Auto steering systemAbstract: With the rapid development of electronic technology, people on the vehicle steering control performance of more and more high. Wire control steering system will be the trend of the development of automobile steering system. Normally according to mechanical steering gear form can be divided into: super-modulus gear type, circulation ball type, worm wheel type, worm gear and worm refers to pin type. The increase of vehicle weight and people to the improvement of vehicle handling performance requirements, simple mechanical steering system can not meet needs, power steering system came into being, it can in the pilot turned the steering wheel and at the same time provide power, power steering system is divided into hydraulic steering system and electric steering system 2 kinds. Hydraulic steering system which is the most widely used steering system.Hydraulic steering system is the basis of the mechanical system increases the system, including hydraulic pump, v-shaped belt wheel, oil injection equipment, power devices and control valves. With the help of the automobile engine driving hydraulic pump, air compressor and generator etc, in order to hydraulic, pneumatic or electric power increases the power of the front wheel steering the pilot control to make drivers can light the flexibility to manipulate car turned, reduce labor intensity, improve the driving safety.Electric power steering system is now the development direction of car steering system, its working principle is: EPS system to the ECU from steering wheel torque sensor and speed sensor signal analysis, control motor to produce the proper power torque, assist drivers finish to the operation.Key words: Wire control steering system Hydraulic steering system Electric power steering system sensor Along with automobile electronic technology swift and violent development, the people also day by day enhance to the motor turning handling quality request. The motor turning system changed, the hydraulic pressure boost from the traditional machinery changes (Hydraulic Power Steering, is called HPS), the electrically controlled hydraulic pressure boost changes (Elect ric Hydraulic Power Steering, is called EHPS), develops the electrically operated boost steering system (Elect ric Power Steering, is called EPS), finally also will transit to the line controls the steering system (Steer By Wire, will be called SBW).The machinery steering system is refers by pilots physical strength achievement changes the energy, in which all power transmission all is mechanical, the automobile changes the movement is operates the steering wheel by the pilot, transmits through the diverter and a series of members changes the wheel to realize. The mechanical steering system by changes the control mechanism, the diverter and major part changes the gearing 3 to be composed.Usually may divide into according to the mechanical diverter form: The gear rack type, follows round the world -like, the worm bearing adjuster hoop type, the worm bearing adjuster refers sells the type. Is the gear rack type and follows using the broadest two kinds round the world -like (uses in needing time big steering force).In follows round the world -like in the diverter, the input changes the circle and the output steering arm pivot angle is proportional; In the gear rack type diverter, the input changes the turn and the output rack displacement is proportional. Follows round the world -like the diverter because is the rolling friction form, thus the transmission efficiency is very high, the ease of operation also the service life are long, moreover bearing capacity, therefore widely applies on the truck. The gear rack type diverter with follows round the world -like compares, the most major characteristic is the rigidity is big, the structure compact weight is light, also the cost is low. Because this way passes on easily by the wheel the reacting force to the steering wheel, therefore has to the pavement behavior response keen merit, but simultaneously also easy to have phenomena and so on goon and oscillation, also its load bearing efficiency relative weak, therefore mainly applies on the compact car and the pickup truck, at present the majority of low end passenger vehicle uses is the gear rack type machinery steering system. Along with the vehicles carrying capacity increase as well as the people to the vehicles handling quality request enhancement, the simple mechanical type steering system were already unable to meet the needs, the power steering system arise at the historic moment, it could rotate the steering wheel while the pilot to provide the boost, the power steering system divides into the hydraulic pressure steering system and the electrically operated steering system two kinds.Hydraulic pressure steering system is at present uses the most widespread steering system.The hydraulic pressure steering system increased the hydraulic system in the