Design Of Steer By Wire Control System Based On Flexray Bus

Steering system as an important component of the automotive chassis has directinfluence on handing stability and security of the whole vehicle. Although steeringsystem has got rapid development in recent years, but it still can’t get rid of thetraditional mechanic structure, limit the further development of vehicle performance.So all the people hope that the steer by wire technology can be used in steering system,realize free design of force transfer characteristic and angle transfer characteristic.If this technology is applied into the steering system, electronic signals willbecome the only medium between the driver and the vehicle. If broken out occurred,the vehicle will fall into out of control condition completely, set the driver in a verydangerous circumstance, therefore put much higher demand on the security of steer bywire system. In order to approach the real condition as far as possible, enhance thesimulation precision, the usual way now is embed the measured element in Hard inLoop System.Taking into full consideration such factors as cost and laboratoryconditon, the author utilizes Carsim RT and Labview RT from NI to constructHardware-in-Loop system.As the pivot of Steer-by-Wire system, it determines the performance of the wholesystem and the improvement on the vehicle. The control system of steer by wire wasconstructed by steering manipulation module and the steering execution module. Ifsteer by wire want to be applied in real vehicle, realize industrialization, then thetransfer bus between two control nodes must has characters such as high speed goodcertainty and punctuality.Complete the hardware and software design of the control system based onFlexRay bus in this paper. In hardware design, choose the MC9S12XF512fromFreescale as main processor which integrated FlexRay communication controller andCAN communication controller at the same time, so respectively design the controlsystem based on FlexRay and CAN, the transceiver choose TJA1080A and TJA1040from NXP and complete the circuit design too.The double lane change condition can reflect the influence that steering systemput on handing stability well, let the designed control steer by wire system finis h thispath in the Hard in Loop. Compared the FlexRay-based scheme with the CAN-basedscheme, it is found that the former is closer to the reference value, while the latter is featured by response lag and big overshoot and thus can’t meet the requirementsCompare the steer by wire based on FlexRay with the module applied traditionalsteering system in Carsim, find that the handing stability was improved, the burden ondriver was relieved, the designed purposed was reached after employing the steer bywire based on FlexRay.