Research On The Control Strategy Of Steering-by-Wire System Matching With The Whole Car

Along with people to car safety, comfortable, economy of continuously pursue, automotive steer-by-wire system is commonly considered as the next generation automotive steering system. Since the mechanical connection between the steering wheel and the turning vehicle wheel are eliminated definitely, automotive steer-by-wire system get rid of limitation of tradition steering system, which can not only design force transfer trait freely, but design angle transfer trait for vehicle steering. Automotive steer-by-wire system is a important innovation which bring infinity design space for automotive steering system.This paper firstly introduces the development process of steer-by-wire system, as well as the structure and the key technologies. Then the safety and dependability of the steer-by-wire system is analyzed, a hard and soft architecture suitable for the system is presented.In chapter three, the tire side-slip character is analyzed as well as the two-freedom steering vehicle was modeled, then the tire self-aligning torque can be estimated. We give this information to the driver to get the road condition. Vehicle yaw rate control for steer-by-wire system with unexpected disturbance observe of the steering wheel is studied, some simulations are carried out.In chapter four, the vehicle yaw-rate is set as the controlling aim, we study the control FUZZY strategy. First we carried on the simple fuzzy controller the design, then proposed one kind of parameter self regulating Fuzzy - PI control used by steering-by-wire. We affected it on the automobile dynamics model which established in the third chapter. The hypothesis automobile moving velocity, carries on the simulation to the automobile common operating mode, obtained the simulation result chart, after the analysis compares has joined the self regulating to decide the fuzzy -PI control strategy, spread horizontally the angular speed and between the steering wheel corner can maintain the vehicles system ideally to spread horizontally the angular speed gain value this proportional relationship well, caused the vehicles the controllability enhancement, further enhanced the vehicles the initiative security.In chapter five, we propose the virtual design method of the steer-by-wire system, the characters of the virtual design are described, also the application of the virtual design is presented on the steer-by-wire system. At the end, we analyzed the human -vehicle - road closed loop simulation system and the key technologies under the virtual design environment.Finally, we sums up above contents, it proceeds to analyze and discuss for some problems and places that need the further improvements.