Method of managing assisted steering with indirect reconstruction of the steering wheel torque information

A method of managing a power steering device for a vehicle, said power steering device comprising a steering wheel which allows a driver to maneuver said power steering device by exerting a force, called «steering wheel torque», on said steering wheel, as well as an assist motor intended to provide an assist force to assist the maneuver of said power steering device said method being characterized in that it comprises a step (a) of reconstructing a steering wheel torque during which the steering wheel torque is evaluated, as it is actually exerted by the driver on the steering wheel, by reconstructing a representative information of said steering wheel torque, called «estimated steering wheel torque», from data called «external data»which are collected within the power steering device or within the vehicle, but excluding a steering wheel torque sensor specifically dedicated to measuring of said steering wheel torque, said external data comprising a value called steering wheel angle»representative of the angular position of the steering wheel, a value called «motor angle»representative of the angular position of the shaft of the assist motor, as well as the time derivatives of said steering wheel angle and said motor angle and in that, at step (a) of reconstructing a steering wheel torque, on the one hand, a value called «steering wheel angle»representative of the angular position of the steering wheel, and on the other hand, a value called motor angle»representative of the angular position of the shaft of the assist motor are collected as external data, the difference, called «relative displacement», between the steering wheel angle and the motor angle is calculated, then the relative displacement is multiplied by a predetermined stiffness coefficient, so as to obtain a first component of the estimated steering wheel angle, called «stiffness term».