The Research And Design Of 77GHz Automotive Radar System

With the rapid development of research relating with the concept of Autopilot,as one of the most important sensors in the advanced assisted driving system(ADAS),the vehicle's millimeter-wave radar(mm W Radar),has become a key research technology owing to its unique advantage that is not susceptible to smoke,rain and snow.Researchers and manufacturers are committed to a high-performance automotive millimeter-wave radar design at a suitable cost in a limited space,which will be mass-produced and widely used in the automotive market.Therefore,the research of 77 GHz millimeter wave radar system is of important theoretical research significance and engineering application value.The main work of this thesis is as follows:At first,this thesis investigate the research status of automotive millimeter-wave radar at home and abroad,and analyze its development trends.Secondly,the working principle of linear frequency modulated continuous wave system radar is expounded.The extraction process of detection target information is derived,including target distance and distance resolution,target relative speed and speed resolution,target angle and angular resolution.Accordingly summarizing the radar parameters affecting the performance is to guide the radar design.In engineering implementation,this thesis is started with the determination of the vehicle's millimeter-wave radar design scheme and decomposing the task.After comparing the solutions from various manufacturers,the solution based on the integrated transceiver chip is determined.The 77 GHz microstrip array antenna of the radar is designed,which is achieved higher gain by means of array,and lower side lobes by amplitude taper unit.According to the requirements of the integrated transceiver chip which has been selected,designs of its power management and storage circuit and peripheral circuits such as highspeed interfaces are accomplished,including circuit schematics and layout designs,as a single-chip solution.Furthermore,in order to improve the detection performance of the radar system,this thesis proposes a system scheme of cascading multiple transceiver chips based on the MIMO principle.Afterwards,this dissertation analyzes and overcomes the difficulties of the scheme with the arrangement of multiple transceiver antennas to improve the azimuth and elevation angle resolution;three key signals synchronization design of local oscillator signal,frame synchronization signal and clock signal;and optimizing the design of local oscillator signal power division network by back drilling technic after analyzing the influence of via stubs.Finally the cascade system circuit and PCB design is completed.The final work is to design the experiment,and design a general direction pattern test method for the on-board antenna radar,and complete the performance index test of the 77 GHz vehicle radar.The resolution of the distance is up to 8cm with the 3GHz sweep bandwidth,and the minimum angular resolution is about 16 in the case of 2TX with 4RX antennas.In outdoor measurement experiment the detection distance can reach 280 m.Experiment results show that the radar can meet the design requirements.