| 摘要 |
An active front-wheel steering device of a vehicle and a control method thereof are provided to cut down the production cost by omitting the existing output angle sensor, receiving signals from a motor position sensor installed at an auxiliary power mechanism, and regulating a gear ratio changing unit through an electronic control unit. An active front-wheel steering device of a vehicle comprises a steering shaft(103) connected with a steering wheel(101) of the vehicle; a steering column(105) surrounding the steering shaft; a rack-pinion mechanism unit(121) converting rotation of the steering shaft into linear movement of a rack bar(119); a vehicle speed sensor(117) detecting speed of the vehicle; a gear ratio changing unit(109) connected with the lower end of the steering shaft; a first motor(111) driving the gear ratio changing unit; a second motor(123) for supplying auxiliary steering power to the rack bar; an input angle sensor(107) detecting size of input angle by rotation of the steering shaft; a motor position sensor(401) installed at the second motor; and an electronic control unit(125) setting a proper steering gear ratio by inputting condition of the vehicle and regulating the first motor after receiving input angle signals from the input angle sensor to place a difference between a result of the input angle multiplied by the desired steering gear ratio and output angle caused by the motor position signals in a predetermined range.
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