave radar,as well as its domestic and foreign research status in vehicle systems,waveform design,and defuzzification algorithms.Subsequently,through the derivation of the target detection principle of triangular frequency modulation continuous wave,sawtooth frequency modulation continuous wave,and constant frequency continuous wave,the target detection ability of different waveforms is analyzed from a mathematical perspective.Through the introduction of doppler effect,doppler ambiguity,radar equation and other principles,it provides a theoretical basis for algorithm research and implementation.Secondly,the mixed waveform design of 24 GHz millimeter wave radar is researched.Aiming at the disadvantages of millimeter-wave radar's single waveform in detecting high-speed and long-distance targets and the coupling of distance and velocity,a hybrid waveform is designed based on the original single waveform.The hybrid waveform is composed of up-frequency modulated continuous wave and down-frequency modulated continuous wave,constant frequency continuous wave composition.At the same time,the signal processing algorithm has been improved accordingly,so that the target information can be obtained from the mixed waveform echo.The simulation results show that the designed mixed waveform and algorithm can accurately obtain high-speed and long-distance target information.Finally,the speed defuzzification algorithm of 77 GHz millimeter wave radar is researched.Aiming at the disadvantages of the traditional speed defuzzification algorithm based on the Chinese remainder theorem,such as poor robustness and high algorithm complexity,an improved speed defuzzification algorithm based on the Chinese remainder theorem is proposed.The improved algorithm avoids directly solving the congruence equations.In the speed range of interest,the target actual speed is predicted based on the fuzzy speed,and the target actual speed is finally obtained by comparing the two sets of predicted values.Simulation comparison results show that the improved algorithm has better speed defuzzification performance and robustness than traditional algorithms.At the same time,the program design of the improved speed defuzzification algorithm based on the77 GHz millimeter-wave radar hardware platform IWR1843 is completed,which shows that the improved algorithm has certain engineering application value.