| As Advanced Driver Assistance System(ADAS)has the advantages of reducing the vehicles’ accident rate and improving the safety and comfort ability,it has attracted extensive attention from domestic and foreign researchers in recent years.However for special vehicles like emergency vehicles,border patrol vehicles,armed vehicles work in the harsh environment of extreme weather and complex terrain,it is difficult to ensure the safe movement of vehicles without effective perception of the environment.In addition,there is the requirement for formation and cooperation when multi vehicles take task execution collaboratively.So it is significant to study the ADAS system for special vehicles.At present,ADAS system for special vehicles faces technical challenges like complex environment perception,single-hop fully connected network establishment and multi-hop AD hoc network establishment.In view of the above requirements,this dissertation carries out research in four aspects: two dimensional millimeter wave radar,three dimensional millimeter wave radar,multi-channel information interaction and vehicle AD hoc network.The innovation points are as follows:1.Aiming to solve the receiving bandwidth oversize and power limitation problems for Multiple Input Multiple Output(MIMO)technology which is used to improve angle resolution,this dissertation proposes a low complexity method of diversity phased array in horizontal direction.Firstly,it adopts diversity phased array in horizontal direction.At the transmitting end it conductes beam scanning to coverage the detection area;at the receiving end by using Discrete Fourier Transform(DFT)it realizes the space beamforming.After the transmitter-receiver synthesis,the angular resolution is the same as virtual aperture of MIMO radar.Secondly,according to the number of transmitting channels,the digit of phase shifter and the number of scanning beats are designed to cover the whole horizontal detection area.Finally,by comparing the performance with the existing phased array radar and MIMO radar,it is proved that this method has higher angular resolution than phased array radar and better anti-noise performance than MIMO radar.2.When it comes to the beam scheduling it is not flexible for diversity phased millimeter wave radar to realize 3D Angle measurement.This dissertation proposes a method to combinate diversity phased array(horizontal direction)and MIMO(pitching direction)in antenna disposal and signal processing area.To maintain the advantage of beam scheduling flexibility for MIMO,a three-dimensional radar combining algorithm of diversity phase array and MIMO is designed.The virtual receiving aperture is formed by using the pitching MIMO transmitting array,so as to realize the function of pitching angle measurement without increasing the receiving array elements.Secondly,the radar operation timing sequence is designed to realize the joint measurement of radar azimuth and pitch angle for the diversity phase control and MIMO combination.Finally,by performance comparison with existing sparse distribution radar,it is verified that the proposed method can effectively avoid false alarm caused by azimuth sidelobe elevation and the pitch angle measurement error caused by targets aliasing.3.For polyphase filter banks it can’t meet the optimal sampling rate and the minimum channel bandwidth requirements simultaneously.This dissertation puts forward a method of channelized receiver for polyphase filter banks based on the embedded resampling.Firstly,under the premise of given input signal and sub-channel bandwidth,the time-varying shift deviator is introduced to the input signal to change the sub-channel sampling rate,thus decoupling the relationship between sub-channel bandwidth and sampling rate,achieving the purpose of optimal sampling.Secondly,in order to realize the resampling filter the time-varying shift deviator is embedded into the polyphase filter bank channelized receiver by window sliding and output inverting for the filter data of the receiver,so as to realize the channelized receiver using polyphase filter banks based on the embedded resampling.Finally,by comparison with the results between conventional polyphase filter banks,it is verified that the variable resampling can effectively avoid the interpolation error of the symbol recovery.4.In view of the broadcasting way for routing packet exchange in wireless mobile network,it easily causes packets lossing problem.This dissertation proposes the time division multiple access routing protocol(TDRP)based on cluster head coordination.Firstly it proposes a multiple access protocol based on super frame structure.Under the manage span of the super frame it uses TDMA for routing information exchanging;and under the data span of the super frame it uses CSMA/CA for data exchanging.Secondly,in order to control the media resources occupied by routing information it designs the nodes login and logout process.So the cluster head only distributes time slots for the nodes which have already joined the network successfully.Thirdly,to reduce the transmission delay,cluster members take the interaction of two-hop routing information between adjacent nodes.So all nodes can get the three-hop routing table steadily.Meanwhile the cluster head can get the complete routing table by the interaction of manage frame.Finally,through comparison with cluster-based life-time routing(CBLTR)routing protocols,the performance improvement of the proposed method in average delay and average transmission efficiency is proved.Among this four innovative points,the innovation points 1 and 2 for millimeter wave radar in 2D and 3D sensing technology,they belongs to sensor information acquisition for special vehicle advanced driver assistance system.The innovation points 3 and 4 for channelized receiver and Vehicle Ad Hoc,they belongs sensor information transmission for special vehicle advanced driver assistance system.The four innovation points combined with each other realize the perception and interaction of the special formation thus enabling the vehicles to obtain complete environmental information. |
